Baxi Genesis 80 not firing

[JohnFeeney]

Thanks for the replies. Does anyone know if the pump has a separate flow switch or is it just the 2 flow switches on CH and DHW.

John

 

[bazdaman]

Just the two flow switches one for a dhw demand the other to prove pump is running, thought you had a
Ready tested this and its ok?

 

[JohnFeeney]

Am I right in thinking both must work (short) in order for the DHW to work, but only CH for to get the CH to work

John

 

[bazdaman]

Yes you are correct in what you are saying, i hope your linking harness end and not the switch! (Obvious i know but nothing suprises me) use a multimeter on continuity on the switch themselves when unplugged aswell just to check if not jammed.

 

[JohnFeeney]

Thanks Bazdaman,
I had shorted out the CH (harness side) and turned tap on. I had thought the DHW side must have been ok because pump seemed to be running but the DHW side was open circuit - so it was the flow switch on this side. On top of this the thermistor on the CH side was faulty. Sorted now. Thanks to everyone who replied.

Many thanks

John

 

[Agile]

I am surprised that it took you so long to realise that the DHW switch was not operating and the sensor was faulty.

Both very simple meter measurements!

Tony

 

[JohnFeeney]

Tony,
Although i'm an electronic engineer this is the first time I have tackled a boiler and the manual provides limited information. Experience is a great thing - I doubt you could tackle an aircraft avionics system as I would.

John

 

[Agile]

I think that I would get on fine with an aircraft avionics system.

As you probably would with my background of high power RF equipment.

In electronics terms a boiler is very simple!

Tony

 

[bazdaman]

Tony is in the uk top 100 engineers you know

 

[Agile]

John, your boiler has a pretty unique feature but perhaps similar to something that might have been used on early planes for something.

We are not permitted to give advice on DIY gas repairs but I don't think there is any risk involved in describing the unique feature on your boiler. Probably described in the MI anyway.

The gas valve has three solenoids. The first is an enabling safety solenoid allowing gas to pass on to the other two solenoids.

The second was a restricted valve which only allowed 1/3 of the full gas flow. The third was restricted but to 2/3 of the full gas flow. So step modulation of 1/3 or 2/3 or 3/3 was achieved by whatever combination of the solenoids were powered.

Nowadays modulation is fully proportional either by an analogue proportional solenoid or a stepper motor.

Tony

 

[45yearsagasman]

Tony is in the uk top 100 engineers you know

And has a collection of trumpets that he blows louder than most.
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