DIY Doctor

Central Heating Boiler

Postby CDunn » Fri Nov 23, 2007 11:55 am

I have a Potterton 28i boiler giving trouble. It keeps heating the hot water by turning the pump for the central heating off and it won't re-start. I have discovered by turning the hot water control to off, the central heating fires up again and works fine. Is this a sensor problem?
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Simply Build It

Postby DONFRAMAC » Sat Nov 24, 2007 12:51 am

My newly installed Potterton Promax 28 HE+ condensing combi has hot water priority as is standard with combi's. My "duty selector dial" has positions for "reset", "rads. & DHW", "O" for off, and "DHW". The rads. and DHW are sketches. Try your hot taps when apparently deselected ;--- you may find that the unit is actually in DHW priority mode, and suitable for continuous use, alternating flow from taps to rads.
Detailed info. on control set-up for your particular will be available from BAXI POTTERTON. Aftersales service 08706 017 017, Technical Enquiries 08706 049 049.
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Postby htg engineer » Sat Nov 24, 2007 9:57 am

not sure what you mean by turning the heating pump off to heat the hot water ?

When heating or hot water is selected the pump will run.

When you run the hot tap does the green demand light (tap) come on, and go off when the tap is closed ? when the heating is on does the green radiator demand light come on ?

If you run the hot tap when the heating is on the green light should go to the tap then back to the radiator when the tap is turned off. If it's not then it could be a problem with the diverter valve.

How old is the boiler ?
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Postby CDunn » Sun Nov 25, 2007 11:51 am

The boiler is 6 years old. When the heating is running the radiator light switches off and the tap light comes on without turning a tap on. The radiator light will not come back on until the water control is turned to off. ie to get hot water, I have to turn water control on then off when finished, otherwise we get no radiator heating as it stays constantly on the hot water.
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