Combi boiler and a hot bath?!!?!?!
Hulio
after freezin mi nuts off for a few days i now have a new CH system
along with new boiler. I opted for a combi boiler to save on space
with tanks and mess, and wad recommended the Ideal Response 120
Okay so it's installed and my heating is RED HOT in like 5mins but can
i run a hot bath....can i ph#ck!(excuse my french) About to get on the
blower now but it seems accodring to company that fitted you can only
have a low fow rate like a the sink tap to have piping hot
water...?!?!?!!? So it seems at the mo i have to run the hot tap very
low to get how water coming out for the bath, my experience so far
with combi is v dissapointing, only hope i have a duffer or something,
can anyone shine any light on this??
many thanks
Al
whiteogs
"> Okay so it's installed and my heating is RED HOT in like 5mins but can
> i run a hot bath....can i ph#ck!(excuse my french) About to get on the
> blower now but it seems accodring to company that fitted you can only
> have a low fow rate like a the sink tap to have piping hot
> water...?!?!?!!? So it seems at the mo i have to run the hot tap very
> low to get how water coming out for the bath, my experience so far
> with combi is v dissapointing, only hope i have a duffer or something,
> can anyone shine any light on this??
>
> many thanks
>
> Al
Yes this is the norm with combis as the water flows to fast for the heat
exchanger to heat the water hot enough. What is your water pressure like
now the combi is in higher or lower than before? What I do when I run a
bath is run it slow till its hot enough then slowly open the bath tap till I
get a decent flow rate that's hot enough, seems to work for me
regards whiteogs
Tony Jackson
That's normal. It takes a huge amount of energy to heat water, and the
amount transferred to the water by the heat exchanger largly depends on the
volume of water per unit time. It's *much* better in the summer when the
water that comes out of the main isn't so cold.
Unfortunately it's the price you pay when you want to heat water on demand.
The only ways around it are by
- reducing the rate of flow
- installing a larger boiler
- storing water that is heated in advance
Tony
Richard J.
news:8qs52ugatcae05v7t...@4ax.com...
Well, I'm glad I'm not alone. We've just inherited a combi when we moved
house, and it was fine until the cold weather came. Now, we have to run the
bath slowly to get the water hot enough. For the shower, which has no
flow-rate control, we have resorted to running the cold tap in the basin in
order to reduce the flow through the boiler to a level that it can cope
with.
Funny how nobody seems to mention this when you ask whether they are happy
with a combi!
--
Richard J.
(To e-mail me, swap uk and yon in address)
The Natural Philosopher
"Richard J." wrote:
> Well, I'm glad I'm not alone. We've just inherited a combi when we moved
> house, and it was fine until the cold weather came. Now, we have to run the
> bath slowly to get the water hot enough. For the shower, which has no
> flow-rate control, we have resorted to running the cold tap in the basin in
> order to reduce the flow through the boiler to a level that it can cope
> with.
>
> Funny how nobody seems to mention this when you ask whether they are happy
> with a combi!
> --
Funny how everybody ran to scrap their hot water 'geysers' iin the 60's
and replace them with boilers and hot water tanks...because they were so
crap.
And now here we are - the 'combi'
:-)
lee
The Natural Philosopher wrote:
I have no wish to take a side in this debate, just to say that our combi
will fill our 5ft bath almost to the brim in about 10 mins and at 60C.
This is plenty quick/hot enough for us :-)
Lee
Dave Plowman
lee <lee.b...@virgin.net> wrote:
> I have no wish to take a side in this debate, just to say that our combi
> will fill our 5ft bath almost to the brim in about 10 mins and at 60C.
> This is plenty quick/hot enough for us :-)
You *fill* a bath with water at 60C?
--
* Strip mining prevents forest fires.
Dave Plowman dave....@argonet.co.uk London SW 12
RIP Acorn
lee
Dave Plowman wrote:
You don't know how cold our bathroom is......... :-)
Lee
Jaybee
when I stay at my sister's! I am so used to turning the tap on full at home
(water and heating from back boiler), that I invariably get a lukewarm bath
at her house.
Jayne
Dave Liquorice
> You *fill* a bath with water at 60C?
Your assuming he's bathing in it. I think he's cooking Lobsters.
If you got into a bath at 60C it would more than likely kill you, well
the high body percentage scald and subsequent shock would after a
while. 45C is a *very* hot bath, legislation now states that 43C is
the maximum tapwater temperature in institutions (hospitals etc) that
is a hot bath in my book.
--
Cheers new...@howhill.com
Dave. Remove "spam" for valid email.
Chris French
<rjn...@blueukder.co.yon> writes
>"Hulio" <nospams...@hotmail.com> wrote in message
>news:8qs52ugatcae05v7t...@4ax.com...
>> Morning all,
>>
>> after freezin mi nuts off for a few days i now have a new CH system
>> along with new boiler. I opted for a combi boiler to save on space
>> with tanks and mess, and wad recommended the Ideal Response 120
>>
>> Okay so it's installed and my heating is RED HOT in like 5mins but can
>> i run a hot bath....can i ph#ck!(excuse my french) About to get on the
>> blower now but it seems accodring to company that fitted you can only
>> have a low fow rate like a the sink tap to have piping hot
>> water...?!?!?!!?
>
>with a combi!
If you had searched the Google Groups Usenet archive on uk.d-i-y you
would find endless debates about Combi pros' and cons - including me
saying that I am happy with it (it is a bit slow to fill bath compared
to a tank) but I don't fill baths often so it isn't an issue for me.
--
Chris French, Leeds
Dave Plowman
lee <lee.b...@virgin.net> wrote:
> > > I have no wish to take a side in this debate, just to say that our
> > > combi will fill our 5ft bath almost to the brim in about 10 mins and
> > > at 60C. This is plenty quick/hot enough for us :-)
> > You *fill* a bath with water at 60C?
