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Central Heating

What's up with my combi boiler?

I have a boiler (Alpha 240p) that has a permanent pilot, so the fan stays on all the time - usually quietly when the radiators are off and there's no hot tap running. Recently I got the fan replaced because a blade had snapped, and the air pressure switch was replaced too. The fan now stays on full blow all the time and is noisy at night. Got a new pcb yesterday to try to solve the problem, but that fan is still running full blast. What can the problem be? It's like sleeping next to a tumble dryer, so I have to turn the whole system off at the mains every night to get a sleep. When my radiators are off it should be quiet. It always was before it was *fixed. Any advice? Thanks.

--- Update ---

Flamemaster Ltd. replied to me that my problem with my Alpha 240p could be with my air pressure switch. i.e. my fan isn't slowing down when heating is off, but stays at full speed and the noise is annoying at night when all the demand for heating is off, so I have to put it off at the mains to get some peace.

Now, the engineer who's been fixing things did mention that he had to swop the wires to my air pressure switch because the "common" wasn't showing any signal, but the other wire was. * Could it be that he just wasn't putting juice through that wire at the time? I'm sick of phoning them (it's through Homeserve) and wonder that could be the very problem, and could I do it myself? Cheers.

*He says his paperwork AND the diagram on my boiler both showed the black as common but he could only get things to work if he used the brown instead, (or the other ways around), or something along those lines. When I think about it, nobody told me I needed an air pressure switch, only that the fan was broken in the first place.

2 Answers from MyBuilder Heating Engineers

Best Answer

Sounds like air pressure switch installed incorrectly.
I would seriously advise you to task an independent gas safe registered engineer to review this fault for you.
From your update it would appear the polarity has been reversed at the field wiring to the air pressure switch.
If this is the case , a reputable independent engineer will correct this at a minimal cost in a very short time. However I do not advise you to attempt it yourself.


Answered 26th Mar 2015

Check the wiring to the Fan
Alpha 240 has 4 wires going to the Fan, there is a wiring diagram
on the back of the front panel
your guy has wired the fan up wrong
if the boiler fires up then the air pressure switch is fine


Answered 1st Apr 2015

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