Glycol Power Pack Problems in Long-Draw Draft Systems
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Updated October 14, 2026
Quick answer
A glycol power pack chills a bath of food-grade glycol and pumps it through a trunk line alongside the beer lines. When pours turn warm or foamy across many taps at once, suspect the power pack: a dirty condenser, a failed pump, a frozen or low bath, or a faulty temperature probe. These are refrigeration repairs, and few draft-service companies handle the refrigeration side.
How it works
The refrigeration system cools the glycol bath. A pump circulates glycol through supply and return lines bundled with the beer lines in an insulated trunk, keeping beer cold from the keg room to the tower. Most systems are designed to run the bath between 28°F and 34°F, per the Brewers Association manual.
Common failures
| Symptom | Likely cause |
|---|---|
| All taps warm and foamy | Power pack not cooling: dirty condenser, refrigerant leak, compressor or fan |
| Bath warm, pump silent | Pump motor or coupling failed |
| Solid ice in the bath | Thermostat or probe failure, glycol too diluted |
| Display reads normal but beer is warm | Bad probe; one forum case showed a panel reading 61°F with the bath actually at 27°F |
| Some taps warm | Trunk line damaged, kinked or poorly insulated in one run |
| Beer freezing in lines | Glycol too cold or line idle too long |
Owner checks
- Check the condenser coil and clearance; power packs often sit in hot storerooms.
- Confirm the pump runs and glycol returns.
- Check the bath level and look for ice.
- Feel the trunk line for warm or sweating sections.
Glycol replacement
Glycol dilutes and degrades over time. Many draft-service guides recommend testing the mix and replacing it on a schedule; follow your power pack manufacturer's interval.
After a power outage
When power returns, check that the power pack restarted, the pump is running and the bath is cooling. A pump that does not restart lets beer in the trunk warm while the bath gets colder, which can freeze the bath. See power outage guide.
Glycol power pack maintenance schedule
The Brewers Association manual lists these routine checks for glycol chillers:
| Task | Frequency |
|---|---|
| Check glycol bath temperature against the manufacturer's range | Every two weeks |
| Check motors for smooth operation and overheating | Monthly |
| Check pumps, connections and insulation | Monthly |
| Inspect and clean the condenser | Monthly |
| Inspect trunk lines for ice, damaged insulation and leaks | Every six months |
| Check glycol mixture viscosity and condition | Every six months |
| Test freezing point with a refractometer; adjust or replace | Every 18 months |
The manual cites typical mixes of 20 to 25% glycol, following the manufacturer's recommendation. Micro Matic's own guidance for its Pro-Line packs calls for replacing glycol every 18 months, or yearly in humid regions, and checking condenser fins every 60 days.
Owner checks, in order
| Step | Check | What the finding means |
|---|---|---|
| 1 | Bath temperature on the gauge | Above spec: pack not cooling |
| 2 | Pump running and glycol returning | No flow: pump or coupling |
| 3 | Bath level | Low: top off per manufacturer |
| 4 | Ice in the bath | Control or probe fault, or weak mix |
| 5 | Condenser fins | Dust or grease: clean |
| 6 | Trunk line where visible | Sweating or ice: insulation damage |
Bay Area factors
Power packs often sit in basements, storerooms or on roofs. Rooftop packs in the South Bay and inland East Bay face summer heat that pushes head pressure up; basement packs in San Francisco face poor ventilation. Monthly condenser cleaning matters in both.
What our technician does
- Measures bath, supply and return temperatures.
- Checks condenser, fan, compressor and refrigerant charge.
- Tests the pump, motor and probe or thermostat.
- Checks glycol strength and level.
- Inspects accessible trunk line runs.
Regular hours are 8 AM to 5 PM, with emergency service until 9 PM.
Why power packs fail
A power pack is a small refrigeration system that runs nonstop. Its condenser often sits in a dusty storeroom or hot roof, its pump runs continuously, and its bath depends on the right glycol mix. Most failures we see trace to a dirty condenser, a worn pump or a neglected mix. A pack that runs nonstop without reaching temperature is telling you something has changed.
Air-cooled vs water-cooled packs
Most packs are air-cooled and need clean condenser fins and open air around them. Water-cooled packs, such as Perlick's 4410W and 4420W versions, reject heat to a water loop and depend on steady water flow; a closed valve or scaled heat exchanger stops them cooling. Know which you have before you call.
When to call a technician
Call a refrigeration technician when the bath will not cool, the pump fails or ice forms. Warm beer across all taps is a power pack problem, not a line cleaning problem.
Open 7 days, 8 AM to 5 PM, with emergency service until 9 PM. CA Lic. #776244.
Frequently asked questions
Why is my glycol chiller not cooling?
A dirty condenser, a refrigerant leak, a failed condenser fan or compressor, or a bath so full of ice the refrigeration cannot keep up.
What temperature should glycol be?
Typically between 28°F and 34°F (Brewers Association manual; check your power pack spec) for long-draw systems.
How often should glycol be changed?
Follow the power pack manufacturer's schedule and test the mix regularly.
How often should glycol be tested?
The Brewers Association manual calls for checking condition every six months and testing freezing point every 18 months.
What happens if glycol is too weak?
It can freeze on the coils, slowing cooling; test and adjust the mix per the manufacturer.
Where should a glycol power pack be installed?
In a ventilated space with the clearance the manufacturer lists, close enough to keep the trunk short.
Can I top off glycol myself?
You can top off with the manufacturer's premixed glycol; a full replacement and mix test is best done during service.
Why is my glycol pack running nonstop?
Dirty condenser, low refrigerant, high load from added taps, or poor trunk insulation.
Related guides
Sources
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