I have an old Servowarm Elite 50 Central heating boiler and the pum
failed. I have replaced the pump but the Pump does not shut down whe the boiler turns off.
Does anyone know, if I purchase a new programmer, if this has the pum overrun facility on it or do I have to find the fault, "solenoid o relay?" in the original Timer/programmer.
Thank
-- Nigel Hewer
Do you mean when the boiler is switched off by the programmer? Older systems will often have the pump running while the boiler cycles. On those the two aren't really interdependent - the pump is controlled by the room stat while the boiler by its own.
Pump overrun devices are usually part of the boiler rather than programmer.
Of course Servowarm tended to have a mind of their own. ;-)
My room stat controls the pump only and the boiler is controlled by it's own stat. If the boiler stat has shut off the boiler and the room stat is calling for heat the pump continues to run.
So the pump stops allowing the boiler to heat really quickly and then shut itself off ? That sounds very dodgy indeed. My boiler would shutdown and require resetting if I were to do that.
Quite a common arrangement for older systems. When the heating demand is satisfied the pump is switched off by the roomstat and the boiler then continues to run until the water temperature in the boiler rises high enough for the boiler stat to shut it off. Conversely if the boiler water temperature reaches the boiler stat setting before the heating load is satisfied the pump will continue to run although the boiler has shut off. In fact some vintage heating systems have no roomstat at all and the heating is controlled by the boiler stat alone.
Depends on the boiler's water content, and this was the norm with higher water content boilers.
They were (are?) specialists in rebadging and used reasonable kit from major manufactuers including Aqualisa shower mixers. My wild guess is that this might be a rebadged Ideal Elite such a boiler could well have an overrun implemented as a simple temperture sensitive changeover switch. It has become stuck in the hot over-run position.
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