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jaydebruyne

Plumbers Arms member
Plumber
Gas Engineer
Apr 6, 2014
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London, UK
Member Type
Heating Engineer (Has GSR)
Went to a job today. Tenant complaining that the rads were getting hot when the room stat was off.

Y plan system fully pumped, old potterton heating only boiler.

On investigating I found that the programmer had been wired so it gave a permanent live to the room stat regardless if the heating was set to on, auto or off. BUT the room stat was functioning fine.

3 port was functioning fine, I.e was opening easily and was firing up the boiler when put in demand by the room stat. Got correct voltages from the white, orange and grey when in demand on heating only etc.

Took the face off the programmer and boiler was still firing up.

I think the programmer has been wired wrong personally but what else could or should I have checked?
 
I thought that, but since the rads/pipework were already hot how could I confirm this?

Feel the htg side or the 3port you'll feel the temperature increasing as it creeps through. If it's a relatively new fault it would point to the 3 point rather than wiring.
 
Plus, since I took off the programmer surely there should be no demand on the boiler unless there was a wiring issue, no?
 
Feel the htg side or the 3port you'll feel the temperature increasing as it creeps through. If it's a relatively new fault it would point to the 3 point rather than wiring.
Not sure how new the fault is as the tenants weren't in..
 
If it fired with the clock face off there must be a live feed in a junction box somewhere giving it power through the valve. Just work through the wiring and ask her what work has been done recently.
 
Not if the clock face is off and it still fires. No perm live on a mid pos.
Wiring fault at a box somewhere and as its an old system its something that has been recently done or a new tennant.
 
might be best to start again and re wire the thing

512px-Y-Plan-Wiring.gif
 
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Just come across something similar , fully pumped system, tenant complaining that hot water & heating always hot, same as you old boiler, (Ideal classic) turns out that boiler was wired with a permanent live even when turned off at isolating switch in cupboard, boiler would fire every time boiler stat cooled down, so check that boiler only needs switched live, the old classic boiler terminal inside was marked L.N.E but live in these boilers should be switched ! can be dangerous , you think power is off but boiler still live
 
Not if the clock face is off and it still fires. No perm live on a mid pos.
Wiring fault at a box somewhere and as its an old system its something that has been recently done or a new tennant.

Hw off gives live to valve.
 
Hw off gives live to valve.
But that's not a permanent live. Its dependent on the programmer.. Unlike a 2 port which has a dedicated permanent live.

I think its a wiring issue stemming from the programmer.. That's what I'm writing in my report.

I'll let you know what happens...
 
But that's not a permanent live. Its dependent on the programmer.. Unlike a 2 port which has a dedicated permanent live.

I think its a wiring issue stemming from the programmer.. That's what I'm writing in my report.

I'll let you know what happens...

report can you fix it ???
 
Nah to be fair, I've only just got to grips with the theory of mid positions and 2 ports.. It wouldn't be economical to send me to do a rewire unless we were quiet, but we are stupidly busy at the no so its all about getting the jobs done asap...
 
Nah to be fair, I've only just got to grips with the theory of mid positions and 2 ports.. It wouldn't be economical to send me to do a rewire unless we were quiet, but we are stupidly busy at the no so its all about getting the jobs done asap...

it might not be economical on this one but i bet the next two or three would as you have learned on the first on
 
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