Fermzilla - dry hop under pressure

[muppix]

Afternoon everyone!

I've been using my Fermzilla to ferment under pressure for about a year now and I'm very happy with it, but I still want to improve my technique when it comes to dry-hopping. Leaving discussions of hop-rockets, internal magnets etc aside for a moment, I wonder what you think of this approach to dry-hop a brew that's nearly at the very end of fermentation at 12 PSI:

1. Close butterfly valve
2. De-pressurise and drain collection jar via one of the fitted carbonation caps
3. Check that the butterfly valve is holding the vessel sealed - i.e. collection jar isn't filling up
4. Remove collection jar, clean, fill with hops
5. Flush collection jar with external CO2 source, pressurise to match the FV @ 12 PSI
6. Open butterfly valve

In the past I've either chucked hops in the top of the FV after temporarily de-pressurising it, or removed the collection jar and done it that way, again after de-pressurising, because the instructions that come with the Fermzilla state that you should not use the butterfly valve under pressure. Looking at said butterfly valve I think it'll probably be just fine holding back 12 PSI, and my reason for giving this a go is that I've also got a Tilt Pro bobbing around in there, and it's the Tilt that I want to protect from successive pressure changes.

Does this approach make sense? If there's a problem with the butterfly valve under pressure I'm hoping it'll show itself while the collection jar is still fitted, so I shouldn't end up with an uncontrolled beer explosion. Am I worried too much about pressure changes affecting my Tilt Pro? After all, the FV gets depressurised in the end for cleaning anyway, so a couple of cycles for DDH shouldn't affect the device.

Thanks for reading - input most welcome!

 

[hoppyscotty]

Done this a couple of times and I'm not 100% satisfied. You get a nice satisfying whoosh as you open the valve and most of the hops are flushed up into the main body of the fermenter, but some are left in the jar and shortly after the remainder just settle back down to the bottom f the fermenter.

Just a word of warning if you are doing this....take the whole system off pressure. If you open the valve with a pressure differential then there is risk of shattering but I guess you already know this as you specify you're going to match the pressure, but I think it would just be easier and safer to dump the pressure totally. I'm not sure if the jar can tolerate even 1 or 2 psi pressure differential with the hydraulic 'hammer' action of any pressure differential combined with the weight of all the beer dropping down into the empty jar. Some of the failures I've seen online appear to be from small micro fractures around the two threaded bosses where people have potentially used them to grip onto to unscrew the jar rather than using the supplied strap wrench. so if you've always used the strap wrench then maybe you'll be fine.

I think this is the intended function of this arrangement and design but I think it has limited effectiveness. Maybe I've been too greedy and tried to shove too much hops into the jar which might have impeded them being ejected from totally from the jar when the valve is opened and with less hops - say no more than half filling the jar, then you might have more success than me. Maybe, if you're quick, open the valve, give it half a second or so then close the valve again to keep the hops in the main body of the fermenter longer before settling back into the jar. You wont have to fully close the valve, just enough to prevent hops from getting by back into the jar.

 

[muppix]

Hey @hoppyscotty, thanks for coming back to me.

Done this a couple of times and I'm not 100% satisfied. You get a nice satisfying whoosh as you open the valve and most of the hops are flushed up into the main body of the fermenter, but some are left in the jar and shortly after the remainder just settle back down to the bottom f the fermenter.

My experience is exactly the same, and it's a shame to have a substantial chunk of hops just sitting there underutilised until the day you chuck 'em out. I too had thought of shutting the valve again as soon as the newly added hops are released, but the neck above the butterfly valve is fairly narrow too, so I'm not sure if it'll make a lot of difference. I'm also not sure if the 'whoosh effect' will be as good at distributing the pellets if the collection jar is at equal pressure with the FV, but that remains to be seen.

