Installing your own central heating
Daljit
installing my own gas central heating system. Now before CORGI or
anyone else for that matter gets upset, i should explain that i am
only planning to install the water pipes and hire a gas fitter to
connect and commission the boiler. I do plan to mount the boiler and
flue. Also, although there is quite a lot of techie stuff about
valves, wiring and ports on diyfaq.org.uk, there's little for the
amateur to hold on to. Basically, i need reassurance as much as
advice.
Before my questions/issues, some background. I have a one bedroom
flat that currently has a CW cistern (top of the hall cupboard) and a
HW cylnder a couple of feet off the floor in the kitchen. I plan to
install a combi boiler with 4 radiators on a sealed sytem and do away
with the noisey tank in the cupboard.
1. I'm planning to go for a Vaillant Turbomax 828E that's costing me
£744 (inc VAT) - does anyone know of a better price?
2. I expect that the boiler's instructions will tell me, but does
anyone know if i wll need an external expansion vessel with this
boiler?
3. The various formulas i've used to calc. radiator sizes required,
vary wildly - has anyone else found this? What's the solution?
4. What is the best method of cutting floor joists to lay piping under
floorboards?
5. I have never in my life soldered a joint. Yet , i plan to use
copper piping with capilliary fittings - am I being way too ambitious
in my plans?
All views appreciated.
Daljit
Andy Hall
"Daljit" <d...@mishnish.freeserve.co.uk> wrote in message
news:ecafca31.02072...@posting.google.com...
>
> Before my questions/issues, some background. I have a one bedroom
> flat that currently has a CW cistern (top of the hall cupboard) and a
> HW cylnder a couple of feet off the floor in the kitchen. I plan to
> install a combi boiler with 4 radiators on a sealed sytem and do away
> with the noisey tank in the cupboard.
>
> 1. I'm planning to go for a Vaillant Turbomax 828E that's costing me
> Ł744 (inc VAT) - does anyone know of a better price?
Ł10 less from www.discountedheating.co.uk but check regarding delivery costs
etc.
Depending on the size of the flat, it might be a bit too large, but you will
have to calculate. This one modulates down
to 10kW but will cut off below that.
>
> 2. I expect that the boiler's instructions will tell me, but does
> anyone know if i wll need an external expansion vessel with this
> boiler?
>
The data sheet does not say one is included in this boiler, whereas it does
for others in their range.
Either way you do need to have one in the system. The size depends on the
water content of the system,
which will mainly be in the radiators unless the pipe runs are very long.
Radiator manufacturer's data sheets have water capacities per section for
each radiator type and then you multiply by the number in your chosen size.
Expansion vessel manufacturers then have vessels suitable for systems up to
certain water contents so you pick from there - if there isn't one in the
boiler of course.
> 3. The various formulas i've used to calc. radiator sizes required,
> vary wildly - has anyone else found this? What's the solution?
>
The ready reckoner ideas usually make assumptions about the property and the
temperatures to try and simplify the process. I have never found them
accurate, and after checking properly found them to be up to 50% out either
way. Some of them have incorrect thermal factors used (U values). Others
don't factor in any heat transfer between rooms which can be significant.
The rigorous way would be to draw a sketch of the place and dimension it in
metres, including window dimensions and indicating which are inside and
outside walls (or part each sometimes). You will need room heights as well.
Mark the desired room temperatures on the sketch.
You can then calculate the heat loss for each surface by taking the U-value
and multiplying by the area and again by the temperature difference. It
is conventional these days to assume an outside worst case temperature of -3
degrees. So for example, if an outside wall is 5m long, 3m high and has a U
value of 0.5 then if the desired inside temperature is 21 degrees you have
a 24 degree temperature difference. The heat loss in watts will be 5 * 3 *
0.5 * 24 = 180 watts.
You repeat this for each surface including floor and ceiling. If you are
calculating for an internal wall and the adjacent room is at a higher
temperature, you will have a heat gain, so the number obtained should really
be subtracted from the heat losses for the room - more in a moment on that.
Finally you calculate a heat requirement for warming the air in the room.
This is done by multiplying the volume of the room by 0.33 and by the number
of air changes per hour. Standard numbers for this are 1.0 for a bedroom,
1.5 for a living room and 2.0 for a hall and 3.0 for a bathroom or shower.
You can plug in different ones if you think the rooms will be more or less
well sealed than average. Add these together for each room and you will
have the total heat loss which is your basis for radiator sizing.
The important thing is to check that the U values used are correct for the
surfaces. You can get a fairly comprehensive set from the Building
Regulations part L which are published on their website under the auspices
of the Office of the Deputy Prime Minister. (What John Prescott knows about
the subject I'm not sure :-).
You can also download them from radiator manufacturer's web sites. Myson
and Barlo have quite good calculating software, where you can plug in your
numbers and they do the sums for you. Myson's program is a bit easier to
use but it does not account for heat gains from warmer adjoining rooms -
just rounds them to zero. The Barlo one does the correct calculation.
Whether you care about taking heat gains into account depends on the layout
of the property. If you had a conventional two storey house and work on the
basis of all rooms on a floor being at the same temperature then it doesn't
matter anyway. You might take into account heat gains in a bedroom due to a
warm living room below though. On the other hand, if you have a bedroom
witha long wall adjoining a living room and you want them to be at 16
degrees and 21 degrees respectively, the heat gain in the bedroom may well
allow you to use a smaller radiator.
In the case of a flat you may want to be more careful and allow for more
flexibility. For example if the bedroom gets used as a study as well then
treating it as a living room may be the right thing to do.
Radiator manufacturer's data sheets now quote output according to a
Euronorme (EN) standard which assumes a higher average water to air
temperature than is standard in the UK. Therefore you have to apply a
correction factor to get the correct sizing.
The data sheet figures will assume an average water to air temperature of 60
degrees. On a UK system with a flow temperature of 82 degrees and return
of 70, the average water temperature is 76 degrees, and for the water/air
temperature will be 55 degrees ( to a 21 degree room). For most
radiators, the correction factor is 0.9, so let's say you calculate 2kW of
heat loss, you divide that by 0.9 to give the radiator size of 2.2kW.
Then select the next size up from the manufacturer's data.
> 4. What is the best method of cutting floor joists to lay piping under
> floorboards?
the conventional way is to notch them with a saw and chisel, and then to put
some felt or other packing around the pipes to avoind them binding and
clicking as they expand.
>
> 5. I have never in my life soldered a joint. Yet , i plan to use
> copper piping with capilliary fittings - am I being way too ambitious
> in my plans?
>
No, I don't think so. Before I did my first system many years ago, I bought
some fittings and a length of pipe
and did a load of trial joints - elbows, tees and so on. I practiced a
little and soon got the idea. One important thing is to get the joint hot
as quickly as possible, remove the flame and then don't disturb the joint
until it cools a bit.
I made up an array of pipes and then put caps on the ends and filled it with
water. Then I applied a hose to one remaining open connection and hooked it
up to a tap to apply some pressure. There were no leaks and I felt ready to
go.
