Topping up keg with fresh beer

[emerson909]

Has anybody got experience of topping up a half empty keg with fresh beer? I can brew about 25l on my kit, I normally fill a keg and bottle the rest but I’ve brewed the same recipe twice and was thinking of just putting the extra in to the half empty keg with the same beer. I’m using a fermzilla to ferment so can pressure transfer into the half empty keg. Just wondering what could go wrong (something normally does!)?

 

[Paul Roberts]

It might affect taste as different batches ?

 

[emerson909]

Yeah I’m not too bothered about the taste being consistent, they should hopefully come out similar enough being same recipe / process etc.

 

[fury_tea]

Has anybody got experience of topping up a half empty keg with fresh beer? I can brew about 25l on my kit, I normally fill a keg and bottle the rest but I’ve brewed the same recipe twice and was thinking of just putting the extra in to the half empty keg with the same beer. I’m using a fermzilla to ferment so can pressure transfer into the half empty keg. Just wondering what could go wrong (something normally does!)?

One problem I can think of is that you are adding uncarbed beer to carbed beer, aren't you? I don't know if it could lead to excessive foaming in the original keg? Not sure about that though, it could be fine.

 

[Dorst]

One problem I can think of is that you are adding uncarbed beer to carbed beer, aren't you? I don't know if it could lead to excessive foaming in the original keg? Not sure about that though, it could be fine.

I think the bigger issue could be oxidation. The agitation when transfering flat beer to carbonated beer will not be good for oxidation; and a closed transfer to a pressurised keg is not really possible.

Perhaps you can buy smaller kegs (I know they have 5 liter mini kegs) and daisy-chain them together? Like in the image below: It will get you to 19+5 liters.. close to your requirements..

 

[emerson909]

It will be carbonated as I’m fermenting in a fermzilla under pressure, just slightly less carbonation than the keg. Do t see why a closed transfer wouldn’t work, guess that’s what I’m checking to see if anybody else has done it

 

[Dorst]

In a keg-to-keg transfer you would vent most of the pressure out of the receiving keg. This way you can push the beer with very low pressure from one keg to the next. I guess this is quite similar to your fermenter to keg setup.

I would personally not be very keen on pushing beer from pressurised fermenter to pressurised keg - which is why I opted for the daisy-chained keg solution.

But it seems you are bent on trying it out - so please report back what your findings are.

 

[emerson909]

Haha yeah I’ll give it a go and let you know!

plan is to pressurise fermenter after cold crashing to match the keg pressure then use gravity for the transfer. Will vent the keg slightly to get the siphon going then link the gas ports to equalise the pressure.

 

[emerson909]

Well it didn’t quite go to plan, first of all the ‘half empty’ keg became empty much faster than expected, I’m blaming lockdown

thought I would just fill one keg and put anything left in another but think I dropped the pressure too much while racking and the yeast cake started to break up and float just as the first keg was getting full. I was brewing another batch and needed the fermenter so didn’t have time to let it settle again. You live and learn!

 

[An Ankoù]

I regularly top up a half-empty belly with fresh beer and rarely encounter any ill-effects.
Go for it.