Biasi Boiler pump runs continuously even when thermostat is satisfied

DaveDiyNot · 27 Aug 2015

With Winter setting selected on my Biasi 24s (2001 vintage), the central heating works fine but even when the desired room temperature is reached and no combustion is taking place, the pump never stops.
Has anyone got any ideas?
Thanks
Dave

Agile · 28 Aug 2015

Has this always happened or is it something recent?

Can you take a photo if necessary and post it here?

Tony

DaveDiyNot · 28 Aug 2015

Agile said:
Has this always happened or is it something recent?

Can you take a photo if necessary and post it here?

Tony

Thanks Tony
I feel a bit silly as it turned out that the problem is that the thermostat knob is about 7 degrees out. When I eventually turned it down to point to 15 (the room had got pretty cosy) the pump soon cut out. I moved in only recently so hadn't tried the heating before except to check that the radiators got warm.
However, the thermostat knob is very stiff and and I cannot see any way to adjust its position. This is it:
http://www.heatingspares247.com/siemens-room-thermostat-raa20-gb.html
Can you advise on how to deal with that?
Dave

Agile · 28 Aug 2015

Only by opening it and lubricating it.

Earlier than your Biasi 24 S had a PCB with different options for running the pump.

I was wondering if somehow yours had been replaced with the early type and it was wrongly set.

Tony

DaveDiyNot · 6 Sep 2015

I haven't been able to open the thermostat. The front seems to be clipped in but pressing on the clips doesn't seem to allow it to open. Not really a big problem though.
On another matter, the pump is a Salmson and doesn't seem to have a speed control. Is there a way of changing the speed? I want to reduce it because I don't heat all the rooms.
Dave

Agile · 7 Sep 2015

The pump must be on max speed for hot water.

I think you have to remove stat knob and find screws under it.

Tony

DaveDiyNot · 8 Sep 2015

Thanks Tony
Dave

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Biasi Boiler pump runs continuously even when thermostat is satisfied

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