It's important to have a decent torch that can deliver an adequately sized
flame to warm the joint quickly, and don't forget at least one heat-proof
mat.
Do leave the joints all visible until you have filled and applied pressure
to the system.
.andy
Lee Blaver
> <snip lots of useful stuff)
>
> Do leave the joints all visible until you have filled and applied pressure
> to the system.
>
> .andy
And until the system is up to temperature as well, some joints that don't leak
when cold
can do when hot ...
Lee
Rick Dipper
outset to work some stuff out.
Then get him to do the boiler bits at the end, and maybe fix the odd
leak. You WILL have leeks, some are easy to fix, some turn into real big
problems.
I fitted a whole heating system, having never done any thing like it before.
Before you get him in, work out your pipe runs, with a block of chalk
mark up the floor. WOrk out if you want a cylinder or not, work out wear
the boiler, and header tank, if needed go.
Having an empty house helps, cause you need access to all the joints
when you fill up, so you can work out which ones are leaking.
You also need to make friends at the plumbers merchant, some will even
do lessons and design work with you.
Oh, and it will take you ages to do a neat job, the 2 day fits british
gas do have pipes tacked to walls and skirting borads, which you don't want.
Rick
Jim Arnold
wrote:
>I have limited plumbing experience but am keen on the idea of
>installing my own gas central heating system. Now before CORGI or
>anyone else for that matter gets upset, i should explain that i am
>only planning to install the water pipes and hire a gas fitter to
>connect and commission the boiler. I do plan to mount the boiler and
>flue. Also, although there is quite a lot of techie stuff about
>valves, wiring and ports on diyfaq.org.uk, there's little for the
>amateur to hold on to. Basically, i need reassurance as much as
>advice.
>
>Before my questions/issues, some background. I have a one bedroom
>flat that currently has a CW cistern (top of the hall cupboard) and a
>HW cylnder a couple of feet off the floor in the kitchen. I plan to
>install a combi boiler with 4 radiators on a sealed sytem and do away
>with the noisey tank in the cupboard.
>
>1. I'm planning to go for a Vaillant Turbomax 828E that's costing me
>£744 (inc VAT) - does anyone know of a better price?
>
>2. I expect that the boiler's instructions will tell me, but does
>anyone know if i wll need an external expansion vessel with this
>boiler?
>
>3. The various formulas i've used to calc. radiator sizes required,
>vary wildly - has anyone else found this? What's the solution?
sounds like it may be more than powerful enouigh
>
>4. What is the best method of cutting floor joists to lay piping under
>floorboards?
Notch them fit a plate over if you are nervous - Are your boards
plain or tongue & grooved
Which way do the joist run ?
>
>5. I have never in my life soldered a joint. Yet , i plan to use
>copper piping with capilliary fittings - am I being way too ambitious
>in my plans?
>
Avoid end feed they require skill - 'Yorkshire' type are easy except
28 mm which require a lot of heat
use a pipe curtter not a hacksaw to get nice clean ends Clean up the
ends. I used Wickes flux.
Make sure you have a good circle of solder arounmd each joint, Think
about your pipe runs always try and solder all the bits of a joint
together.
I never had a bad joint except the 28mm from boiler to 3 way vavle - I
didn;t fit a combi
don't forget the electrical connections to the boiler you need a
dedicated circuit
fit TRVs
>All views appreciated.
>
>Daljit
Dave
> dedicated circuit
Do you mean a dedicated circuit from the consumer unit?
I was under the impression that all you needed was a FCU (or even a
plug) on the ring!
Dave
Daljit
> On 20 Jul 2002 03:44:07 -0700, d...@mishnish.freeserve.co.uk (Daljit)
> wrote:
>
> >4. What is the best method of cutting floor joists to lay piping under
> >floorboards?
>
> Notch them fit a plate over if you are nervous - Are your boards
> plain or tongue & grooved
>
> Which way do the joist run ?
>
I don't quite follow... a plate?
Other than half the kitchen, the flat's got varnished floorboards thru
out. So lifting them as carefully as poss is pretty important (and
partly the reason i've chosen to install my own CH). The floorboards
are tongue & grooved.
Andy Hall
"Daljit" <d...@mishnish.freeserve.co.uk> wrote in message
news:ecafca31.02072...@posting.google.com...
You can buy steel plates that can be fitted over the pipes where they are
going through a notch in the joist.
The idea is so that you will not be able to easily drive a screw or nail
through, and therefore afford the pipes some protection.
.andy
Daljit
the following.
I'm now ready to place my order for a gas central heating system.
Just to recap, I'm fitting a combi boiler (NG) in a one bedroom flat,
on a sealed system. I will be ordering the following (from
discountedheating.co.uk):
1 Vaillant Turbomax Plus 828
RSF 800mm Std Flue Kit
1 Danfos TP5 programmable room thermostat
4 radiators: Stelrad Compacts (2 x K2, 1 x K1, 1x P+)
3 TRVs
22mm & 15 mm copper piping
assortment of capilliary fittings
1 stop valve
1 gate valve
I'm not sure if I should order a pump or expansion vessel at the
moment - was planning to read the boiler instructions first.
I'm not quite sure why I'm going for the Stelrad 'Compact' - they're
more expensive than their 'Savanna Compact' or 'Elite' range but
cheaper than anything Myson produce. In terms of output, there's
hardly any difference. Somebody did mention that the 'Compact' were
lighter and therefore more expensive.
One concern I do have is that the Vaillant 828 modulates itself (is
that the right term?) to cope with CH output varying between 35 -
95,000BTU. However, the combined output of my 4 radiators is only
28,000 BTU - my flat's that wee. The reason I'm going for the 828
model is cos I want a decent HW flow rate (more for showers than
baths, about 80:20 I guess). Although I don't mind waiting for a bath
to fill, I definitely want a decent shower.
Other things I'm not sure about is the need for and application of:
- isolating valves
- drain valve
- air separator or air-vent valves (if there is such a thing)
Your comments will be much appreciated.
thanks
Daljit
Dave Plowman
Jim Arnold <jim.a...@tesco.net> wrote:
> >5. I have never in my life soldered a joint. Yet , i plan to use
> >copper piping with capilliary fittings - am I being way too ambitious
> >in my plans?
> >
> Avoid end feed they require skill - 'Yorkshire' type are easy except
> 28 mm which require a lot of heat
Sorry but that's crap. They *both* require some skill, but end feed are so
much cheaper (and neater) it's worth practising first. It's perfectly
possible to make a mess of a Yorkshire joint as well - especially if you
can't see round the back. With an end feed type it's obvious when that
part is hot enough because you'll see 'your' solder melting.
--
* Bills travel through the mail at twice the speed of cheques *
Dave Plowman dave....@argonet.co.uk London SW 12
RIP Acorn
Andy Hall
> Many, many thanks for the advice posted above. Please do comment on
> the following.
>
> I'm now ready to place my order for a gas central heating system.
