Potterton Combi 80 Lockout

[Trickster]

I have inherited a Potterton Combi 80 which was installed approx 4 years ago. There was no instruction manual left with it, so the only guidance I have comes from a fault-finding flow chart on the inside of the front cover.

The problem I currently have is that the boiler is reluctant to fire up first time when the central heating is turned on. When I bought the house 2 years ago I got a plumber to fit a manual time clock so that I could have the house warm when I get up / return from work (just like a real boiler). I also had the pump replaced soon afterwards as it was noisy and clearly struggling.

Now I am frequently returning from work to find that the boiler has locked up when trying to fire up from cold. With a bit of persuasion it will fire up and soon everything is working fine.
I've followed the procedure on the chart and can't pinpoint anything that might be causing this. Can anybody help?

2 observations which may or may not have a bearing on the above:
there is a small but persistent leak from the valve on my downstairs bathroom radiator. I am too lazy /stupid to get it fixed, so periodically I have to recharge the system using the valve below the boiler. I am setting it at about 2 bar, but reading other comments I think this may be a bit high. It usually settles at about 1.5 bar after a day or two.

I also think that the temperature of the hot water is unneccesarily hot, to the point of being dangerous. Unless I'm going blind, I can't see any means of controlling it, like a manually operated thermostat. Can this be correct?

 

[ChrisR]

Is it an 80 (with permanent pilot) or an 80E?
Whaddaya mean exactly by lock up?
Does it fail to start equally for CH ans well as HW?
How far through lighting does it get?

 

[Trickster]

Thanks for your time, ChrisR.

It's definitely a plain Combi 80 - no mention of an 'e' anywhere on it.
It has never failed to fire up when hot water is called for, just these mysterious occasions when you wake up or come home to find that it has failed to respond at all to the central heating timer.

I think I will have to do some cold start tests at the weekend while i'm around to watch it (not much fun in this weather). It can't be overheating as the heating's been on for 4 hours tonight with no problem.

By locking up I mean to say the red lockout indicator is on and the reset button eventually does the trick.

 

[ChrisR]

Most of the boiler doesn't "know" whether it's been asked to come on for HW or CH, so I'd be looking for bad solder joints on the pcb where the CH temperature sensor, etc are connected. In fact have a good look over the whole board - it's common to find many bad joints, which show as dark lines across the solder. First to go is usually the top left pin connection as you look at the board when installed.
Call Potty for a manual. If they ask for a corgi number give them a 6 digit number starting with a 1

 

[rajni]

Hello! I have also just moved into a flat with a Potterton Combi 80 boiler, about 4-5 years old, and (guess what?) it also keeps going into lockout. It also seems to me that the radiators and water get very hot and then it goes into lockout. After a while, or sometimes straight away, I can reset it and it will work again. Just wondered if you'd had any luck solving this problem- mine does not seem to have a thermostat and there is not one externally either- I feel that maybe this is the problem? Do you have a thermostat?

rajni.

 

[Trickster]

Thanks for the advice, Chris R.

At the moment things have settled down again now the system is charged correctly. I will try and get a manual from Potterton, as you advise.

Unlike Rajni, I do have a wall thermostat (albeit stupidly positioned in the warmest room in the house!) but I am still concerned at the lack of a manually controllable thermostat on the boiler itself; how can this be safe?