Clicking Radiators

11 Feb 2021
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United Kingdom
Hi all

I've already read a few posts on this already but wanted to post a separate thread.

Since moving into our house last year, the upstairs radiators have been noisy with various clicking and thudding sounds which are driving my potty every morning the central heating fires up.

Some of the clicking I've put down to the radiators being fairly old, but there is a definite chattering from the TRVs whilst the heating is on, which would suggest the flow rate is too high based on various other comments.

Boiler is a Baxi Combi ERP

Upstairs radiators are:
  • - One towel radiator (no TRV)
  • - 3 Radiators in total (all with TRVs).
    • 1 x Double Panel Radiator
    • 2 x Single Panel Radiator
Steps taken so far:
- Bleed all radiators throughout the house
- All upstairs TRVs are installed on the return side
- All TRVs are bi-directional
- Checked all lockshield valves and re-adjusted to 1/2 turn open
- TRV heads have been replaced with Drayton Wiser heads

From what I understand I'm not able to change the pump speed on my boiler, so I guess that leads me to ask - what steps should I take next?

- Make sure the towel radiator is fully open
- Wind back the upstairs radiators to 1/4 turn
- Check to see if there is an automatic bypass valve
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Having posted this I've just doubled checked everything.

Actually the TRV is installed on the flow side in our bedroom.

The TRV is bi-directional but I'm guessing this is the culprit.

I guess for the moment the lockshield either needs to be fully open to accommodate what the TRV is doing?

Moving forward am I best spinning these around instead - so I have the lockshield on the flow side?
Last edited:
I had a problem of clicking radiator, coming into winter 2019. Changed the pump earlier that year, which might have been connected.
Diagnosed the TRV as the source. As a stop-gap, I opened the TRV fully, and throttled the iso valve to get room temperature about right, and it got rid of the noise. I thought about swapping the TRV from one of the other rads, to see if it was the TRV at fault or something else, but never got round to it.
Then at the beginning of last winter I opened the iso valve fully and turned the TRV back down, and the problem had disappeared. Been OK since.
I guess thats one of the problems with smart trvs you don't have that same level of manual control.

Just been testing it now, and it seems to be quieter with the lockshield valve wide open.

We'll see what tomorrow morning to admit its beginning to affect my sleep all this clicking every morning :sleep:

I guess the only issue is not being able to balance the radiators properly with this approach.

If that solves it, I'll most likely leave as is until I come to change the radiator later in the year and switch them round
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I guess the only issue is not being able to balance the radiators properly with this approach.
What approach is that?
Didn't know it was a smart TRV, or whether that makes a difference. You could still try taking the head off, and throttling the iso valve.
Actually I've got myself in a muddle here.

Are the TRVs better on the flow side or return side?

Current layout

Lock Shield Fully Open

Bedroom 1
Flow Side - TRV (Bi Directional)
Return Side - Lock Shield Fully Open

Bedroom 2
Flow Side - Lock Shield - 1/2 turn open
Return Side - TRV (Bi Directional)

Bedroom 3
Flow Side - Lock Shield - 1/2 turn open
Return Side - TRV (Bi Directional)
I have Honeywell non-smart TRVs. They can be on the flow or return, install the body vertical on flow, horizontal on return. Don't know whether that applies to yours though.

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