Vaillant Combi Boiler : Central Heating Microswitch
tim_...@my-deja.com
can help me out.
I have a Vaillant combi boiler and the system is
working fine for domestic hot water. When a tap
is turned on, the system kicks into life and
supplies hot water. However, when I turn on the
central heating switch, nothing happens.
I have checked various fuses on the system (all
ok) and have checked the switch and incoming
power etc. I believe the cause of the problem is
a piece of equipment that moves left and right
activating microswitches for water/central
heating. The part moves out to the right for hot
water and the boiler kicks in. However, for
central heating I believe it should move inwards
towards the left, but it does not. If I manually
activate the microswitch, then the heating comes
on ok.
Does anyone have any ideas about this problem ?
Thanks.
Sent via Deja.com http://www.deja.com/
Before you buy.
Adam
The "piece of equipment that moves left and right activating microswitches
for water/central heating"???? Is this a 3-way electric valve on this? If
so, does the end-microswitch make contact when the valve has moved over? If
this is the case look at the electric valve, its motor or circuitry that
actually opens it. Vaillant make good kit, it may the circuit that activated
the valve. All assuming electric valve of course.
The "piece of equipment that moves left and right activating microswitches
for water/central heating", may actually be a mechanical valve. When there
is cold water flow a diaphragm is lifted that makes a microswitch. Sounds
like and electric one to me as the left-right is usually electric.
geoff
<ad...@NOSPAMmail.com> writes
--
geoff
geoff
>I wonder if any plumbers / combi boiler experts
>can help me out.
>
>I have a Vaillant combi boiler and the system is
>working fine for domestic hot water. When a tap
>is turned on, the system kicks into life and
>supplies hot water. However, when I turn on the
>central heating switch, nothing happens.
>
>I have checked various fuses on the system (all
>ok) and have checked the switch and incoming
>power etc. I believe the cause of the problem is
>a piece of equipment that moves left and right
>activating microswitches for water/central
>heating. The part moves out to the right for hot
>water and the boiler kicks in. However, for
>central heating I believe it should move inwards
>towards the left, but it does not. If I manually
>activate the microswitch, then the heating comes
>on ok.
>
>Does anyone have any ideas about this problem ?
>
It sounds like you need a diverter valve kit which is available from
most CH suppliers - look up Heating Replacement Parts (HRPC) in the
yellow pages
Be very careful to note exactly how it comes apart and what goes where
as you take it apart, otherwise, you could have major problems (plenty
of drawings)
--
geoff
Adam
"geoff" <ge...@cetltd.demon.co.uk> wrote in message
news:$yFicrBB...@cetltd.demon.co.uk...
If DIYing and not much experience it is better to buy the complete valve. It
still works out cheaper than getting a professional.
> --
> geoff
Adam
> In article <8s1lo5$35o$1...@newsg2.svr.pol.co.uk>, Adam
> <ad...@NOSPAMmail.com> writes
> ><tim_...@my-deja.com> wrote in message
news:8s1coa$s9j$1...@nnrp1.deja.com...
> >> can help me out.
> >>
> >> I have a Vaillant combi boiler and the system is
> >> working fine for domestic hot water. When a tap
> >> is turned on, the system kicks into life and
> >> supplies hot water. However, when I turn on the
> >> central heating switch, nothing happens.
> >>
> >> I have checked various fuses on the system (all
> >> ok) and have checked the switch and incoming
> >> power etc. I believe the cause of the problem is
> >> a piece of equipment that moves left and right
> >> activating microswitches for water/central
> >> heating. The part moves out to the right for hot
> >> water and the boiler kicks in. However, for
> >> central heating I believe it should move inwards
> >> towards the left, but it does not. If I manually
> >> activate the microswitch, then the heating comes
> >> on ok.
> >>
> >> Does anyone have any ideas about this problem ?
> >
microswitches
> >for water/central heating"???? Is this a 3-way electric valve on this?
If
> >so, does the end-microswitch make contact when the valve has moved over?
If
> >this is the case look at the electric valve, its motor or circuitry that
> >actually opens it. Vaillant make good kit, it may the circuit that
activated
> >the valve. All assuming electric valve of course.
> >
microswitches
> >for water/central heating", may actually be a mechanical valve. When
there
> >is cold water flow a diaphragm is lifted that makes a microswitch.