> You don't know how cold our bathroom is......... :-)
Presumably caused by the combi cutting the central heating while
achieving the apparent miracle of filling a bath? ;-)
--
* No word in the English language rhymes with month, orange, silver,purple
Andy Hall
"Dave Plowman" <dave....@argonet.co.uk> wrote in message
news:4aec8dddd2...@argonet.co.uk...
> In article <3C23AACE...@virgin.net>,
> lee <lee.b...@virgin.net> wrote:
> > > > I have no wish to take a side in this debate, just to say that our
> > > > combi will fill our 5ft bath almost to the brim in about 10 mins and
> > > > at 60C. This is plenty quick/hot enough for us :-)
>
> > > You *fill* a bath with water at 60C?
>
>
> > You don't know how cold our bathroom is......... :-)
>
> Presumably caused by the combi cutting the central heating while
> achieving the apparent miracle of filling a bath? ;-)
>
Maybe I'm missing something here, but so far the only advantage I can see of
these things
is a small saving of space through not having CW tank and HW cylinder
(although combi boilers
are larger for equivalent capability); and mains pressure HW with a bunch of
caveats on flow.
I don't see the point.
.andy
Dave Plowman
Andy Hall <an...@hall.gl> wrote:
> Maybe I'm missing something here, but so far the only advantage I can
> see of these things is a small saving of space through not having CW
> tank and HW cylinder (although combi boilers are larger for equivalent
> capability); and mains pressure HW with a bunch of caveats on flow.
I'll add another couple of disadvantages. Their heat exchangers
invariably clag up in a hard water area - sooner or later.
Mains pressure water around the house makes more noise than that from a
lower pressure storage system.
--
* A picture may be worth a thousand words, but it uses up a thousand times more memory.
stuart noble
Hulio wrote in message <8qs52ugatcae05v7t...@4ax.com>...
>So it seems at the mo i have to run the hot tap very
>low to get how water coming out for the bath, my experience so far
>with combi is v dissapointing, only hope i have a duffer or something,
>can anyone shine any light on this??
have to think ahead a little i.e. start running it at tea time for your
evening bath :-), and pop in every five minutes to make sure the reduced
flow is enough to keep the boiler running. Bit of a pain but, after 15 years
of having one, I wouldn't go back to tanks in the loft etc.
Chris French
>
>Maybe I'm missing something here, but so far the only advantage I can see of
>these things
>is a small saving of space through not having CW tank and HW cylinder
>(although combi boilers
>are larger for equivalent capability); and mains pressure HW with a bunch of
>caveats on flow.
>
cubicle (with a decent shower inside it) rather than an over the bath
job.
This for us was much preferable to being able to fill a bath a little
quicker - we rarely have baths, but have showers everyday. The larger
boiler was not an issue it just takes up a little more space on the
kitchen wall.
--
Chris French, Leeds
lee
Dave Plowman wrote:
> In article <3C23AACE...@virgin.net>,
> lee <lee.b...@virgin.net> wrote:
> > > > I have no wish to take a side in this debate, just to say that our
> > > > combi will fill our 5ft bath almost to the brim in about 10 mins and
> > > > at 60C. This is plenty quick/hot enough for us :-)
>
> > > You *fill* a bath with water at 60C?
>
> > You don't know how cold our bathroom is......... :-)
>
> Presumably caused by the combi cutting the central heating while
> achieving the apparent miracle of filling a bath? ;-)
>
> --
<BFG>
Lee
lee
Dave Liquorice wrote:
> On Fri, 21 Dec 2001 20:40:55 +0000 (GMT), Dave Plowman wrote:
>
> > You *fill* a bath with water at 60C?
>
> Your assuming he's bathing in it. I think he's cooking Lobsters.
>
>:-)
>
> If you got into a bath at 60C it would more than likely kill you, well
> the high body percentage scald and subsequent shock would after a
> while. 45C is a *very* hot bath, legislation now states that 43C is
> the maximum tapwater temperature in institutions (hospitals etc) that
> is a hot bath in my book.
>
> --
> Cheers new...@howhill.com
> Dave. Remove "spam" for valid email.
I said it *could* fill it at 60C in 10 mins, and also that this is a small
5ft bath.
Of course I run cold water as well, which means that I can run a
comfortably
warm bath in about 6 or 7 minutes. My in-laws also have a combi and a
normal
sized bath, but the flow rate from their combi is pitiful, takes a good 15
mins to
run a warm bath :-)
I said I wasn't taking sides here, I know a cylinder can fill a bath much
quicker,
provided you have enough head on the cold feed,
but we don't have a loft to put a header tank in, much less the room for a
cylinder.
As for the secondary heat exchanger scaling up, ours is stainless steel, in
common
with most I think, and is a simple push-fit with 4 clips, it won't take
much work to
descale, should it become neccessary :-)
Lee
lee
lee wrote:
Back-of-postcard guestimate gives about 90 litres (said it was a *small*
bath!),
incoming temp is around 10C so energy needed is something like 18000KJ to
heat to 60C.
The combi is rated at 29Kw DHW (33Kw input), so this would be about
right -- a standard bath will take *much* longer to fill, naturally.
If we were fortunate to have a house with room for a proper sized bath and
a HW cylinder,,we'd probably go
for a "conventional" system as well :-)
I also agree that the higher pump speed of our combi -- neccessary for DHW
performance -- does make the CH noisy :-)
Lee
Dave Plowman
lee <lee.b...@virgin.net> wrote:
> I said I wasn't taking sides here, I know a cylinder can fill a bath
> much quicker, provided you have enough head on the cold feed, but we
> don't have a loft to put a header tank in, much less the room for a
> cylinder.
Yes - there's no doubt combis are an excellent solution to the problem of
space in some situations.
