Damper for central heating zone valve?

abenn · 18 Dec 2019

For a while now my central heating has been making a significant banging/hammering noise whenever one of our heating zone valves shuts off. An engineer has been and says the valve and actuator are fine, so the banging is because some of our pipework beneath the floor is not secured properly, and is being vibrated when the motor-open-spring-close valve closes quickly.

That explanation makes some kind of sense to me, but is there not a valve or an actuator with a damper, to slow down the closure, that could be fitted as a direct replacement for the present one without too much trouble?

D_Hailsham · 18 Dec 2019

Have you checked that the water is flowing the correct way through the valve? There is an arrow on the side of the body showing the correct direction.

abenn · 18 Dec 2019

Thanks D_Hailsham. I've just checked both the zone valves (the noise only happens when one closes, and it's always the same one) and I can't see an arrow on either of them. They both seem to be installed the same way round though. The BG engineers have looked at it at least three times and haven't commented on flow direction. I would add that the valve itself hasn't been changed for many years, and the banging has only started in the past couple.

oldbuffer · 18 Dec 2019

1. I'm not aware of any motorised valves with built in dampers.
2. If this has just started to happen, and there have been NO changes to the system, it suggests wear and tear, or a slowly developing blockage.
3. If the actuator heads of the zone valves can be removed without taking the whole valve off, do so and try turning the valve shaft by hand. They mostly only turn a few degrees (20 to 30, but there are some exceptions). If it feels sloppy, its possible the seating has worn, and the valve is "bouncing" as it closes. With most this requires a new valve. With Honeywell (and possibly others) it is possible to replace the innards. If they are old, I'd replace the whole valve(s) if worn.

abenn · 18 Dec 2019

Thanks oldbuffer. The BG engineers took the actuator off and turned the valve by hand, reporting that it was turning smoothly. They didn't mention any sloppiness. How do I check it myself -- I've never taken the actuators off, and don't want to mess anything up?

stem · 18 Dec 2019

There is a MOMO valve. These valves 'Motor On' and 'Motor Off' so they close slower than a spring return.

But wouldn't it be easier just to secure the pipe?

ianmcd · 18 Dec 2019

have you had a new boiler fitted recently ?

abenn · 19 Dec 2019

Thanks guys, I haven't had a new boiler since about ten years ago. Also I'm aware of MOMO valves, and mentioned it to the engineer, but he says a different controller is needed for them.

Securing the pipe, if that is the cause of the noise, is an option except that it involves taking up floors to find where the issue is and to fix it. On the other hand, if it is simply a juddering pipe, and not true water-hammer, then it's not likely to do any harm is it?

stem · 19 Dec 2019

abenn said:
I'm aware of MOMO valves, and mentioned it to the engineer, but he says a different controller is needed for them.

Most controllers provide a 'satisfied' connection that some MOMO's need to be connected to. However, SUNVIC say theirs doesn't even need that. Can't say I have any experience of them though.

abenn · 19 Dec 2019

Yes, I read that line stem. But for the moment I have to take the word of the "professional" engineer who suggested it can't be done. I suspect he means that BG have standardised on everything so far as their service contracts are concerned, and it doesn't include MOMO actuators. Maybe it's time to pay for an independent engineer to come have a look at it for me because, whatever good advice I get from this forum, I don't think I'm going to meddle with the system myself other than straight like-for-like replacements.

stem · 19 Dec 2019

abenn said:
I don't think I'm going to meddle with the system myself other than straight like-for-like replacements.

Spot the difference

Honeywell spring return 2-port motorised valve. [Drayton & Danfoss valves are the same]

Sunvic MOMO

CBW · 19 Dec 2019

Apart from the different names and top picture has image of motor and switch

stem · 19 Dec 2019

oilhead · 19 Dec 2019

Most domestic systems would not readily convert to MOMO operation without additional wiring, and probably new thermostats.
The banging is usually caused when pump pressure 'assists' the spring return. The problem is more usually encountered on 3 port valves. If the valve isHoneywell, then the ball can bereplaced, but you need to drain down to do this, so you might as well replace it complete,( or put up with the noise).

ericmark · 19 Dec 2019

The motorised valve needs a permanent line to close it so yes some rewiring required, it's not like for like with the wiring, however fitting a bypass valve which is other method (if not already fitted) is to my mind a harder job as it requires some plumbing and the water draining and more inhibitor added so becomes expensive.

I like the by-pass valve as one if using TRV control you don't really know when they are all closed to turn off pump, and two the pump micro switches can stick, had them stick with father-in-laws central heating and the boiler was cycling and the pump always running which damaged the pump meaning both valve and pump needed changing.

The micro switch is pushed in with a cam, returns on spring pressure so if starting to stick it could mean boiler and pump are not stopped early enough.

Personally I don't like spiting house into two zones, I would prefer to control it room by room with programmable TRV heads, I am not a plumber, so not sure about this, but when I had zone valves fitted to stop reverse flow due to having two pumps, I wired up the heads a few months before the plumber fitted the valves, so heads work OK without being fitted to valve. So if you un-clip head and manually turn the valve on, then the system should still work, and it will show if due to motorised valve or not, programmable eQ-3 heads I have found for under £10 each so each room becomes its own zone.

Maybe not best cure, but no wiring and no plumbing required.

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Damper for central heating zone valve?

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