Loud running water sound through radiators

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When turning the central heating on, our two downstairs radiators seem excessively noisy. There's a constant running water sound through them, almost like a tap, yet the upstairs ones are absolutely fine. I've tried bleeding them just to see if it's trapped air, but that's done nothing. They're getting fully hot all over.

Are there any obvious reasons as to why this might be? Not the end of the world if they're working I know, but it's noisy enough to hear over anything else you're doing.
 
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Has the system been balanced? It's likely there was a very healthy flow through these radiators and their lockshield valves have been turned right down low (to almost off) to restrict the amount of water going through them.
Make a note of how far you open them if you decide to experiment with the setting. Too much may affect the balance of the system, with other radiators in the house possibly running cooler.

Thermostatic radiator valves can also get noisy at the point where the room is warming up and they start to close.
 
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So I finally got round to experimenting and attempting to balance the radiators myself. Oddly it's our 3 downstairs radiators that get hot first (I thought this was usually the other way round?), usually pretty instantaneously, with the 3 upstairs taking maybe 10-15 minutes to feel hot.

Even with the upstairs radiator lockshields left fully open and the downstairs ones open the smallest possible amount so as to actually work, they're still very noisy. Is this indicative of any kind of problem, or do I just have a rubbish system that I'll have to get used to?
 
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Do the valves quieten down when they're fully open? How many rads do you have in total?
Not at all, they're very noisy unless they're totally shut. We've got three downstairs and three upstairs, but two are towel rails (one upstairs, one downstairs).


Is your pump set on Max speed? Can it be turned down?
Tried doing this for the first time, its factory default setting was 'automatic', so I set it to minimum instead but unfortunately this didn't make any difference.


EDIT: Strangely doing some experimenting, turning the thermostatic valves slightly down (to about 3 rather than 5) as opposed to the lockshield valves does make a difference, but then doing that means none of the radiators upstairs can then get hot.

Is that normal? I always thought thermostatic valves were independent of one another?
 
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I don't suppose there are any other obvious solutions?

Am I right in thinking that if the downstairs thermostatic valves prevent heat from getting upstairs as efficiently, someone somewhere along the line has done a bodge job of the installation?
 
D

durhamplumber

When turning the central heating on, our two downstairs radiators seem excessively noisy. There's a constant running water sound through them, almost like a tap, yet the upstairs ones are absolutely fine. I've tried bleeding them just to see if it's trapped air, but that's done nothing. They're getting fully hot all over.

Are there any obvious reasons as to why this might be? Not the end of the world if they're working I know, but it's noisy enough to hear over anything else you're doing.
Air in system? Water is noisier if valves almost closed..Forces the water to speed up as it goes through a tiny hole
 
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Are the TRV's directional? I.E. they have only one arrow on them?
Unfortunately I'm not sure! Is there an easy way to tell? From what I can see mine don't seem to have any arrows underneath them whatsoever...

Air in system? Water is noisier if valves almost closed..Forces the water to speed up as it goes through a tiny hole
The solution to that would just be to bleed them, right? I've tried that unfortunately to no avail.


Doing some more research online, I think the problem closest to mine that I've been able to find elsewhere is that it sounds like they're 'kettling' - if I'm correct in thinking that means it almost sounds like you're turning the kettle on when the radiators turn on.

I did have them powerflushed not long ago, but could it be that they're just so old and clogged up that replacing them might be the only solution? The water down here (Reading) is very hard, so if they'd not been serviced for a few years (I've not been able to find record of any boiler services from the previous owners in the 5 years they lived here), it wouldn't surprise me if they were more clogged than your average.

Strangely though, that same sound also comes through the towel rail in our brand new downstairs loo when the valves are fully open, the radiator now closest to the boiler, so perhaps that's not the problem.
 
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Here's the TRV. Judging by which side of the radiator gets hot first, I think it's been installed on the return side rather than the flow side if that matters. As mentioned, strangely leaving everything else fully open, turning this down to around 3 prevents the radiators upstairs from getting any heat.




The boiler was at the default setting of 75 degrees, but I've noticed that turning this down to say 60-65, the radiators still get basically as hot (still too hot to leave your hand on for more than a few seconds), but the noise is slightly lessened (albeit not removed entirely).

I've also had a look through my boiler manual and you can adjust the KW setting - the default is the highest 30, but you can set it anywhere between that and as low as 8. Is that likely to change anything if the boiler is actually too powerful for our system, or is that completely unrelated? I only ask as playing with the lockshield valves, if they're anything more than about 1mm open it essentially just sounds like too powerful a stream of water is rushing in.

It does seem like the closer the radiator is to the boiler, the worse the noise is - the towel rail in the downstairs bathroom is by far the noisiest and also right next to the boiler room, then the next one slightly less so and the third slightly less so after that. The 3 upstairs, and last in the row, are relatively silent.
 
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Don't suppose anyone knows if there's anything apparently wrong with this connection? I've tried setting the boiler temperature down to 50 as well as its KW setting as low as 8 but to no avail.
 
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Some TRV's dont like being fitted on the return, as they're trying to shut with the flow of water rather tan against it, and can react by making a noise. My OH was renting a property a while back, Worcester Bosch Boiler, and several rads with TRV's on the return, the noise was horrendous, it howled at times. (Brilliant when the heating came on in the middle of the night.) Landlord thought she was making a fuss until the Neighbour rang him complaining!

Cant see any arrows on them, but might be your issue if they're on the return. Some are Bi directional, hence dont have the arrows, so would expect these to be ok. More to the point, I cant understand why, if turning some rads down, the others dont get hot. How old is the system?
 
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Cant see any arrows on them, but might be your issue if they're on the return. Some are Bi directional, hence dont have the arrows, so would expect these to be ok. More to the point, I cant understand why, if turning some rads down, the others dont get hot. How old is the system?
Agreed, this is what puzzles me. The same happens when turning off the lockshield valves on the 3 downstairs radiators, that seems to completely shut off any heat getting to the radiators upstairs as opposed to just bypassing them.

Truthfully I'm not sure, the house was originally built in the 60s/70s I think but the previous owners refurbished a lot of it when they bought it in 2015. I think the owner was an electrician however he quite clearly attempted a lot of other jobs where he made a few bodges, which is what leads me to think this could have happened here.
 

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