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Plumberpro
Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience:  Heating and hot water heating appliances experienced
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my boiler, located in the loft, only lights at random times.

Resolved Question:

my boiler, located in the loft, only lights at random times. Especially not in the morning though. Why is this and how can i rectify?
Submitted: 2 years ago.
Category: Appliance
Expert:  Plumberpro replied 2 years ago.
Plumberpro :

Hi . what you have to establish is , that when the boiler is supposed to be on , ie programmer and room stat calling for heat, that the boiler is running and trying to light or is doing nothing. Once you can do this then we have something to go on. You may be able to do this by staying by the boiler and getting someone to switch the programmer/ room stat on and off till the fault is replicated. Once this happens , you will have an idea of what is going on and we can take it from there , rather than guess work

Plumberpro :

Also you say random times ? This could be a warm start or frost stat setting on the boiler

Customer:

We switch it on manually and this has always worked, the boiler is about 7 / 8 years of age. i looked at what the engineer did yesterday and have stripped the boiler to that point. I notice that only one of the electrodes is giving a spark, shouldn't bot of them be doing this?

Customer:

i didn't mean to post that bit. i thought i was starting a new paragraph. i know i shouldn't probably be mucking about with this and don't really feel comfortable but I'm beginning to think the only way i can rectify this is to learn how to do it myself from scratch. i don't think it's on a frost setting the controller - the fros icon isn't on. i have run the water and the heater but whatever i run it fails to ignite and goes to re-set after a couple of time trying. it's like the gas isn't coming

Customer:

the boiler wants to start - fan starts - electrodes try to ignite - just the one but then that's it.

Plumberpro :

Ok . do you get a flame / ignition if only for a second?

Customer:

no

Customer:

this has happened because i have seen it but typically speaking, nothing

Plumberpro :

Ok . can you just confirm the boiler is a Combi?

Customer:

yes

Customer:

performa 30 HE

Customer:

GC 47-393-13 if that's any help.

Customer:

i thought you'd gone then!

Plumberpro :

Ok thanks . can you hear the fan running when this happens?

Customer:

yes - runs like a good 'un - everytime

Customer:

and then the one electrode starts sparking away while the other one does nothing.

Plumberpro :

Ok , but no flame . you said the air pressure valve was changed . do you mean air pressure switch?

Customer:

yes

Plumberpro :

Ok , do you have any fault codes come up with the LEDs flashing / slow flash ,fast flash ?

Customer:

just the red re-set

Customer:

but will just go up and check that. will take computer with me

Plumberpro :

Ok , thanks

Customer:

temp light steady green. red flashing light on the 30 degrees sign - by the flame - this is re-set isnt it?

Plumberpro :

2 mins , I'll just check fault codes in the manual , thanks

Customer:

bit cold up here :-)

Plumberpro :

Lofts are freezing in the winter and like a sauna in the summer, lol.

Customer:

i know - not too bad really. it was doing this last winter, but not quite to the same extent and i thought it was because condenser pipe was getting blocked. it has a shallw run off

Customer:

that's when it was really cold - re-setting then.

Plumberpro :

KnowingKnowing these boilers pretty well , I can confidentlconfidently say that you need to replace bthe temperature stats/ thermistors . most probably thethe central heating one but I would change the hotvwater one as well at the same time. When these start to go the boiler is thinking it is up to temperature and didn't need to fire upn. Luckily they are not too expensive ( well compared to other components ) around 25 each.

Plumberpro :

Sorry for my typing

Customer:

ok

Customer:

i don't know what these are

Customer:

what are the components again?

Plumberpro :

They are small temperature sensors that sense the water to temperature and regulate the flow temperatures of the radiator or hotvwater .they are fairly easy to fit

Customer:

i know where a plumbing place is - maybe I can order them there. Wonder how long they generally take to arrive

Customer:

i'm just not clear what to ask for - a temperature stat

Plumberpro :

Most will stock them , pretty common part to fail

Customer:

if you could just tell me what to ask for specifically then thank you very much

Plumberpro :

Sure let me see if I can find thecvpart numbers

Customer:

cheers

Plumberpro :

Ok . take the boiler model and GC number . this is the part you vneed temperature sensor x 2. Manufacturers part number 247394 part GC number 342 571 . by the way the manual ( free boiler manual.com) shows exactly where they are if you want to change them yourself .

Customer:

i don't have a manual - maybe i could download one

Customer:

i only jus tsaw that you included the website - sorry! Thanks a lot

Plumberpro :

Yes go to free boiler manuals.com. click on potterton. , scroll down for the model and check the GC number is ***** .

Plumberpro :

Page 32. Did you find it?

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