... H R407C,R22,R290 heat pump water heater .(Air source heat pump for hot water only)Model: HRFKZTC(D)010 ... CIRCUITCopper tube connection with charge valve, filter, sight glass, gas-liquid separator, thermostatic expansion valve, low pressure switch with automatic ... also with 4-way valve, liquid receiver and one way valve.HYDRONIC CIRCUITBuilt with air vent valve, water drain connection, and female ...