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Boiler probs
hearbear - 15/4/17 at 10:45 PM

Got a ravenheat boiler its a heat only not combie boiler had a new igniter fitted as it wasn't sensing the pilot flame lit now noticed the main burner once light burns well for for a short period and then starts to thin out and then boiler shuts down, it then relights and then goes through this cycle all the time. Could this be caused by a faulty fan in the boiler not putting enough air through to keep the flame lit?

adam1985 - 15/4/17 at 11:16 PM

Get it checked out by a professional,possibly a issue with the flue so could turn out dangerous.

SteveWalker - 16/4/17 at 07:57 AM

Unless it is an extremely old boiler (and probably even then), fans are normally proved working by a differential pressure switch before the burner is lit, so it is probably not a fan fault.

Maybe the boiler has other sensors or there is a fault on the PCB?

chris - 16/4/17 at 08:05 AM

i would check pump is running correctly if pump running slow or a partial blockage that could cause the probs you are describing run boiler feel pipes at boiler when boiler shuts down then feel pipes at pump if there is a big temp diff then there is a flow problem
unlikely to be a fan problem because boiler is lighting enough air pressure from fan to make air pressure switch light boiler most likely boiler sensing has reached temp so will shut down boiler cools down a bit then relights usual cause flow problem causes pump prob blockage or three port valve

[Edited on 16/4/17 by chris]

r1_pete - 16/4/17 at 11:04 AM

quote:
Originally posted by adam1985
Get it checked out by a professional,possibly a issue with the flue so could turn out dangerous.


+1 sounds like a good source of carbon monoxide.....

coozer - 16/4/17 at 12:15 PM

Does it not have a display showing a fault code?

HowardB - 16/4/17 at 05:58 PM

if you are determined to try a diy fault find, I would recommend a look at DIYnot.com very useful.

chris - 16/4/17 at 06:46 PM

Very unlikely to be a monoxide problem on a fan flued negative pressure boiler
Usual sings of an air problem black marks around boiler case yellow flame and or flame lift
Causes not enough oxygen in burner chamber
If vertical flue check that it has not come apart
If as you have described boiler lights goes to full flame for a minute or two then goes to small flame then shuts down boiler is up to temp but heat not going anywhere pump problem or motorised valve or blockage

hearbear - 16/4/17 at 10:25 PM

quote:
Originally posted by chris
Very unlikely to be a monoxide problem on a fan flued negative pressure boiler
Usual sings of an air problem black marks around boiler case yellow flame and or flame lift
Causes not enough oxygen in burner chamber
If vertical flue check that it has not come apart
If as you have described boiler lights goes to full flame for a minute or two then goes to small flame then shuts down boiler is up to temp but heat not going anywhere pump problem or motorised valve or blockage


Reason having a look at the simple things myself is because had a few people out over the years of owning it and it's a ravenheat don't know anything about this and don't have the cash just now to replace it for a better branded one. Water is circulating fine and fitted a new pump recently and when boiler is running the system is fully heating up. The flame is lifting from the burner then it starts to reduce and then goes out boiler then relights pilot flame starts the burner again and just keeps going through this cycle, the flame lifting was why I thought the fan may be the problem as lack of oxygen. Had a look and the flue is all ok no blockages and connected it runs at 90 degrees from the top of boiler. There are no displays it is as basic as basic can get.

spudkey - 17/4/17 at 09:03 AM

As said, sounds like a circulation issue check pump and bypass if fitted,
Also could be boiler flow temp sensor NTC is faulty