Flow; Freeze Protection System; Maintenance And Service - A.O. Smith 910 Installation Manual And Owner's Manual

On-demand gas tankless water heater
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The flow rate through the water heater is limited to
a maximum of 14.5 GPM (54.9 L/min).
The temperature setting, along with the supply
temperature of the water, will determine the flow
rate output of the unit.
Please refer to the temperature vs. gallons per
minute charts on p. 52 to determine the likely flow
rates based on your local ground water temperature
and your desired outlet water temperature.
Refer to the table on the right for typical household
plumbing fixture flow rates to determine what the
water heater can do in a household application.
This unit comes equipped with heating blocks to protect it from damage associated with freezing.
For this freeze protection system to operate, there has to be electrical power to the unit. Damage
to the heat exchanger caused by freezing temperatures due to power loss is not covered under the
warranty. In cases where power losses can occur, consider the use of a backup power supply.
The freeze protection system will activate when the air temperature inside the case or water in the
heat exchanger is less than 36.5 °F (2.5 °C).
In any areas subject to freezing temperatures, the manufacturer highly recommends an indoor instal-
lation with an indoor model. In such an installation, freezing issues can occur if cold air enters through
the venting into the heat exchanger, whether by negative pressures within the installation location or
by strong outside winds.
The manufacturer also highly recommends the use of a backflow preventer (sold separately)
to minimize the amount of cold air entering through the exhaust venting when the water heater is off.
It is the installer's responsibility to be aware of freezing issues and take all preventative measures. The
manufacturer will not be responsible for any damage to the heat exchanger as a result of freezing.
If you will not be using your heater for a long period of time:
1. Completely drain the water out of the unit. Refer to p. 40.
2. Disconnect power to your heater.
This will keep your unit from freezing and being damaged.
Only pipes within the water heater are protected by the freeze protection system. Any
NOTICE
water pipes (hot or cold) located outside the unit will not be protected. Properly protect
and insulate these pipes from freezing.
Turn off the electrical power supply and close the manual gas shutoff valve and the
manual water control valve before servicing. Failure to do so could result in serious
personal injury or death.
WARNING
Clean the cold-water inlet filter. (Refer to "Unit Draining and Filter Cleaning" on the following page.)
Be sure that all openings for combustion and ventilation air are not blocked.
The venting system should be checked annually for any leaks, corrosion, blockages or damage.
The burner should be checked annually for dust, lint, grease or dirt.
gasoline, flammable vapors, and liquids.
If the relief valve discharges periodically, it may be due to thermal expansion in a closed water supply
system. Contact the water supplier or local plumbing inspector on how to correct this situation.
Visually check the burner flames (see the following page) through the burner window in the burner
assembly located at the middle of the water heater.
Appliance/Use
Lavatory Faucet
Bath Tub
Shower
Dishwasher
Washing machine
Taken from UPC 2006
39
Page
Household Flow Rates
Flow rate
GPM (US)
L/min
1.0
3.8
4.0 – 10.0
15.2 - 37.8
2.0
7.5
1.5
5.6
1.5
5.6
4.0
15.2

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