Just a word of warning if you are doing this....take the whole system off pressure. If you open the valve with a pressure differential then there is risk of shattering but I guess you already know this as you specify you're going to match the pressure, but I think it would just be easier and safer to dump the pressure totally. I'm not sure if the jar can tolerate even 1 or 2 psi pressure differential with the hydraulic 'hammer' action of any pressure differential combined with the weight of all the beer dropping down into the empty jar.

That's interesting. I hadn't considered the jar being a weak point, only the butterfly valve. I do know that the jar is incredibly fragile as I'm one of those people who used the carb-cap fittings to seat the jar on one occasion, only to find the thing coming apart in my hands far more easily than anticipated. Looking on the bright side, I now have a spare O-ring.

I'm still tempted to try it though, probably using a spunding valve to make sure the pressure in the jar is exactly the same as that in the vessel before I go near that butterfly. Maybe I'll drop the pressure to 5 PSI just to be sure.

Going off at a slight tangent, I like your idea involving a pump to circulate hops through a separate container and wanted to ask what kind of pump you'd use for this, but it didn't seem right to kidnap that thread. Let me know if you develop that idea.

 

[hoppyscotty]

It's never ruined the beer when I've done this but just feel I'm not getting maximum utilisation from the expensive hops. I do tend to load up hops during dry hopping when doing hoppy beers as I find the normal recipe quantities to not give the same hoppy aroma and flavour you get from commercial beers, so I will add more hops so that fills the jar more.

Regarding the jar there are plenty of examples of it shattering when people have done this if you google, but in all the cases I've read its when people have done it under pressure so you should be fine if you dump all the pressure. I've also tried disturbing or rousing the hops in the jar by connecting co2 to a ball lock connector post on the jar but it is not particularly successful and just seems to drill a hole in the saturated hops. Probably extracts some goodness from them, but doesn't push them up into suspension at all. Now I just transfer to a keg for dry hopping - drop in a hop tube or two into a keg, purge and close transfer. Have alot more control over contact time too and wit the hop tube stood vertically in the keg it feels like you're getting alot more contact and without the trub you get at the bottom of the fermenter I'm happy to give the keg a good swirl every now and again to help beer moving in and around the hops. This was a pointer from the head brewer from Verdant when I got the Even Sharks Need Water NEIPA all grain kit from the Malt Miller done in conjunction with Verdant and was supplied with some pretty comprehensive notes from their head brewer and how to approach it as a home brewer. Now my stock dry hop method.

I have also read recently that dry hopping on the yeast cake means some hoppy goodness is absorbed into the yeast cake so either drop the yeast cake if you can (or looking for biotransformation during active fermentation) or transfer to another vessel to dry hop when fermentation is over.

Would love to give the recirculation idea a go but would need to buy a pump to give it a go so would have to remain an idea for now. I would think any old pump you're happy moving beer through would be fine, but in my mind you'd want decent speed control as you probably want to do it gently.

 

[Graz]

Potentially dumb question as I don't pressure ferment but if as proposed all the pressure is dropped from the fermenter before adding the dry hops then why not just take off the top lid and lob them in? It's not like there's any concerns over oxidisation as the whole headspace in the vessel is still full of CO2. Just pressure up from a CO2 cylinder and burp it a few times after if really paranoid about it.

 

[foxy]

Potentially dumb question as I don't pressure ferment but if as proposed all the pressure is dropped from the fermenter before adding the dry hops then why not just take off the top lid and lob them in? It's not like there's any concerns over oxidisation as the whole headspace in the vessel is still full of CO2. Just pressure up from a CO2 cylinder and burp it a few times after if really paranoid about it.

Exactly, not like there is a mass exodus of co2 when removing the top. Since the advent of pressure fermenters, there is suddenly a huge concern among some brewers of the ingress of oxygen into their brews. brewers have been brewing for years with nary a worry of oxidation.
Don't be a slave to the spin.