I'm just conditioned to respond to the 'Adam' view that they are
perfection for all cases - and if one isn't then two, three, or four will
be.;-)
--
* Ham and Eggs: Just a day's work for a chicken, but a lifetime commitment
Andy Hall
> I'm just conditioned to respond to the 'Adam' view that they are
> perfection for all cases - and if one isn't then two, three, or four will
> be.;-)
>
Adam who?
.a
Ed Sirett
Andy Hall wrote in message <3c23d89c$1...@nt1.hall.gl>...
HW and no shower is not good enough for many/most people) with unvented
cylinders being the cost of a boiler.
I guess the fact that they are cheaper to install is probably the biggest
single benefit.
- -
Ed Sirett - Property maintainer and registered gas fitter.
Chris French
writes
>I also agree that the higher pump speed of our combi -- neccessary for DHW
>performance -- does make the CH noisy :-)
>
(which is more than can be said for the old pre-combi system)
--
Chris French, Leeds
Dave Plowman
Chris French <newsp...@chrisfrench.org> wrote:
> >I also agree that the higher pump speed of our combi -- neccessary for
> >DHW performance -- does make the CH noisy :-)
> >
> Our CH system is silent
> (which is more than can be said for the old pre-combi system)
I can't really see why there should be any difference in noise between a
combi and a 'conventional' system for heating. It was hot water I was
referring to.
--
* When it rains, why don't sheep shrink? *
Tony Bryer
> Adam who?
That's one of life's mysteries <g>
--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
http://www.sda.co.uk/qsedbuk.htm
Al
Yes well I’d like to continue on with this, spoke to IDEAL about
my combi as I have the 120(btu) high flow combi. Anyway after asking
him about the flow rate he assured me I should be able to run a 'hot'
bath with the tap fully open, and advised me there was a problem in
the system, says I should have a flow rate of 14.7 litres/min of 'HOT'
water.
Not sure how you define hot, nor do I know what the cold water flows
at, a few bits on mi checklist, also hot water fluctuates still in
temperature, allot colder when the boiler isn't fired up for rads!!!!
On the plus side for combis:
The rads now fire up red hot (although I suppose that's down to the
new CH system :)
Someone on here asked me about pressure for shower now, well it is
tops, only got hand shower installed at mo but it's v impressive,
can't wait to install shower!!! Ive now removed the old immersion tank
etc that has made room for a decent sized shower cubicle in my
bathroom, so for me I think they are superb.
Willing to persevere to tune combi check gas pressure etc, in exchange
for ridding of all that messy pipework in my loft.
cheers,
Al
"stuart noble" <stuart'no...@ntlworld.com> wrote in message news:<KCYU7.19179$US4.2...@news2-win.server.ntlworld.com>...
Tony Kershaw
(nbot much more than the Ideal) and I can run a v.hot bath with no probs.
The only time the flow reduces is if your running two or more hot taps on
sinks etc. at the same time.
At our old house we had a smaller combi and still didn't experience any real
problems with that one. I think possibly there is something wrong somewhere.
Tony
"Hulio" <nospams...@hotmail.com> wrote in message
news:8qs52ugatcae05v7t...@4ax.com...
> Morning all,
>
> after freezin mi nuts off for a few days i now have a new CH system
> along with new boiler. I opted for a combi boiler to save on space
> with tanks and mess, and wad recommended the Ideal Response 120
>
> Okay so it's installed and my heating is RED HOT in like 5mins but can
> i run a hot bath....can i ph#ck!(excuse my french) About to get on the
> blower now but it seems accodring to company that fitted you can only
> have a low fow rate like a the sink tap to have piping hot
> water...?!?!?!!? So it seems at the mo i have to run the hot tap very
> low to get how water coming out for the bath, my experience so far
> with combi is v dissapointing, only hope i have a duffer or something,
> can anyone shine any light on this??
>
> many thanks
>
> Al
>
>
Richard J.
"Al" <shiv...@hotmail.com> wrote in message
news:a85d7f4d.01122...@posting.google.com...
> Anyway after asking him about the flow rate he assured me
> I should be able to run a 'hot' bath with the tap fully open,
> and advised me there was a problem in the system, says
> I should have a flow rate of 14.7 litres/min of 'HOT' water.
But surely 'HOT' means X degrees hotter than the cold water temperature? In
cold weather, X may not be enough to heat the cold water to what you or I
would regard as 'hot'. Do the specs for combi boilers specify what X is,
or specify a minimum temperature of cold water that they can deal with?
--
Andy Hall
"Richard J." <rjn...@blueukder.co.yon> wrote in message
news:qwOV7.10877$ZB2.56...@news-text.cableinet.net...
Mostly it's X which is why people end up turning the tap down to make it run
hotter.
Generally X is 35 degrees C which would mean just enough to run a.warm bath
at the specified flow rate in the winter without adding any cold.
.andy
Stewart Aitken
>snip
>For the shower, which has no flow-rate control, we have resorted to running the cold tap in the basin in
>order to reduce the flow through the boiler to a level that it can cope with.
We have had a multi point for longer than combi's were available and
our shower has been great all the time, power shower without the pump.
It's an Aqualisa Classic thermostatic with a pressure balancing valve
on the main inlet which reduces the incoming water pressure from 10
bar to a nice 4 bar.
>Funny how nobody seems to mention this when you ask whether they are happy
>with a combi.
I think that I'll stay with my less efficient system.
Stewart
Ade
"Hulio" <nospams...@hotmail.com> wrote in message
news:8qs52ugatcae05v7t...@4ax.com...
