potterton netaheat 10-16 mk2f no main burn

[dog]

My potterton netaheat 10-16 mk2f stopped working recently...

The fan works, the pilot lights, but no main burn. I had a corgi guy in, but he took one look and wanted to sell a ne boiler instead. I tried replacing the relay, but this gave the same result. Th pressure switch seems to work fine, in that the pilot is cut if disconnect the pipe.

The timeline of events is:

0s Loud click, fan starts up 10s Loud click, sparking heard for a few seconds until pilot lit 40s quiet tick, I think this is coming from the black box (mercur switch?) on the right of the gas valve.

Any advice greatly appreciated. I've read the HSE warning, I don't ru it with the case off

-- dog

[Ed Sirett]

Either a) the gas valve is broken (it clicks but does not let out gas to the main burner) or b) the main injector is blocked and so does not let out much gas. or c) The pilot is not igniting the gas ... but when it does you'll know about it.

The boiler has seen better days and so if you can't get it repaired it's time to replace it.

[Ian]

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Hi Dog, I've got a Potterton Netaheat 16-22 MkII which produced the same symptoms in November, during the coldest bit of the winter so far, obviously. First Corgi heaved the cover off, diagnosed a leaking heat exchanger and suggested it was time for a new boiler. Second Corgi replaced the leaking gasket in the heat exchanger at the RHS, and tightened the nuts of the matching inspection cover (?) at the LHS because they were loose and access to replace the gasket was not good. This stopped the leak nicely. He dried it all out and........it still didn't work. He replaced the gas valve and it did work - once or twice at any rate, then failed again. With the lighting sequence at the 'pilot on' stage, he tapped around the gas valve with the handle end of a small screwdriver, and a gentle tap on the mercury switch got the boiler to fire immediately. I used this ruse for the following 4 days or so until the required thump was beginning to get a bit vicious. Meanwhile, AMAZINGLY, I actually found someone selling a 2nd hand 1 month old mercury switch on Ebay for 15ukp (rrp about 100ukp). Corgi2 fitted that as soon as it arrived and I've had no problems since. It looks like the differential diagnosis between gas valve failure and mercury switch failure may be difficult.

[ianmcook2]

I had exactly the same problem with our 16-22 over Xmas.

If you go to

you can view the user manual, installation manual, service manual and parts list for this boiler. These include a fault tracking flow chart.

Basically, you can check the mercury vapour switch is working for sure by checking for 240V on the red wire from the gas valve at the PCB terminal.

I got a replacement gas value for about £130 (inc VAT) online and paid a local independent corgi registered guy £68 (inc VAT) to install it. Most local heating companies tried to sell us a replacement boiler for £2000+.

[dog]

Useful link, cheers Thanks to everyone who posted, I'll get a multimeter on i

-- dog

[dog]

235V on red so I guess I need a new gas valve.

Thanks guy

-- dog