Section 658-109-21 - TEMPORARY Repair of Heat Exchangers1. Furnace cement or other materials used to seal cracks in the heat exchanger or parts which provide closure therein may be sealed for a maximum of 45 days with furnace cement or other materials.2. Whenever a Compliance Officer conducts an inspection and finds a heat exchanger which has been repaired with furnace cement more than 45 days prior to the inspection, he or she shall order it removed unless a purchase order is provided evidencing that replacement of the heat exchanger is in process.02-658 C.M.R. ch. 109, § 21