Thermo Pride OH8FA119D60C Installation And Operation Manual page 51

a. With the oil shut off, remove the 1/8 in. NPT threaded pipe plug located on the lower rear side of the oil
pump, refer to Figure 22. Attach a pressure gage, capable of measuring pressure in pounds per square
inch gage, PSIG, in this opening, on the discharge side, of the oil pump.
NOTICE: It may be necessary to remove the oil pump to attach the plumbing
required to connect a pressure gage to the pump.
b. Turn on the fuel oil and cause the appliance to activate the heating section by answering a "call for
heat".
NOTICE: It may be necessary to bleed air from the oil line before the burner can
be fired.
c. Allow the heating section to operate for 10 to 15 minutes.
d. Note the oil pressure at the pump.
e. To adjust the pressure, use a common screwdriver to turn in the pressure adjustment screw, located
on the upper front of the oil pump body.
f. Allow the fuel flow rate to stabilize for a moment. Recheck the oil pressure.
g. If required, repeat the oil pressure adjustment again.
h. When the input rate adjustment has been completed, shut off the fuel oil to the appliance. Remove the
pressure gage. Reinstall the pipe plug using a thread compound resistant to the action of LP gases and
fuel oil.
To insure the combustion air supply is adequate, it is now necessary to repeat the steps in the previous
Initial Burner Adjustment section of this manual.
4. Setting Supply Air Temperature Rise:
: To avoid injury from moving parts or electrical shock, shut off the
power to the appliance before removing supply air blower compartment door and
servicing this appliance.
All OH6 & OH8 models are designed and wired at the factory for a blower speed during heating that
should result in an approximate temperature rise of 66°F. The temperature rise through the heating
section, for any given blower speed, may vary depending on a number of factors. A few of these factors
are variations in, the actual resistance of the duct system to airflow at any time, the return air
temperatures, and the fuel oil heating value.
Also, fouling of the heat exchanger surfaces will reduce temperature rise. In general, a lower temperature
rise through the heating section will result in higher heating efficiency.
Temperature rise = supply air temperature - return air temperature.
After 15 to 20 minutes of continuous operation, the temperature rise through the furnace must fall within a
range of 51° to 81° F. If the outlet or supply duct temperature is too high, check to make sure the return
air filter is clean, the return air registers are free from obstruction, the outlet registers are properly
adjusted and clear, and the supply and return air ducts are open. The circulating air blower is not moving
enough air if the supply air temperature is still too high. Before proceeding further, turn off the power
supply to the appliance and remove the vestibule cover. The speed of the blower must be increased by
changing the switch setting on the control board, please refer to Figure 18.
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