Singing radiators after moving TRVs

Spoonie_Turtle

Driving me barmy.  Not sure the other family members can hear it, it's fairly high-pitched, almost a whistling sound but not quite loud or piercing enough.

Background: Heat pump and rads were installed summer 2019.  Never knew how to use the TRVs so never touched them.  They have been bled a couple of times in the years since installation.  The first time I adjusted the one in the kitchen, it was making the sound all the time afterwards, even at night when the heating wasn't running (though I think the water circulation pup was still going for frost protection?)  That time I turned it from 6 (fully open) to about 3.  After identifying the sound the next night, I put it back up to 6 and it stopped.

Few months later, taking us to last week, and the plumber doing our bathroom told us to turn all the rads off as he needed to disconnect the bathroom one, then back on once he'd done that.  The idea was to not fully drain them so they didn't need bleeding, I think?  We did, and the kitchen one started singing again.  So I turned it down to somewhere between 3 and 4, but then the kitchen was cold for washing at night so I turned it up to full again but thankfully it was okay and din't make a noise.

This evening one of the rads upstairs is doing it (not been touched since last week).  It was on 4, where the green button is.  Turn it down and it got louder, turn it up just past 4 and it stopped.

Anyway, at the end of a long story: does anyone have any ideas WHY the radiators might be doing that?

[Incidentally on our Housing Association's heating page on their website, they say under no circumstances must we drain down or bleed the radiators ourselves, so that's not an option.  Though once the bathroom's finished and that radiator reconnected, if the plumber doesn't bleed them I'll check the temps at the top and bottom to see if they indicate needing it.]

Lorian

When it's making the noise try closing the lockshield valve off a bit on the other end of the radiator. Could be the valves are on the wrong way round but reducing the flow a bit might do the trick.

diystarter7

Contact the owners of the property for advice/help.

Thnaks

Spoonie_Turtle

diystarter7 said:

Contact the owners of the property for advice/help.

Thnaks

Thanks but it takes hours to get through even for important things so that's a last resort.  I wanted to ask here first for any ideas and an indication of whether it might be an actual problem or not.

Lorian said:

When it's making the noise try closing the lockshield valve off a bit on the other end of the radiator. Could be the valves are on the wrong way round but reducing the flow a bit might do the trick.

Interesting, I'll look into that, thanks.  Is it something that could have shifted or moved slightly, internally, in the 4 years since installation?

Apodemus

Can you change the speed setting on the circulation pump?  Indeed has the plumber done something that might have changed this?  Just like any whistle ("just pucker up and blow..."!) the pitch changes with speed and aperture and TRVs often whistle at that point where the aperture is almost, but not quite closed.  I have one that can sit at that point for surprisiingly long periods before shutting itself off.  Manually opening or closing the TRV can stop the whistle, but defeats the purpose of having a TRV, so you need to work on the speed/volume combination somewhere else.  The lockshield is one possibility, but so is the pump, especially if it is a modern one with variable speed settings rather than just three fixed speeds.

matelodave

Don't turn down the pump speed unless you know what you are doing, Heatpumps require a high flow rate to function properly, so turning it down could cause the heat pump flow switch to shut the HP down.

IMO the best course of action would be to open up the TRV and reduce the heat pump flow temp a bit and ensure that weather compensation is turned on. Don't try using a heatpump like a conventional boiler.

The trick with a heatpump is to get it running at the lowest flow temp you can get away with to keep the house temperature fairly even and run it for longer and just use the TRVs to avoid the rooms getting over heated.  Weather compensation should reduce the flow temp when its wormer outside and increase it when it gets colder to balance the heat loss.

Spoonie_Turtle

Apodemus said:

Can you change the speed setting on the circulation pump?  Indeed has the plumber done something that might have changed this?

No I don't think so, he is plumbing in a shower and moved the rad, hasn't touched anything else.  We had someone come for the actual heat pump because it stopped communicating with the controller, and he repressurised the hot water but didn't touch the heating.

Apodemus said:

 Just like any whistle ("just pucker up and blow..."!) the pitch changes with speed and aperture and TRVs often whistle at that point where the aperture is almost, but not quite closed.  I have one that can sit at that point for surprisiingly long periods before shutting itself off.  Manually opening or closing the TRV can stop the whistle, but defeats the purpose of having a TRV, so you need to work on the speed/volume combination somewhere else.  The lockshield is one possibility, but so is the pump, especially if it is a modern one with variable speed settings rather than just three fixed speeds.

That is interesting, and really useful to know what the mechanism is behind the whistling. 

Maybe just leaving them all open like before would solve it - the setup seems to work because the thermostat is in a colder room, and the rooms that get warmer whilst the thermostat room is getting up to temp are rooms we're happy to have warmer.

matelodave said:

Don't turn down the pump speed unless you know what you are doing, Heatpumps require a high flow rate to function properly, so turning it down could cause the heat pump flow switch to shut the HP down.

No I definitely won't.  I've been too scared to do the 'system off' needed to check the frost stat temperature, messing about with bits I really don't understand is not something I'll be doing!

The trouble with weather compensation is it needs lots of tweaks when it's cold to find the best settings - I don't think my family would put up with that, and the way we run it at the moment seems to be a decent balance between efficiency and comfort.

ripongrammargirl

That would be driving me crazy too. Women are said to hear high pitched tones that men can’t. A classic example was 10 years ago whilst lying in bed I heard a constant humming but hubby couldn’t hear it. Three nights later I had gone round the bend and decided to track it down. Turned out the air vent in the bedroom wall had a HUGE wasp nest in it with 1000s of the little blighters😬.A phone call to the council sent us an exterminator and the noise disappeared for good, but I thought I was going mad!!! Whining radiators usually means trapped air or not enough open valve to let the water run through properly. Ask the plumber to check them all before he leaves. Can’t see why you are “not allowed” to bleed or drain your radiators??!!! How long do you have to wait for them to send a “man” in for a simple job that even I can do, as a 50 year old disabled lady who is a DIY disaster area!

Apodemus

ripongrammargirl said:

... Women are said to hear high pitched tones that men can’t. A classic example was 10 years ago whilst lying in bed I heard a constant humming but hubby couldn’t hear it. Three nights later I had gone round the bend and decided to track it down. Turned out the air vent in the bedroom wall had a HUGE wasp nest in it with 1000s of the little blighters😬...

I'm afraid that's not actually a good example.  Your wasp hum would be somewhere in the 80-150 Hertz range of frequency, which is a low frequency hum.   There will be slight genetic variation in how low you and your husband can actually hear and parts of the hum from the wasps' wings might be in that range.  The whistling from a radiator is a high frequency sound, I'd be guessing in the 6,000 to 8,000 Hertz range. Ability to hear high frequency sounds diminishes with age and my son can hear our whistling TRV at times that I can't.