Potterton Netaheat Electronic 16/22 - won't start when hot

[TomP]

My Potterton Netaheat Electronic 16/22 runs OK for 15 mins then won't start again until it cools down. I see the tiny blue spark trying to light the burners and the fan is running but it won't start.

In the last 2 years I've had a new PCB, new fan and just had new spark electrode (metal finger), so don't think it relates to these.

Strangeley I have found that when the bolier is trying to restart when hot and can't, a quick thump on the bottom right corner of the front casing gets it started.....it works every time!!!

I wonder why this works? I wonder what's wrong? Previous posts have suggested the gas valve.....any suggestions please?

 

[Fluffster]

Sounds like the gas valve to me and they are more or less impossible to get new, plenty of s/hand on e bay but I would not trust them.

Pete

 

[Aquaheat]

I think you have pretty much answered your own question.

The gas valve isn't opening but on these it can be one of 2 things.

Firstly was the PCB reconditioned or brand spanking new? cos the problem i get with these is the relay.

Secondly, when it wont light you need to check voltage at the gas valve. If you have the correct voltage then you need to check the downstream gas pressure.

This will determine your fault.

 

[Agile]

Could it not also be the APS ?

Tony

 

[Aquaheat]

I see the tiny blue spark trying to light the burners and the fan is running but it won't start.

Not really because its getting to the ignition stage. If the APS was faulty then there would be no spark.

 

[Aquaheat]

If the APS was faulty then there would be no spark.

sorry i meant were faulty!

 

[Agile]

Sorry, yes of course! Its late now!

I have seen this too and its the first stage ( pilot ) solenoid fails to open when it gets warm. I have never noticed them starting when banged but thats a repair technique I dont normally use.

The solenoid only can be changed if you can find one.

Tony

 

[Aquaheat]

I have known banging to start it because a relay is sticking. Much in the same way that worcester rsf's get dry relays and a hit will bring them back into life, all be it for a short period of time.

 

[TomP]

Really appreciate the replies and the fact that you guys share your knowledge so willingly.....much appreciated.

The PCB was brand new (I think!). So sounds like either the solenoid (difficult to get part now) or a sticking relay (sounds more likely as a thump makes it spring to life instantly).......is a sticking solenoid repairable/replaceable?

Or perhaps it's time to get the boiler replaced soon (20 years old now).

Anyone recommend a good installer in the North Hants area?