DIY Doctor UK DIY Forums

Hi,

I have a Polypipe Touchscreen thermostat with underfloor heating that has got itself a bit confused and I've no idea how to fix.

The symptom is that when the temperature goes above the set temperature the heating goes on, it then gets warmer in the room and never drops below - which would cause it to turn off - inevitably the heating stays on

Anyone ever seen this problem/offer any advice to fix?

HI

This sounds like an issue with possibly the thermostats itself. Have you contacted Polypipe directly and informed them of the issue. They may be able to tell you what you need to do to reset the thermostat

Kind Regards

Hi,

I had completely forgot I posted here! I managed to get the answer from the manufacturer, here's the solution (which is undocumented in the manual):

PBTSP FAULT FINDING GUIDE

The most common one is that of the unit switching in to ‘Cooling’ mode which means that the heating system switches on when the temperature in the room rises which in turn obviously causes the temperature in the room to massively overshoot.

As this particular thermostat can be used for both heating and cooling the internal relay has two assigned positions, ‘Normally Open’ (NO) which is the heating mode and ‘Normally Closed’ (NC) which is the cooling mode.

Switching the unit between these two modes only involves the pressing of a couple of buttons on the screen and so this is sometimes done accidentally when either adjusting a setting or even simply cleaning the screen.
It will be fairly obvious that this has occurred as the customer will undoubtedly be complaining that the room is very hot and the heating system will not switch off.

The first thing to check is the assignment of the relay and this can be done by first pressing the time/programme icon.
Then immediately press the mode setting icon.
The current operating mode will appear on the screen and either ‘COOL’ or ‘HEAT’ will be displayed.
If ‘COOL’ is displayed then the unit is operating in the cooling mode and will need to be changed.

To do this press the mode setting icon again to change the display and ‘HEAT’ should then be displayed.
Press the OK icon to confirm the change.

*At this point you should be able to hear an audible click as the relay assignment switches.

The unit can now be switched back to Auto mode and normal operation should be resumed.

* Please note that the unit must be plugged on to its backplate for the relay reassignment to work correctly.

If after carrying out the above process you do not hear an audible click then this may highlight the second complaint that we have been receiving which is the fact that the thermostat is stuck in a particular mode and does not seem to respond to changes in temperature.

If this occurs then it may be a sign that the relay has stuck and therefore will not switch freely between the NO and NC assignment.

In order to resolve this issue it is sometimes possible to simply carry out the above procedure a few times in the hope that the relay will eventually free up and begin to work correctly. If this does not work then it may be possible to loosen the relay poles by removing the front cover gently tapping the relay as this could also help to free up the poles.

If all of the above fails then it may become necessary to replace the thermostat unit with either our PBPRP or an alternative battery operated thermostat with volt free relay operation.

As the PBTSP also utilises a two wire connection the replacement should a relatively straight forward process when using our range of control products.

Hi

Fantastic, glad you have now resolved the issue and many thanks for the detailed explanation of how it was resolved.

Kind Regards