This water test kit will work with and without propylene glycol antifreeze present in the furnace water sample. Complete kits include pH test strips. It's a good idea to check your water at least 3 times a year. This kit replaces water test kits, p/n 405 & 597-SP, as of 7/23/2019. The water in your outdoor wood furnace/boiler is the lifeblood of the system. If left unchecked, untreated water can clog expensive heat exchangers and corrode the boiler from the inside out.