Having just gone through a nightmare with a leak fault on our Glow Worm Ulracom 30cxi Combi boiler I am now having lots of grief with radiators that will not turn down on the TRV.
The boiler was leaking through the pressure relief valve, about a bucket or so every 2 days.
Heating Engineer changed the valve and checked the expansion vessel to see if it was holding pressure, all OK. Next we were not getting any decent hot water pressure or temperature. Plumber comes back and fits a new plate exchanger that I sourced on EBay (genuine part), did a power flush of the whole system which had very little muck in it, almost clear water, cleaned the Magnetic reservoir also.
Still getting the relief valve leak and finally tracked it down to one of the filling loop valves which was passing water. Fitted new valve and leak is cured now.
Strange as we never use these as we have an separate filling loop?
Refilled the system after adding Fernox, bled all the rads starting at the top and pressurised the system to 1.5 Bar cold.
Hot water pressure and temperature now good and heating mostly works with the new Hive thermostat I fitted.
I have removed the TRV and shut off the small radiator which is near the Thermostat to avoid fals readings.
EXCEPT we have two radiators (large doubles) one downstairs in lounge and one in our upstairs bedroom which do not seem to respond to the TRV settings just stay full on whatever we do?
I have removed the TRV heads and checked the pins for movement and tapped the side gently with a hammer and they seem free not stuck.
Have tried swapping each valve for the one from the hall but makes no difference?
Now out of ideas! ???
Any help welcome please!
Martin