Table F: Boiler Temperatures and Minimum Pipe Size at Varying Return TemperaturesSystemReturn Temp Supply Temp1 Supply Temp 1 Supply Temp 1(°F) (°F) <80' equiv. 80-200' equiv. (°F) <80' equiv. 80-200' equiv. (°F) <80' equiv. 80-200' equiv.60 138 2"NPT 2 1/2"NPT 147 2"NPT 2 1/2"NPT 154 2"NPT 2 1/2"NPT80 138 2"NPT 2 1/2"NPT 147 2"NPT 2 1/2"NPT 154 2 1/2"NPT 3"NPT100 138 2 1/2"NPT 3"NPT 147 2 1/2"NPT 3"NPT 154 2 1/2"NPT 3"NPT120 145 2 1/2"NPT 3"NPT 158 2 1/2"NPT 3"NPT 170 2 1/2"NPT 3"NPT140 165 2 1/2"NPT 3"NPT 178 2 1/2"NPT 3"NPT 190 2 1/2"NPT 3"NPT160 185 2 1/2"NPT 3"NPT 198 2 1/2"NPT 3"NPT 210 2 1/2"NPT 3"NPT1 -Approximate high fire heater outlet temperature based on the standard heater pump and the recommended connecting pipe size.Model 1005Minimum Pipe Size2Model 1505Minimum Pipe Size2Model 2005Minimum Pipe Size22 -Minimum pipe size based on total equivalent feet of supply and return piping between the system loop and heater.Fig. 14: Single Heater with Primary/Secondary PipingFig. 15: Dual Heaters (Reverse/Return)with Primary/Secondary PipingFig. 16: Single Domestic Hot Water Heater and StorageTankDomestic Hot WaterWhen designing the hot water piping system fordomestic hot water applications, water hardnessshould be considered. See Table H on page 18 for therequired tubing sizes and expected supply tempera-tures for different operating conditions. Waterhardness is expressed in grains per gallon.Fitting Type Equivalent Length (ft)2-1/2” NPT 3” NPT90° Elbow (Std.) 8.5 9.490° Elbow (Long rad.) 3.5 3.645° Elbow 3.0 3.4Gate Valve (Full open) 1.6 1.6Swing Check Valve 22 25Table G: Equivalent Lengths of Pipe for Typical FittingsNote: Equivalent lengths are calculated based on typical operatingconditions with typical Schedule 40 pipe fittings and valves.Equivalent lengths are approximate and may vary greatly.*Maximum 4 times the pipe diameter or 12”, whichever is less.*Maximum 4 times the pipe diameter or 12”, whichever is less.California Hot Water Supply, Inc.(800) 249-724416