Radiators heat up when Hot Water comes on

[KevinRussell]

Chaps

Since we tested the Central Heating a few days ago the Radiators heat up despite the CH no longer being switched on.

I have wiggled the slider on my two-way Zone Valve and it moves freely - I don't know if that is important. Apart from ripping the Zone valve out - is there anything else I should be looking at?

Regards
Kevin

 

[stardanny]

What make of zone valve?

Probably be sticky.

Daniel

 

[KevinRussell]

Daniel

Honeywell. Can I free it up, or should I replace it?

Kevin

 

[Brigadier]

I do not know how relevant my experience is, but here goes anyway.

Our rads were heating up when hot water was demanded i.e. running the shower.
Seemed likely to be a stuck diverter valve in the combi boiler. General consensus was to replace it.

A recommended plumber came out to do the work, and advise merely to flush the system through with cleaner, leave for a fortnight, then drain and refill.

The valve became unstuck after less than 30 mins, and was fine then for a couple of years afterwards.

Now, with shower problem (other thread) and three rads to be replaced, another flush and clean may be in order......

 

[stardanny]

Daniel

Honeywell. Can I free it up, or should I replace it?

Kevin

Try free it up. Does the pipe leading from that zone valve to radiators heat up when hot water is on and demand? If yes, it may be letting by. Try free it up, failing that, replace it.

Daniel.

 

[ianmcd]

Chaps

Since we tested the Central Heating a few days ago the Radiators heat up despite the CH no longer being switched on.

I have wiggled the slider on my two-way Zone Valve and it moves freely - I don't know if that is important. Apart from ripping the Zone valve out - is there anything else I should be looking at?

Regards
Kevin

you do not have a two way zone valve you have a mid position Y plan valve , all the information you have received is wrong, you probably just need to change the Synchron motor if it worked OK before and you have not been messing about with the wiring

 

[KevinRussell]

Ian

Brutal, by true. All three pipes get hot - can you get the Motor separately?

Kevin

 

[flameport]

All three pipes get hot - can you get the Motor separately?

You can, but the default position of a Y plan valve is hot water only, it's held there by a spring so even with a failed motor it would not do what you are describing.
The whole actuator head may be replaceable separately - assuming the valve itself hasn't seized.
Some types can be dismantled and the insides replaced, but that requires draining down so you may as well have a new valve installed.