> Just to recap, I'm fitting a combi boiler (NG) in a one bedroom flat,
> on a sealed system. I will be ordering the following (from
> discountedheating.co.uk):
>
> 1 Vaillant Turbomax Plus 828
> RSF 800mm Std Flue Kit
> 1 Danfos TP5 programmable room thermostat
> 4 radiators: Stelrad Compacts (2 x K2, 1 x K1, 1x P+)
> 3 TRVs
> 22mm & 15 mm copper piping
> assortment of capilliary fittings
> 1 stop valve
> 1 gate valve
>
> I'm not sure if I should order a pump or expansion vessel at the
> moment - was planning to read the boiler instructions first.
Makes sense.
>
> I'm not quite sure why I'm going for the Stelrad 'Compact' - they're
> more expensive than their 'Savanna Compact' or 'Elite' range but
> cheaper than anything Myson produce. In terms of output, there's
> hardly any difference. Somebody did mention that the 'Compact' were
> lighter and therefore more expensive.
>
> One concern I do have is that the Vaillant 828 modulates itself (is
> that the right term?) to cope with CH output varying between 35 -
> 95,000BTU. However, the combined output of my 4 radiators is only
> 28,000 BTU - my flat's that wee. The reason I'm going for the 828
> model is cos I want a decent HW flow rate (more for showers than
> baths, about 80:20 I guess). Although I don't mind waiting for a bath
> to fill, I definitely want a decent shower.
The boiler will simply turn off at times when the heat demand is too low
(i.e. below
modulating range) and come back on when needed.
>
> Other things I'm not sure about is the need for and application of:
> - isolating valves
Generally on the boiler water connections but take the advice of boiler
manufacturer.
> - drain valve
If radiators are being piped from below then one is really enough as they
will naturally drain.
If from above, then put a drain at each low point so that you can drain that
section of the system.
> - air separator or air-vent valves (if there is such a thing)
You shouldn't need an air separator in a sealed system. A decent automatic
air vent (e.g. Honeywell) at any high points is useful for getting the
initial air out of the system.
.andy
Ed Sirett
The boiler already contains everything you need, including filling loop,
expansion vessel, pump, isolating valves.
You will need to add drain point(s) to the CH circuit.
The boiler already contains auto air bleed valves.
I strongly recommend you install/upgrade the shower/bath mixer to a
thermostatic one.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
cetltd
<d...@mishnish.freeserve.co.uk> writes
>Many, many thanks for the advice posted above. Please do comment on
>the following.
>
>I'm now ready to place my order for a gas central heating system.
>Just to recap, I'm fitting a combi boiler (NG) in a one bedroom flat,
>on a sealed system. I will be ordering the following (from
>discountedheating.co.uk):
>
>1 Vaillant Turbomax Plus 828
>RSF 800mm Std Flue Kit
>1 Danfos TP5 programmable room thermostat
>4 radiators: Stelrad Compacts (2 x K2, 1 x K1, 1x P+)
>3 TRVs
>22mm & 15 mm copper piping
>assortment of capilliary fittings
>1 stop valve
>1 gate valve
>
>I'm not sure if I should order a pump or expansion vessel at the
>moment - was planning to read the boiler instructions first.
>
--
raden
Daljit
<Ja...@tortshel.demon.co.uk> writes
>My partner and I have been installing a central heating system. It's
the
>simplest layout: just a combi boiler and radiators connected by
pipes.
>We've just finished the pipework and hit a snag. The instructions for
>the boiler say that we should clean out the pipework before
connecting
>the boiler to it. Now all the books we've read that mention the
subject
>say that you should leave the central heating cleaning fluid in the
>pipework for a week with the boiler running. So how do we clean the
>pipework properly before we connect it to the boiler?
>
>Does anyone here have any experience of installing this kind of
system?
>selves a get-out in the event of a warranty claim.
>However, in the case you describe, a good flushing with clean water
is
>all that is required.
>Using hoses, jubilee clips and other paraphanerlia <sp?> send water
in
>through the flow pipe to the central heating and run the water
issuing
>from the return to waste. Turn on each radiator in turn so that you
can
>be sure that the flushing water went through each part of the
circuit.
>After getting the heating running it would be a good idea to drain
down
>once more while the water is hot. Then refill, with an inhibitor if
>required.
>I do not think the use of a chemical cleaner as you envisage is
required
>on this new system.
>The mains cold feed to the boiler can of course be simply run into a
>bucket to flush it out.
>--
>Richard Gethin
Re the above. Where would you attach the hoses to? I'm planning to
fix a drain valve a couple of inches from the floor beneath the boiler
on the return pipe, so this of course could be the exit point for a
hose-flush. But where would you connect the entry side of a hose?
Also, thinking ahead, if i wanted to repeat this operation in a few
year time to get rid of the build up of sludge, would it not make
sense to fix some kind of entry point (another drain valve?) on the
flow pipe too?
thanks in advance
Daljit
Andy Hall
> In article <vee19DAl...@tortshel.demon.co.uk>, Jane Carlton
>
> Re the above. Where would you attach the hoses to? I'm planning to
> fix a drain valve a couple of inches from the floor beneath the boiler
> on the return pipe, so this of course could be the exit point for a
> hose-flush. But where would you connect the entry side of a hose?
Depending on the location of the connections, it could be the feed tank if
you are going open vented or
the filling loop if sealed.
> Also, thinking ahead, if i wanted to repeat this operation in a few
> year time to get rid of the build up of sludge, would it not make
> sense to fix some kind of entry point (another drain valve?) on the
> flow pipe too?
You could do - it depends on the layout. If you use and maintain
inhibitor you should not have any notable sludge anyway.
.andy
Daljit
Can someone tell me if it would ok to run just one 22mm HW pipe to my
bathroom for the bath (22mm), basin (15mm) and shower from a combi
unit? I'm not planning to plumb the shower in at the moment - i'll
stick to the electric one i have until the dust settles on this job
and i've worked out the pros and cons of different thermostatic
mixers. But when i do decide to connect the shower to the new system,
will it be ok just to tee off (with a 15mm pipe) from this single pipe
or does it need a run of its own?
thanks
Daljit
Dave Plowman
Daljit <d...@mishnish.freeserve.co.uk> wrote:
> Re the above. Where would you attach the hoses to? I'm planning to
> fix a drain valve a couple of inches from the floor beneath the boiler
> on the return pipe, so this of course could be the exit point for a
> hose-flush. But where would you connect the entry side of a hose?
> Also, thinking ahead, if i wanted to repeat this operation in a few
> year time to get rid of the build up of sludge, would it not make
> sense to fix some kind of entry point (another drain valve?) on the
> flow pipe too?
If you use the correct inhibitor, there won't be any sludge to speak of.
Sludge is usually the interiors of the steel radatiors corroding away.
Don't think you really want this.
--
*How can I miss you if you won't go away?
Alan James
"Daljit" <d...@mishnish.freeserve.co.uk> wrote in message
news:ecafca31.02081...@posting.google.com...
