11
16. Inlet/Return water connecon
17. Supply/outlet water temperature sensor
18. Return/Inlet water temperature sensor
19. Low water cut o probe and reset box
20. Temperature and pressure gauge
21. Pressure relief valve
22. Condensate drain trap
23. Minimum combuson air proving switch
24. Blocked vent switch
25. Combuson air lter box
26. Exhaust vent connecon
27. Heat exchanger
IV(continued)