> Morning all,
>
> after freezin mi nuts off for a few days i now have a new CH system
> along with new boiler. I opted for a combi boiler to save on space
> with tanks and mess, and wad recommended the Ideal Response 120
>
> Okay so it's installed and my heating is RED HOT in like 5mins but can
> i run a hot bath....can i ph#ck!(excuse my french) About to get on the
> blower now but it seems accodring to company that fitted you can only
> have a low fow rate like a the sink tap to have piping hot
> water...?!?!?!!? So it seems at the mo i have to run the hot tap very
> low to get how water coming out for the bath, my experience so far
> with combi is v dissapointing, only hope i have a duffer or something,
> can anyone shine any light on this??
We have recently installed the Response120, and held back from connecting
the DHW as it was Christmas, and the wife said,'no more mess'
After seeing your query, I have just connected the DHW feed in place of the
Immersion Heater and tried filling our old Cast Iron bath,
No problems at all,
There's snow outside, so I presume the incoming feed is fairly cold, and the
bath filled in approx 12minutes, with water that you couldn't hold your hand
in.
We have fed the Gas Supply direct from the meter Via 22mm Pipe
My only problem is with losing CH Pressure as per my recent post.
Hope this helps
Adrian
The Natural Philosopher
lee wrote:
>
> The Natural Philosopher wrote:
>
> > "Richard J." wrote:
> >
> > > Well, I'm glad I'm not alone. We've just inherited a combi when we moved
> > > house, and it was fine until the cold weather came. Now, we have to run the
> > > bath slowly to get the water hot enough. For the shower, which has no
> > > flow-rate control, we have resorted to running the cold tap in the basin in
> > > order to reduce the flow through the boiler to a level that it can cope
> > > with.
> > >
> > > Funny how nobody seems to mention this when you ask whether they are happy
> > > with a combi!
> > > --
> >
> > Funny how everybody ran to scrap their hot water 'geysers' iin the 60's
> > and replace them with boilers and hot water tanks...because they were so
> > crap.
> >
> > And now here we are - the 'combi'
> >
> > :-)
> >
> > > Richard J.
> > > (To e-mail me, swap uk and yon in address)
>
> I have no wish to take a side in this debate, just to say that our combi
> will fill our 5ft bath almost to the brim in about 10 mins and at 60C.
> This is plenty quick/hot enough for us :-)
What about simultaneously delivering hot water to the other two
bathrooms and teh washing machine?
>
> Lee
Chris French
<Now...@there.org> writes
>
>
>What about simultaneously delivering hot water to the other two
>bathrooms and teh washing machine?
>
Then I wouldn't chose a combi for that usage/ situation. (I'd look to
mains pressure HW tank)
For our situation a combi is a good option though.
--
Chris French, Leeds
Peter Fielding
> In article <3C248062...@virgin.net>,
> lee <lee.b...@virgin.net> wrote:
> > I said I wasn't taking sides here, I know a cylinder can fill a bath
> > much quicker, provided you have enough head on the cold feed, but we
> > don't have a loft to put a header tank in, much less the room for a
> > cylinder.
>
>
> Yes - there's no doubt combis are an excellent solution to the problem of
> space in some situations.
>
> I'm just conditioned to respond to the 'Adam' view that they are
> perfection for all cases - and if one isn't then two, three, or four will
> be.;-)
It seems there are as many different opinions as there are boilers (or
boiler owners!)I have had a Puma 100e for about 7 years, it runs 11
radiators (3 of which are cast iron) with a twelfth soon to be
connected. the water it produces
is too hot to get straight into, (yes I could turn the temp down!)
Yes it will only supply 1 tap effectivley at one time, but then I
don't know of many cylinders that will fill (I mean FILL!) 3 baths one
after the other.
So my experience is only good!
Just my .06 Euros worth
My opinion's not SSMB's, They're a bank, what would they know about
this?
Dave Plowman
Peter Fielding <peter.f...@ssmb.com> wrote:
> Yes it will only supply 1 tap effectivley at one time, but then I
> don't know of many cylinders that will fill (I mean FILL!) 3 baths one
> after the other.
Mine will - it has a fast recovery cylinder. But of course assuming
you'll actually use the bath you've drawn. It'll certainly do it in the
time it takes an average person to bath and dry themselves. Of course,
it'll also turn the heating off while doing this so not to be recommended
this time of year. ;-)
--
* Never kick a cow pat on a hot day *
International Man of Mystery
news:KCYU7.19179$US4.2...@news2-win.server.ntlworld.com...
>
> > So it seems at the mo i have to run
> > the hot tap very low to get how water
> > coming out for the bath, my experience so far
> > with combi is v dissapointing, only hope
> > i have a duffer or something,
> > can anyone shine any light on this??
>
> Standard behaviour for a combi I think.
> You'll soon get used to it.
Not so. This is obviously a budget low floerate model. High flowrate
combi's work very, very well. Do not generalise and pass off low flowarte
combis as the norm. they are not.
International Man of Mystery
news:PPnzkgcj...@chrisfrench.org...
> In message <ZWKU7.8072$E02.41...@news-text.cableinet.net>, Richard J.
> <rjn...@blueukder.co.yon> writes
> >> Morning all,
> >>
> >> after freezin mi nuts off for a few days i now have a new CH system
> >> along with new boiler. I opted for a combi boiler to save on space
> >> with tanks and mess, and wad recommended the Ideal Response 120
> >>
> >> Okay so it's installed and my heating is RED HOT in like 5mins but can
> >> i run a hot bath....can i ph#ck!(excuse my french) About to get on the
> >> blower now but it seems accodring to company that fitted you can only
> >> have a low fow rate like a the sink tap to have piping hot
> >> water...?!?!?!!?
That is balls. The response is a decent flowrated combi.
Here is a guide to combi's which I post occassionally.
Here is an outline of "combi's":---
A "combi" is a combination of boiler and hot water system, packaged in one
box. A "one box solution".
Firstly, you size combi's by their flowrate. Flowrate is the important
figure for combi performance.
