Rayburn 368k Glow Coils not lasting

[leeicmobile]

Hey

I have an elderly neighbour who's had an issue with there Rayburn 368k over the last 18 months.

They started needing to replace the Glow Coil every 8-10 weeks (at a princely sum of £120) this was tenable till the most recent one only lasted 3 days.

I'm wandering if there is anyone has any ideas on possible root causes for the coils burning out so soon and how to confirm?

Thoughts so far:

- Coil transformer over powering
- Something making the glow coils take to long to ignite the oil vapour leading to them being 'on' far too long every ignition sequence
- Something causing the boiler to go out and re-ignite far too often leading again to over-use of the glow coils.

There engineer who's serviced the boiler for > 20 years couldn't find the root cause and suggested there just wasn't anything else to be done so the neighbours out getting quotes and I'm just hoping at best to give him the time to not have to be forced to make a rash choice out of desperation.

I did manage to track them down cheaper glow coils compatible with the same Landrover and the first one lasted 10 days.

Thanks for any help in this puzzle.

 

[oilhead]

Have you checked the ignition transformer voltage?
When flame established, does the current cease from the transformer?
Either situation will overload the element and produce the result you have. Time to get the multimeter out.

 

[leeicmobile]

Have you checked the ignition transformer voltage?

Checked it with my multimeter in AC mode just to see the fluctuation - will check in DC mode at the risk of frying my little multimeter that has a 10A max unfused.

When flame established, does the current cease from the transformer?

Yes it does cease - but seems to take a while to light the boiler. Will time it but I'm not sure what 'normal' looks like.

I assume the off signal is controlled by the thermocouple? Or is there an optical sensor that detects flame?

 

[leeicmobile]

I went down and took another reading today and checked out the first one that's burned out.

On my multimeter the weird thing is I don't get a DC reading across the glow coil when it's igniting but do get a reading when in AC V mode of 1.3v. It's a cheapo digital multimeter ordering one with TRMS and will try again.

Does seem though that the transformer is most likely culprit since it's correctly turning on and off once it ignites.

Am I crazy for thinking the transformers are soooo expensive? seeing like £2-500 for an AC-DC transformer :s

 

[oilhead]

Anything 386K is expensive. The Glow plug lights a small reservoir beneath the thermocouple, and once that is hot, the ignition circuit is shut off and the main solenoid opens. It takes time for the flame to build up. You also need to ensure the flueways and fan are clear. Blocked flueways reduce combustion air, as does a 'fluff' filled fan.