>
> Can someone tell me if it would ok to run just one 22mm HW pipe to my
> bathroom for the bath (22mm), basin (15mm) and shower from a combi
> unit?
I would suggest that you just run a single 15mm HW pipe. This is more than
adequate for the combi HW delivery. Unless your bathroom is very close to
the combi you will find that the delay in HW to the basin is an annoying
problem. If you run 22mm the delay doubles. Its not such a problem for the
bath because the fill time is longer. Tee off as much as you like as long
as there is only going to be one use of HW at a time.
Alan
Daljit
> I would suggest that you just run a single 15mm HW pipe. This is more than
> adequate for the combi HW delivery. Unless your bathroom is very close to
> the combi you will find that the delay in HW to the basin is an annoying
> problem. If you run 22mm the delay doubles.
Thanks for that Alan - it certainly makes sense. However, can someone
out there confirm Alan's right before i go ahead and do it? You see
there's already a 22mm HW pipe there from the old system that i was
hoping to use. And won't a 15mm pipe make running a bath considerably
longer?
I guess what i'm looking for is for someone to say stick with the 22mm
just so i can save myself some extra work!
cheers
Daljit
Andy Hall
He is, the question is whether you care or not.
There are several factors.
You can calculate how long it will take for hot water to come through by
measuring the flow rate (time how long to fill a 10litre bucket for example)
and then calculate from the pipe size and length. 15mm pipe holds 0.145
litres/m and 22mm holds 0.320.
The other factor is whether you care about running more than one tap at a
time. For example if you had a shower and ran that in 15mm branched from
the 22mm to the bath, hot to the shower will drop off substantially. If
everything were 15mm run from near the boiler there would at least be
equality. Roughly.
If you care only about sharing the flow reasonably between multiple taps
running, then you could put something like a lever ball valve or flow
restriction device in the 22mm to the bath to cut it down. However, that
would make the time to getting hot water even longer.
.andy
International Man of Mystery
> "Alan James" <alanREMOVE...@hotmail.com> wrote in message
news:<3d60...@212.67.96.135>...
>
> > I would suggest that you just run a single 15mm HW pipe. This is more
than
> > adequate for the combi HW delivery. Unless your bathroom is very close
to
> > the combi you will find that the delay in HW to the basin is an annoying
> > problem. If you run 22mm the delay doubles.
>
> Thanks for that Alan - it certainly makes sense.
> However, can someone
> out there confirm Alan's right before i go
> ahead and do it?
Depends on the combi flowrate. A two bathroom job needs 22mm.
> You see there's already a 22mm HW
> pipe there from the old system that i was
> hoping to use. And won't a 15mm pipe
> make running a bath considerably
> longer?
Depends on the combi flowrate. If a small combi od 10-13 litres/min then
15mm is generally fine.
> I guess what i'm looking for is for someone
> to say stick with the 22mm
> just so i can save myself some extra work!
You can, as Alan says, the delay is getting hot water to the taps will be
longer. Your choice.
Daljit
> Depends on the combi flowrate. If a small combi od 10-13 litres/min then
> 15mm is generally fine.
>
> > I guess what i'm looking for is for someone
> > to say stick with the 22mm
> > just so i can save myself some extra work!
>
> You can, as Alan says, the delay is getting hot water to the taps will be
> longer. Your choice.
Okay, i'm well and truly convinced it's the right thing to do. Thanks.
Daljit
Geoff Williams
> In article <ecafca31.02081...@posting.google.com>,
> Daljit <d...@mishnish.freeserve.co.uk> wrote:
> > Re the above. Where would you attach the hoses to? I'm planning to
> > fix a drain valve a couple of inches from the floor beneath the boiler
> > on the return pipe, so this of course could be the exit point for a
> > hose-flush. But where would you connect the entry side of a hose?
> > Also, thinking ahead, if i wanted to repeat this operation in a few
> > year time to get rid of the build up of sludge, would it not make
> > sense to fix some kind of entry point (another drain valve?) on the
> > flow pipe too?
>
> If you use the correct inhibitor, there won't be any sludge to speak of.
> Sludge is usually the interiors of the steel radatiors corroding away.
> Don't think you really want this.
Don't rely on manufacturers isolating valves (only designed to last
the warranty). Unless the combi is the highest point of the system fit
BS gate valves on the flow and return and a 22mm stopcock on the cold
feed. Also consider using a physical corrosion inhibitor rather than
chemicals - remember combis are junk and end up getting drained down
every few years for repairs and checking expansion vessel pre-charge
(resulting in under-dosing of inhibitor).
Make sure you use decent rad valves (with a seperate gland seal)- all
the imported Italian rubbish leak with the higher pressures of sealed
systems.
Lastly no point in getting a big combi if your incomming mains supply
is low pressure/flow - check flow rates and pressure.
Geoff Williams
Andy Hall
> Daljit <d...@mishnish.freeserve.co.uk> wrote:
> > Re the above. Where would you attach the hoses to? I'm planning to
> > fix a drain valve a couple of inches from the floor beneath the boiler
> > on the return pipe, so this of course could be the exit point for a
> > hose-flush. But where would you connect the entry side of a hose?
> > Also, thinking ahead, if i wanted to repeat this operation in a few
> > year time to get rid of the build up of sludge, would it not make
> > sense to fix some kind of entry point (another drain valve?) on the
> > flow pipe too?
>
> If you use the correct inhibitor, there won't be any sludge to speak of.
> Sludge is usually the interiors of the steel radatiors corroding away.
> Don't think you really want this.
>
Even so, it is worth putting an in-line strainer into the return to the
boiler if it's a low water content one.
I've just been thoroughly cleaning and flushing my (17 year old) system in
preparation for a new boiler. It's had
Fernox in it, regularly maintained, all the time. This has worked well in
that there is no sludge, although when I took the radiators outside and put
the pressure washer through the tappings, there was a brief tinge of brown
in the flushing water.
I connected mains pressure water to the pipework to flush that, on radiator
position at a time. This brought out a range of copper swarf and solder
that was probably there from new when the lazy builders didn't bother to
flush it properly.
I swapped all the radiator lockshield valves as I've been going with Pegler
ones that have a drain point on the radiator side of the valve. One or
two had begun to leak on the existing vented primary system, so I felt sure
that this would become worse as the primary is pressurised for the new
boiler.
.andy
International Man of Mystery
"Andy Hall" <an...@hall.gl> wrote in message news:3d63fe42$1...@nt1.hall.gl...
> for the new boiler.
What boiler make and model?
Andy Hall
"International Man of Mystery" <I...@NOOSSPPAM-IMM.com> wrote in message
.andy
International Man of Mystery
Andy Hall
"International Man of Mystery" <I...@NOOSSPPAM-IMM.com> wrote in message
They are one of the distributors, along with MHS Boilers and I think one or
two others...
The manufacturer is MAN B&W Heiztechnik (part of the same group that make
trucks).
http://www.man-heiztechnik.de/frameset/produkte/frameset6.html
Solidly engineered product, selected after quite a bit of research.
