Raypak 503-2003 manual Model, Min. Flow, Max. Flow, P ft

Model	20°F	T	30°F	T	40°F	T	Min. Flow			Max. Flow
No.	gpm	P (ft)	gpm	P (ft)	gpm	P (ft)	gpm	P (ft)	T	gpm	P (ft)	T
503	44	2.8	29	1.4	N/A	N/A	25	1.1	35	100	11.3	9
753	65	6.4	44	3.1	33	1.9	33	1.9	40	100	13.8	13
1003	87	12.0	58	6.0	43	3.7	43	3.7	40	113	18.6	15
1253	109	20.9	73	10.2	54	6.2	54	6.2	40	113	22.2	19
1503	N/A	N/A	87	16.0	65	9.5	65	9.5	40	113	25.5	23
1753	N/A	N/A	102	22.5	76	13.4	76	13.4	40	113	27.2	27
2003	N/A	N/A	116	32.0	87	18.9	87	18.9	40	116	32.0	30
Notes: Basis for minimum flow is ∆T . Basis for maximum flow is gpm.
			Table F: Heater Rates of Flow and Pressure Drops

Piping

All high points should be vented. A heater installed above radiation level must be provided with a low wa- ter cut-off device (sales order option F-10). This heater, when used in connection with a refrigeration system, must be installed so that the chilled medium is piped in parallel with the heater with appropriate valves to pre-vent the chilled medium from entering the heater.

The piping system of a hot water heater connected to heating coils located in air handling units where they may be exposed to circulating refrigerated air, must be equipped with flow control valves or other automatic means to prevent gravity circulation of the heater water during the cooling cycle. It is highly recommend- ed that the piping be insulated.

Air-Separation/Expansion Tank

All heaters should be equipped with a properly sized expansion tank and air separator fitting as shown in Fig. 11.

THERMOSTAT OR

SYSTEM SENSOR

*

*Maximum 4 times the pipe diameter or 12”, whichever is less.

Fig. 12: Single Heater - Low-Temperature (Heat Pump)

Application with Primary/Secondary Piping

		THERMOSTAT OR
		SYSTEM SENSOR
		*
Fig. 11: Air-Separation/Expansion Tank		*Maximum 4 times the pipe diameter or 12”, whichever is less.
		Fig. 13: Dual Heaters (Reverse/Return)
	15	with Primary/Secondary Piping