* VAILLANT VCW 242 CH HEATING NOT WORKING!! PLEASE HELP *

[xpressbuyer2day]

Hi all,

I'm new to this site and it seems like a cool place. I was wondering if anyone could help with my CH problem. I have a Vaillant VCW 242 boiler and have had the DHW Heat Exchanger changed due to a pin hole leak in the plastic and have just had the Main Heat Exchanger changed aswell due to a leak.

The boiler is 16yrs old and now the CH system is not working properly . Sometimes the boiler goes on and the CH gets hot very well, but often the boiler is making a noise but the flame isn't coming on. The pump is working, and DHW works perfectly. This has been happening on and off for apx 3 weeks.

Now, the CH doesn't work at all. When the CH switch is turned on the boiler makes a noise but fails to light up. I don't know whats wrong, I think it might be some sort of thermostat or something which is supposed to check that the water needs to be heated.

Any help will be most appreciated,

Roger

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[bengasman]

try to find out if it is the pump you hear, or the fan.

 

[xpressbuyer2day]

ok i'll try .....

 

[scatmanjohn]

If you know where the diverter valve is have a look to see what happens to it when you run the heating.

 

[Agile]

Hi all,

I'm new to this site and it seems like a cool place. I was wondering if anyone could help with my CH problem. I have a Vaillant VCW 242 boiler and have had the DHW Heat Exchanger changed due to a pin hole leak in the plastic and have just had the Main Heat Exchanger changed as well due to a leak.

Have you called back the person who changed the parts for you?

What does he say?

Tony

 

[xpressbuyer2day]

ok, the pump and fan both work.

the engineer is telling me I need a new boiler. (I've spent a lot of money on my boiler and I think it has a couple of years left on it so I wanna fix it)

I do know quite a bit of DIY, so I'm not a complete amateur...

I've checked the diverter valve and nothing happens when I put the hot water on and nothing happens when the CH is switched on either.

any ideas anyone?

 

[weareleeds]

Make sure ALL of the impulse pipes are clear & change servo valve

 

[Agile]

Has it worked at all since the main heat exchanger was changed?

He sounds a cowboy if he changes an expensive part and THEN says you need a new boiler.

Chances are he is incompetent and does not know how to find the fault. There are lots like that about!

Tony

 

[Agile]

Has it worked at all since the main heat exchanger was changed?

He sounds a cowboy if he changes an expensive part and THEN says you need a new boiler.

Chances are he is incompetent and does not know how to find the fault. There are lots like that about!

You could measure the resistance cold of the temperature sensors.

Tony

 

[bengasman]

Make sure ALL of the impulse pipes are clear & change servo valve

first clear the pipes and check.
then see if you can adjust the valve, can not remember if you can or not on this model, but should be obvious
see what happens if you operate dhw switch manually.

if your rgi first charges a lot of dosh to replace both h/e and then tells you, you need another boiler, he is a cowboy

i also expect a lot of dirt in your system if your primary h/e has gone. try to fush it out using the mains. procedure is described on various threads.
follow up with hyperflush treatment when the boiler is running

 

[xpressbuyer2day]

ok so now that I've found all the mentioned components in my boiler I have used the manual and have checked and found that the diverter valve does not move when the CH is switched on....

The manual tells me to remove air in system, I done this by getting rid of air in the radiators....

So now the manuals says it could be a prob with the servo valve....

The servo is slightly corroded and has been like that for ages (apx 1yr).

I will order a new servo valve and will change this just to be sure...

Prior to the change of my heat exchanger I had some weird noises coming from the boiler and was told it was limescale or sludge causing a blockage, so, all of you who says something might be blocked, I agree with you. Only thing is, how do I check if these impulse pipes are clear??

Once the Heat exchanger was changed it worked on and off, just as before...

Last thing I wanted to clear up was;

Does the servo valve move mechanically when the DHW is turned on and also when the CH is switched on? because I have only seen it move when the DHW is turned on.

 

[xpressbuyer2day]

ive been reading some stuff on the site and I was wondering if it would be worthwhile if I check and replace the diaphragm within the water section....

 

[namsag]

The diaphragm in the water section doesn`t have anything to do with the heating side, but the pin that it pushes up to activate the servo valve can get scaled up and not move properly and so can stop the servo going fully back to rest position thus stopping the heating coming on.
So when changing the servo split the water section take the pin out clean it and grease it and as you have it apart you may as well change the diaphragm

 

[DP]

You will be wise to call someone who knows this boiler. The operation is quite complex. Do not buy parts needlessly. Do not get someone to change parts without good cause. If parts have been changed and boiler still fails to work, it can only be assumed, a little bit of guesswork was involved instead of good solid detective work.

Post your location. One of the regulars may come forward and breath life into your boiler. Good boiler. Get ride of 'boiler replacement' brigade instead.

 

[xpressbuyer2day]

Sorry Namsag, I think I meant diaphragm in the diverter valve. I'm quite new to all this terminology and i'm causing confusion.

What I've just done is I removed the diverter valve switches bracket and saw this little stick which is connected into the diverter valve. i tried to move the stick, it was slightly stiff, (dunno if it's supposed to be like that)

I was thinking of trying to get to the diaphragm but I'm gonna wait to see wot u all think....

thanks,

Rog,