The Vaillant 242 saga continues

[dfarry]

Hi all...

Yes it's me again and hoping once more for helpful advice and assistance.

My Vaillant 242 has not been too happy of late... Most recently the DHW was the problem but back at January that problem was fixed (for how long I have no idea though). This was the outcome of that problem //www.diynot.com/forums/viewtopic.php?t=74857&start=35

Anyway today it seems we have no heating.

The DHW remains fine... the boiler fires up and the temperature is very hot. But with the heating on the boiler makes it's usually whirring noise but does not fire up. I also noticed that the boiler temperature was at about 60 degrees but then rapidly decreased to zero (I assume this may be because the pump is pushing around cold water). The boiler pressure is at a stable 1bar.

Apart from calling the boiler engineer who came here last month I have no idea what else I can do - any initial thoughts please folks?

(Bleddin' boiler, it's going to stuff my plans to get a new motorbike)

 

[kevplumb]

servo valve is sticking or the pin in the water section is

 

[Agile]

That fellow you had was very reasonable and seemed totally competent.

I suggest you call him and perhaps to remind him to bring a 3/4" PRV as he did not have one before.

If there really is no trace of water on the PRV vent then perhaps you could drop that.

There are many things on your model which could cause the problem but the main components are OK as shown by the DHW being OK.

Tony

 

[kevplumb]

There are many things on your model which could cause the problem but the main components are OK as shown by the DHW being OK.

are you well ****ed

 

[dfarry]

Thanks Agile/Kev...

There has been some leaking from the PRV vent, but the pressure remains at 1bar.

Also the Filling loop is 100% disconnected and even capped!! so the system is fully sealed.

I have emailed the fitter who came here before... and will call him early next week if I don't hear anything. Last time round the secondary exchanger was full of rusted crap but he cleaned all that out... the DHW side was as clean as a whistle. He said the rest of boiler was fine, except for the expansion tank that he re-pressurised with a compressor (apparently Vaillant used to supply you all with footpumps?)
Also when the timer kicks in the bolier seems to make all the right noises... but just no flames

 

[dfarry]

Just had a response from the guy who came around before...

sounds like the servo has got stuck, or its getting stuck. Pretty common fault, and easily fixed even if you have to replace it. Could possibly be the water section spindle worn or corroded, or even the spindle shaft dried up....

Just as Kev suggested

Unfortunately he can't get around to us for another week as he is going away... is there a easy way to check for/release the stuck servo...
If I could just get it going temporarily myself that would be a help.

Regards

DAN

 

[kevplumb]

if you know where the valve is you can press it back down

but you will have to do everytime the hot water is run

 

[Agile]

If you are adventurous you might see which switch is not quite pushed enough to make it fire up and adjust the lock nutted screw a tiny bit until he gets there.

Tony

 

[kevplumb]

If you are adventurous you might see which switch is not quite pushed enough to make it fire up and adjust the lock nutted screw a tiny bit until he gets there.

Tony

THERE IS ONLY ONE SWITCH

the two are on the diverter

 

[Agile]

If there are two on the diverter there must be three in total!

 

[dfarry]

Yup I am adventurous... and with some guidance mechanically competant (I think) lol

I can't see any apparent valves though at the moment... (probably starring me in the face)

Look directly at the boiler and all the pipe work etc under the boiler I can see for example the the pump I believe (large black round housing with a large slotted plate that can be adjusted). To the right and just behind is a bell type component - a valve or servo?... it has a valve on the top of it. Above and at the rear of the pump? is a black recangular box (possibly plastic) there is a round rubber grommit on the front, this feels like there is a switch beneath it?

Am I looking in the right area... I'll find it eventually

Cheers guys..

 

[dfarry]

ahaha looking promising.... Diverter.... to the right looks like a valve (some springs) all protected by a clear plastic cover?

 

[kevplumb]

yup that's the diverter

the servo valve which controls it is right in the middle with 3 pipes going into it

there is a cam on the back that operates the microswitch to tell the boiler to fire for water

press the back the opposite end to the switch of the cam down

and HEATING till you run a hot tap

PostPosted: Sat Feb 24, 2007 9:50 pm Post Subject:
If there are two on the diverter there must be three in total!

thank you sherlock

 

[dfarry]

Nice one guys... I took off that clear cover... and found the valve... and a slighty weird plate flapping around and sprung pushrods... I then realise that these would press onto the two microswitches when the valve rod actuates...

The rod is quite tiff but will push in. I switched the biler on and held the plate as the rod moved in... then the microswitches were pressed and the burners lit...

I'm not sure if the problem here is that the rods that press onto the microswitches need adjusting or if the the plate is not mounted properly... I'm going to take a better look in a moment.

 

[kevplumb]

I'm not sure if the problem here is that the rods that press onto the microswitches need adjusting or if the the plate is not mounted properly... I'm going to take a better look in a moment.

neither the servo valve controls the movment of the diverter

if it ain't right the diverter ain't right