Radiators hot even though heating switched off

Been experiencing a problem for the last couple of weeks (since the warmer weather). The heating is switched OFF on the timer, but whenever the hot water kicks in (morning & evening) the radiators get piping hot.

Prior to this we had an issue where we couldn't get the radiators to come on without having the hot water switched on as well.

We live in a flat (1 floor), boiler is a Baxi back-boiler fitted in the fireplace/chimney breast (can't remember the model off top of my head). Hot water tank and timer is in the airing cupboard.

Read a few posts indicating similar problems, with responses that it could be the 2/3-way motorised valve or the gravity valve. I know the motorised valve is on the pipework in the airing cupboard...has 3 pipes to it so assume it's a 3-way?

I just don't know how to check it. It has a little sliding arm on the front which is free to move when nothings switched on, but a little more restrictive in movement when h/w is on.

No idea where I locate the gravity valve....?

Any ideas welcome. I'm just an average guy, not a heating engineer

If the rads get hot without the heating being on then you must be getting free heat from somewhere.

I would suggest you keep very quiet about it otherwise everyone will want to have that!

Tony

Can you post a photo showing the airing cupboard with the cylinder, valve, pump, pipework etc.

(You can do this via the Images facility)

It sounds as if you have "reverse circulation" through the heating system; this can happen if the return pipes are not properly connected together.

or it could be 3 port valve letting by. to test, turn whole system off and allow to cool, then turn on hot water, the pipe from 3 port to cylinder should get hot but the one to the rads shouldn't, if it does 3 port needs replacing, if not then probably reverse circulation as mentioned earlier.

I reckon it is the 3 port valve stuck due to gung or the electrics are kaput inside!
Try this! Along the side of the valve is a little lever, try moving it to the other side. It may spring back a bit, see if that works and it stops heating the other ciruit.

What make is the 3 port valve? If it is Grunfoss or Honeywell you will probably be able to change the electrical controller ontop without draining and disconnecting the valve assy.

If it is an ACL? Well, looks like the whole lot will need to be changed, ie. valve and the electric box on top as a whole unit!