Sounds
> >like and electric one to me as the left-right is usually electric.
>
> No Adam, it's activated by water pressure
geoff,
Firstly the electrics to the microswitch must be checked (see if power is
actually there. Then check the switch. If all OK then new valve. How old
is the combi?
John
<tim_...@my-deja.com> wrote in message
news:8s1coa$s9j$1...@nnrp1.deja.com...
> I wonder if any plumbers / combi boiler experts
> can help me out.
>
> I have a Vaillant combi boiler and the system is
> working fine for domestic hot water. When a tap
> is turned on, the system kicks into life and
> supplies hot water. However, when I turn on the
> central heating switch, nothing happens.
Hmm - well thats different - the common failure with the majority of combis
is for the DHW flow detector to suffer first FWIW the Vaillant combis use a
diaphragm operated flow detector. You seem to have an unusual fault.
>
> I have checked various fuses on the system (all
> ok) and have checked the switch and incoming
> power etc. I believe the cause of the problem is
> a piece of equipment that moves left and right
> activating microswitches for water/central
> heating. The part moves out to the right for hot
> water and the boiler kicks in. However, for
> central heating I believe it should move inwards
> towards the left, but it does not. If I manually
> activate the microswitch, then the heating comes
> on ok.
The model of boiler would make things clearer but I have the service manual
for the Vaillant Combicompact VCW GB 240/280H to hand and the diverter
valve assembly is at the bottom right hand side with the microswitches in a
transparent plastic case. As you say the water flowing through the DHW
circuit causes the diverter valve to move to direct the boiler hot water to
the DHW heat exchanger and operates a microswitch via a pushrod. when the
DHW stops flowing this "should" return to its rest position and the burner
then depends on a continued demand for heat from the central heating
section but do bear in mind that there is an anti-cycling delay circuit in
the CH mode in this boiler which can be up to 12 minutes but is normally
factory set to 5 minutes. Its easy to get impatient and assume the thing is
faulty when all it needs is patience <g>
>
> Does anyone have any ideas about this problem ?
If you manually operate the (correct?) microswitch and the unit fires there
may be some physical obstruction to the diverter restoring to rest position
fully. Possible considerations are lump of debris/scale/mains borne gravel,
or deposits on the spindle or in the stuffing box of the diverter.
I would suggest you obtain the service manual for your particular boiler
model from Vaillant 01634 292310
>
> Thanks.
>
HTH
P.S. Vaillant are in the process of making a rectification call to many of
their boilers as they found a defect which could lead to a dangerous
situation arising. While on the phone you may care to quote the serial
number of your boiler to them to find out if yours falls into this
category.
Adam
"." <cr...@hotmail.com> wrote in message
news:9hu9usgqgorf2hkst...@4ax.com...
> On Wed, 11 Oct 2000 20:42:57 +0100, geoff <ge...@cetltd.demon.co.uk>
> wrote:
>
> >In article <8s1coa$s9j$1...@nnrp1.deja.com>, tim_...@my-deja.com writes
> >>can help me out.
> >>
> >>I have a Vaillant combi boiler and the system is
> >>working fine for domestic hot water. When a tap
> >>is turned on, the system kicks into life and
> >>supplies hot water. However, when I turn on the
> >>central heating switch, nothing happens.
> >>
> >>ok) and have checked the switch and incoming
> >>power etc. I believe the cause of the problem is
> >>a piece of equipment that moves left and right
> >>activating microswitches for water/central
> >>heating. The part moves out to the right for hot
> >>water and the boiler kicks in. However, for
> >>central heating I believe it should move inwards
> >>towards the left, but it does not. If I manually
> >>activate the microswitch, then the heating comes
> >>on ok.
> >>
> >>
> >>
> >>
> >>Sent via Deja.com http://www.deja.com/
> >>Before you buy.
> >
> >It sounds like you need a diverter valve kit which is available from
> >most CH suppliers - look up Heating Replacement Parts (HRPC) in the
> >yellow pages
> >
> >Be very careful to note exactly how it comes apart and what goes where
> >as you take it apart, otherwise, you could have major problems (plenty
> >of drawings)
> diverter valve down on the lower right hand side as you open and close
> the hot tap. Does it move freely back and forth? if not then cast your
> eyes over the water diaphragm chamber which is sited in the middle of
> the appiance about 5 inches up from the bottom front of the case and
> behind the control panel cover. You will note that atop of this
> diapragm chamber there is a strange looking black plastic widget valve
> with a spring attached to it. If you operate the tap you will note
> that a pushrod operates this widget valve. When you close the tap,does
> the spring FULLY return the black plastic valve to its rest position?
