heating/hot water valve stuck half way?

[Peter Harding]

Hi,

When our hot water is switched on and heating off via the controller, our heating is still coming on (as well as the hot water). The heating controller doesn't appear to be able to swtich off/on the heating. It appears that when the hot water is on, so is the heating and when the hot water is off so is the heating.

I suspected that the 3-way diverter valve (?) may be stuck. On inspection, it's a Honeywell valve with a square silver metal case. There is a lever which is totally loose, it swings free. I can't switch it in any of the positions, there is no resistance at all to this lever.

What do you think the problem is, is it a controller problem or is there a mechanical/electrical problem with the valve?

Thanks very much.

[Set Square]

The fact that the lever is free means that the valve is in either the mid or CH position. The most likely causes are either that the mechanical part of the valve has stuck or that the spring return in the actuator has failed.

You should be able to remove the actuator from the valve by undoing a couple of screws. You can then see whether the valve is stuck. If it's ok, you should be able to turn the spindle by hand - or at any rate using light pressure with a pair of pliers. If it *is* stuck, you may be able to free it by turning it backwards and forwards - otherwise it will need replacing.

If the actuator returns to the HW position when removed from the valve, this is further evidence of a stuck valve. If it *doesn't* it could indicate a broken return spring or an electrical problem. Try turning off *all* power to the heating system at the FCU (*not* at the programmer) and see if then returns.

If the actuator is duff, you can replace it without affecting the 'wet' part of the valve - so no need to drain the system.

[mike ring]

"Set Square" wrote in news: [e-mail]:

The description of the valve makes it sound a lot like a honeywell I replaced a couple of years ago, that was a one piece effort.

Just thought I'd mention it in case Peter's does _not_ easily split

mike