Active airlock despite nothing in fermenter!

[TheCluelessBrewer]

Hello Folks,

Having fully cleaned, sanitized and drained my Grainfather SF70 with ChemSan I then went ahead with the mash (Brewzilla).

However, to my surprise, as I was mashing, the air lock on the fermenter started bubbling periodically! There was nothing at all in the fermenter! It kept doing so throughout my mash.

Is this due to pressure equalisation within the fermenter or something like that?

I should add that I have always-on brewing heat belts and heating pads around the fermenter. The unit is definitely airtight as the inner airlock tube would drop when pressure was released.

Could it just be Chemsan residue evaporating under heat or something? It's never been used before prior.

Any ideas would be appreciated!

Cheers.

 

[MashBag]

All that is going on it the air in the tank is warming up a little and expanding.

Most liquids and gases expand with temp change.

This is the reason airplanes load fuel in pounds and not gallons.

 

[TheCluelessBrewer]

All that is going on it the air in the tank is warming up a little and expanding.

Most liquids and gases expand with temp change.

This is the reason airplanes load fuel in pounds and not gallons.

It sounds obvious now that you've said it! Thanks.