Running water/hissing sound through radiators?!

[davecon70]

Afternoon all.

Hope you’ve all had a good Easter. Like many mine was full of house DIY or at least my best attempt.

I cannot figure out why my two radiators upstairs are so much noisier than all the rest. It sounds as if water is hissing/running through the when the heating comes on.

It’s only the two upstairs though and I opened up the lock shield fully and then turned it back a quarter.

Any ideas what’s causing it? Each time it hisses and then seems to stop or die down a little later.

The radiators have been bled.

Cheers for any input!

 

[JohnD]

Please show photographs of the valves at both ends.

Are the rest of the radiators balanced?

Have you got a hot-water cylinder?

 

[davecon70]

Thanks for the quick reply. I have a Valliant boiler and megaflo as opposed to a combi.

I don’t think the system has ever been balanced. The radiators are both in the loft and were added to the CH when the loft was built years ago. They’ve hissed ever sense then but I normally can tone it down a bit by turning down the TRV or turning it off in the loft bathroom. Then it will start hissing again.

I can hear the water going though other radiators but nowhere near the same volume.

 

[JohnD]

Is the circulation pump accessible?

Or, it might be the TRVs are fitted the wrong way round. Does the noise stop if you open or close them a little?

 

[davecon70]

Yes I believe it’s on the megaflo and accessible

 

[davecon70]

I’ve noticed that when I turn the bathroom radiator valve down the hissing almost stops but then seems to start up again. Even when the radiators are not on I can hear that sound

 

[omph]

I’ve noticed that when I turn the bathroom radiator valve down the hissing almost stops but then seems to start up again. Even when the radiators are not on I can hear that sound

If you play with the pump speed, does the hissing change along with it ?

 

[JohnD]

I’ve noticed that when I turn the bathroom radiator valve down the hissing almost stops but then seems to start up again. Even when the radiators are not on I can hear that sound

What happens when a radiator is hissing, and you turn the TRV UP?

(Also when you turn it down but that is a different change)

 

[JohnD]

The bathroom radiator might be plumbed to heat up when the cylinder is bring heated, but that is an extra complication we can put aside for now. It is not "wrong."

 

[davecon70]

Will try playing around in the morning but I looked at the megaflo and cannot see a hot water cylinder. Could have sworn it had one!

 

[JohnD]

A megaflo is a variety of hot water cylinder

 

[davecon70]

Soooo adjusting the valve do anything to the noise. The rad did turn on and off though.

The strange thing is that I had thought it was running through the radiator- I don’t think that’s the case- it sounds as if it’s running around it!

 

[omph]

Soooo adjusting the valve do anything to the noise. It though at least the radiator turned on an off.

The strange thing is that I had thought it was running through the radiator- I don’t think that’s the case- it sounds as if it’s running around it!

put the pint down and fix the spelling - you are making no sense mate.

 

[davecon70]

put the pint down and fix the spelling - you are making no sense mate.

I edited it. Walking and typing not my strong point!

 

[davecon70]

A few days on. If I leave the rad on in the upstairs bedroom then I still hear the sound of water all the way from the boiler to the bathroom rad next door. If I turn off the bedroom rad and turn off the bathroom rad then there’s no sound. I’m guessing this is because the loop is completely closed off as the TRVs are closed.

All the radiators in the house come on and ‘feel’ the same temperature so I would assume it’s balanced. Has to be something that relates specifically to these two rads in the loft!