If beer pours warm or foamy at the far taps of a long-draw system, the glycol power pack is usually undersized. This guide covers how to size a glycol chiller for a commercial draft beer system, the rule of thumb the pros use, and how to match a unit to your run length and tap count.
What a glycol power pack does
A glycol chiller (power pack) chills a food-grade propylene-glycol and water bath and pumps it through lines bundled alongside your beer lines inside an insulated trunk line. The glycol holds beer within a degree or two of your walk-in temperature the whole way from the keg cooler to the faucet, and it never touches the beer. Without it, beer warms in the line on long runs and you get foam, flat pours, and wasted product.
The dominant sizing factor: run length
The single biggest input is the length of your longest beer-line run, measured from the cooler to the farthest tap. The longer the run, the more glycol you circulate and the more heat the compressor has to reject. Tap count and ambient temperature add load on top of that.
Rule of thumb
Plan for roughly 3/4 HP of compressor per 100 ft of insulated trunk-line run, then add a tier of headroom for a high tap count (16+) or a hot mechanical room. Undersize and the beer warms at the far taps; oversize slightly and the unit simply cycles less, which is fine.
| Longest run | Typical compressor | Example models |
|---|---|---|
| Under 75 ft | 1/6 to 1/3 HP, 1,150 to 2,300 BTU | UBC ChillPro 1150, Micro Matic Pro-Line MMPP4301 |
| 75 to 250 ft | 1/2 HP, 3,600 BTU | Pro-Line MMPP4302, Perlick 4410QC |
| 250 to 500 ft | 3/4 to 1 HP, 5,100 to 7,250 BTU | Pro-Line MMPP4303 / MMPP4305, ChillPro 7500 |
| 500 to 825 ft | 1.5 HP, 11,500 BTU, multi-pump | Pro-Line MMPP4307, Perlick 4420QC |
Tap count and pumps
More taps means more glycol lines and more circulation load. A single pump handles a typical bar; multi-tower or high-tap-count systems use 2, 3, or 4 pumps to keep flow and temperature even across every line. As a guide, step up a tier past about 16 taps, or whenever you run multiple trunk lines from one cooler.
Air-cooled, water-cooled, or remote?
Air-cooled is the default: lowest cost, but it rejects heat into the room and needs clearance around the condenser. Water-cooled holds output in hot or tight mechanical rooms (sometimes code-required) at the cost of water use. Remote condensing puts the compressor outside the space for a quiet room and full output on the hottest day, for higher install cost. Micro Matic Pro-Line and Perlick offer all three; the self-contained UBC ChillPro and BVL lines are air-cooled.
Glycol fluid and install
Fill the bath with food-grade propylene glycol and distilled water (commonly around 40% glycol to 60% water; follow your unit's manual). Distilled water keeps minerals out of the heat exchanger. Connect the power pack with glycol jumper lines and insulate every run. Uninsulated trunk line is the most common cause of warm far-tap pours, and no chiller size fully overcomes it.
Common sizing mistakes
- Sizing off tap count alone and ignoring run length.
- Forgetting the ambient derate: a hot keg room or rooftop run needs headroom.
- Undersizing pumps for multi-tower layouts, so the farthest tower runs warm.
- Skipping trunk-line insulation.
Match a chiller to your system
Browse the full lineup of commercial glycol chillers and power packs, or the Perlick 4400 Quick Chill line for rugged self-contained units. Not sure which size fits your run length and tap count? Talk to a specialist and we'll size it with you. We have spec'd commercial glycol systems for over 20 years.
Frequently asked questions
What size glycol chiller do I need for a 100 ft run with 8 taps?
A 100 ft run is right around the 1/2 HP / 3,600 BTU tier (for example the Micro Matic Pro-Line MMPP4302 or Perlick 4410QC). With 8 taps you are within a single-tier load; if the room runs hot or you expect to add lines, step up to the 3/4 HP class.
Can a glycol chiller be too big?
Oversizing is far less of a problem than undersizing. A larger unit simply cycles less often. The main downsides are higher purchase cost and footprint, so size to your run with a tier of headroom rather than maxing out.
How much propylene glycol do I need?
It depends on the bath capacity of your power pack (often 4.5 to 12 gallons) plus the volume held in the trunk-line loop. Mix about 40% food-grade propylene glycol to 60% distilled water. Shop propylene glycol fluid here.