Raypak 503-2003 Hydronic Heating, Pump Selection, Feedwater Regulator, Piping, Three-WayValves

SECTION C: Installation

Hydronic Heating

Pump Selection

In order to ensure proper performance of your heater system, you must install a correctly-sized pump. Ray- pak recommends designing for a ∆T within the range of 10°F to 40°F. See Table F for acceptable flow rates for each model (∆T is the temperature difference be- tween the inlet and outlet water when the heater is firing at full rate).

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. 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 recommended 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. 9.

Fig. 9: Air-Separation/Expansion Tank

Three-Way Valves

Three-way valves intended to regulate system water temperatures by reducing flow in the boiler should not be used. Raypak heaters are high-recovery, low-mass heaters which are not subject to thermal shock.

Fig. 10: Single Heater - Low-Temperature (Heat Pump) Application with Primary/Secondary Piping

See Fig. 14 and instructions on page 16 for adjusting the manual bypass.

Fig. 11: 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 G indicates the suggested flow rates for soft, medium and hard water. Water hardness is ex- pressed in grains per gallon.

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