Potterton Netaheat 16/22 cutting out

[john1000]

Thanks ChrisR. Is is possible to repair the GV? Have it rewound or something? Alternatively, would you pay £230 for a new GV for this 20 year old Netaheat, or put it towards a new condensing boiler? My Corgi mate suggests savings in running costs soon cover the cost of the new boiler, especially as gas prices are due another hike in 2008.

Thanks Lesley - the fan runs OK, the pump's running, the two water valves are working (in place of a diverter), and the spark is sparking, but the boiler won't restart until it's cooled down.

Thanks everyone else: I'll check the pilot injector (but would the boiler work OK twice a day, plus instantly on manual, if it was blocked?). Also, could the pilot injector or the spark earthing plate/bracket be affected by the boiler getting hot? Maybe if corroded/grungy over time? The whole problem only occurs when the boiler has been running for 30 mins, and there's no problem starting it when it's cold.

What about the mercury vapour valve/switch? (sounds like out of Star Trek). Could that cause this problem?

Cheers,
John

 

[leew]

It won't be the mercury vapour switch from what you have described as this is used to detect the presence of the pilot before turning on the secondary solenoid on the gas valve which in-turn fires up the main burner. I would almost suspect the gas valve is the culprit.

My old gas valve primary solenoid was knackered and hence pilot would'nt come on (kept sparking continuously), I'd verified this by measuring the resistance of the gas valve and was getting infinite ohms (a break) on the bad primary solenoid and 4kohms on the good secondary one. If you can somehow remove the front cover of the valve you can test this yourself with a multimeter, be sure to isolate the electrics beforehand.

 

[john1000]

Thanks leew. Can the solenoid be repaired? A replacement gas valve is very expensive (£230).

 

[leew]

I really do not know if it can be repaired, looking at my old valve it does look possible for it to be dismantled (few screws to take off). Might be worth to just bit the bullet and fork out for a new valve. I do beleive the valve for the 16/22 electronic is hard to find whereas the valve for the normal 10/16 16/22 (non-electronic) model is still widely available from most places, strange as both models are just as old.

 

[john1000]

£230 sure is a lot for a component for a 20-year old boiler. And a relatively minor component too! You can buy a new boiler for not much more than a couple of these valves! If I replace the valve, something else might go wrong...

 

[john1000]

It occurred to me that maybe we could live with the boiler running for 30 mins, cooling for 30 mins, running for 30 mins, etc, so what about replacing the original Potterton twice-a-day timer with a modern electronic one and set it to come on in the morning, run for 30 mins, shut down for 30 mins, come on again for 30 mins etc, all day? Would that work? Any reason that might not be a good idea? If worth a try, can you suggest a good timer (or do I take any the plumbers' merchant offers)? Cheers, John

 

[dogdays]

All sounds a bit strange.
First have you got the fault-finding diagram on page 23 of the boilers manual. If not, raise an email address and I will scan and send to you.

The procedure to check the start procedure is as follows. If you have a good spark and the pilot does not light, check the gas flow to the pilot and the jet for blockage. If still no go check for 240Volt across terminals T2 & T3 on the electronic board. If no volts, suspect circuit board. If yes and wiring OK to solenoid, its your gas valve solenoid.

The Netaheat is great old boiler and as long as the exchanger is still good and the caseing sound you should hang on along as you can. P.S £200 is peanuts compaired to what you will pay if a condensing combi gives you trouble.

Opinion only

 

[dogdays]

Hang this is a 16/22. Do you have an overheat stat fitted and is the fan running when the boiler will not start?

 

[john1000]

Thanks dogdays. I've got the faultfind flowchart.
The boiler does have a stat and the fan does run when it won't start.
Cheers, John

 

[dogdays]

So I guess you are looking for a gas valve?It must be breaking down as it gets warm.
I was warned about the non-supply of White Rogers gas valves last year and managed to pick up a servicabule spare from ebay. I did look into getting the solenoid rewound if nesessery, but without any luck.In the old days you could get coils wound to order from specialist fims in Practical Wireless mag. Alas we now live in a throw away age. Its worth getting an electrican to mega the coil though.

Did you do the voltage test on the board?

Good luck

 

[peetc]

John, did you ever sort out what was causing the problem? I have an old Potterton Netaheat 10/16 which is behaving in just the same way - it fires up fine when cold but not when warm. Thanks, Pete

 

[TomP]

Does anyone know the answer to this? Was it the gas valve?

I have a Potterton Netaheat Electronic 16/22 with the same problem.
Also in the last 2 years had new PCB, new fan and just had new spark electrode (metal finger).

I have found that when the bolier is trying to restart when hot and can't (I can see a tiny blue spark trying to light the burners), a quick thump on the bottom right corner of the front casing gets it started.....it works every time!!!

I wonder why this works?

 

[corgiman]

start a new post mate this one is old



Sounds like PCB of AFS prob

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