some boilers do 'ave 'em...

[Jimbob]

recently got called out to a myson floor standing natural draught boiler.

Very simple boilers so you would think them not to be much of a problem when it comes to troubleshooting. When i first arrive the burner would not light, despite there being a nice steady pilot. So i test everything down to the gas valve and all was fine, thermostat functioned, thermocouple workes fine holding open the pilot and i was getting 230v to the gas valve.

So i replaced the gas valve thinking sorted... but no. Still no burner ignition despite there being 230 at the valve, and even the burner pressure getting upto 19.5mbar as specified. So i cleaned the burner and the injector, still no flame. What am i missing?

im starting to think it could be down to a blockage in gas pipe, i suppose i could test for this by letting the gas valve open and doing a gas rate. Surely cant be it though

 

[washer]

Is the 19.5mb the burner pressure or gas valve inlet pressure?

If you are getting 240 at the gas valve, and then 19.5mb at the burner pressure point, theres got to be a blockage somewhere

 

[Jimbob]

19.5 burner pressure. Really can't get my head round it as burner looks fine and so does the injector. Got a friend with a bit more breakdown experience to go have a look at it.

 

[aggis]

Check if there's 240v neutral to earth, if so you've got a broken neutral