Noisy motorised valve (sometimes) in central heating system

DJ_Mike

When my central heating/hot water comes on in the morning or evening, sometimes I can hear a loud buzzing noise from the airing cupboard. Looking in there I see the hot water tank/pump/etc., and I've traced it to the small motorised valve, which is one of these:

http://www.screwfix.com/prods/31421/Plumbing/Central-Heating-Controls/Honeywell-V4073A-3-Port-Motorised-Valve

The unit is powered via the downstairs heating controls - if I turn off the power to the heating controls, it also switches off the valve (as well as switching off my central heating!) - but it does kill the noise!

Waiting a few seconds then switching back on, the central heating and pump come back on, and usually the noise from the valve will not return.

So my question is - what's likely to be causing this motorised valve to make a noise from time to time? It's extremely annoying when it does, and moreover when the central heating comes to the end of its timer program, the valve will not stop making a noise, meaning I'm sat there in my office with this valve buzzing away for hours unless I troop downstairs and switch the heating controls off then on again!

Any help appreciated!

cajef

I have had this in the past, it was the actual motor in the valve sticking, the head can be bought separately from the complete valve and is a simple job to change, I got a replacement from my local Plumb Centre.

ormus

screwfix are doing another 3 port valve on special offer.
Horstmann 3 Port Motorised Valve, 29 quid.

DJ_Mike

Would rather avoid having to change the whole valve if I can help it... Looks like it'd be quite messy.

cajef

ormus wrote: »

screwfix are doing another 3 port valve on special offer.
Horstmann 3 Port Motorised Valve, 29 quid.

Why go to the trouble of draining the system down, changing the whole assembly, refilling, bleeding and having to add new inhibitor, when for a similar price you can just change the head/motor which is an easy half hour job.

DJ_Mike

To be clear - it seems like the valve does work, as the central heating and hot water will switch independently (i.e. they don't come on together whether I want them to or not), but the valve just seems to make an awful lot of noise occasionally when they are both on.

cajef

The actual valves can stick due to corrosion if the inhibitor is weak or if there is dirt in the system, if you switch the system off and take the head off you should be able to check the valve, it will have some resistance but should turn freely without any tight spots.

ormus

cajef wrote: »

Why go to the trouble of draining the system down, changing the whole assembly, refilling, bleeding and having to add new inhibitor, when for a similar price you can just change the head/motor which is an easy half hour job.

why go to all that trouble when you can just turn the 2/3 isolating valves off?

cajef

ormus wrote: »

why go to all that trouble when you can just turn the 2/3 isolating valves off?

Isolating valves for a zone valve, thats a new one.:rolleyes:

caleyles

jimmo wrote: »

We certainly had them on our old central heating system which was installed in the 70s.

been plumbing/gas fitting since 1976 and have never seen valves on a m/zed valve a new one on me - are the ops getting mixed up with pump valves?

eek just realised I started my apprenticeship 33 years ago - how can that be when I'm still only 25:o

DJ_Mike

Sorry yes this is a motorised valve that's in line with the hot water pump - I presume because it diverts pumped flow between the central heating and hot water tank that it sits next to.