> . This black plastic valve switches hydraulic pressure from the pump
> to the changeover valve assembly (lower right hand side) to move the
> valve back and forth.
>
> If the black plastic valve isnt operating correctly,,and it often
> doesnt,,then the changeover valve,bottom right,wont operate properly
> either.
>
> Viallant had a fetish with the 242 range of putting in two controls to
> do the job that one control would easily do.
>
> Have you checked out the method of modulating the burner on a FF
> model? it uses an air pump to top load the gas valve and control the
> pressure/flow rate. It is also a function of the combustion chamber
> pressure.
>
> Dont lash out wads on a new diverter until you are very sure,,the 242
> is a tricky beast.
Or better still. Next time get a less complicated combi. Some Ferrolli and
Keston combi's don't have 3-way diverter valves and the associated
knerpwhistles. Simpler and more reliable.
Joe, which is the simplest Vaillent control wise?
geoff
<ad...@NOSPAMmail.com> writes
>> >The "piece of equipment that moves left and right activating
>microswitches
>> >for water/central heating"???? Is this a 3-way electric valve on this?
>If
>> >so, does the end-microswitch make contact when the valve has moved over?
>If
>> >this is the case look at the electric valve, its motor or circuitry that
>> >actually opens it. Vaillant make good kit, it may the circuit that
>activated
>> >the valve. All assuming electric valve of course.
>> >
>microswitches
>> >for water/central heating", may actually be a mechanical valve. When
>there
>> >is cold water flow a diaphragm is lifted that makes a microswitch.
>Sounds
>> >like and electric one to me as the left-right is usually electric.
>>
>> No Adam, it's activated by water pressure
>
>geoff,
>
>Firstly the electrics to the microswitch must be checked (see if power is
>actually there. Then check the switch. If all OK then new valve. How old
>is the combi?
>
>
operated by water pressure on a diaphragm with a plunger which operates
the two microswitches. I was just clearing up your incorrect assumption
(see above) that it's electrical. I wasn't asking the question
--
geoff
geoff
<ad...@NOSPAMmail.com> writes
>> It sounds like you need a diverter valve kit which is available from
>> most CH suppliers - look up Heating Replacement Parts (HRPC) in the
>> yellow pages
>>
>> Be very careful to note exactly how it comes apart and what goes where
>> as you take it apart, otherwise, you could have major problems (plenty
>> of drawings)
>
>still works out cheaper than getting a professional.
>
more. If you're careful, it's not a difficult task (even a CORGI fitter
could do it with a minimal amount of assistance), but it is worth
making a few sketches to refer to during reassembly
--
geoff
geoff
<ad...@NOSPAMmail.com> writes
>
>Or better still. Next time get a less complicated combi. Some Ferrolli and
>Keston combi's don't have 3-way diverter valves and the associated
>knerpwhistles. Simpler and more reliable.
>
>Joe, which is the simplest Vaillent control wise?
>
>
I thought that you were all for the more hi tech boilers
BTW - Vaillant and Ferroli
- -
--
geoff
Adam
geoff,
High efficient boilers with good design. Good design is generally simple and
elegant. For e.g, a condensing Keston is very simple, very efficient and
reliable. They started from scratch and came up with a superb design, a
spiral tubed heat-exchanger with the burner at the top. The latest one,
just about available, the Celcius, is a modulated burner version of it.
Another example of good design that will even make an old cast-iron boiler
system more efficient, is the programmable thermostats. In virtually all
cases £50 well spent.
Roger Chapman
from "Adam" <ad...@NOSPAMmail.com> contains these words:
> They started from scratch and came up with a superb design, a
> spiral tubed heat-exchanger with the burner at the top.
Theory would suggest that you get a much better result if you put the
object to be heated above the burner rather than below.
HTH
Roger
Adam
"Roger Chapman" <r.ch...@zetnet.co.uk> wrote in message
news:200010130...@zetnet.co.uk...
