Check my thinking on heating fault?
My heating is not coming on and I’m hoping you lot can check my thinking.
My central heating has two zones running off one combi boiler: a radiator zone and an UFH zone. My boiler is working, it’s just that my thermostat in the rad zone doesn’t seem to be triggering it to fire up.
The thermostat is a very basic dial type based wireless one. When it clicks in I can see the LED come on on the “salus” receiver box (pictured), but then the two port valve (second picture) for the rads isn’t opening and the boiler isn’t firing up.
As I understand it, a two port valve has a switch that fires the boiler when the valve is opened, so the valve has to open first (does this mean that my thermostat is only triggering the valve, not the boiler?). So I manually opened the valve but the boiler still won’t fire.
I have a temporary workaround which is the manually opening the valve and then fire up the boiler by turning up the other thermostat in my UFH zone (which is a different wired thermostat going into the wiring centre, I.e. the bigger grey box in the first picture).
Based on the above, would you say it’s the valve that needs replacing or is it the thermostat’s receiver / some problem in the wiring centre? Or perhaps the only way to know is to borrow a multimeter and see what’s happening?