Installation & Service Manual
7 Domestic water heaters
Minimum pump performance
This is based on heating potable water with a hardness of 5 to 25 grains per gallon and/or total dissolved solids not exceeding 350 ppm. See Water Chemistry, page 53.
TABLE 7D
Minimum Pump Performance
Model | GPM | FT/HD |
|
|
|
497 - 747 | 55 | 10 |
987 - 2067 | 90 | 15 |
Heat exchanger
This is a highly sophisticated heat exchanger, designed to carry water in such a way that it generates a scouring action which keeps all interior surfaces free from build up of impurities. The straight line, two pass design of the tubes sends water into the headers at a properly rated velocity. The configuration of the headers, in turn, creates a high degree of turbulence which is sufficient to keep all contaminants in suspension. This “scouring action” provides greater cost savings for owners.
Tubes are always able to transfer heat at peak efficiency. Every surface within this water containing section is of a non ferrous material, providing clear, clean, rust free hot water. Straight copper tubes finned on the outside for maximum heat transfer and coated cast iron one piece cored headers make up an entirely rust proof unit. On all models, header inspection plugs can be removed for field inspection and cleaning of copper tubes. The entire heat exchanger may be easily removed from the unit.
Potable hot water temperature control settings
Domestic water temperature
WARNING You must take adequate care to prevent scald injury when storing water at elevated
temperatures for domestic use.
This unit has an adjustable temperature control to maintain the desired water temperature set point. See Setting Temperature Control, page 39, for instructions to adjust the temperature control. The temperature control is factory preset at approximately 125°F (52°C) or less. Households with small children or invalids may require 120°F (49°C) or lower temperature hot water to reduce risk of scald injury.
Operate this high efficiency hot water heater at a temperature setting high enough to prevent condensing of the products of combustion on the unit’s heat exchanger or in the attached venting system. A water temperature setting that is above the dew point of the gas combustion products should prevent condensate formation
WARNING To guard against scald injury, you must use a properly sized thermostatic mixing valve to
supply domestic hot water at temperatures less than 125°F (52°C).
WARNING Return water temperatures must not be less than 140°F (60°C). If lower return
water temperatures are required, follow the instructions for Low Temperature Return Water Systems, page 30.
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