As it is forced via a fan that is irreevant. The boiler is a one piece heat
exchanger condenser. The condensate runs down the heat-exchanger insides
and washes it. There is no need to clean a cpondensing Keston.
Many condensing boilers are bodges of existing systems boilers. They take
an off-the-shelf heat exchanger and put an aluminium one on the flueway that
condensers. The main heat exchanger still needs cleaning. Keston started
their heat-exchanger design from scratch making it an efficient one-piece
unit. Their claim to fame was that it doesn't require an electronic control
box the exchanger is so efficient. And simple.
Tony Bryer
> Theory would suggest that you get a much better result if you put
> the object to be heated above the burner rather than below.
I had a good look at the Keston boilers at the last Interbuild, and
was impressed. What you say is what one would instinctively think,
but (as Adam says) the gas/air mix is blown in downwards from the top
and the products of combustion can only escape at the bottom. Thus
the flue gases that leave the combustion chamber are the coolest, and
the arrangement lends itself to a condensing boiler.
Although Adam dismisses SEDBUK (www.sedbuk.com) efficiency ratings,
the Keston boilers are up there at the top - the large domestic/
small commercial Keston 170 is, by my reckoning, the most efficient
boiler listed with 91% seasonal efficiency, and the other Kestons at
just under 89% are up there with the best; their new Celsius has yet
to be added to the database but Keston are quoting a figure of 90.8%
which will make it the number 2 in the boiler efficiency league table
So whether burning downwards ought to work or not, it does. The Bosch
Greenstar combi at 91.3% uses the same system,
--
Tony Bryer SDA UK 'Software to build on' www.sda.co.uk
Mark
>
> P.S. Vaillant are in the process of making a rectification call to many of
> their boilers as they found a defect which could lead to a dangerous
> situation arising. While on the phone you may care to quote the serial
> number of your boiler to them to find out if yours falls into this
> category.
This mod only applies to open flued boilers.
Adam
Adam
news:VA.00000e5...@sda.co.uk...
> I had a good look at the Keston boilers at the last Interbuild, and
> was impressed.
> Although Adam dismisses SEDBUK (www.sedbuk.com)
> efficiency ratings,
I don't dismiss them, I am weary of them and don't take them for gospel.
For e.g, a system boiler connected to a thermal store would work very
efficiently for 95% plus of the time as it is at full temp and not cycling.
Not many boilers are connect to thermal stores. You find a SEDBUK 83% rating
many be over 90% when connect to a store. The standing heat loss through
the store is another matter.
> the Keston boilers are up there at the top -
> the large domestic/small commercial Keston
> 170 is, by my reckoning, the most efficient
> boiler listed with 91% seasonal efficiency,
This extracts so much heat from the flue gasses that only 2.5 inch normal
plastic drain pipe is used for the flue. The boilers are cheap, but not that
expensive either. I consider them value for money. But!! If you have an
awkward boiler silting, maybe well away from an outside wall, with a
complicated flue arrangement then these boilers work out cheap overall to
install. Long extension flues and elbows by some makers, make this an
expensive proposition even though a boiler is well priced.
> and the other Kestons at
> just under 89% are up there with the best;
> their new Celsius has yet to be added to
> the database but Keston are quoting a figure
> of 90.8% which will make it the number 2
> in the boiler efficiency league table
I am surprised. the modulating burner was supposed to prevent boiler
cycling, which Kestons were famous for (they said it did not impair
efficiency) and match input closely to output. Using one with a
programmable thermostat with built-in anti-cycling function would improve
matters.
> So whether burning downwards ought to work
> or not, it does. The Bosch
> Greenstar combi at 91.3% uses the same system,
A few other also do. Mainly the top makes, and most tend to be very
efficient.
Adam
> On Thu, 12 Oct 2000 10:58:23 +0100, "Adam" <ad...@NOSPAMmail.com>
> wrote:
>
>
> >Or better still. Next time get a less complicated combi. Some Ferrolli
and
> >Keston combi's don't have 3-way diverter valves and the associated
> >knerpwhistles. Simpler and more reliable.
> >
> >Joe, which is the simplest Vaillent control wise?
> >
> pleasure to work on .of course i found it rare that they went wrong!!.
> The 242 range,even though they are complex,are pretty damn reliable!!
joe,
Which of the current range are good? Especially the combi's.
