THERMOSTAT SETTINGS
1. The Excel 10 temperature controller is adjusted to a low test setting when shipped from the factory.
2.Using the Command Display, adjust the temperature set point to the lowest settings which will satisfy hot water demands and prevent a risk of scald injury.
TEMPERATURE ADJUSTMENT
MINIMUM WATER TEMPERATURES
(Domestic Hot Water Use)
Inlet water temperatures below the specified minimum recommendations can excessively cool the products of combustion resulting in condensation on the primary heat exchanger. The water heater is designed to condense only on the secondary heat exchanger. Condensation on the primary heat exchanger can cause operational problems, bad combustion, sooting, flue gas spillage and reduced service life of the related components.
A minimum water temperature has been established for each model based on the Btu/hr input at 100% of rated burner input. The temperature set point for the Excel 10 controller sensing stored water temperature must not be set lower than the specified minimum for each model. Maintaining inlet water temperatures to the water heater equal to or higher than the specified minimum ensures proper operation of the bypass and allows all condensate formation to occur on the secondary heat exchanger. A water heater allowed to sustain operation at water temperatures lower than the specified minimum may not provide enough heat from the burner to maintain water temperatures in the primary heat exchanger above the 130°F (55°C) dew point of flue products. Operation of a water heater at a temperature below the specified minimum will result in
• Water temperature over 125°F (52°C) can cause severe burns instantly or death from scalds.
• Children, disabled and elderly are at highest risk of being scalded.
• See instruction manual before setting temperature at heating appliance.
• Feel water before bathing or showering.
• If this appliance is used to produce water that could scald if too hot, such as domestic hot water use, adjust the outlet control (limit) or use temperature limiting valves to obtain a maximum water temperature of 125°F (52°C).
TABLE - HH
Minimum Inlet Water Temperatures
Input | Minimum Return | Minimum |
Btu/hr | Temperature | Setpoint |
|
|
|
1,500,000 | 50°F (10°C) | 105°F (40.6°C) |
___________ | ____________________ | _______________ |
1,700,000 | 50°F (10°C) | 90°F (32.2°C) |
___________ | ____________________ | _______________ |
2,000,000 | 50°F (10°C) | 70°F (23.9°C) |
|
|
|
CAUTION
An appliance allowed to operate with return temperatures set point below the specified minimum settings may experi- ence operational problems with the operating controls and safety switches, obstruction of the flue gas passages on the primary heat exchanger, incomplete combustion and possible flue gas spillage. Operation at lower than specified water temperatures may cause hazardous conditions that result in
The maximum temperature set point that can be programmed into the Excel 10 controller from the Command Display for water heater operation is 190°F (87.8°C). The Excel 10 control is factory
The following chart (Table II) details the relationship of water temperature and time with regard to scald injury and may be used as a guide in determining the safest water temperature for your applications.
TABLE - II
APPROXIMATE TIME / TEMPERATURE RE-
LATIONSHIPS IN SCALDS
120°F | More than 5 minutes |
|
|
125°F | 1 1/2 to 2 minutes |
|
|
130°F | About 30 seconds |
|
|
135°F | About 10 seconds |
|
|
140°F | Less than 5 seconds |
|
|
145°F | Less than 3 seconds |
|
|
150°F | About 1 1/2 seconds |
|
|
155°F | About 1 second |
|
|
FIG. 87 Warning Label
75
