Noise from boiler HW only

[Yorkie12]

Hi there,

Boiler is making strange rumbling noise when HW only. Doesn't make the noise with CH only or CH + HW on. Is a Y plan system. Have checked the magnacleanse/filter and all is clear. Boiler has been recently serviced and burner gasket was replaced but I'm assuming that doesn't wouldn't cause this.

Video attached (may need to turn volume up!). Noise happens every few minutes, turning the boiler temp up or down doesn't make any difference.

Any suggestions appreciated, thanks!

 

[Maryplumb]

Can't hear anything on your video.
If it is a Y plan system there won't be any difference between heating and hot water operation within the boiler. Could you be hearing anything in the system eg near the HW cylinder?
But if the sound started after the service you need to phone the engineer ...

 

[Yorkie12]

Can't hear anything on your video.
If it is a Y plan system there won't be any difference between heating and hot water operation within the boiler. Could you be hearing anything in the system eg near the HW cylinder?
But if the sound started after the service you need to phone the engineer ...

Thanks for your reply. The noise is right at the beginning and then again at 20 seconds. Engineer has been back and suggested it's normal. Will see if it goes away by itself and then maybe get a second opinion.

Seems only does it when on HW only and up to temp, very odd.

Thanks again.