Lennox BAC020SNM, Installation, Operating And Maintenance

Page: 59 / 137

VENTILATION BELT TENSION
BALTIC R410A-IOM-0708-E Page 58
BELT TENSION
On delivery, the drive belts are new and correctly
tensioned. After the first 50 operating hours check and
adjust the tension. 80% of the total elongation of belts is
generally produced during the first 15 hours of operation.
Before adjusting the tension, make sure that the pulleys are
correctly aligned.
To tension the belt, set the height of motor support plate by
moving the plate adjustment screws.
The recommended deflection is 20 mm per metre from
centre to centre.
Check that according to the diagram below (figure 37), the
following ratio remains the same.
A (mm) = 20
P (mm)
The belts should always be replaced when:
- The disk is set to maximum,
- The belt rubber is worn or the wire is visible.
Replacement belts must have the same rated size as the
ones they are replacing. If a transmission system has
several belts, they must all be from the same
manufacturing batch (compare serial numbers).
Fig.36
NOTE:
An under-tensioned belt will slip, heat and wear
prematurely. On the other hand, if a belt is over-tensioned,
the pressure on the bearings will cause them to over-heat
and wear prematurely. Incorrect alignment will also cause
the belts to wear prematurely.
Fig. 37