Whistling Boiler - Remeha Avanta Exclusive 39c

[BrigadierBigMoustache]

Hope someone can help with a problem that is driving me crazy.
I recently (6 weeks ago) had a new Remeha Avanta Exclusive 39c condensing boiler fitted, replacing a (very old) boiler that was part of a tank in the loft, hot water cylinder in bedroom cupboard type setup.

The problem is a high pitched whistling noise that can be heard from the boiler and also from all of the radiators throughout the house. It is extremely loud, annoying and wakes me up when the heating comes on in the morning. The installer has simply referred me to the manufacturer and I have had Remeha (Baxi?) engineers out twice to look at it. They tell me they have replaced various parts in the boiler including diverter valve and “all the hydraulics”?, but the problem has not been fixed.

Characteristics of the problem are:

When the system first fires up from cold it usually takes about 5 minutes before the whistling starts and then continues for as long as the heating is on.

If a hot tap is opened, the whistling stops and then starts again as soon as the tap is turned off.

I tried opening and closing all radiator valves (I have thermostats on all but 1 in the hall) and noticed that if I turn all radiators off except the one in the hall the whistling stops. Turning the radiators back on one by one, the whistling starts again once I turn on the 5th or 6th radiator (there are 12 in total). I have tried this a few times and it doesn’t matter which order I turn on the radiators, it is always once there are 5 or 6 ‘open’ that the whistling comes back.

Any ideas?

 

[CBF]

have they set the gas valve up correctly ? have the settings been changed ie with regard to fan speed etc, also it has a built in bypass that is controlled by the pcb, i would get them back out & run through the settings to make sure they are all correct, it could be as simple as something has been altered in the menu that shouldn't have been, these are very good boilers & the only ones i fit but if they aren't set up correctly or someone has changed a setting that they shouldn't have it can cause problems

 

[BrigadierBigMoustache]

Thanks CBF. Yeah, they seem to have double checked all the settings (apparently) but I'll get them out again. I've tried to research this to death on the Internet and there is lots of talk about incorrect gas/air mix possibly causing this so I'll mention this (preparing myself for the loud snort as I suggest something I read on the Internet!!)

 

[Boilerman2]

1) the pump on the Avanta can be programmed to run at Low or High speed when in CH mode, I suggest that this be checked and the pump be set to run at LOW

2) is thre an Automatic By-pass valve fitted between the heating flow & Return? if not, fitting one WILL reduce hydronic noise in your system

Your problem sounds like water velocity noise to me, and the above two points should address this issue

 

[ServiceNumpty]

Were Thermostatic Radiator Valves also installed, or did you keep the old ones. Just as an experiment when the whistle starts turn the trv;s off one by one.