[gIzzE]

We have a Combi 100 and it is pretty much a new boiler, we have had a new pump, stats, pcb, fan etc.
It has been working a treat, all 13 radiators are kicking out proper heat, the unit is silent and we are chuffed as we were going to change it last year, but turned out it was just the fan playing up.

However....... the last few days the heating has not come on in the morning and when I looked the thing had shut down, red light on. Press the button it fires up and is fine again all day and all evening, but next morning it is off again and needs resetting.

Now I presumed this would be the pump overrun not working properly, but I was up at 5am yesterday and when I walked through to turn the heating on the red trip light was not on, but as soon as I fired it up it cut out and red light was up. .

So, obviously not cutting out when it switches off so not the pump overrun.


So, any ideas?


My heating comes on at 7am till 9am and then again at midday for 2 hours and then again at 5pm ready for when we get home until midnight.
That all works fine, it is only when it starts from the morning.

[makkan00]

Search for the service manual. Read the codes by going it to service menu and it will give you the idea what is wrong.

I used to rent a place where 'boiler enginners' had to come three times as they boiler stopped working. They kept changing all sort of things. It did not resolve the issue. At the end I had to find its manual, diagnose it and inform the cowboy company what was wrong.
4th attempt and they changed the part and it all worked.

[rich1068]

One of the things that has surprised me since becoming a member on this BMW forum is the amount of central heating boiler advice asked for and received.

Carry on...

[gIzzE]

The fact that is works when it comes back on at midday and then again at 5pm is what is confusing me.

It seems to be only when it gets really cold it won't fire and trips out, if it is still warm from the rest of the day it is fine, and it obviously turns on and off all day as the thermostat gets the place to temperature.

[gaza01]

We had this problem for the whole of the year and it only just got fixed. Basically it would throw a code meaning gas interruption and shut the unit down for safety reasons. BG boiler repairs were adamant that it was the gas supply being interrupted...turned out the sensor that monitors the gas flow/volume was faulty causing the unit to shut down thinking there was insufficient gas

[gIzzE]

So when it kicked on it would not fire?

Or just shut down?

Once it has been reset in the morning it will turn on and off all day, but the next morning it trips out when firing for the first time again.

[mowflow]

Seems to me like the issue above would happen every time the boiler tried to fire up. Have you tried to change the time it comes on in the morning to see if it's maybe something to do with pressure at a certain time in the morning or something. (i'm clutching at straws)

[gIzzE]

What I might do is get it to come on at 3am for and hour and see if that helps at all.

[makkan00]

Originally Posted by rich1068

One of the things that has surprised me since becoming a member on this BMW forum is the amount of central heating boiler advice asked for and received.

Carry on...

And it makes me laugh when people ask for advice, and then completely ignore the logical answer and still carries on looking for layman response.


Most of the things are computerized and they register the fault codes. Use them!

[gIzzE]

It is not throwing any codes.

Sorry, I meat to say that earlier.

[makkan00]

Originally Posted by gIzzE

It is not throwing any codes.

Sorry, I meat to say that earlier.

Strange. Try to read it when the light flashes and its not working.

[gaza01]

Originally Posted by gIzzE

So when it kicked on it would not fire?

Or just shut down?

Once it has been reset in the morning it will turn on and off all day, but the next morning it trips out when firing for the first time again.

It would be off and need the pilot light re-lit by pressing the button. It would then work for a period before needing relighting again. Became more frequent when it started getting colder

[mikeysix]

It could well be a pump over run issue from the night before after the last heating demand. Another common one is a sticking govenor at the gas meter. With the colder weather this can be an issue and can also affect the gas valve in the boiler trying to lift on first demand. The fact that it works fine for the rest of the day makes me think this might be the issue. Especially as you have had all the usual suspects of pcb's and sensors changed.

[gIzzE]

That's what I am thinking, I posted on diy forum and that was the most likely answer.

They said the gas solenoid gets stuck, I replied...

In the manual....

http://www.acwilgar.co.uk/Boiler-Man...20100,100e.pdf

It says gas valve, first solenoid valve and second solenoid valve, which of these do you think it could be?

Thanks again. It is appreciated.

Read more: http://www.diynot.com/forums/plumbin...#ixzz2mMYGYbax




Then got the usual suspects telling me "Just bite the bullet man and get an engineer to diagnose."


I just wanted to order the parts ready for my guy on Saturday, if he comes on Saturday no doubt it will then be Monday before he orders, Tuesday when they arrive and maybe Wednesday before it is done.

Obviously not a real issue, but if I can get all the suspect parts in it could all be back to normal by Saturday.

[mikeysix]

Originally Posted by gIzzE

That's what I am thinking, I posted on diy forum and that was the most likely answer.

They said the gas solenoid gets stuck, I replied...

In the manual....

http://www.acwilgar.co.uk/Boiler-Man...20100,100e.pdf

It says gas valve, first solenoid valve and second solenoid valve, which of these do you think it could be?

Thanks again. It is appreciated.

Read more: http://www.diynot.com/forums/plumbin...#ixzz2mMYGYbax




Then got the usual suspects telling me "Just bite the bullet man and get an engineer to diagnose."


I just wanted to order the parts ready for my guy on Saturday, if he comes on Saturday no doubt it will then be Monday before he orders, Tuesday when they arrive and maybe Wednesday before it is done.

Obviously not a real issue, but if I can get all the suspect parts in it could all be back to normal by Saturday.

It would be easier and more likely to change the whole gas valve mate. Both solenoids open together then the second one modulates the gas pressure depending on demand. One other thing to look at though is do you use the hot water last thing at night before you go too bed? The hot water flow switches are prone to sticking so once you have turned the tap off they don't fall back into there rest position. This keeps the boiler fired but with no outlet so the boiler overheats. Just another suggestion mate

[gIzzE]

Originally Posted by mikeysix

It would be easier and more likely to change the whole gas valve mate. Both solenoids open together then the second one modulates the gas pressure depending on demand.



One other thing to look at though is do you use the hot water last thing at night before you go too bed? The hot water flow switches are prone to sticking so once you have turned the tap off they don't fall back into there rest position. This keeps the boiler fired but with no outlet so the boiler overheats. Just another suggestion mate

It is not the hot water, we changed the flow switch 18 months ago when we were having issues.
Also, it is fine until it kicks back in.



I will pick up a new gas valve.

I set the heating to come on for an hour a 3am last night and it was fine, so it seems maybe when it gets very cold and sticking as you suggested.

[RCUK]

Is there a pipe running outside at all??

If this freezes over the condensation cant escape and the boiler wont fire.

Its something like that anyway as british gas keep telling me i need to lag that pipe to stop it freezing over.

(You have checked the timer is working properly otherwise right )