Benjamin Heating products WK400, Owner'S Manual

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ADJUSTMENTS OF DAMPER
MOTOR AND CHAIN:
The damper chain should be adjusted when the damper
door is in the down position. In this position the chain
should be adjusted so there is a small amount of slack.
The amount of lift or opening of the damper door is
adjusted by moving the two pinch nuts on the stove
bolt thread closer or further away from the lift strap.
After proper adjustment of the draft chain and damper
door the thermostat and limit controls will keep the fire
within safe limits.
NOTE: The combustion damper shall NOT be
permitted to open more than 1" at the bottom.
Caution: The damper opening should not be altered for increased firing for any reason.
TO THE INSTALLER
It is necessary to ensure that there is sufficient air flow through each furnace after the add-on installation
has been completed. It is suggested that the temperature rise method be used since most installers are
likely to have the necessary equipment. The temperature measurements may be made using a
potentiometer and thermocouples, mercury thermometers. If thermometers are used, sufficient time must
be allowed for the thermometer to reach actual temperature. As much as twenty minutes may be required.
PROCEDURE
To check the existing system, drill a hole 1/4" in the side of the return air plenum on the primary furnace
and a similar 1/4" hole in the side of the main supply air duct, 24" from the supply air plenum. Insert a
temperature measuring device in each of these holes and start the primary furnace. Allow the furnace to
operate until all temperatures have stabilized. This will take at least ½ hour. Read the two temperatures
thus obtained and not the difference, TS--TR (see page 8). This difference should not exceed 85 degrees F.
(29º C.)
Complete the installation of the WK400A in the add-on mode, in accordance with page 8, and drill a third
1/4" hole in the 20" x 12" duct (See TA, page 8). Insert a temperature measuring device.
Operate the primary furnace until the temperature rise TA-TR across the primary furnace is equal to or less
than 85 degrees F. (29º C). Should this temperature difference exceed 85 degrees F (29º C), increase the
blower speed by pulley adjustment and/or change until the temperature rise TA-TR is equal to or less than
85º F. (29º C.)
Shut off the primary furnace and build a fire in the wood unit. When the fire is established, fill the fire box
to the bottom of the smoke shield, in the fire door opening (maximum level). Open the combustion air
damper. Allow the temperature to stabilize and measure the temperature difference TS- TR. should it
exceed 85º F. (29º C), a further increase in blower speed will be necessary.
Once the proper air temperature rise has been obtained, an ammeter should be connected to the blower
motor to measure current draw. If it exceeds the name plate rating, change the motor to a higher rating (if
the old motor was a two stage, ensure that the new motor is as well). It is permissible to change the blower
motor and blower drive pulleys in the primary furnace but NOT the blower unit.
This equipment must be installed according to the manufacturer's instructions and in a manner acceptable
to the regulatory authority having jurisdiction by mechanics experienced in such a service. When required
regulatory authority, such mechanics shall be licensed to perform this service.