 

[hoppyscotty]

True but don't forget the hop pellets are saturated with air which you're dumping in so ideally you want purge the hops, soaking them in CO2 for a good few minutes or so before introducing into the beer. I wouldn't hesitate dry hopping in this way apart for any beer we're I'm after really hoppy aroma and flavour in the resulting beer (queue for those who've not noticed any detrimental affects to their NEIPA's ) I'd always get he beer off the trub and transfer it into a separate vessel for dry hopping where the hops have been soaking in CO2 and the vessel well purged. Those hops are expensive and you want to wring the necks out of them for all they're worth. These are small points of process really if you have gas and a keg so why wouldn't you?

 

[fgoulding]

I almost always just pop the lid and lob the hops in with no issues.

But for a NEIPA I use this PCO1881xPCO1881 ball valve on my fermzilla with 2 Tee Pieces (one for CO2 and the other a party tap to purge the air) on top of a 1.5ltr spring water bottle. It might be overkill and it does take a bit of a shake but it‘s worth it because ruining a NEIPA is expensive.

https://www.aliexpress.com/i/1005001493355889.html

 

[hoppyscotty]

I looked at that but saw a video where the hop pellets got stuck in the narrowing neck and they ended up using a chopstick to poke the hops through so killed any opportunity for an O2 free dry hop. Have you not come across this problem?

 

[fgoulding]

I haven’t had any issues because I make sure that the bottle is dry inside before adding the hops. If it’s wet, then they can get stuck.

 

[muppix]

if as proposed all the pressure is dropped from the fermenter before adding the dry hops then why not just take off the top lid and lob them in?

That's a fair point, but I'm trying to avoid dropping pressure if possible because I'm concerned about the effects of de/re-pressurising my Tilt Pro floating hydrometer. To be honest I can't believe it's remained airtight as long as it has, so I don't want to push my luck by subjecting it to more pressure changes than absolutely necessary.

Now I just transfer to a keg for dry hopping - drop in a hop tube or two into a keg, purge and close transfer. Have alot more control over contact time too and wit the hop tube stood vertically in the keg it feels like you're getting alot more contact and without the trub you get at the bottom of the fermenter I'm happy to give the keg a good swirl every now and again to help beer moving in and around the hops.

I like this idea. I'm assuming that you do this at or very near to the end of primary, and if so do you just go ahead and serve from the same keg (with or without hop tubes in place) or rack to a fresh one?

 

[hoppyscotty]

I wait til fermentation has completed the. Transfer to the purged keg with the hops about 5 days before packaging…3 days hop contact time at 15 degrees then two days cold crash. I’ll then rack to another keg for carbonating and bottling with a counter flow filler (one of the cheap ones) or keeping in the keg for my home made kegarator.

don’t do many DDH brews but if I did I’d probably do the first during active fermentation in the fermenter, and the second by transferring to the keg once fermentation was done.

 

[Kye]

I've done several post fermentation dry hops through the collection jar, mainly to avoid biotransformation of the hops which is something Verdant recommend (if you like their style), but also to avoid oxygen post fermentation. @muppix i also found that I was getting poor hop utilisation. My solution, that's worked pretty good, is to put a short length of silicon tuning from the carb cap on the collection jar that I bend to the bottom of the jar so that any incoming CO2 flushes in right from the bottom. Do a few flushes of CO2 over a few hours and it'll get all those hops pretty broken up. I don't ferment under pressure so can't advise on the tilt issue. I also fill the collection jar with 10psi before opening the valve in order to get a forceful whoosh of CO2 to send the hops upwards. I'm now a bit nervous reading the above though - am I in for a major failure?!

 

[Neil Whittaker]

For Pressure kit users:

1. Fill collection jar with hops and CO2 to the same pressure.
2. Take off spunding valve.
3. Turn the whole fermenter upside down.
4. Open valve and let the hops fall in.
5. Close valve.
6. Give it a shake every now and then.

I've used this method a few times and it works really well.

