34000 Autry Street, Livonia, MI 48150 | 800.968.5530 | Fax 734.419.0209 | www.hamiltonengineering.com | LIT91127US REV 5/2018
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GENERAL INFORMATION
EXAMPLE: Water Heater Control
Controlling sensor
All of the following parameters are controlled by either a storage tank temperature sensor or the inlet temperature
sensor:
•
Setpoint
= Target Temperature (120°F) Low fire only above this point
•
Offset
= Off Setpoint (3) = 123°F off
•
Hysterese
= On Setpoint (8) (120 + 3 - 8 = 115°F)
•
Bandwidth
= Modulation range (4) (120 - 4 = 116°F, modulation begins)
The heater turns on at 115°F and when the temperature reaches 116°F the flame will begin to modulate down
(approximately 25% of the modulation range per degree F of increase in this example) at 120°F, it will be at low
fire and will remain there unless the temperature drops below 120°F and it will modulate back up. If it continues
to increase, it will shut down at 123°F.
Outlet sensor
Its purpose is twofold: first stage as a high limit and second as a sensor for computing ∆T. Default water heater
settings are as follows:
•
Setpoint
= start of modulation (185°F)
•
Offset
= Off Setpoint (5°F) (185 + 5 = 190°F off)
There is a fixed
Manual Reset High Limit
at 198°F (155°F and 210°F also available) on water heaters and
heating boilers.
A number of parameters must be programmed at the factory to provide proper operation and temperature
control, including:
• Controlling Sensor: Setpoint, Offset, Hysterese and Bandwidth.
•
Controlling sensor is the inlet sensor for a stand alone water heater, outlet sensor for a stand
alone boiler or the remote 10k thermistor for either water heater or boiler any time one is
connected. Connection is automatically detected and control shifted to the remote sensor from
the internal sensor by the EVO Controller when a 10k sensor is connected to the appropriate
terminals.
• Secondary Sensor: Setpoint Outlet and Offset.
•
Setpoint:
desired operating water temperature (this is set by the end user)
•
Offset:
amount the temperature is allowed to go above Setpoint before finally shutting off
•
Hysterese:
amount the temperature is allowed to drop under Setpoint plus offset before the
appliance turns on
•
Bandwidth:
the range over which flame modulation occurs (this only takes place below Setpoint)
Modulation Range
Setpoint
Se Offset
Se Offset - Hysterese
Bandwidth
Burner On
Burner Off
115°
119°
120°
121°
122°
123°
124°
125°
126°
116°
118°
117°
Temperature
Low Fire