Zone valve just whirrs

[cjcoffin]

I have a Honeywell zone valve which just whirrs all the time as if the gear drive is slipping. The manual lever is completely free to move as well, I can't feel it opening the valve like I can the other two in the system.

In this thread @ChrisR wrote "your CH valve is stuck partially open. If you loosen the two fixing screws about 1 turn, it'll probably unjam and work for years.
If you're unlucky you need to replace the whole valve because the spoindle's seized."

Do I have the same problem and/or is it likely to be fixed by a replacement motor? Or do I need to change the whole valve body?

TIA

 

[ericmark]

When I have removed the head, there is a drive spindle under the head which can be moved with grips etc. Note not all valve have replaceable heads, but if you can then easy enough to remove head and see if valve is sized.

The TRV with electronic head is replacing the the motorised valve, it is technically also a motorised valve, but it has programmed into it once a week exercise to stop it sticking, and is analogue rather than digital in that it can vary how much it opens, it is not simply open or closed.

However unlike the old motorised valve there is no micro switch to turn boiler on/off, not that a boiler should be turned on/off, it should at least with gas slowly modulate, i.e. turn up/down. So the modern system is to have TRV's linked to the thermostat, maybe that's wrong name, maybe it should be called a hub? And that tells the boiler what to do, there are still loads of old oil boiler that do turn on/off, but one needs to look at the overall control method and decide does this system really suit the boiler and my needs?

I still have motorised valves, they turn whole house or whole flat on/off, since often flat not used it makes sense to be able to turn off whole flat. But in most homes the motorised valve is a remnant of an old system developed before the advent of the modulating boiler designed to capture the latent heat from the flue gases.

 

[oldbuffer]

1. If it whirs all the time, the motor is running, so replacing it is not likely to do anything.
2. If the outside metal cover has a small raised bump in it, then it is one of the later valves, in which the actuator mechanism can be changed without affecting the water side.
3. Try:
3.1 Isolate the electrical supply to the valve. Unless you know how to test for live power, and have the equipment to safely do the test, I'd recommend turning the whole house supply off at the consumer unit.
3.2 Remove the outer metal cover.
3.3 Slacken the two screws which secure the actuator assembly to the actual valve part. The valve part has a brass base.
3.4 Jiggle the actuator mechanism around a bit, then re-fasten it.
3.5 Replace the cover and reconnect the supply.
3.6 Test to see if it now works.
4. If it doesn't work, replace the actuator:
4.1 I'd buy a replacement valve, the whole thing, not just the actuator. The price difference is small.
4.2. Isolate power as above and remove old valve cover.
4.3. Remove old actuator.
4.4. Check the spindle of the actual valve. It only moves through about 20 degrees, but you should be able to turn it with your fingers, or at worst with very light pressure from a pair of pliers.
4.5. If the spindle doesn't turn easily, replace the whole valve. See 5. below.
4.6. Remove new actuator from new valve and fit to the old valve base.
4.7. Replace the valve cover.
4.8. At the wiring centre, or equivalent, identify the 5 wires from the old valve (brown, blue, yellow/green, grey, orange) and cut them about an inch from the wiring centre terminals, leaving the insulation in place. It is best to make a note of all connections in the wiring centre, as these can be very confusing.
4.9. Connect the wires from the new valve to the terminals in the wiring centre, colour for colour, removing the stubs of the old wires at the same time.
4.10. Test.
5. If you have to replace the whole valve:
5.1. Drain the system (radiators and hot water cylinder) to just below the level of the valve to be replaced. If you have an F&E tank (in the loft?) empty and clean this out first, otherwise you will wash any rubbish in it into the radiator circuit.
5.2 Undo the compression nuts securing the old valve in place and remove it. You are likely to get residual water, so lots of old towels.
5.3. Insert the new valve (complete). Provided you are swapping Honeywell for Honeywell, you can re-use the old compression nuts on the pipes and the old olives. Best to use a little jointing paste (Jet Lube V2) on the old olives. If you want to use the new nuts and olives which come with the valve, remove the old olives and nuts first. You shouldn't then need any paste.
5.4. Do the nuts up finger tight, then 1/3 to 1/2 turn with a spanner. If you have a slight weep on refill, nip the nuts up a little more but don't overdo it.
5.5. Connect the new valve's wires into the wiring centre as 4.8 above.
5.6. Refill the system, checking for leaks as you go.
5.7. Test

 

[cjcoffin]

Thanks both.

Tried it again, this time I can hear it turn the valve (once only). So it is not (now) stuck but still doesn't work reliably.

Remembered there is a permanent live to the microswitch so turned whole boiler cct off at DP switch.

Dismantled it and was pleased to find the base screws are semi-captive as is in awkward place (aren't they all!).

Valve spindle easy to turn. Motor no longer runs, just makes faint humming sound so power is still reaching it.

Brass pinion not worn so took motor off to investigate further. Pinion easy to turn and I can hear/feel the gear train turning. Still no torque from motor so I guess it is intermittent at best or has packed up entirely. Will order replacement e.g. this from Amazon or this from BES. If there are any snags please let me know!

Thanks for all your help.