 

[Kye]

haha point 2 is most important here - tried this once and missed this crucial step

 

[hoppyscotty]

I've done several post fermentation dry hops through the collection jar, mainly to avoid biotransformation of the hops which is something Verdant recommend (if you like their style), but also to avoid oxygen post fermentation. @muppix i also found that I was getting poor hop utilisation. My solution, that's worked pretty good, is to put a short length of silicon tuning from the carb cap on the collection jar that I bend to the bottom of the jar so that any incoming CO2 flushes in right from the bottom. Do a few flushes of CO2 over a few hours and it'll get all those hops pretty broken up. I don't ferment under pressure so can't advise on the tilt issue. I also fill the collection jar with 10psi before opening the valve in order to get a forceful whoosh of CO2 to send the hops upwards. I'm now a bit nervous reading the above though - am I in for a major failure?!

Think you'll be fine as you're pressurising the jar. the issues I've seen are where the main body of the fermenter is pressurised so you have the combined force of the pressure differential plus the weight of the beer directly onto the jar.


Not heard of the upside down method though. Might give that a go.

 

[MickDundee]

For Pressure kit users:

1. Fill collection jar with hops and CO2 to the same pressure.
2. Take off spunding valve.
3. Turn the whole fermenter upside down.
4. Open valve and let the hops fall in.
5. Close valve.
6. Give it a shake every now and then.

I've used this method a few times and it works really well.

I use a Fermentasaurus rather than a Fermzilla, but I like to think I’m reasonably strong and don’t think I’d manage to turn a full fermenter upside down to dry hop.

 

[Neil Whittaker]

I only go all out to avoid Oxygen ingress on my heavily dry hopped IPAs.
Most of the time, my batch size is more like 13L, which is no problem to move / flip the fermenter.
I would never drink more than that before it starts to fade.

The rest of the time, I'll echo @foxy, Just dry hop through the top, as for many styles, having the lid off for 10 seconds will make minimal difference.

 

[muppix]

Transfer to the purged keg with the hops about 5 days before packaging…3 days hop contact time at 15 degrees then two days cold crash. I’ll then rack to another keg for carbonating and bottling with a counter flow filler (one of the cheap ones) or keeping in the keg for my home made kegarator.

Duly noted, thanks for that. I don't have any dedicated hop tubes as yet but will probably be OK using one of my fine mesh bags, though I'll have to change my keg purging approach. Right now I tend to fill the entire keg with sanitiser and then drive it out with CO2, but I might have to leave the sanitiser out of the equation and just flush for an extended period via the liquid out post if my bag of hops will be in there. Thanks for the counter flow filler idea, been meaning to try one of those.

My solution, that's worked pretty good, is to put a short length of silicon tuning from the carb cap on the collection jar that I bend to the bottom of the jar so that any incoming CO2 flushes in right from the bottom.

I rigged up something similar to help me purge oxygen from hops in the collection jar before releasing them into the brew; one carb cap for collection oxygen from right under the butterfly valve, another for getting CO2 right into the bottom of the jar and hopefully avoid just diluting the gas by filling the heavier-than-air CO2 from the bottom. I might revisit that idea if I ever dry-hop from the jar again.

For Pressure kit users:
...
I've used this method a few times and it works really well.

It's an interesting idea, but like @MickDundee I don't think I'll be able to lift my Fermzilla complete with 23 litres - that's a recipe for an afternoon of serious floor cleaning.

In the end I did something broadly similar:

1. Almost-close the butterfly valve, trapping spent yeast at the end of fermentation
2. Gently de-pressurise
3. Carefully lob in purged hops via the top
4. Gently re-pressurise

I'm now able to give the Fermzilla a gentle swirl to agitate the hops without mixing in the old yeast, and any biotransformation will be limited to whatever was resting north of the valve. I've no idea how much there is since it's hard to judge, but if this brew is anything like my previous efforts then we're talking about fairly minimal quantities here. As a bonus I'm not letting those hops go to waste in the collection jar, so even if a small amount of oxygen is introduced via the top-drop method I'm hoping the extra utilisation will counter that. QED and all that ...