Fermenter King Unitank Question

[segallis]

I just picked up a 15.8 Gal Ferment King Unitank since there was a huge sale. I have a SS 1/2 BBL conical, but I wanted to try pressurized fermentation (plus I really miss seeing what's going on during fermentation). I am debating on fitting with a 2" Tri-Clamp elbow and butterfly valve, or sticking with the stock "collection bottle".

The bottle seems simpler, although with a butterfly valve I suppose I would not have to install the plunger valve.

The instructions state to ferment with the plunger valve open (and collection bottle attached), so there is no over-pressurization of the collection bottle. I was wondering if I could just ferment with the valve closed, and the bottle not installed. Then when I want to dump trub or harvest yeast, hook up the bottle, and lift the plunger valve (then close the valve and leave the bottle off again). Seems like this may also prevent trub from settling where the valve seal needs to rest and possibly causing a slow leak.

Any reason NOT to do it this way?

The other question is if I install a spunding valve, can I eliminate the PRV safety valve? the reason I ask is I prefer to install the spunding valve in the port currently used for the PRV valve (rather than using the gas ball lock). This is due to my chiller setup which is an enclosed box, so the PRV port will allow me to run a 1/2" NPT tube through the top and then hook up the spunding valve (the gas ball lock will then be unused during fermentation).

I forgot to ask... my typical brews are 10 to 12% ABV and almost always have ridiculously active fermentations. With 11 to 12 gals going into a 15.8 Gal fermenter, I ams concerned about krausen blowoff going into the spunding valve. Would this damage the valve or prevent it from releasing pressure? One idea is to use a blow-off tube for the first few days until I see the krausen safely below the neck, then install the spunding valve. What do you think? Would this waste too much natural CO2 and prevent adequate carbonation (I usually shoot for about 15 psi)?

Thanks,
-Greg

 

[Broken Crow]

The main reason not to is that you'll bubble all the air in your collection bottle up through beer. I faced a similar consideration with my gen 1 Fermzilla and after trying to work out filling the collection vessle with star san and purge with CO2 before opening, I just gave up because all the 'solutions' involved ended up over-complicated, guaranteed messy, and unlikely to completely eliminate O2. I found that I'm ok with just leaving the collector installed and valve open..it really does get most of the trub..though I must must confess; I still tap the bottom just as primary winds down to get as much trub as possible to settle in it.
2/ As long as you're confident your spunding valve won't plug you'll be fine replacing the prv.

 

[segallis]

The main reason not to is that you'll bubble all the air in your collection bottle up through beer. I faced a similar consideration with my gen 1 Fermzilla and after trying to work out filling the collection vessle with star san and purge with CO2 before opening, I just gave up because all the 'solutions' involved ended up over-complicated, guaranteed messy, and unlikely to completely eliminate O2. I found that I'm ok with just leaving the collector installed and valve open..it really does get most of the trub..though I must must confess; I still tap the bottom just as primary winds down to get as much trub as possible to settle in it.
2/ As long as you're confident your spunding valve won't plug you'll be fine replacing the prv.

Good point, I never thought of the air in the empty bottle! So then it seems even with it installed from day 1, you would never really remove it to dump the trub or harvest yeast, else you would again have an empty bottle? So you get 1 fill of the bottle and it must sit there for 3 to 6 weeks (if that's how long you happen to primary). Also, it seems that the amount of trub collected in the bottle (vs. remaining in the fermenter) would depend on the batch size and O.G. Makes me think the TC elbow and butterfly valve has a major advantage here?

As I think about it, what about just leaving the bottle off and still using the plunger valve. When I want to dump trub, I could just put an empty bin below the opening and lift the plunger valve. Seems like the positive pressure in the fermenter would keep any air from getting in the open bottom as the plunger valve is opened, and only trub/wort would flow out the opening???

 

[segallis]

As I think about it even more... it seems that even with a TC butterfly valve, it will never be a good idea to dump trub or harvest yeast after anything more than a few PSI has built up in the fermenter. I'm picturing holding my thumb over the mouth of a shaken soda bottle.

So when do people dump trub when do a pressurized fermentation? I'm thinking of my third question, where I would use a blow off tube until maybe day 4 or 5, then dump the trub into a bin below the plunger valve (or TC butterfly) under 3 psi, then swap the blow off tube for a spunding valve - knowing I probably can't open the plunger or butterfly valve without getting a spay stream out. So one trub dump on day 4 or 5, then leave things for another 3 to 5 weeks until keg day.

Would there be enough CO2 produced after day 5 to even carbonate to 15 PSI (assuming 67 to 75 deg fermentation temp)?

If not, then the only option would appear to be 1 fill of the collection bottle, then close the plunger valve and remove the trub maybe day 5 or even later, but do not replace it.