- 9 -10 litres / min - The cheap end of the scale. Small flat/house with
slow bath fillup and good power type of shower, with cope with two outlets
open at a reduced rate, but usually no problem using a kitchen tap if the
basin is turned on.
- 10 -14 litres / min - small flat with slow bath fillup and good power type
of shower. bath fills quicker and usually will cope with two outlets open at
a good rate, usually no problem using a kitchen tap if the basin is turned
on.
- 14 - 19 litres / min Now getting serious. These fully cope with a fast
bath fillup and the higher end 18-19 litres/ min are rated at 1.5 baths
(bath and en-suite shower).
18-22 - litres /min - Bathroom with en-suite shower to two full bathroom
jobs.
Some combi's have a small hot water storage vessel or pre-heating of the
heat exchanger to avoid the cold lag which the cheaper versions experience.
A combi can cope with up to 2 bathrooms, filling them fast enough, and fast
hot water at all taps.
Secondly, as combi is a "combination" of the heating and water system in one
case, eliminating external tanks and cylinders, and generally supply hot
water at high main pressure (to confuse a little, some can run at very low
pressures and even off tanks. Generally most are fed from the mains). It is
generally a matter of mount the boiler and connect up the pipes. The expert
designers have done the hard work for you taking all the components that are
typically scattered all over your house and put them all in one case.
There are three types of combi:
1) The Instantaneous Combi -
This is the most common combi. It heats cold mains water instantly as it
runs through the combi. It never runs out of hot water. This is the most
common type of combi, generally having lower flowrates than Nos 2 & 3 below.
The largest flow rate instant combi is a two bathroom model, 22 litres/min
ECO-Hometec. Being a condensing boiler it is very economical too.
http://www.eco-hometec.co.uk. This is one of the RRs of boilers.
2) Unvented Cylinder Combi -
An unvented cylinder is similar to a conventional cylinder but run off the
high-pressure cold mains. A combi with an integral unvented cylinder has
approx 60 litre cylinder heated to approx 80C, with a quick recovery coil
that takes all the boilers output. A fast acting cylinder thermostat ensures
the boiler pumps heat into the cylinder ASAP with a recovery rate from cold
around 5-8 minutes (Ariston claim 8 minutes). The 80C water is blended own
to about 45-50C. e.g's, Ariston Genus 27 Plus, Glow Worm.
3) Heat Bank Combi -
Incoming water is instantly heated running through a high-efficiency plate
heat exchanger (these are generally in most instantaneous combi's) that
takes its heat from a "domestic hot water only" store of water at approx 80C
instantaneous combi's take the heat from a heat-exchanger heater heated via
the burner). A fast acting thermostat ensures the boiler pumps all of its
heat into the store ASAP with a recovery rate about 5-8 minutes from cold.
The 80C stored water instantly heats the cold incoming mains water.
This is blended down to about 45-50C for use at the taps. e.g. Vokera &
Worcester Hi-Flow 400 floor standing models (standard washing machine
sizes).
N.B. The heat bank is a variation of a thermal store, but is "not" a thermal
store in the conventional sense in that a coil carrying cold mains water
runs though a store of hot water kept at about 80C. Heat-banks are far more
efficient and give higher flowrates than conventional coiled thermal stores.
The stainless steel plate heat-exchangers do not scale up.
http://www.heatweb.com
http://www.albion-online.co.uk
http://www.range-cylinders.co.uk
4) Combined Primary Storage Unit (a derivative of a combi, but still a one
box solution)
These are a combination of a large thermal store and boiler in one casing.
The units are large (larger than standard washing machine size) and floor
mounted. The heating is taken off the thermal store, with in many cases the
DHW taken off store using a plate heat-exchanger (heat-bank). Unlike the
eat-bank in 3) above the thermal store supplies heating and DHW. They are
available from 1 to 2.5 bathroom models. Gledhill do a condensing version,
the Gulfsream 2000 (not available to the general public) and IMI do the
Range Powermax (the IMI has the highest efficiency for a non-condensing
boiler). http://www.powermax.co.uk
Efficiency data base at BRE http://www.sedbuk.com
Nos. 2) 3) & 4) above have high flowrates. No. 1 "generally" has low
flowrates but some can be high - e.g. ECO-Hometec; actually has a very high
flowrate.
Nos 2), 3) & 4) use stored water, but in different ways. Unlike No. 1 they
will eventually run cold, but that takes quite a time, hence they are
referred to as "two bathroom" models, having the ability to fill two baths
with very fast recovery rates. Hot water is being drawn off as the high
rating burner is reheating. Very rare do these combi's run out of hot water
in average use. When taking one shower the burner may be re-heating faster
than what can be drawn-off.
There are "combi's" that give hot water and heating simultaneously -
Combined Primary Storage Units do this (IMI Powermax and Gledhill Gulfstream
2000). Those that don't, as are most, it is best to have the heating on
sooner in the morning if lots of people use the bathrooms as the priority is
always directed towards Domestic Hot Water heating.
--
International Man of Mystery
Part Time World-wide Playboy
International Man of Mystery
> In message <3c23d89c$1...@nt1.hall.gl>, Andy Hall <an...@hall.gl> writes
> >
> > Maybe I'm missing something here, but so
> > far the only advantage I can see of
> > these things is a small saving of space
> > through not having CW tank and HW cylinder
> > (although combi boilers are larger for equivalent
> > capability); and mains pressure HW with a bunch of
> > caveats on flow.
>
> This small saving in space enabled us
> to install a decent sized shower
> cubicle (with a decent shower inside it)
> rather than an over the bath job.
Small? Sounds like a lot of space saved and much gained in utilising it.
International Man of Mystery
news:3C248062...@virgin.net...
> I said it *could* fill it at 60C in 10 mins, and
> also that this is a small 5ft bath.
> Of course I run cold water as well, which
> means that I can run a comfortably
> warm bath in about 6 or 7 minutes.
