New Combi - tinkling noise from radiators ?

[hammerswinger]

Hi,
We have a new Potterton Gold 33 HE combi boiler that was fitted a few weeks ago & we are very happy with its performance, however we have noticed that since it was fitted the 2 rads in the living room now make what can only be described as a "Tinkling" noise when the HW is ran (Boiler cold), this noise only lasts a second or two & from listening to the noise carefully I can tell you that it's the sound of the convector fins on the back of the rads flexing.

If I close the lockshield (return) valves on the rads there is no noise when the HW is ran.
No other rads on the system make this noise.

The only thing I can think of is that this noise is a result of negative pressure when the pump in the boiler first kicks in, even though the diverter valve is in HW position (CH Flow closed) the return pipe is still open so the pressure to the rads must be being reduced slightly, this is causing the contraction of the panel & the resulting tinkling noise, Would you agree with this?

The rads in question are myson round tops & were fitted to our old combi system & never made this noise with that boiler.

The rads are is good condition & the system was thoroughly cleaned with Fernox F3, each rad was removed & flushed separately with a hose pipe before the new boiler was fitted. There is inhibitor in the system & also a magnaclean fitted in the return pipe to the boiler.

Has anyone experienced radiators behaving like this before?


Thanks.

 

[hammerswinger]

Anyone?

 

[Homesafe]

It could possibly be some solder or something similar moving about in the rads.

You have to look at all the possibilities.

 

[hammerswinger]

Thanks for your reply

A bit of Solder jiggling about was my first though also, but this noise is different to the tinkling noise that solder in a rad or pipework makes.
Maybe describing the noise as "Tinkling" isn't the best description, it's a sort of "Metallic creak" with a hint of tinkling

The noise is definitely the convector fins on the rads flexing as when the system is off & cold if I squeeze the top of the convector fins together it makes the exact noise.

What I can't get my head round is why the rads do this with the new boiler but didn't with the old one?
Could it be that the pump in this new boiler has a higher output so moves the water faster so when it first starts up the negative pressure is greater for a second or two.

The tinkling noise from the 2 rads also happens for a second or two when the CH is first turned on.


Cheers.

 

[sergeantash]

Are you sure it isn't air in the system? Have you completely bled the system? Sometimes if there is still air in there, you'll get tinkling noises as the air moves through the rad...from my limited experience.

 

[hammerswinger]

Hi,
Yeah I know the air sound you mean, but it's not that.

All of the air is out of the system, to do this I closed off ever radiator except one then ran the boiler, this forces all of the air that is in the pipework going to the open rad up into it, I done this for each rad on the system, you get all of the air out of the pipework & into the rads by doing this, then the air can be vented out.

It's definitely the convector fins on the rads that the noise is coming from.


Cheers.

 

[Homesafe]

Sounds like pressure/temp build up in rads causing the rads to expand so slightly then it stops again when it cools down.

Just plug your ears so you don't hear anything.

 

[holty]

youve forgot to mention though.what system you had before.e.g going from gravity fed system to sealed system.as this would give a better indication to your annoying problem.

 

[holty]

sorry just reread your original post,you did mention old combi.yet some older combis were used without being a sealed system.

 

[keego]

How close are the rads to the boiler? when on HW combi boilers dump the excess heat from the boiler to the CH circuit to stop the boiler overheating.

 

[hammerswinger]

holty,
The old combi was a sealed system.

keego,
The rads that make the noise are approx 9 & 6 meters pipe distance away from the boiler.
The closest rad to the boiler is in the kitchen (5 meters pipe distance) & this never makes a noise despite it also having convector fins on it, although this is a different make of rad (Quinn)

This boiler doesn't dump the excess heat after the HW has been ran, it keeps the heat in the boiler circuit to keep the HW heat exchanger hot for longer.

Cheers.