Installation Requirements
Gas Pressure Requirements
Natural gas models require a minimum gas supply pressure of
4.5” W.C. Propane gas models require a minimum gas supply pressure of 11" W.C. The minimum supply pressure is measured while gas is not flowing (static pressure) AND while gas is flowing (dynamic pressure). The supply pressure (static and dynamic) should never fall below the specified minimum supply pressure. The supply pressure should be measured with all gas fired appliances connected to the common main firing at full capacity. If the supply pressure drops more than 1.5” W.C. as gas begins to flow to the water heater then the supply gas system including the gas line and/or the gas regulator may be restricted or undersized. See Supply Gas Regulator section and Gas Piping section of this manual.
The gas valve on all models has a maximum gas supply
pressure limit of 14" W.C. The maximum supply pressure is measured while gas is not flowing (static pressure) AND while gas is flowing (dynamic pressure).
Supply Gas Regulator
The water heater covered by this manual may require the installation of a supply gas regulator. If the supply gas pressure exceeds 14 inches W.C. a supply gas regulator must be used. If the gas supply pressure exceeds 14" W.C. in a multiple water heater installation, each water heater must have its own supply gas regulator. If required, the supply gas
regulator shall be rated at or above the Btu/hr input rating of
the water heater it supplies.
Supply gas regulators shall have inlet and outlet connections
not less than the minimum supply gas line size for the water
heater they serve as shown in Table 9. The Maxitrol
Power Supply
The water heaters covered in this manual require a 120 VAC, 1Ø (single phase), 60Hz, 15 amp power supply and must also be electrically grounded in accordance with local codes or, in the absence of local codes, with the National Electrical Code, ANSI/NFPA 70 or the Canadian Electrical Code, CSA C22.1.
Water Temperature Controland Mixing Valves
Water temperature over 125°F (52°C) can cause severe burns instantly resulting in severe injury or death.
Children, the elderly and the physically or mentally disabled are at highest risk for scald injury.
Feel water before bathing or showering.
Temperature limiting devices such as mixing valves must be installed when required by codes and to ensure safe temperatures at fixtures.
Water heated to a temperature which will satisfy clothes washing, dish washing, and other sanitizing needs can scald and cause permanent injury upon contact. Short repeated heating cycles caused by small hot water uses can cause temperatures at the point of use to exceed the water heater’s temperature setting by up to 20°F (11°C).
Some people are more likely to be permanently injured by hot water than others. These include the elderly, children, the infirm and the physically/mentally disabled. Table 6 shows the approximate
In addition to using the lowest possible temperature setting that satisfies the demand of the application a Mixing Valve should be installed at the water heater (see Figure 10) or at the hot water taps to further reduce system water temperature.
Mixing valves are available at plumbing supply stores. Consult a Qualified Installer or Service Agency. Follow mixing valve manufacturer’s instructions for installation of the valves.
Table 6.
Water Temperature | Time to Produce 2nd & 3rd | |
Degree Burns on Adult Skin | ||
| ||
180°F (82°C) | Nearly instantaneous | |
170°F (77°C) | Nearly instantaneous | |
160°F (71°C) | About 1/2 second | |
|
| |
150°F (66°C) | About | |
140°F (60°C) | Less than 5 seconds | |
130°F (54°C) | About 30 seconds | |
120°F (49°C) | More than 5 minutes |
12
