Central Heating - Continually On!

[smudgersmiffy]

We have a 'normal' system.

Cold water and expansion tank in the loft. Hot water cylinder in the airing cupboard. In the airing cupboard with have a three port motorised valve and central heating pump. Downstairs we have a Potterton Suprima 60 and time clock, and a thermostat in the living room.

On our Potterton time clock, we have the hot water set to continuous, but the central heating set to timed.

Even though the central heating is set to timed, it seems to be on all the time - even though the thermo stat isn't calling for heat (we can hear it click to turn off).

So, does anyone know why our central heating would be on continually, even though it's switched off?

 

[Fluffster]

Your 3 port valve could be stuck in the mid position.
Have a look at it and get someone to turn the system off and on and listen to hear the motor running.
You should have a lever on the side to move it manually.
Pete

 

[seco services]

poss the 3 port valve is letting by.

check the valve it will be hot on the pipe to the cylinder and the pipe to the heating should be cold.

 

[smudgersmiffy]

I've just felt all three pipes at the bottom of the valve.

They were ALL hot, so not much to go on there.

Someone mentioned switching off and on again, whilst listening for the motor. Could you give me some more information on this - ie in easy digestible steps?

 

[seco services]

if your heating is off at programmer hw on.
isolate the fused spur to your heating system and turn back on again
this will reset the mid position valve to it relaxed position
hw open heating closed.

their is a lever on the end of your valve.
with hw only calling for heat and valve being in relaxed position
if you push the lever across it should have resistance on it (not floppy)
push it right across and let go you will hear the valve return back to hw only open heating closed.

if only hw calling for heat and all 3 pipes on valve are hot the the valve is passing.
maybe faulty paddle in the valve or crud blocking the port.


what make/model is the valve ?

 

[smudgersmiffy]

I'm pretty sure the 3 port valve is faulty, so I'm going to take advantage of the long weekend to replace the whole unit.

As far as I can make out, all I have to do is the following...

1. Turn off electricity.
2. Turn off supply to header tank.
3. Drain down system using outside drain cocks.
4. Remove head on old valve, making a note of where each wire goes.
5. Remove old valve.
6. Install new valve
7. Reconnect Wiring.
8. Refill system
9. Bleed system
10. Turn on electricity supply

Have I missed anything.

I'm getting a Honeywell Honeywell V4073A 22mm 3 Port Mid Position Valve, as looking at this forum, they seem to be the ones that people rate as the best.

Look forward to hearing from anyone if they've got any comments.

 

[TicklyT]

It would be a good idea to add some inhibitor when re-filling the system.

 

[smudgersmiffy]

A piece of cake.

The old valve was a Sunvic one, and once removed, it was obviously in a bad way, as the rubber paddles looked very perished.

The new Honeywell one looks a much better design with the ball, and operates very smoothly in comparison to the old one.

Everything working OK at our house now - and we can now have hot water without the radiators being on!

Thanks to all the helpers.