PROBLEM WITH Y-PLAN SYSTEM

[Clipper]

I wonder if anybody can help me, I'd be most grateful.


I have just installed a Worcester 24ri system boiler which is on a Y-Plan system. Everything seems to be working fine until I turn the room stat down. The pump remains on (as it should do) but the burner also remains lit and will not go out even though there is no more demand for heating. The electrician says the room stat is wired correctly and so is the mid-position valve etc.

Has anybody come across this problem before?

 

[Rob]

Impossible to say without seeing. Its unlikely to be the room stat thats keeping it going.

Need to get someone who understands system wiring. i.e heating engineer not an electrician

 

[DP]

Not enough information.

Do you have two thermostats? Where is the live feed for the valve taken off? Does the electrician know what feed to take from where?

I think you need an electrician who is 'boiler electrics' aware or a heating engineer who repairs boiler (I say this as some installers can fit but not repair boilers)

 

[bripl]

permanant live and switched live crossed?

 

[Dan Robinson]

Are you sure the hot water is off

 

[gas4you]

Agree with Dan, you need to check whether you still have a demand coming from the HW stat.

It is certainly a wiring problem and as others say get a heating enginneer in who understands the heating and wiring. It is usually very hard to find a sparks who understands heating wiring

 

[Clipper]

Thanks for your replies. Electrician has changed the cylinder stat and also the programmer twin channel. On consultatiohn with Worcester Bosch Technical they asked for electrician to disconnect switched live to boiler control board, on testing with his meter he found voltage that sould not be there. Not 240v but 50v (approx) was present. The electrician at the end of the day (8hrs) on site, ran a three core cable from the boiler connection block to the wiring centre adjacent to pump and mid-position valve (it worked, the boiler shut off when room stat switched off!) Ready to leave site, programmer left on hot water, no heating I went to check mid-position valve and discovered radiators and hot water were both on!

Boiler still not responding to room stat command i.e not turning burner off on boiler.

 

[Dan Robinson]

I know I'm hungry so might not be thinking straight- but this sounds like a problem with the mid-position valve.

Are you sure the three wires for the cylinder stat are wired correctly?

Don't rate your sparky much (though heating electrics can be a head f*ck if you're not used to them).

 

[Gasguru]

And bear in mind than pin numbers and their designations vary from one make of stat to another.

 

[Clipper]

Problem now resolved!! It was the mid-position valve which was faulty, unfortunately had to remove the whole valve as the new head would'nt fit on valve body which meant having to drain down system again.

Thanks for all your replies.