Raypak HD401 Installation & Operating Instructions Manual

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16Table F: Domestic water Heater Flow Rate Requirements∆T = Temperature rise, °F.∆P = Pressure drop through heat exchanger, ft.SHL = System head loss, ft. (System head loss is based on the heater and tank placed no more than 5 feet apart and 50 feet equivalent lengthof tubing and fittings.)gpm = Gallons per minute, flow rate.MTS = Minimum tubing size.*Must utilize optional cupro-nickel tubes.**With Hard Water (16-25 grains per gallon), the operating control must be set no higher than 130°F for scale free operation. For operating tem-peratures above 130°F, a water softener must be utilized.ModelNo.InputMBTUHOutputMBTUHSoft (0–4 grains per gallon) Medium (5–15 grains per gallon) Hard* (16–25** grains per gallon)∆T gpm ∆P MTS SHL ∆T gpm ∆P MTS SHL ∆T gpm ∆P MTS SHLHD101 100 85 9 20 1.8 1-1/2 3.8 7 26 3.0 1-1/2 6.3 4 45 9.2 1-1/2 18.0HD151 150 128 13 20 1.8 1-1/2 3.8 10 26 3.1 1-1/2 6.3 6 45 9.2 1-1/2 18.1HD201 199 169 17 20 1.9 1-1/2 3.9 13 26 3.2 1-1/2 6.4 8 45 9.4 1-1/2 18.2HD251 250 213 21 20 1.9 1-1/2 3.9 16 26 3.2 1-1/2 6.5 9 45 9.6 1-1/2 18.5HD301 299 254 25 20 1.9 1-1/2 3.9 20 26 3.2 1-1/2 6.5 11 45 9.8 1-1/2 18.7HD401 399 339 34 20 2.0 1-1/2 4.0 26 26 3.3 1-1/2 6.6 15 45 10.3 1-1/2 19.1Pressure Drop in Feet of HeadFeedwater RegulatorRaypak recommends that a feedwater regulator beinstalled and set at 12 psi minimum pressure at thehighest point of system. Install a check valve or backflow device upstream of the regulator, with a manualshut 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 cut-off 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.The 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.System flow must always exceed boiler flow for properoperation. Raypak strongly recommends a minimumsystem flow of 115% of the boiler flow.Air-Separation/Expansion TankAll boilers should be equipped with a properly sizedexpansion tank and air separator fitting as shown inthe piping diagrams (Fig. 10–13).Three-Way ValvesValves designed to blend water temperatures orreduce water circulation through the boiler should notbe used. Raypak boilers are high recovery low massboilers 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.Domestic Hot Water PipingWhen designing the water piping system for domesticwater applications, water hardness should be consid-ered. Table F indicates the suggested flow rates forsoft, medium and hard water. Hardness is specified asgrains per gallon.