Bang when radiators turn on

CarlosV

Hi

We moved into a new build a couple of months ago and have thermostat controlled radiators upstairs. When radiators turn on due to a dip in temperature there is one loud bang. Thought it was coming from the different radiators but may also be coming from boiler. No fault showing on boiler system. No sound after initial bang. Could that suggest radiators need to be bled?

Thanks in advance!

CarlosV

CarlosV wrote: »

Hi

We moved into a new build a couple of months ago and have thermostat controlled radiators upstairs. When radiators turn on due to a dip in temperature there is one loud bang. Thought it was coming from the different radiators but may also be coming from boiler. No fault showing on boiler system. No sound after initial bang. Could that suggest radiators need to be bled?

Thanks in advance!

Or do we have to call in a plumber? Don't want to call him unnecessarily if it's something that can Be fixed ourselves. Total novices so might be an easy remedy!

whizbang

Maybe its one of the thermostatic valves sticking.
There's usually a spring loaded pin that goes into the plumbing pipe under the plastic bits; This can stick.

Turn off all the valves when cold, then when heating is fully hot, open them one by one till rad is hot. If you hear the noise youve found it!

John.G

You say "When the radiators turn on due to a dip in temperature there is one loud bang" do you mean that they are turned on only by their TRVs or is there also a motorised zone valve, if so maybe this is where the bang is from.

CarlosV

John.G wrote: »

You say "When the radiators turn on due to a dip in temperature there is one loud bang" do you mean that they are turned on only by their TRVs or is there also a motorised zone valve, if so maybe this is where the bang is from.

Thanks to you both for the advice. I'm not sure if it's the motorized zone valve. I'm going to check each radiator over the weekend to see if I can identify one causing a problem. At least it might give the plumber some info! The builders are great and tend to fix things if they have gone wrong as we are only in a couple of months so might run it by him.

John.G

You can fairly easily identify if its the zone valve, stand long side it and get somebody to operate the room stat for upstairs, you might also check that it has been installed correctly, ie, the arrow on the body should be pointing in the direction of flow.

DaveyDave

Just bumping this thread as we have a similar issue specifically with our towel rack style radiators in our bathrooms. When the heating comes on there is a bang from them but none of the other radiators, it would be nice to get rid of it as I'm a light sleeper and it would wake me up if I'm half asleep at night. Our main bathroom is beside the bedroom so I hear that one and the ensuite at night.

Brussels Sprout

A friend of mine had an issue similar to this and eventually after much testing it transpired that a check (non-return/one way) valve had been installed backwards. The slamming noise was the sound of the water pushing it shut when the pump started.

stevek93

This is also happening to me, but instead there is a constant banging at short repeated intervals. I got a new boiler in January 2020 with a Hive controller and smart TRV's. All the radiators are fine expect the one in the kitchen, when the TRV turns it on it becomes a jack hammer.

Also there is a whooshing, pssst noise coming from the location of the TRV and a loud trickling noise from the rad.

I put the manual TRV back and when I close it when the heating is on there is a loud BANG.

The plumber when he installed the boiler said the kitchen rad is not heating and has to come back to resolve it, well he got it to heat it up with all the issue's I have mentioned above.

Also if say the bedroom TRV boosts the heating just for that rad and then closes it when it reaches temperature there is a loud bang different to the kitchen rad more like WHOOOSH BANG, on the other side of the house closer to the boiler, the bedroom rad is on the opposite side of the house far away from the gas boiler.

Should I be worried one of the pipes is going to bust one of the days?

John.G

Gas/oil boiler and if the circ pump is external can you note the make/model and setting. Also have you got a ABV (automatic bypass valve) installed.?