Raypak 302-902 Installation And Operating Instructions Manual

Raypak 302-902 Installation And Operating Instructions Manual Manual pdf 14 page image

SECTION E: HYDRONIC HEATING PIPINGPUMP SELECTIONIn order to insure proper performance of your boiler system, you must install a properly sized pump. Raypak recommendsusing a 20∞F Delta T as design Delta T. (Delta T is the temperature difference between the inlet and outlet water when theboiler is firing at full rate). If a Delta T larger than 20∞F is necessary, see Table D-1 for minimum flow rate requirements.PRESSURE DROP IN FEET OF HEADFEEDWATER REGULATORRaypak recommends that a feedwater regulator be installed and set at 12 PSIG minimum pressure at the highest point ofsystem. Install a check valve or back flow device upstream of the regulator, with a manual shut off valve as required by localcodes.PIPING - HEATING BOILERSAll high points should be vented. Purge valves and a bypass valve should be installed. A boiler installed above radiationlevel must be provided with a low water cutoff device. The boiler, when used in connection with a refrigeration system, mustbe installed so the chilled medium is piped in parallel with the boiler with appropriate valves to prevent the chilled mediumfrom entering the boiler.The boiler piping system of a hot water heating boiler connected to heating coils located in air handling units where they maybe exposed to circulating refrigerated air, must be equipped with flow control valves or other automatic means to preventgravity circulation of the boiler water during the cooling cycle. It is highly recommended that the piping be insulated.AIR-SEPARATION/EXPANSION TANKAll boilers should be equipped with a properly sized expansion tank and air separator fitting as shown in the followingdiagrams.THREE-WAY VALVESValves designed to blend water temperatures or reduce water circulation through the boiler should not be used. Raypakheaters are high recovery low mass heaters not subject to thermal shock. Raypak offers a full line of electric sequencers thatproduce direct reset of boiler water temperature. Refer to the Controls Section in our Complete Catalog.Table E-1NOTE: Basis for Minimum flow -20 gpm or 40∞ DTMaximum flow -90 gpm.Flow switch will not operate if flow is less than 20 gpm.14