Radiator hissing - oversized boiler

[Ironman2024]

Hi all,

Hoping to get some advice on my system.

Moved into a second hand house last year, previous owners done the following

New pipes flow / returns throughout house along with new hot/cold water feeds.
New ideal Logic combi 30 max installed upstairs, 2 floor house.
Roughly 9kw of Type 22 radiators

Since day one there has always been , radiators which hiss, I’ve bled everything, tried lowering/higher flow temp to no avail.

The radiators are all working well, heat is great etc but just the noise is quite unbearable.

As a complete noob it almost seems to me like the pump is running too fast. When I adjust the trv to full(5) it mostly stops.

System pressure is 1.3 bar cold and 1.8 bar hot, I’ve also tried adjusting lockshields, this eventually works but they’re closed soo much that the radiator does not heat properly.

Any would would be much appreciated.

Thanks folks

 

[Wayners]

Sounds like a Trv problem. They do hiss at the point they shut off.
Rads can make a noise with water is flowing is through.
Maybe swap one of the rads valves for a different brand to see if that helps

 

[muggles]

Sadly these POS boilers aren't configurable to the system they're fitted to, so yes you're likely hearing excess flow through the system and there's nothing you can really do about it with the boiler you have

 

[Ironman2024]

Thanks @Wayners and @muggles for replying

I’ll try a different TRV to see if it helps.

when it comes time to change the boiler, is there a better model I should have them fit?

 

[muggles]

We can't see 10/15 years into the future to know what boilers will be available then. Right now I'd fit a Vokera Pinnacle

 

[Wayners]

You can bridge flow and return with valve in I thought? That might help.
Not my area so consult a pro

 

[Razor900]

Sadly these POS boilers aren't configurable to the system they're fitted to, so yes you're likely hearing excess flow through the system and there's nothing you can really do about it with the boiler you have

Not even fitting flow limiting TRVs???

 

[muggles]

Not even fitting flow limiting TRVs???

Might help but that excess flow needs to go somewhere, the auto bypass will be screaming

 

[MNW67]

I think others have mentioned before that the only thing you can really configure on the Logic is to choose whether to have the minimum pump speed at 70% or 100%.