Temperature Rise; Circulator Blower Fan Timing Adjustment - Intertek MES80 Installation Instructions Manual

Temperature Rise

Air temperature rise is the temperature difference between
supply and return air. The proper amount of temperature rise
is usually obtained when the unit is operated at the rated input
with the "as shipped" blower speed. If the correct amount
of temperature rise is not obtained, it may be necessary to
change the blower speed.
Temperature rise must be within the range specified on the
unit rating plate. An incorrect temperature rise may result in
condensing in or overheating of the heat exchanger. An airflow
and temperature rise table is provided in the Specification
Sheet applicable to your model. Determine and adjust
temperature rise as follows:
Temperature Rise Measurement
1. Operate furnace with burners firing approximately
15 minutes. Ensure all registers are open and all
duct dampers are in their final (fully or partially open)
position.
2. Place thermometers in the return and supply ducts as
close to the furnace as possible. Thermometers must
not be influenced by radiant heat by being able to "see"
the heat exchanger.
3. Subtract the return air temperature from the supply
air temperature to determine the air temperature rise.
Allow adequate time for thermometer readings to
stabilize.
4. Adjust temperature rise by adjusting the circulator
blower speed. Increase blower speed to reduce
temperature rise. Decrease blower speed to increase
temperature rise. Refer to the following section for
speed changing details.
Circulator Blower Speed Adjustment
T
O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRICAL SHOCK
OFF
TURN POWER TO THE FURNACE BEFORE CHANGING SPEED TAPS
SUPPLY
AIR
RETURN
AIR
Figure 15
WARNING
This furnace is equipped with a multi-speed circulator blower. This
blower provides ease in adjusting blower speeds. The Specifi-
cation Sheet applicable to your model provides an airflow table,
showing the relationship between airflow (CFM) and external
static pressure (E.S.P.), for the proper selection of heating and
cooling speeds.
1. Determine the tonnage of the cooling system installed with
the furnace. If the cooling capacity is in BTU/hr divide it by
12,000 to convert capacity to tons.
Example: Cooling Capacity of 30,000 BTU/hr.
30,000/12,000 = 2.5 Tons
2. Determine the proper air flow for the cooling system. Most
cooling systems are designed to work with air volume
between 350 and 450 CFM per ton. Most manufacturers
recommend an air flow of about 400 CFM per ton.
Example: 2.5 tons X 400 CFM per ton = 1000 CFM
3. Select the heating speed for your model from the
heating speed chart in the Specification Sheet. The
selected speed must provide a temperature rise within
the rise range listed with the particular model.
To adjust the circulator blower speed, proceed as follows:
1. Turn OFF power to the furnace.
2. Select the heating and cooling blower speeds that
match the installation requirements from the airflow
table in the Specification Sheet applicable to your
model. (Please contact your distributor or our website
for the applicable Specification Sheet referred to in this
manual.)
3. Relocate desired motor leads to the circulator blower
heat and cool speed terminals on the integrated control
module. (Terminals are identified as HEAT and COOL)
If a heating speed and the cooling speed are the same,
a jumper wire must be used between the heat and cool
terminals.
4. Connect all unused blower motor leads to the "PARK"
terminals on the integrated control module. Any leads
not connected to the "PARK" terminals must be taped.
5. Turn ON power to furnace.
6. Verify proper temperature rise as outlined in Temperature
Rise section. In general lower heating speeds will:
reduce electrical consumption, lower operating
sound levels of the blower, and increase the outlet
air temperature delivered to the home. The speeds
available allow the blower performance to be optimized
for the particular homeowner's needs.

Circulator Blower Fan Timing Adjustment

NOTE: Items in this section refer to the air circulator blower
fan, NOT to the induced draft blower. The induced draft blower
timing sequence is not adjustable.
The integrated control module on all models provides a
selectable heat off delay function. The delay is factory shipped
at 150 seconds but may be changed to suit the installation
requirements and/or homeowner preference. Other timings
available are 90, 120 and 180 seconds. Heat cycle jumper
,
settings on the integrated control board are A, B, and D
.
respectively.
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