.andy
Andy Wade
> http://www.man-heiztechnik.de/frameset/produkte/frameset6.html
> Solidly engineered product, selected after quite a bit of research.
It must be good, it's 109.5% efficient ;-) (assuming I've understood
"Normnutzungsgrad " correctly).
Seriously though, I'd be interested to hear the reasons for your choice
over more readily available products such as the Keston Celsius or a
Vaillant.
--
Andy
Andy Hall
"Andy Wade" <spamb...@ajwade.clara.co.uk> wrote in message
news:01c24bb9$b49e4760$2d4b08c3@dog40...
Well......
I'll immediately point out that my set of criteria
included issues that are not immediately to do with the boiler but which are
impacted by it - in other words,
other people's mileage will vary. The first bits describe my particular
circumstances and boiler type choice, and then
I've covered vendor choice.
In no particular order of merit:-
1) Overall system and logistics.
The existing system was conventional open vent (CH and DHW) with 120 litre
HW cylinder running two bathrooms. In a house of 2 people and 2 teenagers
this was marginal if both bathrooms are in use.
The airing cupboard housing the DHW cylinder is at the centre of the first
floor, and the boiler in a wall cupboard in the
utiity room. The kitchen and utility room had been remodelled two years
ago and I was not willing to do major surgery to accomodate a boiler - it
had to fit the existing cupboard, which was already oversized for the
ancient Glow Worm that was in it.
The incoming water main delivers about 30 litres/min on a good day, 20
litres on not such a good day.
My performance criterion for the bathrooms was that each shower should be
able to deliver at least 15 litres/min with both bathrooms in simultaneous
use. The existing system delivered that but the hot water volume available
was too small.
These factors together led me to eliminate combi boilers fairly early on
because to achieve an acceptable flow rate, a very
large appliance that would not fit the space would be required. The
pipework from the main to the area of the DHW cylinder and the roof tank
above is in 15mm and the first floor is chipboard flooring. I didn't want
the upheaval of having to lift or carve
up large areas of that to upgrade to 22mm.
For similar reasons, I excluded mains pressure storage of DHW or thermal
store at least for the time being, although I did consider it to be better
than a combi implementation since at least the hot water can be stored at 60
degrees and mixed with cold, whereas a combi is rated at a 35 degree
temperature *increase*. I know that there are combi boilers with water
storage built in, but then the size problem comes back.
I also set aside thermal store as an option because of issues with some
modulating boilers not working properly with them.
The existing system has radiators connected via 8mm microbore fitted behind
the drylined walls. From a heating perspective,
run on a conventional 82/70 degree arrangement it has been adequate (the
house walls are well insulated). Larger rooms have two radiators where
there is a heat requirement of more than 1.5kW (the limit for 8mm tube). I
did not want to perform major surgery on that, except to replace one
radiator in the living room with a larger, double panel finned one. From
that location, I could run 15mm to the area of the boiler quite
unobtrusively. I also wanted to add a radiator for the conservatory and
have it separately zoned.
In the event, I am replacing the DHW cylinder with a 200 litre fast recovery
one, designed for pressurised use but run open vented. That way, if I ever
decide I want to change to mains pressure HW for whatever reason it can be
implemented without changing the cylinder. At the least, the thicker
material will last longer.
2) Boiler type.
The old Glow Worm boiler was "at the end of its useful life" and I had shown
the industry charlatans, British Gas Service (or
whatever A-marketing word they call themselves) the door for non-performance
on the service contract. A new thermocouple and later a thermostat plus
some visual inspection indicated that it was time for a replacement.
In looking for a replacement and talking to a number of contacts in Germany
and Holland, condensing boilers looked interesting from the efficiency point
of view. They have been in use in parts of the rest of Europe for some
considerable time - the UK has tended to lag behind. I looked beyond the
marketing hype and asked a lot of questions of several vendors as to what
would really happen in practice. This was one decision criterion that later
eliminated several manufacturers. I called/emailed manufacturer's technical
departments and several either didn't return calls, were obviously clueless
or didn't want to talk to me since I wasn't a "trade" customer.
It was clear that there were three main factors in condensing boiler
efficiency - condensing mode itself, heat exchanger and burner efficiency
and the control systems. Some manufacturers gave the impression that some
holy grail of efficiency appears the moment that condensing mode happens.
Keston did a good job of explaining that that was not exactly the case and
that efficiency improves *anyway* with falling return temperature - the
*rate* of improvement of efficiency improves with condensing boilers below
the dew point.
While not an out and out environmentalist to the Nth silly degree, if I can
do something that assists the environment (e.g. efficiency/emissions) at
zero or little incremental cost then I will consider it.
Considering boiler lifetime of (say) 20 years and assuming moderate
increases in fuel prices (directly or indirectly) over that period, the
higher capital (and possibly service) cost of a condensing boiler is
probably covered by fuel savings. Having said that, capital cost was not a
major criterion.
3) Vendor Choice.
At the time that I started looking (over a year ago), there were not a very
large number of condensing boilers on the UK market, so I looked also at
what is popular in Germany and Holland as those two countries appear to have
the highest installed bases of condensing units. This made me aware of
vendors such as MAN,Viessmann and Coopra as well as Vaillant.
There were obvious technical factors in addition to those above such as heat
output being adequate but not way oversized.
I did a complete check on heat loss from the house and a heating design from
first principles and discovered that most radiators were adequately sized at
flow/return temperatures of 70/50 degrees. I am replacing two that are
not, although I did have as an initial selection criterion for the boiler
tha tit should be able to operate at 82/70 as well as lower temperatures.
Most of the UK vendors such as Baxi, Ideal,.. either didn't have product,
were new to the market with condensing products, tried to sell me something
else or had poor technical response to questions so were eliminated. It's
a hard criterion, but if a manufacturer can't be bothered to answer
questions then they don't get my business.
Keston was the exception to that and appears to have a good product with the
Celsius 25. I asked several people about them, and also got a favourable
comment from Tony Bryer (frequenter of this NG) who had installed two at his
church. Information from Keston's technical department was good as well.
Vaillant were also quite good on technical response. Sadly, their product
like that of Viessmann, went out on size, although I believe the Ecomax
system boiler was quite new anyway.
One can go on looking for ever and I didn't want to get into really obscure
products with no UK representation.
This basically brought the choice down to Keston and MAN. Keston products
are widely available through the merchants. MAN Heiztechnik products are
sold in the UK through two (possibly more) distributors, Eco-Hometec and MHS
who sell directly with a lot of product going into self build and commercial
applications. I contacted MAN in Bremen who confirmed availability of
spares etc. and answered some questions on the product design.
I wanted to take a look inside the products to see the build quality, so
arranged to see an installed Keston being serviced and went and visited Eco
Hometec in Doncaster. Both products are very well made and would be
acceptable. I suppose I can best describe the difference as between what
you see when you look under the bonnet of a new fleet car and then look in a
BMW; or at a typical washing machine and then a Miele - solid German
engineering.
