What type of system should CPVC pipe and fittings be protected against freezing with?

The correct approach for protecting CPVC pipe and fittings against freezing is to use glycerin. Glycerin is a non-toxic, biodegradable substance that can lower the freezing point of the fluid within the pipe system, thus preventing freezing in colder temperatures. This is especially significant for systems where maintaining a fluid state is crucial to avoid rupturing the pipes and fittings, which can lead to significant damage and costly repairs.

Using glycerin also offers compatibility with CPVC pipes; it does not cause degradation or adverse reactions as some other substances might. In contrast, while using water-based antifreeze options or fluorinated fluids could potentially be considered, they might introduce toxicity or chemical interaction concerns. Standard insulation, while helpful in mitigating temperature drops, may not be sufficient on its own to prevent freezing, particularly in extreme cold conditions.

Thus, glycerin not only provides freeze protection but does so in a safe and compatible manner for CPVC systems, making it the ideal choice among the options available.