My Potterton Netaheat was working fine but failed to fire this morning. I can hear the fan running but it is not trying to fire! no pilot, no spark nothing! can anyone help me with what I need to check?

Roy, January 2008

My 10-16 electronic has 2 silicone tubes - 1 running to the APS and another running to the back of the ignition/ flame control box. In the second tube there is a joint in the tubing with a metal insert to make the joint. However, this is not a full bore connector, but instead, at one end, is blanked off with just a tiny hole in it. This hole can get blocked with crud from years of use so find it, clean it, and then return it. If you doubt the integrity of the silicone tube ends then, if they are long enough, you can trim of the expanded end so the a better seal is made between the spigots and the tubes. Fans can also run slow thus not operating the APS and the APS itself can be faulty. Lots of things to check althoughthe symptom is the same no signal from the APS to indicate closure.

Graham Hall, February 2011

Aha - same problem on my boiler. Would jump into life if you gave the air pressure switch a flick.

Spent ages looking at outer case trying to make sure it was air tight, the hoses to make sure they were clear. Finally read the post above (what I had thought was a simple hose connector in fact turned out to be a flow restrictor.) Cleaned it out and bobs your uncle!

PS Everyone says these boilers kill people but I have a CO monitor nearby and haven't registered a single blip. If I die now, I'll look like a right tool.

Mr P. Otterton, December 2008

The only fault I've had (since 1981) with mine was like this.
There is a fault-finding guide in the installation manual. In my case there was no 240v across T4 and T6 after 10-15 seconds
which implies either air tubes not properly connected to pressure switch (they were OK) or replace pressure switch (Potterton 642204, British Gas 387607). This fixed it.
The pressure switch (a changeover microswitch) should click
over when there is a pressure difference showing that the air flow is OK for the burner lighting sequence to start safely.
Otherwise the fault-finder leads to either the control box or
the solenoid valve (check leads and connections.)
I recently found that my solenoid valve was 'chattering' sometimes and I realised that this was when mains voltage
was low (216), so I added 6v to the mains using a transformer
until EDF brought my supply up again. I am not going to allow John Prescott to tell me what boiler to fit, so if/when my Neatheat gives up I intend to leave the country.

John Chambers, February 2008

I had that problem a couple of years back on our boiler at home and it turned out to be the ignition generator, still available and not a difficult job to replace, but do check for the blocked restrictor in the hose first.

David Bingham, January 2008

air pressure switch and associated hoses. also the restrictor in hose just before the aps

Paul the gas man, January 2008