Central heating on for the first time since spring, won't turn off again

[Toby G]

Hi all,

We turned our heating on yesterday for the first time in a few months, and now it won't turn off again.

It was turned on at the timer/control panel, but when it was turned off again at the panel, the boiler kept going and the radiators were still being fed hot water. (Hot water control was off at the time).

In the meantime we turned all the radiators down to 0 and they went cold, but the boiler kept going.

Here are a few pics of our installation, this is all the in the loft, with the hot water tank one floor below.



Any suggestions?

Cheers,

Toby

 

[gasmanrob]

Three 2 ports suggest you have two heating circuits, so I'd guess only one of those circuits is heating up?

Those valves have a plastic arm that holds a spring and they often snap off preventing the valve from spring returning shut again.

Unless you had hot water on when that picture was taken its the valve on the left at fault. Looking at the position of the manual lever.

With you're finger tip just check it hasn't locked into manual by sliding the lever to to left and at the same time lifting it with you're finger nail it should move with little resistance and naturally begin to return to the right same as the other two pictured. If it's all floppy then it has snapped if it's extremely stiff and reluctant to move then it's holding voltage either from a control or the internal board in the valve has gone south.

If anything I've written is unclear let me know and i try and explain a little better

 

[gasmanrob]

Oh forgot could also be a sticky paddle holding it on. On the side of the valve there is a little bottom push it and twist the valve head, you'll then see a spindle with two flat sides the head sits on with some pliers is a small adjustable see if it moves freely it won't move much maybe 30 degrees so be gentle.

 

[Toby G]

OK, will have a look this evening - thanks Rob

 

[plumben]

I'd go with above as well, faulty two port is where I would start

 

[Old Account]

What about the room stat did you check that the room stat is turned down?
If yes then most likely the 2 port valve as mentioned before.

 

[Best]

Drayton valves actuators (the white electrical part of them) are troublesome.
The brass body also seems to seize up on the spindle on those types and can cause same problem also.
I just buy entire one of those and replace the brass part as well if it is seizing. They are as cheap that way.
Good luck moving those pipes apart to replace entire valve though! Looks like they are a bit one piece!

 

[Toby G]

It does seem to be the 2 way valve, yep. The switch would move and had some resistance, but wasn't too stiff.

When I manually returned the switch to the right, the boiler went off. I then turned the heating control back on, but set the thermostat low so that it didn't fire, and nothing happened. Set the thermostat higher and the boiler started up, as it should.

The 2 way valve though went back to the left (on?) and didn't go back when the heating was turned off again. I manually put it back and we won't turn the heating on again until we've fixed it.

From this description, do we need just the electrical bit, or a whole new valve?

 

[AWheating]

Swap the head from the other heating circuit and see if it works, if yes then change the head

 

[gasmanrob]

Just the actuator head (grey box).

If you removed the head and shook it you'd hear a bit of plastic rattling around inside it.

Whilst these are easy enough to change I would advise you had someone come in depending on your abilities. Don't forget if you switch the wrong fuse off or discover you have two points of isolation you'll be getting a nice bout of 230v.

Glad to see it appears we've gotten to the bottom of it