>
John
> the combustion heat exchanger on a CF vailliant sine 18 must be
> removed and washed through to clear any debris from the fins. I have
> come across many sine 18;s which are regularly serviced but upon which
> this process has not been done. On inspection it appears that the fins
> are clear but any build up causes excessive resistance to the POC
> through the fins leading to spillage of products of combustion/sooting
> up etc. I have known ambulance/hopsital cases becuase of this.
> Presumably,becuase they cant pursuade engineers to service them
> properly,they are going to fit some kind of vitiation/spillage
> detector??
>
From questioning Vaillants techie service dept apparently they found that
there was a problem with many of these boilers being installed with an
inadequate gas supply. This led in some cases to the gas regulators being
screwed down beyond the regulation range and if the gas supply then was
improved the boilers were overgassed. The mod apparently is to fit a
restrictor into the gas way to prevent said problem. In my area Vaillant
had sub-contracted this work to BG
As to the wisdom of producing a boiler that requires the heat exchanger to
be removed and washed (including a drain down and new seals to boot) as
part of a routine service - I'll let others pass judgement on that!
--
Please note antispam measures - do not hit reply
Horse sense is what horses have that makes them not bet on people - W.C.
Fields
Regards,
John
Bhupesh Parekh
Hi,
Reading this thread I am hoping that someone here can provide answers to this
problem I have with my Vaillant combi.
It seems that when you turn the hot tap you have to turn it on quite fast inorder
for the boiler to kick in. The boiler is downstairs in the kitchen and I think
that therefore the kitchen tap is OK with this (ie provide you turn that tap on
fat enough the boiler heats the water). But upstairs sometimes even with the tap
on full the boiler does not heat up.
I have had the water pressure tested by the Anglian who say that it is OK (shared
with next door but OK). If the neighbours have their tap on then we cannot get
hot water (as the flow goes down).
I cant seem to remeber when this problem started, but I would think that you
should be able to trickle the hot water tap and still get hot water. Currently we
have to have the hot tap on fast for ages in order to get hot water.
I am hoping to call out an engineer so please any specific technical info would
be useful(checks etc) so i can pass this on to him.
Many thanks
Bhupesh Parekh
bhupesh...@hotmail.com
Brett
"Bhupesh Parekh" <bhupesh...@hotmail.com> wrote in message
news:3A1BFF63...@hotmail.com...
A mate with the same bolier had exactly the same problem. The microswitch
is indeed the problem.
--
Brett
I'm moving to Mars next week, so if you have any boxes...
Thomas Prufer
<bhupesh...@hotmail.com> wrote:
>I cant seem to remeber when this problem started, but I would think that you
>should be able to trickle the hot water tap and still get hot water. Currently we
>have to have the hot tap on fast for ages in order to get hot water.
It may be a problem with the combi itself, but there are a few simple
things that you can check first. The flow rate is too low for the
boiler to realize you want water. This can be scale buildup in the
heat exchanger (which I'd think most likely) or some switch or
diaphragm on the blink.
But it can also be some other restriction in the pipework between the
mains, combi and hot water tap. Check to see if all the valves etc.
are opened fully -- while you're at it, close the valves and open them
fully, close again just a bit so it's not jammed open. This will keep
the valves moving easily if you do it every so often, maybe once or
twice a year. If there's some sort of filter thing in the mains, see
that it isn't full of rust, and perhaps flush it. Trun the
temperature selector (if your combi has one) to full hot. If you have
some sort of sieve at the end of the tap spout, take it off and drop
it in descaler or vinegar until it is clean. Turn on the tap full with
the sieve off to flush any crud, rust, or scale out of the pipework.
Hope this helps,
Thomas Prufer
Dave Hannigan
They dont last forever and even a pinprick will stop the diverter from
working. Flick the microswitch with a screwdriver and if the boiler fires
then the diaphram is the problem
"Bhupesh Parekh" <bhupesh...@hotmail.com> wrote in message
news:3A1BFF63...@hotmail.com...
>
> Hi,
>
> Reading this thread I am hoping that someone here can provide answers to
this
> problem I have with my Vaillant combi.
>
> It seems that when you turn the hot tap you have to turn it on quite fast
inorder
> for the boiler to kick in. The boiler is downstairs in the kitchen and I
think
> that therefore the kitchen tap is OK with this (ie provide you turn that
tap on
> fat enough the boiler heats the water). But upstairs sometimes even with
the tap
> on full the boiler does not heat up.
