Control Board Operation

Operation

WATER TEMPERATURE

MAX. TEMP.

MIN. TEMP.

Aquastat Sensor - This sensor is located behind the control panel. This sensor, along with the outdoor air sensor, is what the control board uses to regulate the burn rate based on the observed conditions. (Boiler Temp. & Outdoor Air Temperature)

Outdoor Air Temp - Sensor (OAT): This sensor is located outside the building (on the north side of the house and out of direct sunlight). The Outdoor Air Sensor is used to perform hot water reset based on outdoor air temperatures.

When the OAT sensor is installed, at 20° F. or below (outside temperature), the boiler will operate at the temperature set on the MAX. TEMP. knob. The boiler water temperature will decrease by 1 degree F. for every 1 degree F. in temperature rise (above 20°) of the outdoor air.

NOTE: Pellet Boiler Outdoor Air Reset Operation Graph located on page 28.

Setting The Boiler Temperature

Without the Outdoor Air Temp - Sensor Installed To set the maximum boiler water temperature, simply turn the Max. Temp. water temperature dial to the desired setting. The control and the boiler will then perform to achieve and maintain the set temperature. The Min. Temp. Knob is the boiler water temperature minimum, or the lowest temperature the water will go before the unit re-starts. Turning the knob fully counterclockwise is the “OFF” position, while turning the knob clockwise, past the 140 degree marking, is the “ON” position.

With The Outdoor Air Temp - Sensor Installed Maximum boiler temp setting is as described above, with the added feature of automatic maximum water temp controlled by the OAT sensor.

The MIN. TEMP. knob, in addition to being the mode setting (on or off), also has the function of setting the minimum boiler water temperature. This would be the lowest boiler water temperature that you want to have based on the following factors;

1.) Outdoor Air Temperature (OAT)

2.) Domestic Hot Water Use a.) Hot Water Coil Option b.) Indirect Hot Water Storage

3.) Overall Volume of the Heating System

The boiler is designed to withstand lower return water temperatures. However, extended return temperatures below 140 degrees F can cause condensation.

NOTE:

If the system is run at the lower temperature settings, conditions of the firebox, boiler tubes, secondary ash chamber and venting should be monitored closely. If any indications show excess condensation, the boiler water temperature will need to be increased until condensation does not occur.