Condensate drain service (timer, zero-loss, float)
Service and verify automatic condensate drains on receivers, dryers, and filters — the cheapest fix with the biggest air-quality payoff.
This guide is general field reference for trained, qualified service technicians. It is not a substitute for the original equipment manufacturer's service manual, applicable codes (NEC, OSHA, ASME, local), or the judgment of a licensed professional. Procedures, torque values, pressures, refrigerants, and safety requirements vary by make, model, jurisdiction, and revision. Always verify against current OEM documentation and follow your employer's safety program. Working on compressed-air, electrical, pressure-vessel, and refrigerant systems can cause serious injury or death. By using this guide you accept all risk; AirCompDX and its authors disclaim all warranties and are not liable for any damage, injury, loss, or code violation arising from its use.
Drain lines discharge at full line pressure and can whip. Isolate and vent before opening any drain body, and point the discharge into a container, never at yourself.
- Adjustable and open-end wrenches
- Multimeter for solenoid coil checks
- Small pick and brush set
- Bucket and rags
- Drain rebuild kit or replacement valve
- Y-strainer screen
- Ball valve for isolation (add one if there is not one)
- PTFE tape / thread sealant
- 1Test before you touch
Watch a full cycle. A timer drain that fires but expels only air is wasting money; one that fires and expels nothing is plugged. A zero-loss drain that continuously hisses has a failed seal.
- 2Isolate and vent
Close the isolation valve, open the manual test/bypass to vent the drain body to atmosphere.
- 3Clean the strainer
Nearly every drain failure starts at a plugged Y-strainer full of rust scale. Remove, wash, and reinstall — replace if the mesh is torn.
- 4Service the valve body
Timer/solenoid types: pull the coil, remove the plunger, clean the seat and orifice. Zero-loss types: replace the float, seat, and diaphragm from the kit and check the sensor probe for oily film.
- 5Check the electrical side
Measure coil resistance and confirm control voltage at the coil during the commanded open. A drain that never opens is often a dead timer board, not a dead valve.
- 6Set the timing
For timer drains, start at roughly 2 s open every 3 min and tune: shorten the interval if water carries over, lengthen it if only air is expelled. Every unnecessary second of blow-down is compressed air out the door.
- 7Route the discharge properly
Full-size, downhill, no long horizontal runs, and never manifold multiple drains into a common line that can back-pressure.
- 8Handle the condensate legally
Lubricated-compressor condensate is oily wastewater. Route it through an oil/water separator and follow local discharge limits — typically under 10–20 ppm oil to sanitary sewer.