Baxi Combi Boiler

9 Feb 2010
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United Kingdom
I looked for other issues like this one, but this is slightly different.

I have a Baxi combi boiler which recently has been flashing the LED for "Fault on pump or low pressure". It only does this when the central heating is off i.e. the timeclock has switched it off. While this light flashes, the boiler doesn't operate and I can't get any hot water.

Trying to turn the heating back on via the timeswitch doesn't work. If I switch the boiler off with the switch at the front then back on, all fine. Boiler works and I can get hot water (even with heating off).

Pressure is 1.75.

Any ideas? I might have to call an engineer but wondered if there's anything else I can check. I bled the rads and repressurised the boiler a while ago and the pressure is pretty constant at the mo.

Thanks in advance.
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We dont know which boiler model you have.

If it has a pressure switch then this may be blocked/out of calibration.

Increasing the pressure to say 2.0 would lessen the onset of this problem IF thats the cause.

Would say its either on eof the 80's or 105's by description of LED.
As per Agile. Could do with knowing the model. Regardless of the model inside the boiler on the left hand side you will see the brass hydraulic outlet assembly. On this, either at the front or on top, is the primary flow switch. it is a small black box approx the size of a small box of matches with two RED wires. When the pump is running. Does the pin underneath this lift the small metal switch?
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Apologies, I meant to add it. It's a BAXI Combi 105e.

The weird thing is, I had it set to come on intermittently overnight and that actually worked. Woke up about 7am and the heating had come on via the timeswitch.

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