Radiators stop heating when HW cylinder is up to temperature

Postby Andrew N » Fri Nov 13, 2009 4:39 pm

I have recently had a new (non-combi) boiler to replace a 25yr-old one. The radiators in my bathroom & en-suite come off the HW circuit. Since the new boiler was fitted, the radiators are no longer effective. They used to keep the rooms toasty but now only heat up for a short period after the HW comes on. The plumbers who fitted the boiler say that HW is fed to the rads only as long as the water in the cylinder is below the thermostat setting, and that I will have to live with the situation.
Is there any value in:
a. reducing the boiler temperature so that it takes longer for the HW to heat?
b. Changing the setting on the Grundfos pump so that it runs slower?

Increasing the HW temperature might work, but I don't want scalding hot water. Any help would be greatly appreciated.
Andrew N
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