S-201 Checking Temperature Rise; S-300 Testing Primary Limit Control; S-301 Testing Auxiliary Limit - Daikin DP14UM Service Instructions Manual

SERVICING

S-201 Checking Temperature Rise

Temperature rise is related to the BTUH output of the
unit and the amount of air (CFM) circulated over the heat
exchanger.
All units are designed for a given range of temperature
increase. This is the temperature of the air leaving the unit
minus the temperature of the air entering the unit.
The more air (CFM) being delivered through a given
unit the less the rise will be; so the less air (CFM)
being delivered, the greater the rise. The temperature
rise should be adjusted in accordance to a given unit
specifications and its external static pressure.
1. Check BTUH input to unit do not exceed input rating
stamped on rating plate.
2. Take entering and leaving air temperatures.
3. Select the proper speed tap or dip switch setting for
direct drive units.
4. Take motor amperage draw to determine that the
motor is not overloaded during adjustments.
SUPPLY
T
SUPPLY
T
RETURN
Checking Temperature Rise
RETURN
T T
RISE = SUPPLY - RETURN

S-300 Testing Primary Limit Control

APG/GPG units use a snap-disk type primary limit device.
Sometimes referred to as "stat on a stick". The limit setting
is fixed and must not be readjusted in the field.
Testing Primary Limit Control
Refer to the specification section to determine the proper
limit cutout temperature for the model being serviced.
In all instances the limit control is wired in series with the
ignition control.
If the temperature within the furnace should exceed this
setting, the control will open, de-energizing the ignition
control which in turn will open the electrical circuit to the
gas valve.
The control will automatically reset when the temperature
within the combustion chamber is sufficiently lowered.
High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be
present. Failure to do so may cause property
damage, personal injury or death.
1. Remove electrical power to unit. Some units may
have more than one source of power.
2. Remove the wires from the limit control terminals.
3. Using an ohmmeter, test for continuity across the two
terminals.
4. If limit test open allow unit to cool and retest.
5. If still open, replace the control.
WARNING
27