Bleeding radiators!

[moggie 939]

Hi Builders Mate or anyone who can help.

In my brand new apartment I have GCH and 5 rads. The first rad on the system has no contols on it, but all the others have therm. controls going fron 0 to 7 and inbetween there is a * and the a 'heart symbol' which I am told is an optimum setting. The first rad in the hall without a contol on it is I am told always on when the wall stat is set to on and goes on and off with the stat. So far so good.

I have bled all the rads and there was some air in the first one. What happens is:

There is always a wooshing noise thru the rads when they are on which I never had on my previous old system - they were completely quiet rads. However I notice that if I turn the rads down from say '3' or 'heart' to between 1 and 2 the noise disappears and there is no noticeable change in the heat output!!

The boiler is brand new and unlike my old boiler there is no pump which can be adjusted to reduce tha actual flow of water thru the rads.

Am I doing something wrong here? Surely you should not be able to hear water thru the rads?
Thanks a lot
r

[Mosaic]

I think this varies from system to system. If you have a new property perfectly plumbed by a seventh-dan central heating engineer, perhaps it will be quiet, especially if you live near a road where you've unconsciously got used to general traffic noise. If you live in an older property in a quiet area you could hear noises.

[The Builder]

Moggers ........... there must be a pump somewhere (it does sound as though you need to reduce the flow). Do you have a combi boiler? The pump is inside the cabinet.

Also, have the rads been balanced?

[chas2008]

i had a new condensing boiler fitted last year and there is no doubt the pump works at a far higher pressure/output than the old fashioned in line pumps. The consequence of this is all the rads heat up simultaneously so need to balance but the one thing i have noticed on the one rad with a TRV it does make a wooshing sound on a couple of the settings...

[scotman]

It may be that one or more of the rads is connected the wrong way round. I have heard that this can cause noise.

[ChuckFickens]

Unidirectional TRVs, doc.

They needed to be fitted the correct way round (and on the inlet if I recall) otherwise they could be noisy.

[ChuckFickens]

Other way round I believe, the old ones needed to be fitted the correct way, the newer ones are bidirectional and can be fitted either way.

[carrust]

I fitted some TRV's last week, the instructions said it didn,t matter if they were on the inlet or return sides of the rad.

[scotman]

Given that the flat is new I would imagine the TRVs will be bi-directional. Pump setting too high is most likely.

[moggie 939]

Thank you so much everyone! Yes the trvs are bi directional according to what the engineer who put them in said (I at last managed to contact him). I have a Potterton Promax HE Plus combi (6 months old). Everything seems to work well except for the noise which goes completely when I put the trv to 3 or less.
The boiler does seem noisier when it is going compared to my very old ordinary baxi at my last place - that was quiet as a whisper!
Will get him to look at the flow rate on the pump.

Thanks again all

Moggie

[AlBags]

1. Many TRV's are non-directional now.
2. Rads are definitely not directional : )
3. You probably have a whistling TRV .. or a lock-shield valve that is turned down almost onto it's seat. Try to ascertain which rad and control it is first. A TRV like this is either gone like it (Honeywell/Drayton liquid filled have this habit) or there is too much flow near it's heat setting limit. If it is the lockshield, try opening a little.

[moggie 939]

Thanks for that - will try this.