Drayton Motorised Valves

[Sheepy1209]

Hello - we have a heating system that was installed by British Gas around ten years ago. It's got two two-port motorised valves.

These were originally British-Gas branded but as we discovered when one failed they're actually re-branded Drayton ZA5's.

Both the original actuators have failed over that time and now it looks like one's gone again; symptoms vary depending on which one has failed.

Anyway, it's an easy enough job to remove the actuator and replace it, but I've had to do it too often and I'm getting a bit too creaky to wire it in with my head upside down under the floorboards.

The fault every time has been that one of the moulded anchor points for the springs has broken off; so the valve is then returned by only one spring so partially closes.

The valve bodies both seem fine - easily turned by hand.

I've had a look through other posts here and it does like this is a known problem with Drayton valves; so before I order yet another new actuator I'd just like to check a few things:

- Is it possible that something about the installation is putting strain on them? (Both are mounted on the side, not the top)
- Any reliable, safe fixes? I've seen posts about using a screw but I'm a bit wary what with having electrics nearby.
- Is it best instead to get someone in to replace both valves in their entirety with another make? Any recommendations?

Ta

 

[JBPHS]

Twist end of springs with a pair of long nose pliers so that they hook into the hole where the lugs have snapped off.

Can't recall having this problem with Honeywell valves.

James.

 

[diverdee]

or just change them for better valves ie honeywell or danfoss wiring is just the same.instead of getting to the wiring centre you can just cut the wire half way and join the new valve there with a suitable junction box

 

[Whitespirit66]

+1 for Honeywell. Unless it's a budget job, I always try to fit Honeywell valves. They're a little bit dearer for a reason.

 

[Sheepy1209]

Thanks - sorry I was a few days replying, I've only just had a chance to look.

It turns out it's NOT the plastic housing that's broken; instead the hot water valve tries to open but sticks about halfway; enough to briefly trigger the microswitch and fire the boiler, but then it backs off a bit and the boiler switches off.

What this means is that with HW only, I get nothing; with CH + HW, I get both, but the HW is slow to heat up because the valve's not fully open.

I took the motor out, and tried to turn the geared actuator against spring pressure; it seems to 'snag' halfway, but get it past that point and it moves fully. I can't see what's making it snag, but it's freed up again and now seems to be working - the motor is opening the valve fully.

No idea why it's doing it; this is the older of the two valves and I think I'll just replace the head in the spring; the system itself is pretty old (boiler ten years old, but pipes / radiators seem to be of Roman origin) so I'm not sure that it's worth swapping the valves out altogether.