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Quick answer: Charlotte Pipe covers ABS, CPVC and PVC for HVAC condensate drain lines, with a warning: some refrigerant systems contain POE (polyolester) oils that can damage CPVC, ABS and PVC, and that exposure may cause pipe or fitting failure regardless of cleaning or flushing. Charlotte says to check with the HVAC equipment maker that residual oils and refrigerants are compatible with the plastic before you install, and to be especially cautious with CPVC.
Guidance comes from Charlotte Pipe’s Plastics Technical and Installation Manual (page 81), read October 9, 2026. We read the page from the rendered manual. For pumping condensate up and out, see our best condensate pump guide. This page has no buy buttons.
Charlotte’s Steps Before Piping a Condensate Line
- Ask the HVAC maker. Confirm that residual oils and refrigerants in the equipment are compatible with the ABS, CPVC or PVC you plan to use.
- Flush the equipment. Charlotte says the inside of heat exchangers and the outside of evaporator or condenser coils should be flushed thoroughly with a mild ionic detergent solution (2% trisodium phosphate in water, for example) to remove incompatible oils.
- Rinse. A final rinse with clean water is advisable.
- Know the limit. Even with flushing, Charlotte says equipment leaks can release POE oils or other contaminants that are incompatible with CPVC or PVC and may cause failure.
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Extra Caution With CPVC
Charlotte specifically says to exercise caution using FlowGuard Gold CPVC for HVAC or refrigerant condensate lines. Some refrigerant systems contain oils that may damage CPVC, and some heat exchangers or condenser coils carry residual manufacturing oils that can crack it. The same caution applies to combination hot water/air handling units.
Charlotte states it will not accept responsibility for failures caused by exposure to compressor oils in HVAC or refrigerant condensate lines.
Hydronic and Boiler Systems
For hydronic radiant heating, Charlotte also says to verify that all boiler cleaning and sealing chemicals are compatible with CPVC or PVC before installing.
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FAQ
Can I use PVC for an AC condensate drain?
Charlotte allows plastic for condensate lines but says to confirm with the HVAC maker that residual oils and refrigerants are compatible, because POE oils can damage CPVC, ABS and PVC.
What are POE oils?
Polyolester oils used in some refrigerant systems. Charlotte says they may damage plastic pipe regardless of flushing.
How do I clean oils out before piping?
Charlotte suggests flushing heat exchangers and coils with a mild ionic detergent solution, such as 2% trisodium phosphate in water, then rinsing with clean water.
Is CPVC OK for condensate?
Charlotte says to exercise caution with CPVC for HVAC condensate, since some oils can crack it.
Will Charlotte warranty a failed condensate line?
Charlotte says it won’t accept responsibility for failures from compressor oil exposure in condensate lines.
Sources
- TM-PL (PDF) (charlottepipe.com), read 2026-10-09