>
> I have had the water pressure tested by the Anglian who say that it is OK
(shared
> with next door but OK). If the neighbours have their tap on then we
cannot get
> hot water (as the flow goes down).
> I cant seem to remeber when this problem started, but I would think that
you
> should be able to trickle the hot water tap and still get hot water.
Currently we
> have to have the hot tap on fast for ages in order to get hot water.
> I am hoping to call out an engineer so please any specific technical info
would
> be useful(checks etc) so i can pass this on to him.
>
> Many thanks
>
> Bhupesh Parekh
> bhupesh...@hotmail.com
>
>
Bhupesh Parekh
I have heard many people suggest the diaphram.
Where abouts is this microswitch? Perhaps I'll have a go at testing it myself
Is there some sort of flow detector of some kind that could be a problem. I say this
sincce I seem to have to turn that tap on very fast in order to heat water.
Finally does anyone have problem that the boiler heats the water up too much
(scolding!)
Any average quotes for fixing the diaphram would be very much appreciated.
Many Thanks
Bhupesh Parekh
Simon Ashley
Combi. It cost about £130 for the unit and fitting.
The water just stopped coming on. I managed to get it going by pushing the
lever on the diaphram mechanism (with a small screwdriver) which swiches the
hotwater on by switching the microswitch. If, when you press this lever and
the hotwater stays on then it sounds like a problem with the diaphram.
Simon.
Bhupesh Parekh <bhupesh...@hotmail.com> wrote in message
news:3A1E37AF...@hotmail.com...
geoff
<simon....@zoom.co.uk> writes
>I've just recently had a new diaphram fitted on my 3 year old Vaillant
>Combi. It cost about £130 for the unit and fitting.
I think that the kit which contains the diaphragm costs about a tenner
>
>The water just stopped coming on. I managed to get it going by pushing the
>lever on the diaphram mechanism (with a small screwdriver) which swiches the
>hotwater on by switching the microswitch. If, when you press this lever and
>the hotwater stays on then it sounds like a problem with the diaphram.
>
>Simon.
>
--
geoff
Dave Hannigan
entire diverter valvenews:MO0Z8dBR...@cetltd.demon.co.uk...
Simon Ashley
time). The boiler man told us we'd be better off changing the whole unit as
he'd have to take the whole thing apart to see if it was the daiphram, and
there was a chance it may have been something else.
Where can you get the kits from and does anyone know how to service a
vaillant combi boiler, including descaling?
SimonA.
Thomas Prufer
<simon....@zoom.co.uk> wrote:
>Where can you get the kits from and does anyone know how to service a
>vaillant combi boiler, including descaling?
I'll take the descaling: There's the temperature control knob in the
bottom middle front. The stem goes back into a flat metal mixer
thingy, with a pipe going into it on the left and right sides. These
are the ones you want to hook up to. Standard thread, they are.
You'll need a bucket of acetic acid, diluted down to 10-20%, several
liters. Then one of those pumps driven off a drill -- this should be
reversible. Mount it on a board and clamp it down for convenience.
Then hosepipe, preferably clear so you can see what's coming out,
clips, and appropriate fittings to connect to the threaded nuts on the
pipes. The drill pumps can build up considerable pressure, so get it
tight to avoid acid all over the place. The pipes are sealed with
fiber washers (if I recall correctly) -- you'll want these, and the
ones that go on the other ends of these two pipes. Moving these pipes
so you can get clearance may require loosening the nuts at the other
ends, or the washers may start to leak just from moving the pipes a
bit. You want the washers beforehand, starting without when the shops
are closed will guarantee leaks! Set the temperature thing to full
hot.
Connect the pump to bucket, pump to one pipe, other pipe to a drain
hosepipe. *Slowly* start pumping acid through the system. The scale
will foam and gas, and the pipe will want to jump from the bucket
spraying acid, so be warned. Pump it both ways, too, loose bits of
scale will try to clog the heat exchanger. You pump acid through the
system until it stops foaming and until the acid turns blue, which is
a sign the copper is being attacked. Check to see if the acid is still
"live" by dropping a bit of eggshell in: the acid may be neutralized
before all the scale is reacted away.
