Amana GUIA Series Service Instructions Manual page 146

SERVICING
S-22 CHECKING TEMPERATURE RISE
The more air (CFM) being delivered through a given furnace,
the less the rise will be; so the less air (CFM) being deliv-
ered, the greater the rise. The temperature rise should be
adjusted in accordance to a given furnace specifications
and its external static pressure. An incorrect temperature
rise may result in condensing in or overheating of the heat
exchanger. An airflow and temperature rise table is pro-
vided in the blower performance specification section. De-
termine and adjust temperature rise as follows:
1. Operate furnace with burners firing for approximately
ten minutes. Check BTU input to furnace - do not ex-
ceed input rating stamped on rating plate. Ensure all
registers are open and all duct dampers are in their fi-
nal (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.
HEAT EXCHANGER
RADIATION "LINE OF SIGHT"
AIR C O MMAN D
H I EF FIC IEN C Y 80 G ASFU R N ACE
Checking Temperature Rise
(80% Furnace Shown, 90% Similar)
146
Rev. 1
SUPPLY
AIR
T
SUPPLY
T T
RISE = SUPPLY - RETURN
T
RETURN
RETURN
AIR
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 Circulator Blower Speed section in the Product
Design section of this manual for speed changing de-
tails. Temperature rise is related to the BTUH output of
the furnace and the amount of air (CFM) circulated over
the heat exchanger. Take motor amperage draw to de-
termine that the motor is not overloaded during adjust-
ments.