Potterton Netaheat - pilot on but no big flames...

[Chud]

Hi there

As per the subject line we've got a Potterton Netaheat boiler (not sure of exact model as no medel number is shown on front).

When the thermostat/timer tells the boiler to fire up the pilot lights fine, then the main burner. However after a couple of minutes the main burner goes off and will not relight unless I turn the heating/hw off for 15 minutes or so until the boiler has cooled down a bit. This problem has occurred sporadically and I'm waiting for a call back from my gas engineer and from reading on here it sounds like it could be the PCB or a dry joint but I was wondering if anything outside of the boiler could be causing this issue (pump, valve etc?)

Cheers

Richard

 

[tonybhoy]

More likely external fault ,pump or motorised valve etc or even controls etc.

 

[bathjobby]

Does the thermal trip out on the boiler when the main burner goes out ? Under the boiler the is a small plastic lug which pulls down to expose a screw for removing the lower cover, the model number is usually on a label on the inside of that lug.
If the thermal trip is tripping, it sounds as though you may have no or limited circulation of water through the boiler causing it to overheat. Check your pump and also check for air blockages i.e. bleed your rads if needed and check the bleed screw that you probably have above the pump.

 

[Chud]

Does the thermal trip out on the boiler when the main burner goes out ? Under the boiler the is a small plastic lug which pulls down to expose a screw for removing the lower cover, the model number is usually on a label on the inside of that lug.
If the thermal trip is tripping, it sounds as though you may have no or limited circulation of water through the boiler causing it to overheat. Check your pump and also check for air blockages i.e. bleed your rads if needed and check the bleed screw that you probably have above the pump.

Thanks tonybhoy and bathjobby.

If the thermal trip is tripping would that not shut down the boiler completely? We had a problem before with one of the pipes going into the hot water tank scaling closed.

Currently the fan remains going and the pilot remains lit - i.e. the boiler sounds like it's still going but it's not heating the rads or the water.

 

[namsag]

Picture of boiler would help or approx age discription of case as there are several versions of the netaheat and they are completly different boilers

 

[tonybhoy]

Boiler must be up to temp then so either the pump etc is the fault or the boiler thermostat is satisfied and is faulty.

Are the flow and return pipes at the boiler hot?

Some of these boilers are well over 25 year old BTW.

 

[Chud]

Picture of boiler would help or approx age discription of case as there are several versions of the netaheat and they are completly different boilers

Ok - here's a bad photo hope this helps

View media item 163
Obviously that's only really the bottom half of the boiler...

 

[Chud]

Just thought I'd post the outcome on this one...

It turned out to be one of the relays on the PCB sticking - cost for a new replacement PCB £155 +VAT which had both gas fitters swearing...

Fortunately my gas fitter has exactly the same boiler as me and as a result hoards spare parts when he can get them for a reasonable price - he was able to fit a PCB that he bought a couple of years back for £60 inc VAT - OK the warranty on the part has expired but he said if it goes he'll get hold of a new one and charge the difference.

I think I'm in the wrong business if you can get away with charging £155 for a small PCB when a computer MB (at elast 10x the complexity) can be had for £30...I think I'll set up making PCB's for boilers!

 

[tonybhoy]

I think I'm in the wrong business if you can get away with charging £155 for a small PCB when a computer MB (at elast 10x the complexity) can be had for £30...I think I'll set up making PCB's for boilers!

That's the thing though you can't .

You can only fit a boiler manufacturer's part.

I agree that the cost of boiler parts is ridiculous particularly PCBs relative to other electronic equipment.

Yesterday I was trying to buy a Siemens RWB29 programmer and was quoted in the range £28 to £61 plus vat for the same item from about six different suppliers (I was trying to get one yesterday for fitting yesterday).