Cold radiators, burner lighting ok, hot water ok? Pump? PCB?

[jonnydoe]

Hi

My central heating is not working intermittently (always in the evenings). Hot water is fine it's just all the radiators are cold around 9-10pm. Thermostat seems ok and I hear it click then shortly after triggers the burner on the boiler no problems.

I reset the boiler (turned off and on lol) a few times and this usually works and the radiators get hot. It has been getting worse lately.

Is this either

a) The pump or
b) the pcb

or something else?

Haven't had it serviced for 2 years so probably a good idea... Boilker is only 4 yrs old

Thanks for your help

Steve

 

[chrishutt]

It might help if you say what boiler you have - make, model.

 

[jonnydoe]

Glow worm Micron 40ff

 

[Mr. Tickle]

Hi there Johnny - I've got a gloworm 30FF and seem to have had the same symptoms as you have - read my older thread here:

http://www.diynot.com/forums/viewtopic.php?t=21658&highlight=

Does any of it sound familiar?

 

[jonnydoe]

Thanks Mr Tickle, hmm very similar problem.. but my rads don't even get warm. They seem to be ok during the day it's just the evening they don't work unless I reset the boiler.

It could be a 3 way valve, my gf had a similar prob recently (£150inc vat). HW is always fine its just the CH.

If it was the pump It wouldn't work at all would it? Or could it work intermittenly.

Now I'm confused, wish I knew more about these things

 

[Agile]

I see a common pattern in a lot of these postings, boiler never serviced, dont want to call a proper boiler engineer etc.

It does not sound like any obvious DIY problem from what has been said so far.

If the problem is inconvenient then I suggest you call an experienced heating engineer who is competent with wiring and controls.

I was born in Ipswitch, Valley Road !

Tony Glazier

 

[jonnydoe]

I've now read through hundreds of posts and would say it is more than likely the 3 way valve.

I'll give an engineer a ring this week and get the boiler serviced at the same time.

Cheers Tony, keep the flag waving for Ipswitch

 

[Agile]

You may well be right!

It could be that by the evening the demand for HW is satisfied and using CH only produces the fault.

You could try leaving the HW off until 9 pm and see if that changes the pattern. Neither the boiler nor the valve can read the time

Tony

 

[jonnydoe]

Ok took the actuator off the 3 way valve put back on seems to work ok when switching between hot water and CH.

Boiler looks to be the problem, I give it a knock on the side and the burner suddenly ignites.. Defo needs a service.

I'm certainly not happy that it's only 4 yrs old and has been serviced before (I know not in the recommended 1yr interval but certainly 2 yrs which is what most people recommmend.)

They don't make em like they used to!

 

[Mr. Tickle]

The main problem i found when calling out an engineer is that:

1) you need an engineer to look at the boiler
2) you need a plumber to look at the rest
3) no one beleives you when you tell them what is happening (see my thread)
4) engineers want to come out and do EVERYTHING and book out a week of their time
5) all the ones i called wanted to replace everything, step by step to see what the problem was.


It does pay to do some diagnostic work first.

Good Luck!

 

[jonnydoe]

Yes I totally agree Mr. Tickle just calling an engineer out without knowing what's going on could cost dearly. So many rip off merchants around I just wish i could do some of these jobs myself!

Latest update is the 3 way motorised valve is playing up again.. and maybe the boiler has a problem so 2 issues there. Boiler needs a servicing and a new actuator to fit.

The actuator looks dead simple to replace (apart from the electrics which I'm a bit worried about). New Drayton actuators go for about £80 I Think

 

[bripl]

glowworms do have a problem with the pcb i think it is a thermistor connection onto the board does not always make connection very difficult to diagnose as the fault can be very intermittent

 

[jonnydoe]

Yes mine is very intermittent, sometimes is ok for days. A swift smack on the side of the boiler generally helps lol

However the motorised valve defo needs replacing, ooh this could be costly...

 

[andsam]

What colour is the pcb ?
G/w had some probs with pcbs going down. If it is the cream coloured one they some times burn out .The more modern ones are green.

 

[jonnydoe]

I don't know I dare look at the pcb. I'll call out an engineer it's happening almost all the time now. Actually think it may be the pump now haha

3 way motorised valve works
boiler is firing up and burner is going.

Just cold pipes and radiators, pump?