Why Line Size Matters

One of our techs showed up to a job and found something that explained months of foam complaints the owner couldn't fix: the lines running to the tower were sized for a brewery taproom, not a bar. Someone had installed wide, low-resistance tubing meant for a long-draw system in a setup that needed much narrower lines. It wasn't dirty lines causing the problem — it was the wrong tubing from day one.

How Draft Systems Get "Balanced"

A draft system is balanced when the gas pressure pushing beer out of the keg is fully absorbed by the resistance of the line, the elevation it climbs, and the hardware it passes through — arriving at the faucet at a controlled rate instead of blasting out. Line diameter is one of the biggest levers in that balance: narrower tubing creates more resistance per foot, wider tubing creates less.

What Goes Wrong With the Wrong Diameter

Too wide for the run, and beer moves through with too little resistance — it flows too fast, turns turbulent, and pours mostly foam. Some operators try to fix this by dropping the gas pressure instead of fixing the line, which just trades one problem (foam) for another (flat, undercarbonated beer). Too narrow for the run, and it's the opposite: a slow, weak, lifeless pour, because the beer can't move fast enough against the added resistance.

Long-Draw vs. Direct-Draw — Different Systems, Different Line

There's a real, standard distinction in the industry between direct-draw systems (the keg sits right at or behind the tower, using narrow tubing — commonly 3/16") and long-draw systems (beer travels a much longer distance, often from a remote cooler, through wider, lower-resistance tubing designed for that longer run). Breweries' own taprooms are very often long-draw by circumstance — their cold storage is frequently some distance from the taproom bar — which is why line stock sized for that kind of setup sometimes ends up mislabeled as "brewery" tubing. Installed in a standard bar with a short run from keg to tower, it's simply the wrong size, no matter where it came from.

Why This Isn't a DIY Fix

Correcting a line-diameter mismatch means re-running tubing sized for the actual distance, elevation, and pressure of that specific system — not swapping in a different hose and hoping. It's a one-time fix, not a recurring service, but it has to be diagnosed correctly first, which is why a foam complaint that doesn't clear up after a proper cleaning is worth a real line-balance check instead of another round of cleaning.