Smaller factors in the decision for the MAN product were
- modulation down to 4kW
- weather compensation controls included
- analogue temperature sensor for DHW
- operational information from serial interface
- 5 year warranty
As I say, if the size factor had not been critical, Viessmann and Vaillant
would have been in the frame, and then I would probably have put Viessmann
and MAN as first choices and Vaillant and Keston as close seconds, but that
would have been based on information that I could easily obtain - I didn't
do detailed research on the two that fell out.
To answer your question about Normnutzungsgrad, basically the method used to
assess boiler efficiencies in the rest of Europe is different from the UK.
Sedbuk uses a particular measurement method and scales efficiency to 100%.
The normative method in Germany and elsewhere uses, as I understand it, 100%
for conventional boilers and 110% for condensing - I believe something based
around the latent heat gain being taken into account. On the SEDBUK scale
the MAN is shown as 90% efficient. I didn't use these numbers as decision
making criteria because there is a statistical error factor of up to 5% in
them anyway.
.andy
Andy Wade
> Well......
> These factors together led me to eliminate combi boilers fairly early
> on because to achieve an acceptable flow rate, a very large appliance
> that would not fit the space would be required.
Not to mention the fact that heating your total of 30 l/min through 35C
needs 73 kW output for HW alone, well beyond the 60 kW limit (AIUI) of a
normal domestic gas supply.
> I also set aside thermal store as an option because of issues with some
> modulating boilers not working properly with them.
Ooh, I've not come across that issue before. Are we talking about
feedback loop stability problems due to the high thermal mass of the load
- or what?
> In the event, I am replacing the DHW cylinder with a 200 litre fast
> recovery one, designed for pressurised use but run open vented. That
> way, if I ever decide I want to change to mains pressure HW for
> whatever reason it can be implemented without changing the cylinder.
What a good idea.
> Keston did a good job of explaining that [...] the *rate* of
> improvement of efficiency improves with condensing boilers below
> the dew point.
Yes, the step change is in the gradient of the efficiency curve. This is
well explained in the CIBSE AM3 applications manual that I've cited here
before.
> Having said that, capital cost was not a major criterion.
...and the price of the MAN Micromat is?
> Keston was the exception to that and appears to have a good product
> with the Celsius 25.
Agreed, I followed Tony's articles too.
> although I believe the Ecomax system boiler was quite new anyway.
I thought those had been around for several years. Ed Sirett will
probably know - he seems to be a fan of Vaillant.
> Smaller factors in the decision for the MAN product were
> - modulation down to 4kW
> - weather compensation controls included
> - analogue temperature sensor for DHW
> - operational information from serial interface
> - 5 year warranty
That's an attractive list. Is there a (PDF) data sheet for it available
anywhere - it wasn't obvious on the web page you quoted, but the lack of
an English version doesn't help.
> To answer your question about Normnutzungsgrad,
Question? That was a little dig at you-know-who - hence the ;-) smiley.
> The normative method in Germany and elsewhere uses, as I understand it,
> 100% for conventional boilers and 110% for condensing - I believe
> something based around the latent heat gain being taken into account.
Continental efficiency figures are based on the net calorific value (NCV)
of the fuel, which excludes the latent heat in the water vapour in the
combustion products. If you condense the vapour and recover the latent
heat you can get a apparent efficiency of >100%. In the UK we've always
used gross calorific values (GCV) which includes all the heat of
combustion, both sensible and latent. A GCV efficiency of >100% is not
possible (second law of thermodynamics).
Anyway, thanks for an interesting and well-reasoned piece. Have you got
your control scheme fully worked out? If so there are probably several
of us who would be interested in the details...
--
Andy
Andy Hall
> Andy Hall <an...@hall.gl> wrote in article <3d68a54c$1...@nt1.hall.gl>...
>
> > Well......
>
> > These factors together led me to eliminate combi boilers fairly early
> > on because to achieve an acceptable flow rate, a very large appliance
> > that would not fit the space would be required.
>
> Not to mention the fact that heating your total of 30 l/min through 35C
> needs 73 kW output for HW alone, well beyond the 60 kW limit (AIUI) of a
> normal domestic gas supply.
>
> > I also set aside thermal store as an option because of issues with some
> > modulating boilers not working properly with them.
>
> Ooh, I've not come across that issue before. Are we talking about
> feedback loop stability problems due to the high thermal mass of the load
> - or what?
I don't know for sure. Keston specifically mention it for one. I guess
that one factor may be that the modulation of the boiler becomes defunct
because the store is maintained always at high temperature, but I am not
sure. It could easily be a ceedback loop issue as you say.
>
> > In the event, I am replacing the DHW cylinder with a 200 litre fast
> > recovery one, designed for pressurised use but run open vented. That
> > way, if I ever decide I want to change to mains pressure HW for
> > whatever reason it can be implemented without changing the cylinder.
>
> What a good idea.
In doing this, one needs to be a bit careful. I wanted to have a customised
cylinder because I wanted to have the
fittings on the side in a fairly narrow arc. My airing cupboard is
rectangular with the door at one end of a long side.
The cylinder fits off to one side - i.e. at the end not behind the door if
you follow me. The original cylinder had its
cold input at 180 deg. to the other fittings and it went in the back corner.
At one stage the fitting leaked and the whole cylinder
had to come out to fix it. Mirrors poked down the back were needed to
check. Never again. So this time I ordered the cylinder with all the
fittings within a 90 degree arc. I also had added a sensor pocket to take
the sensor probe that goes with the boiler and three 22mm fittings on the
top - one for existing DHW, the other two for showers. The cold feed
fitting is 28mm and I've upgraded the pipework to the roof tank to 28mm.
Two immersion heaters are fitted.
This is all relatively do-able and quite quickly in copper cylinders but not
so easily in stainless steel. Most S/S cylinders only have a single 22mm
fitting on the top......
>
> > Keston did a good job of explaining that [...] the *rate* of
> > improvement of efficiency improves with condensing boilers below
> > the dew point.
>
> Yes, the step change is in the gradient of the efficiency curve. This is
> well explained in the CIBSE AM3 applications manual that I've cited here
> before.
>
> > Having said that, capital cost was not a major criterion.
>
> ...and the price of the MAN Micromat is?
Subject to negotiation. In the area of £1k.
>
> > Keston was the exception to that and appears to have a good product
> > with the Celsius 25.
>
> Agreed, I followed Tony's articles too.
>
> > although I believe the Ecomax system boiler was quite new anyway.
>
> I thought those had been around for several years. Ed Sirett will
> probably know - he seems to be a fan of Vaillant.
Combi yes (800 series), but I think the system boiler (600 series) is quite
new.
>
> > Smaller factors in the decision for the MAN product were
> > - modulation down to 4kW
> > - weather compensation controls included
> > - analogue temperature sensor for DHW
> > - operational information from serial interface
> > - 5 year warranty
>
> That's an attractive list. Is there a (PDF) data sheet for it available
> anywhere - it wasn't obvious on the web page you quoted, but the lack of
> an English version doesn't help.
You can get data sheets, technical and installation manuals from
Eco-Hometec's web site and that of MHS Boilers.
