Application: For Armor AWH0400-1000 condensing water heater, outdoor crest OFN(L) 751-2001 and crest FBN(L) 751-2001 heating boilers, Aquas™ APN400-850 commercial pool package heater, Power-Fin® PB/PF 502-1302 and PB/PF 502-1302 heating boilers and hot water supply boilers