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Andrew Smith
Andrew Smith, Plumber
Category: Home Improvement
Satisfied Customers: 3629
Experience:  City and Guilds Qualified plumber
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Have a potterton MF control boiler that seems o have gone belly

Customer Question

Have a potterton MF control boiler that seems o have gone belly up. The pilot light doesn't go on and there is no noise from boiler. Where can I start to find a fault ?
Submitted: 3 years ago.
Category: Home Improvement
Expert:  Andrew Smith replied 3 years ago.

Andrew Smith : No attempt to start at all?
Andrew Smith : Do you have a cylinder?
JACUSTOMER-7h7swnt8- :

yes has a hot water cylinder.

JACUSTOMER-7h7swnt8- :

Was making some noise overnight and now no lights go on

Andrew Smith : Is the programmer still working?
JACUSTOMER-7h7swnt8- :

no attempt to start it seems dead

Andrew Smith : Is there a reset position on the main control knob?
JACUSTOMER-7h7swnt8- :

rest button on front but nothing happen when pressed

Andrew Smith : Even if the boiler does not start then the pump should still run - it is humming or vibrating?
JACUSTOMER-7h7swnt8- :

programmer goes on, but when put heating or water on nothing happens with actual boiler

Andrew Smith : is the pump running?
JACUSTOMER-7h7swnt8- :

yes there is a noise

JACUSTOMER-7h7swnt8- :

so seems that does work

Andrew Smith : ok, just the boiler then, the controls seem to be telling the boiler to fire
Andrew Smith : Is there a fuse in the supply to the boiler that can be checked?
JACUSTOMER-7h7swnt8- :

over last couple of years each time it goes on, green light and goes red very often as well

Andrew Smith : The red light will come on when it fails to light.
Andrew Smith : When was the last time it was serviced and the electrodes cleaned?
JACUSTOMER-7h7swnt8- :

apparently self servicing and no dirt within it

JACUSTOMER-7h7swnt8- :

the fuse, is linked to programmer as well, so if that goes on wont fuse be ok ??

JACUSTOMER-7h7swnt8- :

wel red light kept going on and off, green red, needed to keep pressing it. Not sure if wear and tear

Andrew Smith : yes, sometimes the boiler is fed from the programmer but the boiler's final connection is via a fused spur
JACUSTOMER-7h7swnt8- :

so I will check that same fuse your saying ?

JACUSTOMER-7h7swnt8- :

that links both of the programmer and boiler

Andrew Smith : if there is one there?
Andrew Smith : If it keeps failing to light it could be the fan failing - you should check power to the fan as one of the first checks to make sure the boiler is getting power and the fan is trying to run
JACUSTOMER-7h7swnt8- :

have changed fuse twice. Same humming sound but then no click at the end and no pilot light then

Andrew Smith : It sounds like the fan is having problems if you are humming and not firing - are you able to strip the boiler to check?
JACUSTOMER-7h7swnt8- :

don't have that skill at all. Is it easy ? also how would I test the fan ?

Andrew Smith : You just need to see if it is spinning
JACUSTOMER-7h7swnt8- :

I have an old style system with the water tanks in the attic. however I have some limescale build up in there. Is there anyway of removing this from the hot water cylinder and tanks

Andrew Smith : The limescale should not cause a problem as it will fall to the bottom of the cylinder and the hot water is drawn from the top
JACUSTOMER-7h7swnt8- :

but it comes into the pipes as well and creates noise

JACUSTOMER-7h7swnt8- :

green light went on finally, not sure how. But there is a smell like a burning smell and light has not gone again

Andrew Smith : It would be a good idea to get the boiler serviced
Andrew Smith : If your heating pipework is Hi my name is scaled up then you can get a system cleanser to put in the water
JACUSTOMER-7h7swnt8- :

if when I open it fan isn't working, are these easy to buy, to change ?

JACUSTOMER-7h7swnt8- :

or should be done by a professional

Andrew Smith : Is the fan spinning?
JACUSTOMER-7h7swnt8- :

haven't looked yet. Was wondering how far I can go by myself. I cant hear it

Andrew Smith : You will need to take the outer case off to see the fan, but you have to be careful - perhaps best to leave this to a boiler engineer?
JACUSTOMER-7h7swnt8- :

well I can open it, but if it is the fan, is it simple for me to change it by myself ?

Andrew Smith : You will need to check for voltage at the fan first and then if you do then a new fan will need ordering and fitting.
Andrew Smith : A simple swap if you have the correct tools
JACUSTOMER-7h7swnt8- :

how can voltage be checked ? a little more info would be useful so can sort this out. Would voltage just be written on the fan ?

Andrew Smith : You should get 240V across the L and N on the fan connections, also L to earth (you can use the metal case for the earth)
JACUSTOMER-7h7swnt8- :

lol. I have now opened it but am unsure what is the fan

Andrew Smith : At the top near the flue