Pressure Switch Check - Lennox EL296DF045XV36B Unit Information

Pressure Switch Check

To check pressure switch differential, refer to figure 16 and
use the provided fittings and tubing to follow the steps be­
low.
1 - Remove thermostat demand and allow unit to cycle
off.
2 - Remove the tubing from the negative side (red and black
or red) and positive side (black) of the pressure switch
(leave both connected to cold end header box).
3 - Take the 2" length square tubing and connect to the
positive (+) side of the pressure switch. Take the 10"
length square tubing and tee into the tubing from the
positive side of the cold end header box and the other
side of the 2" square tubing. Connect the other end of
the 10" square tubing the the positive (+) side of the
measuring device.
4 - Take a second piece the 2" length square tubing and
connect to the negative (-) side of the pressure switch.
Take a second piece of 10" length square tubing and
tee into the tubing from the negative (-) side of the cold
end header box and the other side of the 2" square tub­
ing. Connect the other end of the 10" square tubing the
the negative (-) side of the measuring device.
Red and Black
or Red Tubing
(negative -)
PRESSURE SWITCH CHECK
Black Tubing
2" long Square
(positive +)
Tee
10" Long Square Tubing
Measuring Device
FIGURE 16
Page 30
5 - Operate unit and observe manometer reading.
Readings will change as heat exchanger warms.
a. Take one reading immediately after start‐up.
b. Take a second reading after unit has reached steady
state (approximately 5 minutes). This will be the pres­
sure differential.
The pressure differential should be at least
0.15" greater than those listed in the table 17. Read­
ings in table are the set points or "break points".
6 - Remove thermostat demand and allow to cycle off.
7 - Replace original pressure switch tubing.
NOTE - Pressure differential values (set point) in table are
the "break", or "open" specifications. "Make", or "close"
pressure differentials are 0.15" greater than the set points
listed in table.
Tubing