> My in-laws also have a combi and a
> normal sized bath, but the flow rate from
> their combi is pitiful, takes a good 15
> mins to run a warm bath :-)
The combi is too small. Would you use a Mini van to move house? No you would
use a large Luton type van? You get the right tool for the job. You get the
right sized combi.
> I said I wasn't taking sides here, I know
> a cylinder can fill a bath much quicker,
Not so. Some combi's have very high flowrates. Don't take a low performing
model and pass it off as the norm.
International Man of Mystery
news:3C248062...@virgin.net...
> As for the secondary heat exchanger scaling
> up, ours is stainless steel, in common
> with most I think, and is a simple push-fit with
> 4 clips, it won't take much work to
> descale, should it become neccessary :-)
If it is a stainless steel secondary plate heat exchanger then the plates
bend not allowing scale to form.
International Man of Mystery
news:3C31AA6F...@there.org...
> > I have no wish to take a side in this debate,
> > just to say that our combi will fill our 5ft bath
> > almost to the brim in about 10 mins and at 60C.
> > This is plenty quick/hot enough for us :-)
>
> What about simultaneously delivering hot
> water to the other two
> bathrooms and teh washing machine?
And how about supplying all the 200 flats at the same time in the estate
down the road too. If it can't do that is probably is not work getting for
your bath and shower.
Andy Hall
"International Man of Mystery" <I...@NOOSSPPAM-IMM.com> wrote in message
news:a2ccof$fr$1...@newsg2.svr.pol.co.uk...
Make sure you tell the complete story.
For a tank fed system used in a house with two bathrooms, power shower
plus kitchen use I can get over 20 litres/minute from the shower and about
25 to the bath
simultaneously. The shower, being directly attached to the HW cylinder and
roof tank
is completely unaffected by a bath tap being turned on.
To get anywhere close to this you are talking about one of the largeest
sized units of 20litres/minute
hot water delivery rate, even assuming you don't run the bath tap at the
same time as the shower.
OK, so thermostatic blending valves may help, but I can't see how the flow
rate through the shower won't drop
when the bath tap is turned on - assuming you don't want the shower to go
cold of course.
An appliance of this capacity is not the type that will fit in a small
cupboard space on a kitchen wall and so
may need to be located elsewhere - e.g. under a kitchen worktop if it will
go. In a kitchen, floor space under the worktop is typically at a premium
because of other appliances.
In thinking of other spaces, another alternative, might be the airing
cupboard where the HW cylinder was.
There's no saving of space in that case apart from tank space in the loft.
The boiler could go in the loft, but
then there are specific safety requirements that have to be met at extra
cost.
Added to this, on a high capacity boiler the gas service will have to be
upgraded - a 20l/min model will require at least 22mm pipework, perhaps
more. To get the water flow rate, the mains water pipework will need to be
upgraded to at least 22mm as well.
As something to be used in a new build where everything can be designed
around it or as a replacement in a small/medium sized house with one
bathroom and modest HW needs combi boilers may be suitable.
For a replacement in a medium to large house and four people it is far from
clear to me that it makes economic or practical sense in comparison with a
tank fed system.
.andy
Ben Harrington
>
> "International Man of Mystery" <I...@NOOSSPPAM-IMM.com> wrote in message
> news:a2ccof$fr$1...@newsg2.svr.pol.co.uk...
> > "Chris French" <newsp...@chrisfrench.org> wrote in message
> > news:GQ2Bz8Bh...@chrisfrench.org...
> > > In message <3c23d89c$1...@nt1.hall.gl>, Andy Hall <an...@hall.gl> writes
> > > >
> > > > Maybe I'm missing something here, but so
> > > > far the only advantage I can see of
> > > > these things is a small saving of space
> > > > through not having CW tank and HW cylinder
> > > > (although combi boilers are larger for equivalent
> > > > capability); and mains pressure HW with a bunch of
> > > > caveats on flow.
> > >
> > > This small saving in space enabled us
> > > to install a decent sized shower
> > > cubicle (with a decent shower inside it)
> > > rather than an over the bath job.
> >
> > Small? Sounds like a lot of space saved and much gained in utilising it.
> >
>
> Make sure you tell the complete story.
>
> To get the water flow rate, the mains water pipework will need to be
> upgraded to at least 22mm as well.
>
This is the problem that Adam always ignores. I reckon that most houses
more than 20 years old will need the water main replacing. This is
likely to cost £1500. And even then you still won't be able to run two
taps at once without a drop in performance.
Ben
Ben Harrington
Only if the mains feed is good enough.
Ben
International Man of Mystery
> > > > Maybe I'm missing something here, but so
> > > > far the only advantage I can see of
> > > > these things is a small saving of space
> > > > through not having CW tank and HW cylinder
> > > > (although combi boilers are larger for equivalent
> > > > capability); and mains pressure HW with a bunch of
> > > > caveats on flow.
> > >
> > > This small saving in space enabled us
> > > to install a decent sized shower
> > > cubicle (with a decent shower inside it)
> > > rather than an over the bath job.
> >
> > Small? Sounds like a lot of space saved and
> > much gained in utilising it.
>
> Make sure you tell the complete story.
It has been told. It was written.
> For a tank fed system used in a house with
> two bathrooms, power shower plus kitchen use
> I can get over 20 litres/minute from the shower
> and about 25 to the bath simultaneously.
> The shower, being directly attached to the HW
> cylinder and roof tank is completely unaffected by
> a bath tap being turned on.
How often do you have a bath and shower on at the same time? Err very rare
I'm sure. You know can plug a 3kW fore into a 13 amp socket. Plug a 3kW
fire into all your 13 amp sockets and the fuses will blow and the system
can't take it. Ah I hear you say, who would do that and if so how often
would that occur, probably never.