The newer Vaillant heat exchangers on the combis have many small tubes
inside -- these are black plastic on the outside. My Vaillant service
man doesn't ever descale these, as he says that occasionally it will
pump through ok, but some of the tubes will be clogged up with scale
and loosened scale. No way of checking unless you saw one in two. So
he replaces them, as not being much more expensive, better value for
money, and something he can guarantee. So be warned that the thing can
clog, though judicious pumping back and forth will help avoid this.
He'd also mentioned that there would be available an new heat
exchanger made from some alloy commonly used in industrial heat
exchangers that scale doesn't stick to well. I haven't seen him since,
and Vaillant didn't know anything about it when I called their
distributor (this doesn't mean much).
Replace washers and reassemble, done.
My service man's service also consists of removing the burner assembly
off the jets, rinsing with water and detergent, brushing out the
(flame) heat exchanger fins, vacuuming all the crud out, generally
getting the dust bunnies and dirt out. Nothing you can't do yourself
with a long-handled brush and standard vacuum attachments.
There's more, but this is stuff I always let him do: testing the
various safety features (this involves unplugging different sensors
and grunting), checking the maximum heat setting by looking at the gas
meter with the combi full on, and a flue gas analysis for CO, CO2 etc.
You could also get ingenious and pump acid through the system using
the existing pipework: shut off the mains, acid in the hot tap, out
some other cold tap, thus not having to fool with new washers and all.
Don't do this. It is probably illegal to pump acid through drinking
water pipes anyway. Also, it will remove the thin layer of protective
scale from iron pipes and you will have rusty water for a few months
until it builds up again. I know.
Thomas Prufer
geoff
<simon....@zoom.co.uk> writes
>I wish I'd known that at the time. I would have done it myself (I will next
>time). The boiler man told us we'd be better off changing the whole unit as
>he'd have to take the whole thing apart to see if it was the daiphram, and
>there was a chance it may have been something else.
>
>vaillant combi boiler, including descaling?
>
>
Now is not a good time to be doing a descale unless you need to. If you
do have problems you can't handle, bits you need etc, it's not a good
time to be without heating.
You could also have a problem with the Calorifier (or secondary heat
exchanger) if it is the old type (black plastic). A descale could cause
it to leak and you would have to get a new (sardine can) replacement -
not cheap (~£150??) and not usually in stock at your average CH
merchants. Worth waiting for warmer weather for if you don't need to do
it.
It could be worth cleaning out the combustion chamber with a vacuum
cleaner (including the jets and heat exchanger fins)
(Henry not Dyson)
--
geoff
geoff
<pru...@i-dial.de> writes
>>vaillant combi boiler, including descaling?
>
>bottom middle front. The stem goes back into a flat metal mixer
>thingy, with a pipe going into it on the left and right sides. These
>are the ones you want to hook up to. Standard thread, they are.
On all the Vaillants I've come across, the temp control is a
potentiometer, do you mean the diverter valve ?
>
>You'll need a bucket of acetic acid, diluted down to 10-20%, several
>liters.
In the UK, the most commonly used descaler is Fernox DS3 I think
--
geoff
geoff
<pru...@i-dial.de> writes
>On Wed, 6 Dec 2000 19:51:42 +0000, geoff <ge...@cetltd.demon.co.uk>
>wrote:
>
>
>I used a commercial descaler once. The pressure from the pump popped a
>hose off, as I hadn't anticipated the pressure the pumps can generate
>and the violence of the chemical reaction. The damn descaler went
>everywhere, and left small brown spots on the cabinets, ceiling, and
>wall. Repainted, replaced one cabinet front (I'd kept some spare
>material), rubbing the stains out... I've promised myself to treat
>myself to professional descaling henceforth and let the serviceman do
>it now. I have found a well-trained, thorough, well-equipped man, so I
>feel I'm getting value for money. I do still vacuum the inside of the
>combi every so often; this leaves the serviceman more time to be
>thorough in adjusting.
>
>Acetic acid won't stain AFAIK, and is cheap -- I found a restaurant
>supply house (of all places) nearby that sells it for 8 DM (2UKP) for
>a litre at 80%.
>
>
>Thomas Prufer
Actually, I use inhibited Hydrochloric acid, much more entertaining when
a hose comes off (But then I 'm doing it to a removed heat exchanger in
a factory environment)
--
geoff