Underfloor heating not working!

mac123

Just moved into a new place with combi boiler and underfloor in one room (extension). All rads have TRVs and the only thermostat (towerstat RSP) in the house seems to be linked to the underfloor heating – would this be logical? I say that as it’s located right above the system and is powered from the same junction box as the pump

Boiler/rads are working fine as we program boiler to come on and control temperature via the TRVs but as yet can’t work out how to use the underfloor. Warm water (but not hot) is going into the system via the copper pipes on the left but that’s all I know

Is there anything you could recommend I check to see if there’s something wrong with the thermostat, pump or anything else?

Thanks

ThePubLandlord

Is there an isolation switch for the pump? Maybe a redundant light switch nearby.

mac123

not that I can see no, the pump is powered from the junction box right next to it

mac123

Here is a pic of the current layout

ThePubLandlord

Is it powered from a fused spur? First thing I'd check is the fuse and then check you've got power to the pump.

Is the copper pipe on the left hot when the heatings on?

mac123

well there's a junction box which powers the thermostat and pump - the thermostat is working so assume there's power going to the pump

The copper pipe gets warm but not hot

blackshirtuk

looks like your underfloor heating is on a separate zone, is the zone valve activating/controlled separately ?

mac123

nothing seems to happen with the zone valve when i turn the white knob at the top ... i assume this should kick in/close off depending on whether I turn the knob on/off

Hasbeen

The metal box "zone valve" should have a small lever which moves to on position when powered is this moving?
Try pushing it along groove with your thumb you will hear a whirring when opening

mac123

Yes this moves then return back to the start position

chappers

you should be able to lock it in the open position, usually open it and push it to lock, does the heating work then, is the valve opening itself when you call for heat.
Is the pump actually turning, with the heating running undo the big silver screw, is the spindle turning.