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On-Demand Water Heater
System Design Manual
Design information for single and multiple unit
installations for residential, commercial, recircula-
tion and storage tank systems.
PRINTED 0209 186965-001
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Table of Contents Certifications..................................................................................3 Installing Gas Water Heater ...........................................................4-7 Water Quality and Scale ................................................................8 Pump Sizing for Circulation.......................................................... 9 Tank Water Heaters in a Circulation Loop ...................................10 Additional Guidelines ....
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Approvals ATI-305-N GTS-305-NI GT-305-NI ATI-305-P GTS-305-PI GT-305-PI ATO-305-N GTS-305-NE GT-305-NE ATO-305-P GTS-305-PE GT-305-PE ATI-505-N GTS-505-NI GT-505-NI ATI-505-P GTS-505-PI GT-505-PI ATO-505-N GTS-505-NE GT-505-NE ATO-505-P GTS-505-PE GT-505-PE ATI-705-N GTS-705-NI GT-705-NI ATI-705-P GTS-705-PI GT-705-PI ATO-705-N GTS-705-NE GT-705-NE ATO-705-P GTS-705-PE GT-705-PE *ATI-705A-N *GTS-705-NIA *AGT-705-NI *ATI-7
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Installation Consumer Information The on-demand water heaters must be installed according to all local and state codes or, in the absence of local and state codes, the “National Fuel Gas Code”, ANSI Z223.1 (NFPA 54) - current edition. CSA American, Inc. National Fire Protection Association 8501 East Pleasat Valley Road 1 Batterymarch Park Cleveland, OH 44131 Quincy, MA 02269 Check your phone listings for the local authorities having jurisdiction over your installation. Consumer Responsi
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Installation In addition to using the lowest possible temperature setting that satisfies your hot water needs, a means such as a mixing valve, should be used at hot water taps used by these people or at the water heater. Mixing valves are available at plumbing supply or hardware stores. Follow manufacturer’s instructions for installation of the valves. Before changing the factory setting on the thermostat see table below. Using the lowest hot water temperature that meets your needs will also pr
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For Storage Tank System Installation CAUTION - PROPERTY DAMAGE HAZARD The storage tank should be located in an area Figure “1” where leakage of the tank or connections will not result in damage to the area adjacent to the storage tank or to lower floors of the structure. Due to the normal corrosive action of the water, the tank will eventually leak after an extended period of time. Also Storage Tank any external plumbing leak, including those from improper installation, may cause early fa
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For Storage Tank System Installation Temperature and Pressure Relief Valve For protection against excessive pressures and temperatures, a temperature and pressure relief valve must be installed in the opening on the on-demand storage tank. This valve must be design certified by a nationally recognized testing laboratory that maintains periodic inspection of the production of listed equipment or materials as meeting the requirements for Releif Valves for Hot Water Supply Systems, ANSI Z21.22
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3900 3300 2700 2100 1500 900 300 0 Water Quality and Scale A complete water analysis and an understanding of system requirements are needed to protect the on-demand water heaters and water heating systems from scale. Water analysis shows whether water is hard or soft. Hard water, unless treated, will cause scaling or liming of the heat exchanger. The rate of scaling increases with temperature and usage because calcium carbonate and other scaling compounds lose solubility (fall out of solu
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Pump Sizing for Circulation 1. Use the chart below or one appropriate for your conditions to determine the heat loss in the length of the hot water supply and return piping. For example, 100 ft of 1-1/2 in bare copper tubing results in a heat loss of 5300 Btu/h. Approximate Heat Loss from Piping at 140 ºF Inlet, 70 ºF Ambient * Nominal Size, in. Bare Copper Tubing, 1/2 in. Glass Fiber Insulated Btu/h-ft Copper Tubing, Btu/h-ft 3/4 30 17.7 1 38 20.3 1-1/4 45 23.4 1-1/2 53 25.4 2 66 29
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Tank Water Heaters in a Circulation Loop The following applies when using a tank water heater (gas or electric) to provide heat for a circulation loop. Drawing H-1-RP is an example. The heat output of the tank must be equal to or greater than the calculated circulation loop heat loss. (Reference page 5, Step 1 on calculating heat loss). Electric Tank Water Heater Since the input and output are the same for an electric tank water heater, this can be expressed as: Electric Tank Input (Kw