Same with the shower/bath set up. If turned on all your hot water taps in
the house fully when filling your bath and shower simulantiously the flow
would drop and most probably drain your cold water storage tank very
quickly. Ah I hear you say, who would do that and if so how often would that
occur, probably never.
A man put a combi in that satisfied his needs and saved a hell of a lot of
space and he can even fill the kettle with cheap to heat gas and reduce
expensive kettle electricity usage, which can over the years be very high.
Andy Hall
"International Man of Mystery" <I...@NOOSSPPAM-IMM.com> wrote in message
>
> > For a tank fed system used in a house with
> > two bathrooms, power shower plus kitchen use
> > I can get over 20 litres/minute from the shower
> > and about 25 to the bath simultaneously.
> > The shower, being directly attached to the HW
> > cylinder and roof tank is completely unaffected by
> > a bath tap being turned on.
>
> How often do you have a bath and shower on at the same time? Err very
rare
> I'm sure.
Quite frequently with a house of four including two teenagers plus friends
who visit.
Two bathrooms, two showers. Bath in one and shower in the other is quite a
regular occurence.
>You know can plug a 3kW fore into a 13 amp socket. Plug a 3kW
> fire into all your 13 amp sockets and the fuses will blow and the system
> can't take it. Ah I hear you say, who would do that and if so how often
> would that occur, probably never.
>
This is not close to the same thing
> Same with the shower/bath set up. If turned on all your hot water taps in
> the house fully when filling your bath and shower simulantiously the flow
> would drop and most probably drain your cold water storage tank very
> quickly. Ah I hear you say, who would do that and if so how often would
that
> occur, probably never.
Irrelevant.
>
> A man put a combi in that satisfied his needs and saved a hell of a lot of
> space and he can even fill the kettle with cheap to heat gas and reduce
> expensive kettle electricity usage, which can over the years be very high.
>
Why would you fill the kettle with cheap to heat gas?? Does it make the
boiler work better? How do you seal the lid?
I am not saying that a combi boiler is always unsuitable or anything close
to it.
Clearly those of reasonable (not washing machine) size can be effective in
small to medium sized situations
and where the limitations are acceptable.
Larger ones may also make sense if there is the space to accomodate them.
This depends on the layout of the
house and the value attached to different spaces. In a new build this can
be accounted for, but for replacement in a larger house it's less than
clear. Swapping a small wall mount boiler for a something fridge sized in
a kitchen may not be possible.
However, the main point is that infrastructure upgrades (gas and water) at
quite considerable cost may well be required to get anywhere close to the
equivalent operational behaviour of a tank fed system.
There's nothing wrong with suggesting something, but at least present a
complete and fair picture.
.andy
Dave Plowman
International Man of Mystery <I...@NOOSSPPAM-IMM.com> wrote:
> A man put a combi in that satisfied his needs and saved a hell of a lot
> of space and he can even fill the kettle with cheap to heat gas and
> reduce expensive kettle electricity usage, which can over the years be
> very high.
Wonder just how efficient it is to run a combi purely for a pint or so of
hot water? If you're on a water meter as well?
But don't let simple things like that ruin your fantasies.
--
* I will always cherish the initial misconceptions I had about you
International Man of Mystery
> >
> > > For a tank fed system used in a house with
> > > two bathrooms, power shower plus kitchen use
> > > I can get over 20 litres/minute from the shower
> > > and about 25 to the bath simultaneously.
> > > The shower, being directly attached to the HW
> > > cylinder and roof tank is completely unaffected by
> > > a bath tap being turned on.
> >
> > How often do you have a bath and shower
> > on at the same time? Err very rare
> > I'm sure.
>
> Quite frequently with a house of four
> including two teenagers plus friends
> who visit.
...cut disjointed illogical stuff...
The points is that you don't need to have in a domestic situation
(commercial is different such as all showers delivering well in hot water
and flowrate
in a hotel) all hot taps delivering maximum flowrates to what the baths and
showers can deliver.
In a situation where there are simultaneous demands the flow will drop on
the appliances (bath, shower, etc), but not to uncomfortable levels. As
this is generally a rare event it is not worth getting upset about, or
designing the system to cope at all costs. Common sense prevails.
Ben Harington
>
Donkey.
Ben
International Man of Mystery
news:3C4C3D89...@btwinternet.com...
I thought I killfiled this effing idiot. He has been taking Plowmnan
lessons.
Dave Plowman
International Man of Mystery <I...@NOOSSPPAM-IMM.com> wrote:
> The points is that you don't need to have in a domestic situation
> (commercial is different such as all showers delivering well in hot
> water and flowrate in a hotel) all hot taps delivering maximum flowrates
> to what the baths and showers can deliver.
What's the point in having two showers if you can't use them
simultaneously?
--
* How much deeper would the oceans be without sponges? *
Andy Hall
"International Man of Mystery" <I...@NOOSSPPAM-IMM.com> wrote in message
>
> The points is that you don't need to have in a domestic situation
> (commercial is different such as all showers delivering well in hot water
> and flowrate
> in a hotel) all hot taps delivering maximum flowrates to what the baths
and
> showers can deliver.
I didn't say that you did. What I did say is that it's common if you have
two bathrooms to want
to use them simultaneously, especially in a house of four people including
two females and two teenagers as I have.
With an arrangement of roof tank and HW cylinder with separate take offs for
the shower I can have the shower running and have it completely unaffected
by turning on any other tap in the house, including the bath tap.
That's the whole point of a separate take off. I don't care if the bath
tap slows down a bit from a downstairs tap being turned on, but I care a lot
if the shower alters temperature or flow rate because the bath tap is turned
on.
Thermostatic shower valves will help against dangerous hot extremes but
still take a finite time to react.
>
> In a situation where there are simultaneous demands the flow will drop on
> the appliances (bath, shower, etc), but not to uncomfortable levels. As
> this is generally a rare event it is not worth getting upset about, or
> designing the system to cope at all costs. Common sense prevails.
