Noisy valves on radiators

[Mark Hewitt]

We've just had an entirely new radiator system installed, the previous ones never had thermostatic valves on them, so I've not had experience with them before.

It's a Valient Combi boiler with convector radiators.. if that means anything to anyone.

Anyway they work fine except for them being noisy when in operation, this is mostly a problem at night as it makes it very difficult to get to sleep.

When the heating is switched off or the valve is closed there is no noise, however when the valve is set to 3 (out of 5), it emits a very loud hissing noise, similar to what you would expect water wooshing through a pipe to sound like, occasionally emits a whistling noise although not as often. When the valve is fully open (to 5) it doesn't make as much noise but still sufficient to keep me awake.

The noise the valve makes can be quite loud, certainly loud enough to be heard from the next room. The previous radiator setup didn't make any noise at all apart from the metal expanding and contracting.

Anyone got any ideas as to what's causing this noise problem and how to go about solving it? We are going to get the installer back out soon but would be good if I can point to something which may be the problem.

[Christian McArdle]

The pump is probably set too fast. The whole system could do with going through a balancing process, which should hopefully result in a lower pump speed.

Christian.

[Set Square]

If you've got a thick enough duvet, you don't need the heating on when you're in bed!

[Christian McArdle]

Also, replacement of the pump (if possible) with a Grundfos Alpha pump would help. Alternatively, an automatic bypass valve can help relieve excessive pump pressure during low flow situations that can occur when the TRVs are partly open. Finally, ensure that you have a room thermostat and that this room has a radiator with lockshield valves both ends to stop ignorant users turning it off.

Christian.

[Ash]

I had this problem in a previous house, turned out the thermostatic radiator valves on some rads were either the wrong way round or at the wrong end.

Ash

[John Rumm]

I have noticed that you get sightly more noise out of some thermostatic valves when they are on the return side of the rad rather than the flow side (even the supposedly bi-directional valves). Might be worth checking which way round yours are. A good balance may help as well.

[Dave Plowman (News)]

Most TRVs these days will work equally well on the flow or return, but may be noisier on the return. You can check which is which by feeling both pipes from cold - the feed will heat up first. Check that they don't have an arrow on them indicating flow - and if they have and are fitted on the wrong end they'll certainly be noisy. What make are they?

Also, have a look at the FAQ on balancing a system. While one with TRVs might work ok without balancing, doing this thoroughly will almost certainly allow the pump to be set to a lower speed. There are also fancy ones which modulate their speed - but those cost money.

[ski]

You need a differential bypass valve fitted. Even though most trv's say that they can be fitted on both flow or return you will find that some will still make a noise. Sometimes you can reduce the speed of the pump on the boiler but check with the boiler manufacturer first.

[John]

Many Combi manufacturers specify the pump MUST be on full speed. Does your system have a correctly installed bypass?

[Mark Hewitt]

Well at the moment the bypass, which is a heated towel rail has been removed because it was leaking.

[Dave Plowman (News)]

Sounds like you've had more than your fair share of problems with this installation.

[Mark Hewitt]

I woudn't say so, but then anything we install is always frought with problems so when there is just a couple of issues then I regard it as a sucess!

The problems are just the two I described, the towel rail leaking, probably because the connector pipes are different distances from the wall, this resulting in twisting stress being put on the radiator which started to leak. Plus the noise on the valves.

However even now when I turn the valve off to almost zero.. it is still making a noise!

[Dave Plowman (News)]

Thought I read it was losing pressure which would rather worry me as it suggests a leak. If I've confused you with someone else sorry to slander your plumber. ;-)

[Mark Hewitt]

That's right but it does seem to be fine with regards to pressure since. touch wood!

[Charles Middleton]

Hi, I used to say that but Ive started to leave mine ticking over at night now. Although my body was warm breathing in the cold air had an strange effect on me!

CM.