Diverter Valve

[Grenage]

I've an old Potterton Kingfisher, and noticed this morning that the top of one of the radiators was very slightly warm; as you can imagine, we've the heating's not been on in a while.

I assume it's the diverter valve, but is there anything else I should check before I buy a new one?

Cheers!

 

[stem]

It's possible that the pump may have failed, and the radiators are warming up slightly because of natural circulation. Check when the hot water cylinder is being heated up & see if the pump runs then.

By "diverter valve" I assume you mean a 'three port motorised valve' if so, this controls the boiler & pump when required by the central heating only via an internal switch. So, if it had failed and it wasn't moving to the heating only position, the boiler wouldn't come on, so the radiators wouldn't even get warm. A note of caution here is that the boiler would come on, if the hot water was telling it to at the same time.

 

[Grenage]

Hi Stem, thank you for your reply.

Yes sorry, it's an external motorised valve (ACL Lifestyle Mid-Position). I pushed the manual lever all the way over to Heating last night, and it locked in place; I reset the power to release it, and it went to the mid position and I tested both the heating and hot water. I turned off the heating and ran the hot tap, and the boiler fired up, but the lever stayed in the mid position. I manually moved the lever to Hot Water only when I was done.

Would that be indicative of the motor failing?

 

[stem]

When you heat hot water only, the valve is not powered at all and sits at the hot water only position where it is held by a spring. It will stay there until the heating is next used and the motor winds it to the 'mid' position, or 'heating only' position.

It is quite likely that it was simply stuck in the hot water only position as it has been parked there for some time, and your moving it has now freed it off. The motor maybe struggling a bit, but it is working to some extent as it has to inorder to hold the valve in the mid position. If the motor had failed completely, the spring would have pulled it back to the hot water only position.

You can replace just the motor for less than £20 but it may just be that the valve is stiff from lack of use and some WD40 on the operating splindle will keep it moving freely.

However, you didn't say if the pump was working or not or if the radiators actually heated up.

 

[Grenage]

Thanks again, Stem.

I'll give it a once over and see how it fares; that's money saved!