Home › Commercial Refrigeration Guide › Beer & Draft Refrigeration Guide › Foamy or Warm Draft Beer: What Is Causing It?
Updated October 14, 2026
Quick answer
Foamy draft beer is most often a temperature problem: kegs or lines warmer than the system was balanced for, which releases CO2 as the beer pours. Pressure set wrong, dirty lines, damaged faucets and warm or dirty glassware cause the rest. Check keg temperature first; if it is right, check the line and the glycol system.
Refrigeration causes
- Kegs too warm. Brewers Association guidance puts keg storage at about 36 to 38°F.
- Warm lines. On long-draw systems, a glycol power pack that is not cold enough, a failed pump or a damaged trunk line lets beer warm on the way to the tap.
- Warm towers. Towers that are not cooled or insulated pour a foamy first glass.
- Kegs just delivered. A warm keg needs time to come down to temperature before tapping.
Other causes
- CO2 or blended-gas pressure too high or too low for the beer and line
- Dirty lines and faucets (see line cleaning)
- Kinked or wrong-diameter lines
- Warm, wet or greasy glassware
- Pouring technique
Quick checks
- Put a thermometer in a glass of water in the keg cooler overnight, or measure a fresh pour.
- On glycol systems, check the bath temperature and that the pump is running.
- Feel the trunk line where it is accessible for warm spots or sweating.
- Confirm the regulator pressure has not been changed.
Direct-draw vs long-draw
In a direct-draw system the keg sits in a cooler directly below the faucet, so keg temperature is most of the story. In a long-draw system beer travels many feet through a trunk line cooled by glycol, so the keg room, the glycol system and the tower all have to be right. Foam that appears only on some taps in a long-draw system often points to one section of trunk line.
Who fixes what
| Problem | Usually handled by |
|---|---|
| Keg cooler or keg room warm | Refrigeration contractor |
| Glycol power pack not cooling | Refrigeration contractor |
| Line cleaning, faucets, couplers | Distributor or draft-service company |
| Gas pressure and blend | Draft-service company |
Direct-draw, air-cooled and glycol systems compared
| System | How beer is kept cold | Typical use | Refrigeration to service |
|---|---|---|---|
| Direct-draw | Keg sits in a cooler right below the faucet | Kegerators, back-bar keg coolers, walk-in with wall-mounted taps | The cooler itself |
| Air-cooled long-draw | Cold air from the walk-in is blown through an insulated chase around the lines | Short runs from a walk-in to a nearby bar | Walk-in plus the recirculation fan |
| Glycol-cooled long-draw | A chiller pumps cold glycol through lines bundled with the beer lines | Runs longer than 25 feet, remote bars | Walk-in plus the glycol power pack |
Definitions follow the Brewers Association's Draught Beer Quality Manual, which notes glycol systems serve runs longer than 25 feet.
Owner checks, in order
| Step | Check | What the finding means |
|---|---|---|
| 1 | Thermometer in a glass of water in the keg cooler overnight | Above 38°F: the cooler is the problem |
| 2 | Temperature of a fresh pour at the faucet | The manual's target is 38°F at the faucet; warmer points to lines or tower |
| 3 | Are all taps foamy, or only some? | All: cooler or glycol. Some: those lines, couplers or faucets |
| 4 | Glycol bath temperature and pump | Bath warm or pump silent: power pack fault |
| 5 | Regulator pressure vs the usual setting | Changed pressure: gas balance problem |
| 6 | Date of the last line cleaning | More than two weeks: clean first |
| 7 | Were kegs just delivered? | Warm kegs need hours to chill |
How long a warm keg takes to chill
The manual's tables show why fresh deliveries pour foamy. A keg that warms from 38°F to 44°F in four or five hours on a delivery truck needs about 18 hours in the cooler to get back to 38°F. A keg starting at 50°F needs about 25 hours. Rotate stock so kegs chill at least overnight before tapping.
| Keg starting temperature | Hours to reach 38°F |
|---|---|
| 50°F | 25 |
| 48°F | 23.5 |
| 46°F | 21 |
| 44°F | 18 |
| 40°F | 7 |
Bay Area factors
Breweries, taprooms and bars across the Bay Area run long-draw systems through old buildings with warm ceilings and walls. Trunk lines that pass near kitchens, sunny walls or rooftop units pick up heat, and the first foamy pours show up on hot afternoons. Insulation and a healthy glycol pack fix most of it.
What our technician does
- Measures keg cooler, glycol bath and faucet temperatures.
- Checks the cooler's condenser, fans, defrost and controls.
- Checks the power pack's condenser, pump, bath level and probe.
- Identifies whether the rest is a gas, line or glassware issue for your draft-service provider.
Regular hours are 8 AM to 5 PM, with emergency service until 9 PM.
When to call a technician
If the keg cooler or glycol system cannot hold temperature, that is a refrigeration repair. Call before a weekend.
Open 7 days, 8 AM to 5 PM, with emergency service until 9 PM. CA Lic. #776244.
Frequently asked questions
What temperature should kegs be stored at?
About 36 to 38°F, per Brewers Association guidance.
Why is only the first beer foamy?
The beer in the tower and faucet has warmed. Tower cooling or insulation is the usual fix.
Can a glycol chiller cause foamy beer?
Yes. If the glycol is not cold enough or the pump fails, beer warms in the trunk line and foams at the tap.
Does warm glassware cause foam?
Yes. Glasses straight from a hot dishwasher make beer foam; let them cool or rinse with cold water.
Why is my beer foamy only on hot days?
Heat is reaching the lines or the cooler is losing capacity: check the trunk line, the tower and the condensers.
What temperature should beer be at the faucet?
About 38°F, per the Brewers Association manual's troubleshooting table.
Can a dirty keg cooler condenser cause foam?
Yes; the cooler runs warm, the kegs warm, and beer foams.
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