Using a spunding to naturally carb

[brew703]

Been thinking about getting the parts to build a valve. What I want to do is be able to naturally carb beer while waiting for one of my taps to become available. I want to be able to always have a beer in the pipeline ready when a keg finishes.
I checked the web and there are a lot of posts about building spunding valves and didn't really find anything that directly answered my questions.

With that said, I have a few questions:
- Priming Sugar..do you use same formula as when bottling?
-Do you add the sugar/water mixture to keg prior to transfer of fermented beer?
- What would be the best temp to keep the keg at when naturally carbing?
- if I want to carb to say 2.5-2.6 vol how do you determine what to set the PRV to? Would you simply follow the same guidelines as when using CO2 to carbonate? Meaning set PRV to 13-14 PSI? and if so the PRV should remain at that PSI and release any extra correct?
- once the carbing is complete, do you simply remove the spunding valve, place in keezer, attach gas and set to whatever PSI you want to serve at?

 

[GoeHaarden]

I, too, have been wanting to get into spunding...No experience actually spunding yet, but I did build a valve.

You may want to check out this thread: https://www.homebrewtalk.com

EDIT: and this thread https://www.homebrewtalk.com

I know it's more geared towards fermenting, but it has a ton of info on the topic in general plus links. It has like 4 or 5 links to other threads on how to build a spunding valve.

As for your questions, my understanding is purely research based and not experience so take it as you want...

- Priming Sugar..do you use same formula as when bottling?
My understanding is that you transfer to a keg with ~4-6 gravity points left. Put you spund valve on and let the last bit of fermentation carbonate your beer.
-Do you add the sugar/water mixture to keg prior to transfer of fermented beer?
Again, I think you can use priming sugar if you miss the tail of fermentation
- What would be the best temp to keep the keg at when naturally carbing?
I believe to keep it at fermentation temps, this is what I'm going to do anyways, as fermentation is still occuring.
- if I want to carb to say 2.5-2.6 vol how do you determine what to set the PRV to? Would you simply follow the same guidelines as when using CO2 to carbonate? Meaning set PRV to 13-14 PSI? and if so the PRV should remain at that PSI and release any extra correct?
I believe you just follow the normal carbonation chart as you would for force carbing

Like I said, I have no actual experience doing it. Just sharing my understanding and I'm also taking this opportunity to get verification from experts on my own understanding.

 

[specharka]

Been thinking about getting the parts to build a valve. What I want to do is be able to naturally carb beer while waiting for one of my taps to become available. I want to be able to always have a beer in the pipeline ready when a keg finishes.
I checked the web and there are a lot of posts about building spunding valves and didn't really find anything that directly answered my questions.

With that said, I have a few questions:
- Priming Sugar..do you use same formula as when bottling?
-Do you add the sugar/water mixture to keg prior to transfer of fermented beer?
- What would be the best temp to keep the keg at when naturally carbing?
- if I want to carb to say 2.5-2.6 vol how do you determine what to set the PRV to? Would you simply follow the same guidelines as when using CO2 to carbonate? Meaning set PRV to 13-14 PSI? and if so the PRV should remain at that PSI and release any extra correct?
- once the carbing is complete, do you simply remove the spunding valve, place in keezer, attach gas and set to whatever PSI you want to serve at?

I’m just going to answer these with respect to my process, but I’m sure others have different takeaways on it.

1) I don’t prime the kegs before I spund, but you definitely want to use less sugar than when you bottle, as the head space plays much less of an impact (3 oz / 5 gal is plenty). Rather, I would recommend transferring the beer to your serving keg while there’s still 1.5-2P of extract left (0.006-0.008) so the beer can carbonate using the natural sugars and omit oxygen ingress.
2) I wouldn’t recommend adding it as a mixture if you do prime, that way you can limit oxygen ingress.
3) Normal fermentation temperature at the higher end of the range. If lagering, you can perform an extended diacetyl rest which will carb nicely.
4) Spunding valve setting is determined by temperature and CO2 level - 2.5 volumes at 70F equates to 28.8 psi. You can set it to a lower pressure if you like, but the beer will be incompletely carbonated.
5) Yes. The pressure in the head space will reach equilibrium with your serving pressure, if done correctly.

 

[universalfrost]

Get the spunding valvefrom @Bobby_M I've got a couple of them for my f ermentasauraus

Work like a charm

 

[aprichman]

If you're priming the keg why do you need a spunding valve? Just add the appropriate amount of sugar to achieve your desired CO2 volume.

 

[Dland]

I've spunded my last couple batches, it is easy. It is actually easier than forced carbing kegs, which is not hard, and what I used to do. I racked from fermenter to kegs while there is still about .006 left to be worked out, seal keg and either put spund valve on keg, or check pressure and release extra pressure daily.

Below are parts for automated spund valve I made, plus a gas side pin lock fitting for the C keg.

https://www.amazon.com/gp/product/B00CCY09YY/?tag=skimlinks_replacement-20

https://www.amazon.com/gp/product/B007GDY3CU/?tag=skimlinks_replacement-20

https://www.amazon.com/gp/product/B000BQUTBS/?tag=skimlinks_replacement-20

https://www.amazon.com/gp/product/B00CU5VMNM/?tag=skimlinks_replacement-20

Picture of manual and automatic spunding valves I made.

Crash after specific gravity is at target. I've been setting pressure at 30 PSI for 60*F cellar. This is just slightly higher than I normally carb to, but at 34*F lagering and serving temp, it is at pressure after a few pints. After that, bottled CO2 to make up pressure as beer is dipensed, just like before.