Supply/Return Airflow And Air Temperature - Thermo Products VH-BBP Spirit Series Installation, Operation & Maintenance Manual

Oil-fired central furnace
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Furnace Model:
Burner Model:
Standard Nozzle (Delevan):
Oil Pump Pressure (PSIG):
Burner Head Type:
Head / Turbulator Setting:
Air Band Setting:
Air Shutter / Damper Setting:
Overfire Draft (in. W.G.):
Smoke Spot, Maximum (Bacharach Scale):
Carbon Dioxide, CO2, Maximum (%):
Carbon Dioxide, CO2, Minimum (%):
Carbon Monoxide, CO (PPM)
Oil Solenoid Valve Equipped:
Prepurge Time (sec):
Postpurge Time (sec):
Ignition Type:
*
When operating these furnaces at the lowest input rate (84,000 BTUH), the carbon dioxide (CO
value may not be able to be adjusted above 12%. This is normal and does not necessarily indicate
a problem.

Supply/Return Airflow and Air Temperature

The supply/return airflow shall be set to obtain an air temperature rise, across the
furnace, in the range of 55 to 85ºF. Since the flow resistance of each duct system is
slightly different, the airflow (fan speed) may have to be changed in the field to achieve
a satisfactory temperature rise.
One way to measure the temperature rise across the furnace is to insert temperature
measuring devices (e.g. thermometers) into the return air duct and into the supply air
duct about 12 inches from the furnace. After the furnace has been firing continually for
over 20 minutes, read the temperature difference between the two (2) thermometers.
The temperature difference should not exceed 85ºF, nor be less than 55ºF. For better
energy efficiency, a temperature rise closer to 70ºF is recommended.
The blower (fan) speed is adjusted by changing the fan motor winding energized by the
control system. The furnace is set on the med-low fan speed, "ML", at the factory, refer
to Table 2. To adjust the fan speed, follow this procedure.
a. Turn off all electrical power to the furnace at the disconnecting switch.
b. Remove the blower compartment access door on the counterflow/horizontal
furnace.
c. The "Heat" tab is the connection for the heating speed activation thru the
fanboard. If a change in heating speed is desired simply pull the blue (ML) wire
from the heat tab and replace it with the yellow (MH) wire. This changes the
speed from medium-low to medium-high. Black (High) is connected to the "cool"
Table 1: Oil Burner Application and Specifications
0.75 GPH / 80° angle / hollow cone 0.65 GPH / 60° angle / semi-solid
All
R.W. Beckett, AF
130
F3
Z = 1.125 in.
Fully-closed
5
0.02
# 1
13
12*
0
Yes
None
None
Interrupted
21
All
R.W. Beckett, NX
175
N/A
Adjustable
N/A
3.5
0.02
# 1
13
12*
0
Yes
None
None
Interrupted
)
2

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