Programmer fault/wireless stat wiring?

[Chester]

Hi guys, I have a fault on a clients heating system whereby the heating will stay on regardless of what the programmer is doing on its timed function, it'll switch off at the programmer (no light) but boiler will stay on until they turn the stat down, I went and looked at it, they said they weren't sure whether it's ever worked correctly on timed function (handy) it has a Honeywell 2 channel programmer and a Honeywell wireless non programmable room stat not the same models, I thought it was because it had been linked out incorrectly at the receiver unit on the stat, I tested it on its timed function and it switched off and on and so on after removing the weird link and thought happy days, but now they called me back after a day of it working fine saying it continues to stay on even when the programmer is set to auto but off time, saying it came on middle of the arvo? Thinking about it.. (I'm now confusing myself) - are the programmer and stat even compatible, as the wireless stat is constantly supplied a live connection and can essentially switch the zone valve independently of the programmer. The programmer is st9400c and a Honeywell wireless stat and receiver (circular one that looks like a nest). Could someone more electrical savvy than me shed some light as to how it's supposed to be wired, I understand s plan wiring etc but this has really confused me. TIA

 

[Murdoch]

Sounds like a faulty zone valve TBH.

very common fault

 

[Chester]

Sounds like a faulty zone valve TBH.

very common fault

This is what I initially thought it was but it seems to move fine manually, the brown is definitely being signalled to hold it open

 

[Murdoch]

This is what I initially thought it was but it seems to move fine manually, the brown is definitely being signalled to hold it open

The fault is probably the micro switch in the zone valve - providing power all the time

 

[Chester]

The fault is probably the micro switch in the zone valve - providing power all the time

But the Zone valve brown signalled from the stat is live?

 

[Deleted member 120897]

But the Zone valve brown signalled from the stat is live?

Is this live from a demand from the programmer or no demand? If no demand, then it’s likely a wiring fault or the programmer.

 

[Chester]

Is this live from a demand from the programmer or no demand? If no demand, then it’s likely a wiring fault or the programmer.

It remains live regardless of the programmer timings, until they turn the stat down it doesn't stop they say. Although when I was there I set the timings and waited until it clicked off and it did in fact switch off when it was supposed to so I'm led to think the programmer is at fault. I guess I'm more confused as to how an RF stat is supposed to be wired up on a 2 channel without a built in reciever.. as they say now this has never worked properly.

 

[Deleted member 120897]

Wiring could be done at the wiring center for the receiver. As for this live, has it been tested for voltage?

 

[Chester]

Wiring could be done at the wiring center for the receiver. As for this live, has it been tested for voltage?

Yes it was tested when the programmer was in an off time period, yet in the loft where the wiring centre is unfortunately, the pump was on (wired into the switch lives in wiring centre) and the 2 port was open still..but I will double check again before I make any alterations. Let's just assume it is receiving demand from prog/stat. The wiring is definitely not great at all, would really like to put this issue to bed. Could you explain the reciever wiring to me on here? The reciever back plate is N|L|L|A|B|C. Thanks

 

[Murdoch]

Has it ever worked properly?

Do you have any electrical test kit?

 

[Chester]

Has it ever worked properly?

Do you have any electrical test kit?

They say they're not sure but I suspect it hasn't. Yes i have all kit

 

[Murdoch]

You need to determine where the 230vv is coming from ........... not too tricky if you have access to the wiring centre

 

[Deleted member 120897]

Could you explain the reciever wiring to me on here? The reciever back plate is N|L|L|A|B|C. Thanks

Yes sure, obviously L and N self explanatory. Depending on the switching and how the installer has wired it, there might be a link to take 230/240vac to the abc side of the receiver, but unlikely in this setup. Then A will be your common supply (live in) and B is usually Switched live (live out/return path), C is rarely used.

 

[Chester]

You need to determine where the 230vv is coming from ........... not too tricky if you have access to the wiring centre

I have accessed the wiring centre, there is 240v coming up from the programmer/thermostat in fault state. This might be a silly question but how does an RF stat with a permanent live supply to the receiver not override the programmer on timed? I understand that the receiver is hard wired in and the switching is done internally, but the part I'm confused on as I've always just fit combined units is how the programmer has any control in this instance over the heating as the thermostat doesn't need supply sent from the programmer to operate as normal?

 

[Chester]

Yes sure, obviously L and N self explanatory. Depending on the switching and how the installer has wired it, there might be a link to take 230/240vac to the abc side of the receiver, but unlikely in this setup. Then A will be your common supply (live in) and B is usually Switched live (live out/return path), C is rarely used.

Thanks, the installer had linked a permanent live from the L and N side of the stat to A I believe it was, I don't think it's necessary in this scenario.. however in the manual it says do this on a 2 port but absolutely no mention of programmer's etc. The bit I don't understand in this situation is how does the RF stat get controlled by the programmer for heating times? It seems to me it's completely independent of the programmer? Unless I'm missing something?

Okay thanks guys, upon looking at wiring diagrams I now understand where I'm going wrong. I need to brush up