Boiler starting sometimes but not consistently

[Andagain1001]

Hi all
Just hoping that someone may know what's going on with my boiler/HW & CH heating.
I have an Ideal classic HE, which is just over 14 years old.
Last week it wasn't starting for some reason.
All the links seem ok eg stat calls for heat, pump starts running so water is circulating through the boiler, boiler even makes the noise that it makes when it is about to start up. I then notice a hum coming from the boiler.
Then for the next week all was fine, but yesterday the same thing happened. This morning all ok again.

Any ideas?

Thanks in advance for any help.

Andagain1001

 

[Madrab]

Difficult to diagnose over the net. A boiler hums/whirrs/whooses/whines as part of it's natural vocabulary. You may need someone to look at it when it's playing up.

 

[Harry Bloomfield]

All the links seem ok eg stat calls for heat, pump starts running so water is circulating through the boiler, boiler even makes the noise that it makes when it is about to start up. I then notice a hum coming from the boiler.
Then for the next week all was fine, but yesterday the same thing happened. This morning all ok again.

Check the boiler air fan also runs. The hum could be the fan motor, not running or failing to start, due to sticky or worn fan bearings. Wiring loom, from PCB, up the back of the boiler, to the fan, also tends to overheat and short out - taking the PCB out.

 

[Andagain1001]

Thanks both for the replies; Harry - when you say taking the PCB out, do you mean that this could be temporary eg when the wiring loom gets hot and so starts working again when it cools down?
Thanks again

 

[Madrab]

If I am remembering the classic correctly (been a while), any servicing/replacement of components needs the room sealed case to be removed, that would include the PCB. That's really the territory of a GSR engineer and not really for the DIYer to be playing with.

It really needs tested when it's acting up, only way to know what is causing the intermittent fault, anything else is just guesswork TBH.

 

[Andagain1001]

Thanks Madrab
Not going to play around with it, as you say it needs someone who is qualified to do that stuff.
I'll see if it keeps happening when it's hot to try and replicate the fault when someone comes in.

If it is PCB and/or fan, roughly how much would I be looking at to fix?

Thanks

 

[Harry Bloomfield]

Thanks both for the replies; Harry - when you say taking the PCB out, do you mean that this could be temporary eg when the wiring loom gets hot and so starts working again when it cools down?
Thanks again

No, it wrecks the PCB - you then need an new PCB, as well as the failed loom.

 

[Madrab]

if it is PCB and/or fan, roughly how much would I be looking at to fix?

It's not that complicated a swap over and test/setup so it would be the cost of the parts plus local labour costs. Not knowing the rates in Essex then impossible to say I'm afraid.

The PCB's are around £140 and the fan seems to be around £300, maybe not financially viable to repair. That being said it may be worth a punt at a couple of 2nd hand parts if repair is preferred. I wouldn't think that Ideal would do a fixed price repair on such an old boiler but they can only say no over the phone.

Depends on what's wrong really.

 

[Harry Bloomfield]

The PCB's are around £140 and the fan seems to be around £300, maybe not financially viable to repair. That being said it may be worth a punt at a couple of 2nd hand parts if repair is preferred. I wouldn't think that Ideal would do a fixed price repair on such an old boiler but they can only say no over the phone.

I've seen the PCB's on ebay as cheap as £40, so worth a look on there. Not sure I still have them, but I used to have a perfect working used fan, plus a brand new one stored in my hut. If I still have them and they would be of use, and they are the correct models - you can have the pair for £60 + delivery.

 

[gas112]

sounds like common fault of fan sticking . Proper fan lube or 3 and 1 oil can get them working again for years or months its a piece of string really .Wd40 only works for a short time and there is around 3 fans for classics ranging from about 130 quid to just under 300 and sods law probably the dearest one . They are a solid boiler and will last well past 20 years so up to yourself how much your willing to spend on it

 

[Harry Bloomfield]

The fans use a PWM and feed back, to control the speed.

Likely, the PCB watches for the pulse showing the fan is rotating, and if it sees none - shuts the ignition sequence down.

 

[gas112]

The fans use a PWM and feed back, to control the speed.

Likely, the PCB watches for the pulse showing the fan is rotating, and if it sees none - shuts the ignition sequence down.

or it just uses a simple everyday APS

 

[Andagain1001]

Well, the boiler has stopped firing completely now, so GS man coming Friday to take a look.