>
Indeed it does. What is the point in two bathrooms if only one at a time
can be used?
I'm sure it's possible to design a mains pressure instant hot water system
to give good results
provided that
a) the mains water input pressure and available flow rate substantially
exceeds the sum
of the requirements for the bathrooms. Almost certainly this involves
upgrading the supply.
b) the boiler is able to heat the water to constant output temperature over
a wide range of input temperatures
at the same flow rate (implies hefty machine with modulating burner and fast
response to flow and temperature changes.) If this is really the case
with combination boilers, why are they all specified with a flow rate for 35
degree rise in temperature?
.andy
The Natural Philosopher
International Man of Mystery wrote:
> How often do you have a bath and shower on at the same time?
Frequently, in houses with more than one bathroom, where everybody
want's to get dressed for school/work at the same time.
The Natural Philosopher
International Man of Mystery wrote:
>
Are you from Cheam perchance?
International Man of Mystery
news:3C4CEEB2.4FDCFBE4@b.c...
> Are you from Cheam perchance?
I wouldn't lower myself to go to such a second rate place.
International Man of Mystery
> What is the point in two bathrooms if only one at a time
> can be used?
I have two. I use mine in my room and the others use the other. Mine is mine
and only mine.
> I'm sure it's possible to design a mains
> pressure instant hot water system
> to give good results
It certainly is.
> provided that
>
> a) the mains water input pressure and available
> flow rate substantially exceeds the sum
> of the requirements for the bathrooms. Almost
> certainly this involves upgrading the supply.
Not almost certainly. I assume you mean from the road.
International Man of Mystery
I have two bathrooms. At peak times only showers are used as people have no
time for lengthy baths. Common sense again. Why put in a large stored water
system when there is no need to.
Brian Sharrock
"The Natural Philosopher" <a@b.c> wrote in message
>
>
> International Man of Mystery wrote:
> >
> > "The Natural Philosopher" <Now...@there.org> wrote in message
> > news:3C31AA6F...@there.org...
> >
> > > > I have no wish to take a side in this debate,
> > > > just to say that our combi will fill our 5ft bath
> > > > almost to the brim in about 10 mins and at 60C.
> > > > This is plenty quick/hot enough for us :-)
> > >
the Princess Margaret syndrome. AIUI, hospital
handbasins etc. have complicated mixing gizmo's
on their hot water taps to avoid temperatures
above 45C. Do you mean, with a DHW temp of
60C you can fill a bath with an admixture of
water (hot and cold) at (say) 43C 'in about 10 mins'?
--
Brian
Dave Plowman
International Man of Mystery <I...@NOOSSPPAM-IMM.com> wrote:
> I have two bathrooms. At peak times only showers are used as people have
> no time for lengthy baths. Common sense again. Why put in a large
> stored water system when there is no need to.
Why then have baths if you don't use them? Why put in a large item when
there is no need to?
--
* Why are a wise man and a wise guy opposites? *
Andy Hall
"International Man of Mystery" <I...@NOOSSPPAM-IMM.com> wrote in message
> "Andy Hall" <an...@hall.gl> wrote in message news:3c4c...@nt1.hall.gl...
>
> > What is the point in two bathrooms if only one at a time
> > can be used?
>
> I have two. I use mine in my room and the others use the other. Mine is
mine
> and only mine.
Ah. Do you have a token system to avoid the bath being run when the shower
is in use or do you not have a combi?
>
> > I'm sure it's possible to design a mains
> > pressure instant hot water system
> > to give good results
>
> It certainly is.
>
> > provided that
> >
> > a) the mains water input pressure and available
> > flow rate substantially exceeds the sum
> > of the requirements for the bathrooms. Almost
> > certainly this involves upgrading the supply.
>
> Not almost certainly. I assume you mean from the road.
>
If the internal mains pipework was 15mm then at least that. It could be
more if the mains from the road is inadequate.
However, as has already been demonstrated, unless a combi boiler has
substantial direct power (50kW to achieve 13l/min) or that there is a
substantial storage facility, then this wouldn't matter because the heating
arrangements would be incapable of heating the water adequately anyway.
Simple science.
.andy
The Natural Philosopher
International Man of Mystery wrote:
>
> "The Natural Philosopher" <a@b.c> wrote in message
> news:3C4CEE47.B7CF2D2F@b.c...
> >
> > International Man of Mystery wrote:
> >
> > > How often do you have a bath and
> > > shower on at the same time?
> >
> > Frequently, in houses with more than one
> > bathroom, where everybody want's to get
> > dressed for school/work at the same time.
>
> I have two bathrooms. At peak times only showers are used as people have no
> time for lengthy baths. Common sense again. Why put in a large stored water
> system when there is no need to.
>
Ineed, but in other peoples houses, where the whole family does not
leave all at onec, after queueing to use the only available bathroom,
some people are hrunning lonfg soaky baths, whilst others are showering
as yet others are sghaving or scrapimng teh navel fluuf and toe jam into
the baisn, and Granny is washing up the stuff she just took out of the
dishwasher 'because they don't get them properly CLEAN you know' etc.
> --
> International Man of Mystery
> Part Time World-wide Playboy
Obviously impoverished gay bachelor.
The Natural Philosopher
International Man of Mystery wrote:
>
> "The Natural Philosopher" <a@b.c> wrote in message
> news:3C4CEEB2.4FDCFBE4@b.c...
>
> > Are you from Cheam perchance?
>
> I wouldn't lower myself to go to such a second rate place.
>
Oh, You sounded like the chap in the limerick, thats all.
International Man of Mystery
> > International Man of Mystery
> > Part Time World-wide Playboy
>
> Obviously impoverished gay bachelor.
Jealously will get you nowhere.