Eco hometec put their name in the documentation but not the product. MHS
call it the Strata 1.
>
> > To answer your question about Normnutzungsgrad,
>
> Question? That was a little dig at you-know-who - hence the ;-) smiley.
>
> > The normative method in Germany and elsewhere uses, as I understand it,
> > 100% for conventional boilers and 110% for condensing - I believe
> > something based around the latent heat gain being taken into account.
>
> Continental efficiency figures are based on the net calorific value (NCV)
> of the fuel, which excludes the latent heat in the water vapour in the
> combustion products. If you condense the vapour and recover the latent
> heat you can get a apparent efficiency of >100%. In the UK we've always
> used gross calorific values (GCV) which includes all the heat of
> combustion, both sensible and latent. A GCV efficiency of >100% is not
> possible (second law of thermodynamics).
>
> Anyway, thanks for an interesting and well-reasoned piece. Have you got
> your control scheme fully worked out? If so there are probably several
> of us who would be interested in the details...
>
There is going to be two. The initial one will be a slightly enhanced
version of S-plan.
I've fitted conventional motorised valves on the original CH circuit, the
DHW and feeds to two new radiators
which are connected in 15mm. There is a convenient void to locate the vaves
in the utility room.
Other radiators already have TRV-4s.
The eventual aim is to implement a software controlled system with each room
treated as a zone. I had looked at a number
of commercial systems for doing this, but they are either junk or
outrageously expensive, so I am going to implement my own.
I haven't got too far into the detail, but for temperature sensors I was
looking at subminiature digital sensors made by Dallas Semiconductor.
These are accurate to 0.5 degree which is good enough and can be bussed
together. For control, I have found motorised heads that will fit a
TRV-4 base and operate the plunger when fed with 24v for the motor and 0-10v
to set plunger position - i.e. flow rate. Adding zone valves of the
conventional type would not be practicable because of the chipboard floor
and locations of manifold.
I reckon that with some fairly straightforward software on an SBC, I can
have individual room control, automated balancing of the radiators (sensors
on the return pipes) etc. This will obviously take some time to develop,
so I need a simpler control in the interim and for if the sophisticated one
stops working. I'll describe as I do it for anyone interested. Like most
other home automation things the intent is a convenience/interest thing
rather than economic justification.
.andy
Ed Sirett
>
> I thought those had been around for several years. Ed Sirett will
> probably know - he seems to be a fan of Vaillant.
>
I think they have been out for at least a couple of years. I'm a fan of
Vaillants (well turbomaxs actually) because they seem well put together and
well thought out boilers. The price is not the lowest but is not really high
like some other makes, so overall they they seem good value. They also have
a good set of controls that gets the best out of the boiler.
The price for the Ecomax (cf Turbomax = conventional) however is a big leap
upwards and then the Keston looks competitive this is compounded as soon as
the flue is anything other than a very typical direct through the wall.
Andy Wade
> In doing this, one needs to be a bit careful. I wanted to have a
> customised cylinder [...]
So what you've done is to have a high-pressure rated cylinder made, but
without all the trappings needed for mains feed (reducing valve,
expansion vessel, tundish, etc.). The latter would be added later to
convert to high-pressure working. Have I understood correctly?
> I also had added a sensor pocket to take the sensor probe
That's something which ought to be a standard feature on all cylinders,
rather than the continuing reliance on strap-on 'stats (which often come
loose).
> This is all relatively do-able and quite quickly in copper cylinders
> but not so easily in stainless steel...
... and the maker is?
> You can get data sheets, technical and installation manuals from
> Eco-Hometec's web site and that of MHS Boilers.
Thanks, I'll look at those today. I did find the downloads page on the
German MAN site, but it requires a passworded login.
> For control, I have found motorised heads that will fit a
> TRV-4 base and operate the plunger when fed with 24v for the
> motor and 0-10v to set plunger position - i.e. flow rate.
Interesting - who makes those?
> I'll describe [control system] as I do it for anyone interested.
I'm interested.
> Like most other home automation things the intent is a
> convenience/interest thing rather than economic justification.
Although this sounds like something which could have commercial
potential. As you say there appears to be no satisfactory domestic
multi-zone system on the market at a sensible price.
--
Andy
Andy Hall
> Andy Hall <an...@hall.gl> wrote in article <3d68f302$1...@nt1.hall.gl>...
>
>> In doing this, one needs to be a bit careful. I wanted to have a
>> customised cylinder [...]
>
> So what you've done is to have a high-pressure rated cylinder made,
> but without all the trappings needed for mains feed (reducing valve,
> expansion vessel, tundish, etc.). The latter would be added later to
> convert to high-pressure working. Have I understood correctly?
Exactly. The cylinder came with all the high pressure accessories anyway,
so
they can remain in the box and go in the loft. I've organised the plumbing
such that adding the high pressure components can be done easily.
The real challenges, which I'm not going to deal with in the short term are
the inadequate
15mm pipe from the rising main to the airing cupboard and no convenient
drain for the tundish,
although that's easier to implement than the supply because I can run along
the joists.
>
>> I also had added a sensor pocket to take the sensor probe
>
> That's something which ought to be a standard feature on all
> cylinders, rather than the continuing reliance on strap-on 'stats
> (which often come loose).
>
>> This is all relatively do-able and quite quickly in copper cylinders
>> but not so easily in stainless steel...
>
> ... and the maker is?
>
RCM group.
>> You can get data sheets, technical and installation manuals from
>> Eco-Hometec's web site and that of MHS Boilers.
>
> Thanks, I'll look at those today. I did find the downloads page on
> the German MAN site, but it requires a passworded login.
and I think is likely to be in German. If you download the manuals from
the two UK sites you will find them to be virtually
the same, although MHS does more in the commercial arena and their manual
has larger scale examples of hookups with
multiple boilers etc.
>
>> For control, I have found motorised heads that will fit a
>> TRV-4 base and operate the plunger when fed with 24v for the
>> motor and 0-10v to set plunger position - i.e. flow rate.
>
> Interesting - who makes those?
A Swiss company called Sauter Controls. They do two technology types. One
is thermal and is probably based around a heater and wax thermostat module.
These are intended to be open/closed only, but can be made "analogue" by
powering
the element on/off with a varying duty cycle. The other has a highly geared
stepper motor operating a plunger and some
electronics. On power up, the head self calibrates to the end points.
>
>> I'll describe [control system] as I do it for anyone interested.
>
> I'm interested.
>
>> Like most other home automation things the intent is a
>> convenience/interest thing rather than economic justification.
>
> Although this sounds like something which could have commercial
> potential. As you say there appears to be no satisfactory domestic
> multi-zone system on the market at a sensible price.
I looked at the Honeywell Smartfit but it's two zones only. It can be
hooked up to an automation system like Comfort
but only one can be attached. Beyond that there are systems like Seachange
which have been scaled down from the commercial market. The problem is that
it has been mainly done as a marketing exercise - the products and prices
are as for the commercial market. For a typical system there would be little
change out of £5-8k.
