Worcester 240 Combi no hot water

[raze1000]

Hi all
Central heating is fine, hot water is only slightly warm.
I replaced the whole diverter valve last year because i was trying to find another fault (boiler clicking on and off and C/H not always kicking in) which proved only to be the c/h sensor.
I now only get lukewarm to cold water even though the boiler is firing up as normal.
I checked the diaphragm to see if it had got clogged or stuck so drained the system etc removed the 8 screw part of the diverter valve. It was all clean as a whistle and diaphragm not stuck or deteriorated.

Is it possible that the rear part of the diverter valve may be stuck as i only checked the diaphragm part this time as it is a fairly new complete valve.
Is there a part in the diverter valve apart from the diaphragm that could get stuck and cause C/H to work and water not getting fully hot?

When the tap is opened the the valve does push the plunger onto the micrswitches to fire up the boiler but as i said earlier no hot water.

Any help much appreciated.
Ray

 

[newbie1]

are the contacts on the microswitches working and def making contact with the pin..try by manually pushing the microswitch does it fire the boiler up and give hot water

 

[Deleted member 2053]

If the boiler is running at full tilt all the while the hot water tap is open then it must be losing the heat around the CH system which suggests a problem with the diverter. Try it with a cold heating system and test the CH flow pipe from the boiler when calling for hot water.

 

[raze1000]

Just replaced diverter valve.

Now i get hot water.
When C/H is on the return pipe is cold and downstairs rads are only warm, boiler shuts off after a couple of minutes and kicks back in again after a couple of minutes and keeps cycling like this.
I removed all air from system. Shut off upstairs rads and got 2 rads hot downstairs and the other warm.
Still the return pipe is not hot.
When hot water is run, the water is hot but the C/H flow and Return pipes are red hot.
Pump is running ok.

Would this mean the new Diverter may be stuck?

Doing me head in now.

Ray

 

[Deleted member 2053]

Have a look inside the pump. Cycling like that usually means poor circulation. It's even worse when you get a clever boiler like a Vaillant. As soon as the flow temperature is 30 degrees more than the return the thing shuts down to minimum flame and waits for 20 minutes. When I have a day or two to listen to their telephone answering system musack I might ask their tech dept if there is any secret way of changing the parameters!

 

[raze1000]

cheers graham.

Decided to call it a day after faffing around.
Just got British gas in on a fixed price £127 inc parts and labour. Had to join the £2 a month member scheme but can cancel at anytime.

Guy came and reckoned the new Diverter Valve is duff so he's changing that tommorow. Would have cost be £90 for a new bosch dv anyway so hopefully all will be sorted for not too much extra.

Thanks for your help anyway

Ray

 

[raze1000]

Update.
The new diverter valve worked and is still working today.

 

[Terry_the_piper]

Just a note to raze1000. yer vaillants have a partial load setting at installer lever which is normally on auto. You can reset it to what you want in kw. depends what set up you have. Last one I did was an 831 on an underfloor and it had to be on max (24kw) to work properly. Different Vaillants set up slightly differently so check manual.