9. Gas Piping
Follow the instructions from the gas supplier.
The appliance and its individual shutoff valve must be disconnected from the gas supply piping system during any pressure testing of that system at test pressures in excess of 1⁄2 psi (3.5 kPa).
The Appliance must be isolated from the gas supply piping system by closing its individual manual shutoff valve during any pressure testing of the gas supply piping system at test pressures equal to or less than 1⁄2 psi (3.5 kPa).
The appliance and its gas connections must be leak tested before placing the appliance in operation.
The inlet gas pressure must be within the range specified. This is for the purposes of input adjustment.
In order to choose the proper size for the gas line, consult local codes or the National Fuel Gas Code ANSI Z223.1.
Gas Pressure
Size the gas line according to total btuh demand of the building and length from the meter or regulator so that the following supply pressures are available even at maximum demand:
Natural Gas Supply Pressure
Min. 4" WC
Max. 10.5" WC
LP Gas Supply Pressure
Min. 8" WC
Max. 14" WC
Measuring Gas Pressure
Gas Meter
Select a gas meter capable of supplying the entire btuh demand of all gas appliances in the building.
Gas Connection
•Do not use piping with a diameter smaller than the inlet diameter of the water heater.
•Gas flex lines are not recommended unless they are rated for 199,900 btuh.
•Install a gas shutoff valve on the supply line.
•Use only approved gas piping materials.
In order to check the gas supply pressure to the unit, a tap is provided on the gas inlet. Remove the hex head philips screw from the tap, and connect a manometer using a silicon tube.
In order to check the gas manifold pressure, a pair of taps are provided on the gas valve inside the unit.
The pressure can be checked either by removing the hex head philips screw and connecting a manometer with a silicon tube, or by removing the 1/8" NPT screw with an allen wrench and connecting the appropriate pressure gauge.
Sample Gas Line
Noritz Gas Water Heater
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| Clothes Dryer |
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| Outlet C |
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Section 4 |
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| 3m (10') |
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Natural Gas |
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Meter | **See next page for the pipe capacity charts. |
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Instructions
1.Size each outlet branch starting from the furthest using the Btuh required and the length from the meter.
2.Size each section of the main line using the length to the furthest outlet and the Btuh required by everything after that section.
Sample Calculation
Outlet A: 13.5m (45') (Use 15m (50')), 50,000 Btuh requires 1/2"
Outlet B: 12m (40'), 65,000 Btuh requires 1/2"
Section 1: 13.5m (45') (Use 15m (50')), 115,000 Btuh requires 3/4"
Outlet C: 9m (30'), 35,000 Btuh requires 1/2"
Section 2: 13.5m (45') (Use 15m (50')), 150,000 Btuh requires 3/4"
Outlet D: 7.5m (25') (Use 9m (30')), 25,000 Btuh requires 1/2"
Section 3: 13.5m (45') (Use 15m (50')), 175,000 Btuh requires 1"
Outlet E: 7.5m (25') (Use 9m (30')), 199,900 Btuh requires 3/4"
Section 4: 13.5m (45') (Use 15m (50')), 374,900 Btuh requires
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