Implementing the hardware for this is pretty easy - it's almost all
available off the shelf. As always, the work will be in the software.
.andy
International Man of Mystery
news:1030393257.5520.0...@news.demon.co.uk...
> I'm a fan of Vaillants (well turbomaxs actually)
> because they seem well put together and
> well thought out boilers.
They are let down by poor flow rates in their combi's. Pretty pathetic
really. Every other thing you say about them goes.
International Man of Mystery
"Andy Hall" <an...@hall.gl> wrote in message news:3d68a54c$1...@nt1.hall.gl...
> I also set aside thermal store as an
> option because of issues with some
> modulating boilers not working properly with them.
The Keston Celsius is an offender here. The load compensation controls
sense the flow and return and modulate accordingly. The control system is
primarily designed to operate directly on rads, with the replacement boiler
market in mind. The delta t on flow and return is assumed to be the heat
leading of the house. When heating a thermal store this is not the case. A
store/boiler is highly predictable set piece arrangement.
Some boiler can have their load compensation controls disabled. Also Keston
boilers are not exactly quiet.
> In the event, I am replacing the
> DHW cylinder with a 200 litre fast recovery
> one, designed for pressurised use but
> run open vented. That way, if I ever
> decide I want to change to mains
> pressure HW for whatever reason it can be
> implemented without changing the cylinder.
> At the least, the thicker
> material will last longer.
Nice idea. If your mains water pressure flow is upgraded you abandon the
loft tank and go directly onto mains water. I would not do it this way. I
would buy a low pressure open vented quick recovery cylinder. If I wanted
to go over to mains water at any time I would convert it to a heat bank
thermal store using a plate heat exchanger. The cylinder could have the
tappings in place in the correct position to accept the plate heat
exchanger. Far more cost effective. Plate heat exchangers may be simply
added in parrallel to improve efficiency/flow rate. The existing quick
recovery coil may be used as pre-heater too.
Simon Stroud on this ng has installed a Eco-Hometec (MAN) boiler. Look in
Google for his views.
Ed Sirett
International Man of Mystery <I...@NOOSSPPAM-IMM.com> wrote in message
There are cheaper. There are more powerful and with thermal stores, but are
there any which give more than 28kW for less than
680 inc VAT (and flue) ? (or 24kW for 650 inc VAT)?
2)
These boilers often replace either
a) Broken combis that were in no way giving the 24kW before hand.
b) 70s conventional plumbing with no HW pressure and little flow on
account of that.
International Man of Mystery
> > > I'm a fan of Vaillants (well turbomaxs actually)
> > > because they seem well put together and
> > > well thought out boilers.
> >
> > They are let down by poor flow rates in
> > their combi's. Pretty pathetic
> > really. Every other thing you say about
> > them goes.
> >
> 1)
> There are cheaper. There are more powerful
> and with thermal stores, but are
> there any which give more than 28kW for less than
> 680 inc VAT (and flue) ? (or 24kW for 650 inc VAT)?
The 27kw Microgenus is £470 inc VAT, 2 yr guarantee and delivers just under
12 litres/minute. A good reliable boiler. The Wickes Combi 102 (19.789 kW)
(a rebadged Halstead Ace High) is £525 inc VAT and 2 yr guarantee that
delivers 13 litres/min. Once again a good reliable boiler. Both these
combi's are excellent value for money. I find it hard to justify Vaillants
when boilers like these are about.
The Baxi 130 HE 16 litre/min condensing combi is just under £1,000 inc VAT.
Once again for the flow rate and a condenser an excellent boiler and good
value for money.
Ed Sirett
International Man of Mystery <I...@NOOSSPPAM-IMM.com> wrote in message
>
> The 27kw Microgenus is £470 inc VAT, 2 yr guarantee and delivers just
under
> 12 litres/minute. A good reliable boiler. The Wickes Combi 102 (19.789
kW)
> (a rebadged Halstead Ace High) is £525 inc VAT and 2 yr guarantee that
> delivers 13 litres/min. Once again a good reliable boiler. Both these
> combi's are excellent value for money. I find it hard to justify
Vaillants
> when boilers like these are about.
>
temperature rise they can) then so also will the Vaillant!
I openly admit that build quality is subjective and may not be translate
into actual reliability.
The _youngest_ Vaillant combi that I have replaced so far was 17 years old,
others makes have needed replacing earlier.
International Man of Mystery
> > The 27kw Microgenus is £470 inc VAT,
> > 2 yr guarantee and delivers just under
> > 12 litres/minute. A good reliable boiler.
> > The Wickes Combi 102 (19.789 kW)
> > (a rebadged Halstead Ace High) is
> > £525 inc VAT and 2 yr guarantee that
> > delivers 13 litres/min. Once again a good
> > reliable boiler. Both these combi's are
> > excellent value for money. I find it hard to justify
> > Vaillants when boilers like these are about.
>
> If the Ariston or Wickes can give
> those flow rates (which for a certain
> temperature rise they can) then so also
> will the Vaillant!
> I openly admit that build quality is
> subjective and may not be translate
> into actual reliability.
Reliability under a white case is what ipeople want. The quality of the
build in many cases does not translate to reliability. It is
price/performance again.
> The _youngest_ Vaillant combi that I have
> replaced so far was 17 years old,
> others makes have needed replacing earlier.
A neighbour of mine had one replaced after 9 years, although an early model.
Price/performance:- The Ideal Response 120 is also good value for money at
approx £660 complete giving over 14.5 litres/min. Ideal for a one bathroom
house. The bath fill ups I don't find painfully slow, as with 10 litre/min
combis.
International Man of Mystery
> This basically brought the choice down
> to Keston and MAN.
Have you looked at the Sogno No-Flame boiler? They claim 96% efficiencies
at all boiler loads.
Ed Sirett
International Man of Mystery <I...@NOOSSPPAM-IMM.com> wrote in message
>
> > The _youngest_ Vaillant combi that I have
> > replaced so far was 17 years old,
> > others makes have needed replacing earlier.
>
> A neighbour of mine had one replaced after 9 years, although an early
model.
>
> Price/performance:- The Ideal Response 120 is also good value for money at
> approx £660 complete giving over 14.5 litres/min. Ideal for a one
bathroom
> house. The bath fill ups I don't find painfully slow, as with 10
litre/min
> combis.
>
The Ideal Response would certainly be in the shortlist if someone want a
33kW unit.
International Man of Mystery
>
> > Price/performance:- The Ideal Response 120
> > is also good value for money at
> > approx £660 complete giving over
> > 14.5 litres/min. Ideal for a one
> > bathroom house. The bath fill ups I
> > don't find painfully slow, as with 10
> > litre/min combis.
>
> The Ideal Response would certainly be in
> the shortlist if someone want a 33kW unit.
I know a few B Gas installers and service engineers. They all swear by them.
Heavy to lift though. Decent flowrate condensing combi's come in at approx
£1,000; Baxi 130 HE Combi at approx 15-16+ litres/minute is an excellent
buy.