Checking The Firing Rate
If firing rate adjustment is required follow these instructions to determine the actual firing rate of the water heater:
1.Ensure there are no other gas fired appliances connected to the gas meter firing during this test.
2.Contact the gas supplier to determine the heating value, in Btu per cubic foot, of the gas supply.
3.Connect a manometer to the manifold gas pressure tap. Follow the instructions for Initial Start Up on page 52.
4.Start the water heater and ensure it is firing.
5.Check the manifold gas pressure, refer to Table 4 on page 14 for correct pressure. See Manifold Gas Pressure Adjustment on page 54 if adjustment is necessary.
6.Locate the gas meter serving the water heater.
7.Time how long (in seconds) it takes for one cubic foot of gas to be used while the water heater is firing with a stop watch.
8.Use the formula below to “clock” the gas meter and determine the actual firing rate of the water heater based on the heating value (Btu per cubic foot) of the gas supply:
3600 x H = Btu/hr
T
Example:
3600 | x 1050 = 300,000 Btu/hr (87.9 kW) |
12.6 |
|
•3600 = seconds in one hour.
•T = time, in seconds, to burn one cubic foot of gas.
•H = heating value of gas in Btu per cubic foot.
•Btu/hr = actual firing rate of the water heater.
Note: 1050 Btu per cubic foot is a standard value for natural gas. Standard propane gas Btu content is 2500 Btu per cubic foot. Btu values may change in certain areas and at high elevations. Check with the local gas utility company.
To Turn Off Gas
1.Change the Operating Set Point to the lowest temperature setting, see Operating Set Point And Differential Adjustment on page 47.
2.When the water heater has completed its shut down sequence and enters the standby mode, turn the water heater’s on/off switch to the “off” position.
3.Close the Main Gas Shutoff Valve, see Figure 52 on page 39.
High Altitude Installations
Fire and Explosion Hazard
Under no circumstances should the input exceed the rate shown on the water heater’s rating label.
Overfiring could result in fire or explosion.
Gas and carbon monoxide detectors are available.
Breathing Hazard - Carbon Monoxide Gas
Under no circumstances should the input exceed the rate shown on the water heater’s rating label.
Overfiring could result in damage to the water heater and sooting.
Gas and carbon monoxide detectors are available.
Breathing carbon monoxide can cause brain damage or death. Always read and understand instruction manual.
SUF 100 120 and SUF 100 150 models are certified for use without modification for altitudes up to 7,700 feet (2,347 m).
SUF 100 199 and SUF 100 250 models are certified for use without modification for altitudes up to 10,100 feet (3,078 m).
Most gas utility companies
For installations above the certified elevations listed above call the technical support phone number listed on the back cover of this manual for further technical assistance. Call the local gas or utility company to verify Btu per cubic foot content before calling for technical assistance and have that information available.
Note: The actual firing rate of the water heater must not exceed the input rating on the water heater's rating label under any circumstances.
Note: Due to the input rating reduction at high altitudes, the output rating of the appliance is also reduced and should be compensated for in the sizing of the equipment for applications.
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