American
Homebrewers Association

Hi all,

I've searched the forum and can't find enough answers for my questions so here we go...

I'm building a new house and installing a built-in remote draught system so I need to run the lines once and be correct.  Multi-keg fridge with temp control in the garage.  4 faucet tower in basement.  Elevation drop 5'.  Run length is about 12' faucet to garage wall, with an additional 8 feet garage wall to tap in keg fridge.  for a total of ~20 feet. I wish to glycol cool the lines, so I'm looking at 4 product line/2 glycol line insulated composite hose (~$11 per foot BTW).  I would like to run beer gas 75%/25% for stouts in at least one line, and regular CO2 in the others, though I'm certainly open to pushing all of them with beer gas if it makes things easier.  One problem I see (using the equation Length = (Head pressure - 1)/line resistance) is that 1/4" ID hose at 12 psi gets me 11 feet, but 5/16" ID hose at 12 psi gets me 79 feet!.  I don't think I want 50 extra feet per tap of beer line lying around my keg fridge.

I'm frustrated because, as a homebrewer that brews many different styles of beer, how do I change the carb level/temperature of the beer served or switch to beer gas / stout faucet without changing the line length or line resistance at all?  The composite hose with glycol lines has to be purchased at the correct length, but it's expensive enough that I don't want to overshoot by more than 5' if possible.

The questions:

If I run everything on beer gas, must they all be poured through restrictor plates in stout faucets in order to keep a high enough head pressure (~30-45 psi) to keep them carbonated (lagers, pales, etc.)?

If I use CO2 primarily, should I be shooting for an average head pressure of 12 psi?

Are those perlick adjustable faucets worth messing with?  Are they just for fine tuning or can they adjust large pressure differentials easily?  (Eg. I push a stout through the restrictor plate, but then switch to a lager pushed at a higher psi to keep it carbonated and pour without a faucet restrictor plate...) Should I install those adjustable faucets anyway for fine tuning?

Can I just use 5/16 hose and connect it to 3/16" hose for the last 1 or 2 feet?  Is it better to have the higher resistance line at the keg or faucet end?

How do bars do this with all the different beers on tap?  Surely no one is back there cutting off 1/2 foot of hose at a time every time they switch beers...

Is there a better way to run lines through my floor joists for posterity than the composite cable I talked about?  What do I do with the glycol ends, just attach them to eachother?  Do some faucet towers come with a glycol in/out line running through them?

Here is my answer at this point, so please check my work: 

Length = 20'
Drop = 5' (0.5 x 5 = 2.5 psi added)
CO2 head pressure = 12 psi
3/16 line resistance = 3 psi/ft
5/16 line resistance = 0.17 psi/ft
"Connection point" is between 3/16 line and 5/16 line
1 psi at faucet for good pour
X = end line pressure

Using the equation Length = (Head pressure - faucet pressure - elevation psi change) / beer line resistance

Tap to connection point including elevation change (5/16 line):  20' = (12 - (X) + 2.5) / 0.17

X = 11.1 psi at connection point

Connection point to Faucet (3/16" line) Length = (11.1 - 1) / 3

Length = 3.37

So 20' of 5/16" ID line at 12 psi CO2 basically decreases the pressure by 0.9 psi (negligible), which connects to 3.37 foot length of 3/16" line to give me 1 psi at the faucet.  This seems like the entire first 20 feet don't matter at all, which is great I suppose but doesn't seem right.  Also, if I use a restrictor plate in the stout faucet when I use beer gas at 30 psi it should also pour correctly.  If I switch to pushing everything with beer gas I have to recalculate for high resistance, but won't ever be able to push through a restrictor plate without over carbonating a stout right?

Holy crap thanks for the replies in advance

You are doing an apples to orange comparison because of the 5 foot drop. 

Also the Draught Quality manual (http://www.draughtquality.org/wp-content/uploads/2012/01/DQM_Full_Final.pdf) has the following resistances:
3/16: - 3 ft/psi
1/4" - 0.85 psi/ft
5/16" - 0.4 psi

Yes you can use 3/16" at the end to create the desired pressure drop.  Anyway check out the manual.

Thanks for the link to the Draught Quality Manual!

I'll give this a read through.  Thanks for all the responses.  I have a few months to figure this out.  Sounds like I should add the perlick flow control for fine tuning. 

Highplains, I did a little write up here: https://www.homebrewersassociation.org/forum/index.php?topic=18347.msg286892#msg286892 that may be of interest to you.

I think (based on my recent experience) that using beer gas would be advantageous to your plan.