Expansion tank filling

Kat1170

Every time the pump comes on, on my SFCH a trickle of hot water flows into the expansion tank. As soon as the pump switches off the water stops. Anyone any idea why this happens. The thermostat for the pump is set at 60.

Micky Dolenz

If the pump has speed settings, turn it down one notch.

Kat1170

Three settings on pump. No.III causes a cupful of water to flow into expansion tank when it switches on and again when switching off, No.II causes a constant trickle to flow into exp tank when pump is running, No.I seems to cause no water to flow into exp tank, but runs so quite on this setting it's hard to be sure pump is even pumping.:o

Will No.I setting pump enough water around system. SF stove with 6 radiators.

Pump is a Grundfos type UPS 25-50 130

Settings are, (I think, hard to see.)

P1(v)
I 40
II 65
III 95

Cheers Joe

JamesM

Looks like the pump is in the wrong position in the circuit. Maybe turning on an extra radiator will stop it. If the circuit is designed properly, water should not push up into the header tank on the middle setting.
Jim.

Carlow52

have u room to raise the high point of the expansion pipe before it bends around into tank.

The first setting will be fine, the system should circulate by gravity anyway, without a pump

Kat1170

Pump is about a foot away from the stove, pumping into the stove. Plenty of room to raise bend above the tank. Seems to be Ok on setting 1. Will know better tomorrow when I try a bigger fire. Cheers Joe