Noisy radiator

[Bob H]

A bathroom radiator has recently developed a vibrating noise,which seems to have developed since it was removed and then replaced. The noise at first sounds like a hammer drill into brickwork, and when I just turn the TRV very slightly, it stops for a while before starting up again. Sometimes it stops all on its own, with no intervention from me.

I have bled the radiator, and only get water out now.

Any ideas as to what the actual cause is?

I would guess it is something to do with air in the system.

[Harry Bloomfield]

Bob H was thinking very hard :

Its the TRV, some need to be installed in a certain flow direction and vibrate if wrong way. You can determine the direction of flow, by allowing it to go cold, then opening it and seeing which pipe side gets warm first..

[Andrew Gabriel]

Is the TRV on the same side it was, and the same orientation? Some TRVs can only operate with the flow in one direction, and can do this if the flow is reversed.

[Bob H]

Yes the TRV, a new one, is fitted on the same side as the old one. After a short while there was a leak on the joint, so I had to replace the olive, and now it doesn't leak

[Bob H]

I assume by 'which pipe gets warm first' you mean the pipe on the opposite end of the radiator to where the TRV is fitted.

[Harry Bloomfield]

Perhaps the old TRV was designed to work happily in either flow or return pipes and the new one only on the flow?

[Roger Mills]

That's possible, but was the TRV disturbed when the radiator was removed and replaced - and maybe fitted on the other side? If not, it shouldn't be the TRV on its own - or it would always have done it.

Chances are that the pipework was disturbed a bit, and that one of the pipes is now in contact with some part of the house structure which is amplifying any slight vibrations caused by the TRV. If you find any points of contact, try to move the pipe away a bit, or put some felt between the pipe and the structure to lessen the chances of vibrations being propagated.

[Brian Gaff]

Sounds like air in the pipe its connected to, which may dip or rise nearby. I used to work near one some years ago, and it took numerous so called experts to eventually u cure it by slightly raising the long pipe that went through a wall. Weird stuff central heating. I have none in my house!

Brian

[Bob H]

After allowing the said radiator to go cold, I turned up the thermostat and also on the CH thermostat.

I put each hand on each of the 2 pipes and it is definitely the pipe with the TRV fitted which gets warm first. So I now assume, from what other people have said here, that the TRV is installed correctly.

[Andrew Gabriel]

It's the flow direction through the TRV which matters, not if it's fitted in the flow or return.

[F]

The new one is probably bi-directional so you need to take the sensor head off and have a look at the marking that indicates the direction of flow. It may well be that it's set for the 'wrong' direction. Change the direction (usually by rotating the collar with the marking) and refit the sensor head.

This scenario is the least likely of the two but, if it's not a bi-directional TRV, then you may simply have installed it in the wrong orientation and, again, the flow is against that which the valve is expecting. In that case, take the valve off and either rotate it to swap connections and then put it back on, or swap it for the lockshield and keep it in the same orientation.

[DerbyBorn]

"Brian Gaff" wrote in news:m1dqhh$t63$ [e-mail]:

Some of mine are noisy - where the supposed any-direction TRV is on the return. I can reduce the noise by throttling down the lockshield.

[harryagain]

If your circulating pump is variable speed, try turning it down a notch & see if the system will still work. (Switch pump off before moving the speed switch on the pump body)

Failing that, try tweaking the lockshield valve down (ie clckwise)on the radator. Only move it a quarter turn at a time & note what you have done in case you have to reverse it

[Bob H]

As I am not sure which is the right or wrong direction when I look at the TRV so I have posted some pics for you to look at.

This is the IN pipe and the TRV goes on it http.www//bob2cat.org.uk/ScratchPics/Inpipe.jpg

This is a bottom view or underneath view of the trv http.www//bob2cat.org.uk/ScratchPics/trv.jpg

And this is the trv on its side http.www//bob2cat.org.uk/ScratchPics/TRV_Side.jpg

As can be sen it has the markings for setting the position, but I noticed that after the 1111 marking, there is another one like this 1>. More like 3 vertical lines made to look like an arrow with this at the end >, if you follow.

[Andy Burns]

The blurrycam doesn't help, but is that an arrow pointing down on the TRV body (not the head) of what you say is the inlet pipe? if so it suggests the TRV should be fitted on the outlet, the water flow should follow the arrow

Or if your radiator fittings have tail pipes rather than just a union (doesn't look like it) the TRV could possibly be rotated to be horizontal instead of vertical?

[Bob H]

Yes it is a down arrow on the actual metal part, which is under or below the trv itself

I say its the inlet pipe as it is the one which gets warmer first, maybe I was wrong. The TRV has always been fitted on that pipe, and I only replaced it with a new one because the old one was looking very tired and mucky.

Not having much experience with these sort of things, I was an metal fabrication engineer not a plumber, I don't want to be doing anything which changes the pipes or whatever.

[Bob H]

Oops I made a mess of the URLs. I don't know what I was think there before, doh!

[F]

That lot looks like a Danfoss C2 but the body on the pipe seems to be missing a grey plastic collar just below the metal hexagon at the top and which has two vertical arrows on it, one pointing up, the other pointing down. Unless the collar has been replaced by the fluted ring below the hexagon. Does the ring rotate? Has it got a couple of vertical arrows on it?

The idea is that you rotate the grey collar (fluted ring?) so that the arrow points in the direction the water is travelling in when it enters or leaves the valve as it flows from or into the pipe below. In your case, if this is the end of the radiator that gets warm last, the arrow on the collar should be pointing down.

The '3 vertical lines made to look like an arrow with this at the end >' indicate that the valve is fully open when the head is set to that position.

[F]

Here you go, click on the small right hand image at

to get an enlarged version and then click on that to enlarge it. Grey collar clearly visible.

[Bob H]

The site is not loading for me just now, so I'll try it later.