Raypak 751 Installation And Operating Instructions Manual

Also see for 1001: OPERATING AND INSTALLATION Manual

Raypak 751 Installation And Operating Instructions Manual Manual pdf 13 page image

HYDRONIC HEATINGPump SelectionIn order to ensure proper performance of your boilersystem, you must install a properly sized pump.Raypak recommends using a 20°F ΔT as design ΔT.(ΔT is the temperature difference between the inletand outlet water when the boiler is firing at full rate). Ifa ΔT larger than 20°F is necessary, the bypass mustbe installed and adjusted to ensure proper hydraulicsthrough the boiler while still allowing minimum flow tosatisfy the safety flow switch. See Table E for flow raterequirements.Pressure Drop in Feet of HeadFeedwater RegulatorRaypak recommends that a feedwater regulator be in-stalled and set at 12 psi minimum pressure at thehighest point of the system. Install a check valve orback flow device upstream of the regulator, with amanual shut-off valve as required by local codes.Piping — Heating BoilersAll high points should be vented. Purge valves and abypass valve should be installed. A boiler installedabove radiation level must be provided with a lowwater cutoff device. The boiler, when used in connec-tion with a refrigeration system, must be installed sothe chilled medium is piped in parallel with the boilerwith appropriate valves to prevent the chilled mediumfrom entering the boiler.13The boiler piping system of a hot water heating boilerconnected to heating coils located in air handling unitswhere they may be exposed to circulating refrigeratedair, must be equipped with flow control valves or otherautomatic means to prevent gravity circulation of theboiler water during the cooling cycle. It is highly recom-mended that the piping be insulated.Air-Separation/Expansion TankAll boilers should be equipped with a properly sizedexpansion tank with an air separation fitting as shownin the following diagrams.Three-Way ValvesValves designed to blend water temperatures orreduce water circulation through the boiler should notbe used. Raypak heaters are high recovery low massheaters not subject to thermal shock. Raypak offers afull line of electric sequencers that produce direct resetof boiler water temperature. Refer to the ControlsSection in our Complete Catalog.Table D-140°FΔP Should include typical piping To/From a single tank as well as bypass piping.Table E: Rate of Flow and Pressure DropNOTE: gpm flow rates limited by maximumacceptable velocity through heat exchanger tubes.May be increased by 10% for closed heatingsystems. Pressure drop would increase by 21%.