Haier GE NF96DV, Service Manual

Page: 17 / 52

Page 17
31-5000727 Rev. 0
Pressure Switch Check
To check pressure switch differential, refer to Figure 12
and use the provided fittings and tubing to follow the steps
below.
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
tubing. Connect the other end of the 10” square tubing
the the negative (-) side of the measuring device.
1. 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 pressure differential. The pressure
differential should be at least 0.15” greater than
those listed in Table 6. Readings in table are the
set points or “break points”.
2. Remove thermostat demand and allow to cycle off.
3. 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.
Black Tubing
(po)
Red and Black
or Red Tubing
(negative -)
Tee
2” long Square
Tubing
Measuring Device
10” Long Square Tubing
Figure 12. Pressure Switch Check