Table of Contents
Advertisement
Blower Speed Adjustment
The G21V and GSR21V furnace, and the CB31MV blower
coil unit are equipped with a variable speed blower motor. The
blower motor speed must be adjusted to produce the zoning
CFM requirements managed by the zone control system.
The variable speed motor in the G32V, G21V, or GSR21V is
controlled by the VSP2−1 drive control. The motor in the
CB31MV is controlled by the BDC3 drive control.
The adjustment of these drive controls is by jumper setting
selection and is described in sections A and B.
CAUTION
Electrical Shock Hazard
Disconnect power from unit and wait at least five
minutes to allow capacitors to discharge before at-
tempting to adjust motor speed tap settings.
G32V, G21V, or GSR21V Blower Control Board
Jumper Settings
Locate the VSP2−1 board in the furnace control box area.
The jumper settings on the VSP2−1 board control the blow-
er CFM. See figure 6.
Setting the upper limit of blower CFM −
1− Determine the maximum system CFM requirements
This is the sum of all the individual zones.
2− From the Blower Motor Performance table (see unit
installation instructions) determine the HIGH Speed
(cool) jumper setting that corresponds to this CFM.
3− Set the HIGH Speed (cool) jumper setting on the board
to this value.
Setting the lower limit of blower CFM −
1− Determine the minimum system CFM requirements.
This is the CFM for the smallest zone.
2− From the Blower Motor Performance table determine
the LOW Speed (cool and heat) jumper setting corre-
sponding to this CFM.
3− Set the LOW Speed (cool and heat) jumper setting on
the board to this value.
NOTE − HEAT Speed jumper setting is only used when the
primary limit has been tripped.
NOTE − The HTG BLOWER jumper setting must be set to
position 2.
For more information on setting the blower speed, refer to
section on Blower Speed and Adjustment" in the G32V,
G21V, or GSR21V installation instructions.
CB31MV Blower Control Board Jumper Settings
Locate the BDC3 board in the control box of the CB31V.
The jumper settings on the BDC3 board control the blower
CFM. See figure 7.
Setting the upper limit of blower CFM −
1− Determine the maximum system CFM requirements
This is the sum of all the individual zones.
2− From the Blower Motor Performance table (see unit
installation instructions) determine the COOL Speed
jumper setting that corresponds to this CFM.
3− Set the COOL Speed jumper setting on the board to
this value.
NOTE − The lower limit of blower CFM is factory set. It is not
field adjustable.
For more information on setting blower speed refer to sec-
tion on Blower Speed and Adjustment" in the CB31MV
installation instructions.
Page 12
Hide quick links:
Advertisement
Table of Contents
