Ideal he-24 on thermal store "groaning" on charge!

[DOUBLEPLUG]

Folks,

A strange problem so any guidance would be mucho appreciated.

I have a heat only Ideal Icos 24, installed approx 36 months ago which is used to charge the Thermal store. The issue I have is that when the boiler is asked to heat the store, either through CH just starting or HW being drawn for power showers and the like the boiler starts to "Groan" but this only last until the store reaches back to its normal temperature at which point the boiler just settles down to normal, and is almost silent when the burners are going. Its just fine as I write this

There are no error messages, the boiler doesn't have a pump itself, and given that most of the time it is working fine I'm assuming its not the fan. It just seems to be that initial period when slightly cooler water is drawn through like when the CH kicks in in the morning.

I'm happy to call in help but I made a couple of calls to engineers and they hadn't heard of this before.

 

[payney1974]

is it making the sound when the fan is at full rate ? is it a vertical or horizontal flue?
when icos or isar growl at you its usually the sealing washer on the flue turret starting to creep up the flue.

This is a job for a professional only

 

[DOUBLEPLUG]

Payney. It is a vertical flue. It only growls when there is heavy demand. Once the temp gets back to normal it all calms down.