Baxi Solo 3 PFL 50

[nearlypastit]

I have a Baxi Solo. The hot water side is ok but I cannot get the C/H side to work. I thought at first that it was the room stat as it was quite old. I fitted a new stat and also fitted a new programmer at the same time as it needed an upgrade. I still have the same fault, hot water fine, no c/h.
I was told that it might be the motorised valve but I can only find a solenoid valve sitting next to the gas valve.
Any ideas please.[/b]

 

[45yearsagasman]

Please describe your system in detail,ie all controls like motorised valves which may be near hw storage cylinder.Its most likely to be a zone valve problem.

 

[nearlypastit]

Not sure where to start. I'm not a heating engineer, I am a retired domestic appliance engineer, on a pension so trying to save money by repairing it myself.
The boiler seems to have the main gas valve with a solenoid beside it, a potentiometer, a thermistor, a overheat stat and a pcb (which I change a couple of years ago).
Not sure what else I can tell you.

 

[45yearsagasman]

You will have a hot water cylinder somewhere in the property and close by will be a pump and possibly one or two motorised zone valves.Follow the pipework from the top of the boiler and you will find these controls.

 

[nearlypastit]

The pump is in a cupboard under the stairs and attached to the pipework nearby is what looks like a valve. I could feel some heat on the case and also the pump felt like it was running.
I have got to stop at this point as I am off to the hospital to see a friend who has had an operation this morning.
I will continue checking later.
Thanks for your help.

 

[nearlypastit]

Sorry for the delay, I have had a busy weekend (I'm getting too old for all this DIY lark).
The pipework running from the pump goes to a 3 position diverter valve. The pipe leading to the valve and the two branching off are all hot when the boiler is on but I am still not getting the rads warm, when I switch the programmer to C/H only everything switches off.
Any ideas?

 

[stem]

The motorised valve sits at the hot water only position when at rest. When central heating is required a small motor winds it across to the centre (HW & CH) position or all the way to the end of it's travel (CH only) My guess would be that the valve is sat at the HW position and the motor has failed, or it has stuck.

The 3 port valve should have a small lever to operate it manually. Switch on your hot water only (make sure that the cylinder thermostat is turned up and calling for heat) Now manually open the motorised valve with the lever and latch it open. Do your radiators heat up now?

If so the valve or its control signals are the problem. If you can, check that there is a live on the white wire to the motorised valve when the heating is on and the room thermostst is calling for heat. This is the signal that should wind the valve to the central heating position.

 

[nearlypastit]

Thanks for that, I am just off to the hospital yet again to visit our friend. I will try this when I get back. I had noticed the little lever on the top of the valve and I can see where it should clip in.

 

[nearlypastit]

Thanks for your advice. I think you are right, the motorised valve does seem to be the problem. My problem now is to change it. The valve is situated right at the back of a low cupboard so I am working myself up to crawling in on hands and knees and working in cramped conditions.
The alternative is to send my wife in there (she is a bit younger than me).

 

[sooey]

It sounds like you need to ditch the "nearly" bit from your username.

 

[stem]

With most types of valve, you can change the powerhead without removing the pipe connections so you wouldn't have to drain down the system. But you would have to tell us what sort of valve you have or post a photograph for confirmation.

If it's a Honeywell, the valves with replaceable powerheads have a small raised bump at the opposite end to the cable. You can see it in the picture.

Untitled

• stem
• 1 Apr 2010
• 8

 

[nearlypastit]

Yes it looks like the one in the photo. Honeywell Sundial Y Plan 3 position Diverter Valve.