Hi,
I have a potterton promax sl boiler which does my central heating ( upstairs & downstairs separate circuits) and also hot water ( separate circuit to the 2 CH loops).
A few months ago the boiler was failing to switch off when the upstairs CH reached temperature. I swapped the two 2-way valve actuators for upstairs & downstairs and the problem moved to the other loop so concluded the actuator wasn't working , or an internal switch maybe. So replaced faulty actuator and system appeared to work OK again.
BUT , I have now noticed that the boiler regularly (several times per hour) fires up even though neither of the CH thermostats are calling for heat and the water program is off ( or up to temperature). Basically the boiler fires up for a short while (10 to 20 seconds typically) and the switches off again. Doesn't appear to actually do any heating (radiators don't heat up although unlikely to in 20 seconds I realise) . I can't work out why the boiler fires up if both CH valves and HW valves are closed and thermostats not calling for heat? Is there something internally to the promax sl15 causing it to fire? Frost stat maybe?
Any ideas would be very helpful.
Thanks
I have a potterton promax sl boiler which does my central heating ( upstairs & downstairs separate circuits) and also hot water ( separate circuit to the 2 CH loops).
A few months ago the boiler was failing to switch off when the upstairs CH reached temperature. I swapped the two 2-way valve actuators for upstairs & downstairs and the problem moved to the other loop so concluded the actuator wasn't working , or an internal switch maybe. So replaced faulty actuator and system appeared to work OK again.
BUT , I have now noticed that the boiler regularly (several times per hour) fires up even though neither of the CH thermostats are calling for heat and the water program is off ( or up to temperature). Basically the boiler fires up for a short while (10 to 20 seconds typically) and the switches off again. Doesn't appear to actually do any heating (radiators don't heat up although unlikely to in 20 seconds I realise) . I can't work out why the boiler fires up if both CH valves and HW valves are closed and thermostats not calling for heat? Is there something internally to the promax sl15 causing it to fire? Frost stat maybe?
Any ideas would be very helpful.
Thanks