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Table “C” Pump Sizing for Storage Tank Application The following applies when using on-demand water heaters to recover a storage tank. Drawing H-1-TC is an example. On-Demand water heaters have a pressure loss which must be considered in the system design. Reference the pressure loss curve for the heater model being used to determine the pump size for the desired recovery rate. For recommended pump sizes use the table below. Additional pressure losses in plumbing
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Figure “4” 100/101 Series Pressure Loss Curves Pressure Loss (ft head) 505 305i 305e Pressure Loss (psi) 12 45.0 40.0 60.0 35.0 50.0 30.0 40.0 25.0 20.0 30.0 15.0 20.0 10.0 10.0 5.0 0.0 0.0 01 234 5 6 789 10 11 Water Flow (gpm)
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Figure “5” 200/201 Series Pressure Loss Curves Pressure Loss (ft head) 705 505 305 Pressure Loss (psi) 13 45 100 40 90 35 80 70 30 60 25 50 20 40 15 30 10 20 5 10 0 0 0123456789 10 11 Water Flow (gpm)
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On-Demand Equipment List QTY On-Demand 1 Water Heaters On-Demand Water Heater Gas Supply 3/4” Hot Water Supply Line 3/4” Cold Water Supply Line Domestic Hot Water - Standard Installation 1 On-Demand Water Heater Preferred Piping Installation Key Check Valve Pressure Regulator Boiler Drain Valve 3/4" Ball Valve S Mixing Valve Pressure Relief Valve Circulating Pump Solenoid Valve 3/4" Union Drawing Date: NOTE: This drawing is not intended to describe a complete system and is not a replacem
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On-Demand Equipment List QTY On-Demand 2 Water Heaters Electronic Connection * * Refer to On-Demand Accessories and Model Applicability for electronic connection details. On-Demand On-Demand Water Heater Water Heater Primary Sub 1 Gas Supply Cold Water Supply Line Hot Water Supply Line Domestic Hot Water - Standard Installation 2 On-Demand Water Heaters Preferred Piping Installation Key Check Valve Pressure Regulator Boiler Drain Valve 3/4" Ball Valve S Mixing Valve Pressure Relie
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On-Demand Equipment List QTY On-Demand 3 Water Heaters Electronic Connection * * Refer to On-Demand Accessories and Model Applicability for electronic connection details. On-Demand On-Demand On-Demand Water Heater Water Heater Water Heater Primary Sub 1 Sub 2 Gas Supply Cold Water Supply Line Hot Water Supply Line Domestic Hot Water - Standard Installation 3 On-Demand Water Heaters Preferred Piping Installation Key Check Valve Pressure Regulator Boiler Drain Valve 3/4" Ball Valve S
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On-Demand Equipment List QTY On-Demand 4 Water Heaters Electronic Connection * * Refer to On-Demand Accessories and Model Applicability for electronic connection details. On-Demand On-Demand On-Demand On-Demand Water Heater Water Heater Water Heater Water Heater Sub 1 Sub 2 Sub 3 Primary Gas Supply Cold Water Supply Line Hot Water Supply Line Domestic Hot Water - Standard Installation 4 On-Demand Water Heaters Preferred Piping Installation Key Check Valve Pressure Regulator Boiler
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On-Demand Equipment List QTY On-Demand 5 Water Heaters Electronic Connection * * Refer to On-Demand Accessories and Model Applicability for electronic connection details. On-Demand On-Demand On-Demand On-Demand On-Demand Water Heater Water Heater Water Heater Water Heater Water Heater Primary Sub 1 Sub 2 Sub 3 Sub 4 Gas Supply Cold Water Supply Line Hot Water Supply Line Domestic Hot Water - Standard Installation 5 On-Demand Water Heaters Preferred Piping Installation Key Pressure
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On-Demand Equipment List QTY On-Demand 6 Water Heaters Electronic Connection * * Refer to On-Demand Accessories and Model Applicability for electronic connection details. On- On- On- On- On- On- Demand Demand Demand Demand Demand Demand Water Water Water Water Water Water Heater Heater Heater Heater Heater Heater Sub 1 Primary Sub 2 Primary Sub 1 Sub 2 Gas Supply Pressure Regulator Set to 5 PSI Below Street Pressure Hot Water Supply Line Cold Water Supply Line Domestic Hot Water
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S Minimum 3/4 " C old W ater S upply Line IMPORTANT! With electrical power supplied to a on-demand water heater, it will not freeze On-Demand º in enviornments as cold as -30 F, when protected from direct wind exposure. Equipment List QTY In the event of a power failure at temperatures below freezing, the water Outdoor On-Demand 1 heater should be drained of all water to prevent freezing damage. Water Heater The unit may be drained manually or through the installation of the Optional s
