Architects often specify CPVC and/or PVC piping for Hydronic Heating or Cooling Systems. With these systems water or a glycol solution is recirculated through a heat exchanger. Unfortunately, heat exchangers sometime leak. When they leak, compressor oil will contaminate the fluid inside the recirculated piping system. Since compressor oil is highly incompatible with both PVC and CPVC, failure of the piping system occurs. We have found the failure occurs first in the fittings. This is because the cement inside the fittings is porous and rapidly absorbs the oil concentrating the oil inside the fittings. Because both PVC and CPVC piping will fail if exposed to compressor oil, we do not recommend the use of PVC or CPVC piping for use in HVAC or hydronic heating/cooling systems.