Lennox LCH036 Installation Instructions Manual page 162

B-Check Belt Tension
Overtensioning belts shortens belt and bearing life. Check
belt tension as follows:
1-Measure span length X. See figure 25.
MEASURE BELT TENSION
DEFLECTION 1/64" PER INCH OF SPAN
OR 0.4mm PER 25.4mm OF SPAN
FIGURE 25
2-Apply perpendicular force to center of span (X) with
enough pressure to deflect belt 1/64" for every inch of
span length or 0.4mm per 25.4mm of span length.
Example: Deflection distance of a 40" span would be
40/64" or 5/8".
Example: Deflection distance of a 1016mm span would
be 16mm.
3-Measure belt deflection force. Used belt values apply
when tightening the belt after 24-48 hours.
For a used belt, the deflection force should be:
5 lbs. for
8 lbs. for
7 lbs. for
For a new belt, the deflection force should be:
8 lbs. for 5 & 7.5 HP applications
INSTALLATIONS WITH DUCTWORK
ROOFTOP UNIT
SUPPLY
MAIN
DUCT RUN
5- Referring to Page 20 and Page 21, use static pressure
and RPM readings to determine unit CFM. Use
FORCE
5 & 7.5 HP applications
10 & 15 HP applications
20, 25, & 30 HP applications
LOCATION OF STATIC PRESSURE READINGS
RETURN AIR
READING LOCATION
RE­
TURN
FIRST BRANCH
OFF OF MAIN RUN
SUPPLY AIR
READING
LOCATION
A force
undertensioned belt. A force above these values
indicates an overtensioned belt.
C-Blower Operation
Initiate blower demand at thermostat according to
instructions provided with thermostat. Unit will cycle on
thermostat demand. The following steps apply to
applications using a typical electro-mechanical thermostat.
1- Blower operation is manually set at the thermostat
subbase fan switch. With fan switch in ON position,
blowers will operate continuously.
2- With fan switch in AUTO position, the blowers will cycle
with demand. Blowers and entire unit will be off when
system switch is in OFF position.
In zone sensor applications the blower will cycle with
demand (default). For continuous blower operation change
ECTO 6.17 to option 1. Refer to the Unit Controller manual.
D-Determining Supply CFM
1- The following measurements must be made with a dry
indoor coil. Run blower without a cooling demand. Air
filters must be in place when measurements are taken.
2- VFD Units Only -
Set the VFD to 60Hz using Unit Controller ECTO 0.08.
Refer to the Unit Controller manual provided with unit.
3- Measure the indoor blower shaft RPM.
4- With all access panels in place, measure static
pressure external to unit (from supply to return). Blower
performance data is based on static pressure readings
taken in locations shown in figure 26.
Note - Static pressure readings can vary if not taken where
shown.
INSTALLATIONS WITH CEILING DIFFUSERS
ROOFTOP UNIT
SUPPLY AIR
READING
LOCATION
FIGURE 26
Page 26 when installing the unit in horizontal air
Page 18
12 lbs. for 10 & 15 HP applications
11 lbs. for 20, 25, & 30 HP applications
below these values
RETURN AIR
READING
RE­
SUPPLY LOCATION
TURN
DIFFUSER
LGH/LCH420, 480, 540, 600
indicates an