My boiler lights and runs for 2-3 mins until the radiators are all hot. The flame then stops, there is a ticking noise for a few seconds and then the lockout light comes on.
If I try to reset immediately, the lockout occurs again before the boiler lights. If I wait a few minutes and then reset, the boiler lights and runs for a short time (

Martin Guthrie, September 2005

was at a potterton combi 80 that keeps losing water
the person of the house says the water was coming out of overflow he topped it up but by morning the combi was at zero what is wrong if its emptying it self out the overflow on the out side

willblair, February 2013

its the microswitch on hot water

alan longfellow, February 2011

hi the boiler combi 80 get raising water presser bar from 1.5 for next day it goes 3 bar way does happend?

govineverest@yahoo.com, January 2009

Well I've found a solution to the boiler cutting out. I followed the troubleshooting flowchart on the parts arena web site:

http://www.partsarena.com/baxi/

Follow the links to the combi 80 boiler and the flow chart is near the end. The third box of the flow chart says "Is red LED on modulator board". This LED was on. The suggested solution is "Replace hot water flow switch".

Before doing that I looked at the microswitch on the DHW flow switch. There is a diagram in the data sheet on the parts arena web site which shows the position and adjustment of the microswitch. On measuring the ga, it seemed a little small so I adjusted the gap on the microswitch to be the recommended 5.5mm and lo and behold, the boiler now works again. It does still have a problem with the hot water to the taps only working when the CH is on, and being very slow even then, but that is not new and I am going to post a separate question on that.

Martin Guthrie, September 2005

Sounds like the PCB printed circuit board needs changing a very common problem with most potterton boilers and quite expensive around £200 to £250 fitted.

Sean Gilpin, September 2005

Sorry, something is stopping my question appearing properly. Third try....

My boiler lights and runs for 2-3 mins until the radiators are all hot. The flame then stops, there is a ticking noise for a few seconds and then the lockout light comes on.
If I try to reset immediately, the lockout occurs again before the boiler lights. If I wait a few minutes and then reset, the boiler lights and runs for less than 1 min and then locks out again.
The pressure seems fine at 1.5 bar, but there is sometimes a noise as if air is being pulled through the pump and a pressure surge up to 2-2.5 bar occurs at that time. The fan is working fine.
Any ideas what might be wrong would be much appreciated.

Martin Guthrie, September 2005

The whole question did not appear. Here is the rest....
If I wait a few minutes and then reset, the boiler lights and runs for a short time (

Martin Guthrie, September 2005