Polypipe underfloor heating not working

[jontyking]

Complete amateur here. I had a Polypipe underfloor heating system put into a new extension 3yrs ago but the plumber who fit it is now no longer available - he's just had a career change, he didn't go out of business. It's just a single zone system connected to my main central heating system but for some reason it's no longer getting hot or even warm as far as we can tell, despite cranking the thermostat right up. We used to feel it getting warm at around 19 degrees but now nothing even at 30. The thermostat seems to respond to me turning the dial with a red LED that comes on briefly but nothing happens on the Control unit (Polypipe PB1ZM). I've replaced the batteries and when I do the LED flashes green and red a couple of times and then goes off. The only green LED on the PB1ZM control unit is the power light. The other three (valve, pump and boiler) stay red. I'm very happy to get a plumber out who knows what they're doing but wondered if it's a quick fix before I do. Seems like the thermostat might not be communicating with the control unit? Also it seems to be wired and have batteries - is this normal?

Any help very gratefully received, people with knowledge?

 

[SJB060685]

How competent are you with a multimetre? Above is a wiring diagram for said unit. I would be testing whether you have feed to and from stat in wiring centre and then to zone valve if fitted.

 

[jontyking]

View attachment 42390

How competent are you with a multimetre? Above is a wiring diagram for said unit. I would be testing whether you have feed to and from stat in wiring centre and then to zone valve if fitted.

Thanks very much for taking the time to reply. The answer is not very! I've got an electrician coming to take a look on my previous plumbers recommendation as he thinks its a communication error between the thermostat and the control unit. I've never bee that fond of the thermostat anyway as I'd rather have a programmable one so hopefully it's just that. Thanks again for taking the time to reply - much appreciated.

 

[Brambles]

Your thermostat appears to be hardwired to the control unit. Presumably it has not been configured with an RF unit (which is then hard wired to the control unit).

Polyplumb are not the best bits of kit around for controlling a UFH.

If you want to test the system without the thermostat - to confirm the problem - just link across C and 1 in the control unit and the system should fire up and feed the UFH zone. If that works I would consider getting a better thermostat - either hard wired or through an RF link.

Isolate the power before linking C and 1 - there is a 240v supply in the control unit. If in any doubt get a competent person to look at it.

 

[Brambles]

The thermostat wall unit should only have the batteries fitted if it is being used with an RF receiver.

 

[SJB060685]

Thanks very much for taking the time to reply. The answer is not very! I've got an electrician coming to take a look on my previous plumbers recommendation as he thinks its a communication error between the thermostat and the control unit. I've never bee that fond of the thermostat anyway as I'd rather have a programmable one so hopefully it's just that. Thanks again for taking the time to reply - much appreciated.

Your post has only just become visible due to you being a new user and comments need approving.
If you're not confident with a multimetre then please don't fiddle, theres no shame in that and electricity is a killer after all. Like Brambles and I have said it's most likely the thermostat, this can be confirmed either with a multimeter or linking it out with a short wire. Pass this information on to the electrician and he should have you up and running in no time if you need a new stat. Brambles here is the man when it comes to these so maybe he can advise you on a replacement.

 

[ShaunCorbs]

have you tried pushing the switch down on the room stat eg from the sun to the power eg on

 

[EvilDrPorkChop]

The pump light on the Wiring controller is on, yet theres no green light on the pump. So i'd hazard a guess that it's the pump thats gone or the Wiring centre isn't supplying 230v to the pump.

Without the pump the system won't work at all.

 

[jontyking]

Thanks so much everyone for taking the time to help - much appreciated. I’ll leave it to a pro I think, I just wondered if it might have been something obvious I’ve missed but I don’t think it is. The thermostat is communicating as when I turn it off the the three red lights on the control centre turn off altogether so it’s still connected. My trusted dad took a look as well and we reckon it’s the pump too which has a 5yr warranty. I’ll see what the plumber reckons though - hopefully he’ll come out on Monday. Thanks again for your help - much appreciated.

 

[centralheatking]

Thanks so much everyone for taking the time to help - much appreciated. I’ll leave it to a pro I think, I just wondered if it might have been something obvious I’ve missed but I don’t think it is. The thermostat is communicating as when I turn it off the the three red lights on the control centre turn off altogether so it’s still connected. My trusted dad took a look as well and we reckon it’s the pump too which has a 5yr warranty. I’ll see what the plumber reckons though - hopefully he’ll come out on Monday. Thanks again for your help - much appreciated.

Let us know what the solution was, it helps us learn Centralheatking

 

[jontyking]

Hi all - thanks again for your help before. FYI it turned out to be the safety cutout wiring module attached to the side of the pump so it's currently bypassing that so we've got heat temporarily. According to Polypipe I need to buy a whole new ZRU including the pump (PB970028) rather than just the wiring module which is gutting as it's going to cost about £500 only 3.5 years after the system was installed! I guess I can't do much about it unless anyone knows where to get hold of just the wiring module? I've done the googles and can't find it so think I'm just going to have to spend the cash 🙁 Thanks all for your help anyway.

 

[SJB060685]

So everything was working correctly but this safety cut out was preventing the pump from coming on, was the boiler igniting during this? Just to further my knowledge

 

[jontyking]

So everything was working correctly but this safety cut out was preventing the pump from coming on, was the boiler igniting during this? Just to further my knowledge

Hi SJB060685 - Yes everything except the cutout was working fine so when the plumber bypassed it the system works fine just as before. It's just that there's obviously now no safety cutout if the water is too hot. Obviously not good to leave it like this and I'm monitoring it in case the problem was actually caused by something else like the Thermostatic valve being faulty - he doesn't think it's that though and the temp seems to be regulating completely normally using the wall thermostat. Sorry these replies are taking so long - they're still being moderated every time as I'm a new user. Not sure when that changes?

 

[SJB060685]

Hi SJB060685 - Yes everything except the cutout was working fine so when the plumber bypassed it the system works fine just as before. It's just that there's obviously now no safety cutout if the water is too hot. Obviously not good to leave it like this and I'm monitoring it in case the problem was actually caused by something else like the Thermostatic valve being faulty - he doesn't think it's that though and the temp seems to be regulating completely normally using the wall thermostat. Sorry these replies are taking so long - they're still being moderated every time as I'm a new user. Not sure when that changes?

You're free to comment now friend, theres no more restrictions by the looks of it. Yes by passing is only a short term fix but will get you out of trouble for now. I have to say that your plumber seems experienced to know and do that, no one in this thread including me mentioned that. I hope you can find the offending part online rather than change the whole lot.

 

[jontyking]

You're free to comment now friend, theres no more restrictions by the looks of it. Yes by passing is only a short term fix but will get you out of trouble for now. I have to say that your plumber seems experienced to know and do that, no one in this thread including me mentioned that. I hope you can find the offending part online rather than change the whole lot.

He comes very recommended by a number of friends and diagnosed it within about 10 minutes so I think is very good. I'm still looking for the part but might just have to bite the bullet! Thanks again for your help.