Boiler turns itself on and off - plumber cannot fix

[Pixie001]

Okay, I'll attempt to make this as brief as possible. I have an Ideal Classic boiler, an airing cupboard and a water tank in the loft.

My boiler now has a 3 weeks history of 'playing up'. Some days she will not fire up at all, other days she runs smoothly for hours. At times she does a constant on/off phase where she runs for 4 minutes, turns off and then 20 seconds later turns on again: and repeat.

I've had 2-3 days of no heat or hot water during these 3 weeks and it's wearing me down.

Week one - a reputable company told me they couldn't find anything wrong but I needed a new boiler.

Week two - a second reputable company told me I didn't need a new boiler but had to wait until she failed until they could diagnose. Diagnosis finally made - the pressure switch was replaced. No difference. So then immediately the circuit board was replaced. No difference. Old circuit board put back in - she fired up!

I'm now at a loss as to what to do next. I've spent £200 and no further forward although she is at least heating up my house and water now which is a massive improvement. My only current problem is the on/off issue, although I suspect in a few days time she will stop working again altogether.

Can anyone help me please?

 

[muggles]

What programmer do you have? Have your zone valves been checked? It sounds like an external issue rather than a boiler issue to me, and I'm guessing your reputable company may not have been all that handy with a multimeter

 

[Pixie001]

Hi Muggles, thanks for your reply.

I have a Honeywell C21 programmer, I'm not sure about Zone Valves as I'm not sure where they are. Are they in the boiler unit itself?

 

[muggles]

No, they're normally in your airing cupboard. Might be a single 3-port valve. Definitely sounds like you need some electrical checks doing, but they need to be done while it's in a fault condition

 

[ianmcd]

I suspect that you have 2 x 2 port valves or S plan as we call it and one of the end switches is sticking, quite a common problem but in order to diagnose which one it is that is sticking boiler would need to be false firing while your engineer was there, as you suspect it will most likely stick permanently and then is easily diagnosed , I doubt very much if the problem is inside your boiler and you dont need a new boiler you have a very reliable boiler

 

[Pixie001]

Thank you Muggles and ianmcd, I really appreciate your thoughts and advice.

I have one of these in my airing cupboard (picture attached, hopefully) which was checked and working fine when the guys were here? Is that what you meant?

 

[Agile]

Week one - a reputable company told me they couldn't find anything wrong but I needed a new boiler.

Can anyone help me please?

Your boiler, although old and not very efficient, is one of the most reliable ever made!

So I would like to ask you, why you consider this company reputable when they give you advice like that when the only purpose is to make them some money!

The fault is going to be with external components.

I would also say that you should not be paying for a new air switch when it was not required to fix the fault and not for that incorrect diagnosis either!

Tony

 

[Hugh Jaleak]

Tony, if the OP doesn't understand the workings of a heating system, then they rely on 'reputable' companies to give a correct diagnosis, and fix the issue for a reasonable fee. Only when the problem reoccurs do they realise it hasn't been fixed.

I had a problem with my computer, not knowing how to repair it, I asked a 'reputable' local guy to have a look. He took it away and brought it back a few days later, I paid his fee. The computer has been fine since.

 

[jackthom]

That sort of 3 port valve will at least make it easier to see what the controls are telling the boiler to do. Next time you have problems start by making a note of the position of that valve and try to decide if it is what you would expect?
For Heating only it should be at "H", for hot Water only at "W" and if both are required together it should be in the Middle position.

Is there a timer/programmer in the system? They can play up and cause intermittent problems like this.

 

[ollski]

Presumably the second company saw the problem and established there was a live demand at the boiler and no ignition thereby ruling out external controls?

 

[ianmcd]

as per my last post and after seeing your new photo you have a Y plan system and not an S plan, I would still suggest that you have an external control fault, your boiler is a very simple but very reliable boiler and not much goes wrong with them, fans and sometimes gas valves but not a lot else and neither of these would cause the problem that you have , do you have an external frost stat by any chance ?

 

[gas112]

what ideal classic is it ? , i would be looking at possible dirty pilot or faulty solenoid valves on gas valve as first port of call