Raypak 399B-2339B Pressure Drop in Feet of Head Feedwater Regulator, Piping, Three-WayValves

Pressure Drop in Feet of Head Feedwater Regulator

Raypak recommends that a feedwater regulator be in- stalled and set at 12 psi minimum pressure at the highest point of the system. Install a check valve or back flow device upstream of the regulator, with a manual shut-off valve as required by local codes.

Piping

All high points should be vented. Purge valves and a bypass valve should be installed. A heater installed above radiation level must be provided with a low wa- ter cut-off device (sales order option F-10). The 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. 10.

heaters which are not subject to thermal shock. Raypak offers a full line of electronic sequencers that produce direct reset of heater water temperature.

(Refer to the Controls section of the Raypak Catalog.)

Fig. 11: Single Heater - Low-Temperature (Heat Pump)

Application with Primary/Secondary Piping

*

Fig. 10: Air-Separation/Expansion Tank

Three-Way Valves

Valves designed to blend water temperatures or reduce water circulation through the heater should not be used. Raypak heaters are high-recovery, low-mass

Fig. 12: Dual Heaters (Reverse/Return)

with Primary/Secondary Piping

Domestic Hot Water

When designing the water piping system for domestic hot water applications, water hardness should be con- sidered. Table H indicates the suggested flow rates for soft, medium and hard water. Water hardness is ex- pressed in grains per gallon.

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