On Nov 23, 2:44 pm, John wrote:

Was the system changed to have all TRV if so was a bypass
circuit fitted.
Does the overheat LED flash or is a constant on
Try turning the boiler thermostat knob to just a quarter on,
i.e. water temp lower then about 63c- Hide quoted text -

- Show quoted text -

John - thanks for the reply.

TRV (Thermostatic radiator valves?) - all the new upstairs radiators
have these. The circuit is off at the moment.

On the old bit of the house, 2 of the twelve rads have TRV.

The overheat light is on constantly. Sometimes the bolier on light
(next to it) is also on; and sometimes that light flickers.

I will try the boiler thermostat route.