Vaillant boiler problem

[divlong]

We have a Vaillant combi-boiler coming up to 10 years old. The problem is that the boiler doesn't always fire when a hot tap or the shower is turned on. We have had an engineer out a couple of times to adjust a microswitch but it's just started doing it again. We can usually get it to fire by switching it off and then back on again while the water is running - which seems a bit odd if the problem is a switch!

Anyway, we are now considering replacing it but would welcome any advice on what the actual problem might be.

CHeers

Duncan

[gucciman]

i would have said the diverter valve needs replacing but thats usually the first thing an engineer will look at so if he thinks its the microswitch then perhaps the diverter valve is ok. the valve operates under the pressure of the water pushing up a pin that operates the microswitch. the valve gets full of sludge over the years which means sometimes the pin doesn't travel up enough to make the microswitch. either that or the diaphragm in the water section of the valve is ripped stopping the pin from raising up.
its possibly could be the hot water thermister stopping the burner firing up and needs replacing.
if it sometimes works by turning the boiler on and off then it could be a circuit board problem.
vaillants are regarded as the best quality and most reliable boilers on the market. the older ones were very well engineered, perhaps too much so, for this reason there aren't many people about who are fully competent at fixing them as they simply do not understand how they work.
it may be worth calling vaillant themselves and having one of their engineers call, or ask them if they have a list of approved engineers, or look in the yellow pages for a vaillant specialist.
what part of the world are you from? my old mans red hot on vaillants but we only cover the birmingham area.

[divlong]

Hi Gucciman,

It's been doing the same thing for 3 winters straight. Two years ago we had the diverter valve replaced which seemed to fix it, but the next year it happened again and they managed to tweak the microswitch to get it working. This year they've tweaked the microswitch again but it didn't work for long.

I had to have a new circuit board ust after installation, but that was nearly 10 years ago so I guess it could have gone again. I've also had the DHW heat exchanger replaced when the water wasn't heating up properly.

Any chance that it could be something to do with the temperature of the mains input as it always seems to go at this time of year.

I've been using the company that installed it to try to fix it, but you may have a point about finding a Vaillant qualified engineer.

Many thanks for your input as I was seriously thinking about just replacing the whole thing instead of keep paying call out charges.

Incidentally the model is a Turbomax VUW 242E if that's any help. Also, we have a water softener - don't know if that makes any difference?

I'm in Tring in Hertfordshire - sadly nearly a hundred miles from your old man.

Cheers again

Duncan

[gucciman]

vaillants really are top quality boilers, the old man swears by them (he was the main combi expert at british gas west midlands for many years) 10 years isn't really old at all for a vaillant and yours model isn't one of the very old over-complicated models. i'd think carefully about replacing it as you will have to have a condensing boiler and are looking at considerable cost.
i can't see a logical reason for the temp of the incoming mains water having an effect on the boiler, saying that they are complicated machines and sometimes defy logic.it could still be the diverter valve, the trouble with putting a new diverter valve into an old system is that the new valve can soon become sludged up like the old one, to stop this you would need the system to be de-sludged i.e. a very expensive powersludge or at the least a chemical de-sludger and then a manual empty and re-filling of the system.
i stand by my earlier advce, ring vaillant and ask them how much they want to send an engineer out, they may offer a service where they come out for a fixed price like baxi's do (225 inc all parts and labout) or have a look thru the yellow pages and see if anyone mentions they repair vaillants i their ad.
and lastly, im not disparaging anyone but sometimes people who install boilers aren't that good at repairing them. we have several friends who install boilers and have to call us in to repair them as they don't have a clue so id look for a repair specialist.

[gucciman]

sorry i meant to type powerflush not powersludge!

[cfrost]

Hi, I dont have an answer for you but I know exactly what you are going through and how frustrating and expensive it is. I have a Vaillant Boiler, I am not sure how old as it was in when we moved in 3 yars ago but since the day we moved in we have had a similiar problem and always around the coldest time of year.

It starts by the pilot light going out for no reason however you just relight it and it works for a couple of days. then it does it again and you relight etc etc. Then it stays lit whislt central heating is on for about 3 hours before clicking off, but as soon as hot water goes on and it fires up the pilot light goes out. I use to dread putting the water on as you heard the click when it happened.

I am currently going through it again at the moment. We use to be with british gas and they struggled, it has had new thermo couples, mag valve, and more (not sure of spelling) and once it starts every engineer struggles to stop this problem. I have not had one person out yet who has said , ah this is the problem, they have simply changed everything on it and it has worked for few months and then started again.

I am sick of paying out money and getting nowhere. This is why I just thought I would search the web and see if anybody had any advice. Really struggling. I have had no central heating and hot water for over a week now. Had 3 different guys out cost me each time but still not fixed. Dont really want to go down route of new boiler when ahve just paid out �300+ in engeering fees to be no wiser. At least before engineers came out I had central heating every 3 hours, now they cannot get it lit at all for more than 5 minutes before just clicking off. They are saying that the flame is not high enough to touch thermo couple but there is no valve to allow more or less gas through etc.

Any suggestions?

[brumboy]

is gucciman's dad still serving vaillants?