Harman Stove Company PB 105 - Manual (Page 25)

25 3-90-07205R19_05/13
Setting The Boiler Temperature
Without the Outdoor Air Temperature 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
counter-clockwise 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.
The MIN. TEMP. knob in addition to being the mode
setting (on or off) now 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 in the
secondary ash chamber area and also in the venting
system, which could cause damage in these areas.
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
conditions show excess condensation, the boiler water
minimum temperature will need to be increased until
condensation does not occur. You should also consider
some form of tempering of the return water system.
Discuss this with your plumber.
Operation
Control Board Operation
Aquastat Sensor - This sensor is located in the
aquastat well on the top of the water jacket. This
sensor along with the outdoor air sensor is what the
control board uses to regulate the feed rate based
on these two 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 25.
WATER TEMPERATURE
MAX. TEMP. MIN. TEMP.