GENERAL
Page 5
HARMONY IIIT ZONE CONTROL SYSTEM
System Components (Continued)
Dampers
Motorized 24VAC powered closed/spring return open
dampers are standard for the Harmony IIIt zone control
system. However, power-open/spring-close" and power-
open/power-close" dampers can be accommodated.
Remote Vacation Switch
The Harmony IIIt zone control panel includes connec-
tions for an optional remote vacation switch (see figure 1).
The same connections are also used for connecting an op-
tional Humiditrol
®
Zoning Accessory controller (see Humi-
ditrol
®
Zoning Accessory Installation Instructions for de-
tails).
NOTE − If a remote vacation switch is connected for
routing to a convenient location for end user opera-
tion, be sure the switch (field-provided) is properly la-
beled and instructions provided for proper operation.
DO NOT LOCATE THE REMOTE VACATION SWITCH
NEXT TO OTHER HOUSE SWITCHES! THE REC-
OMMENDED LOCATION IS NEXT TO ZONE 1 THER-
MOSTAT.
Installation planning & selecting heating and cooling equipment
Installation Considerations
The total HVAC system must be properly sized to provide
the best comfort. Also, for best performance, zones should
be similar in size so that each zone would require about the
same CFM. Each zone’s ducting lengths should be similar
in length whenever possible. Always attempt to keep CFM
requirements per zone within 25% of the average CFM
(see table 2).
If a small" zone cannot be avoided, give consideration to
increasing the CFM of the small zone and linking a damper
in a nearby zone that will open along with the small zone’s
damper(s). The procedure for zone linking is described on
Page 7.
Table 2. Adjusting for average CFM Example
Required CFM CFM adjusted to within average
Zn CFM Avg %CFM Adj Avg %CFM
1 500
713
0.70 600
738
0.81
Damper linked
with Zn 2
2 825 1.16 825 1.12
3 775 1.09 775 1.05
4 750 1.05 750 1.02
Variable Speed Blower Motor (VSM)
Indoor units with variable speed blower motors (VSM) are
required to allow the zone control system to distribute ade-
quate air to each zone. Use only units recommended in
the following 3 options as only those will work with the
Harmony IIIt zone control system; other types of units will
not allow the Harmony IIIt zone control system to propor-
tion the amount of air going to each zone.
Selecting/Installing Indoor and Outdoor Units
Outdoor units may be single or two−stage; use table 3 to
determine which to use, based on the number of zones be-
ing implemented, and whether the air conditioned zones
are of equal or unequal size.
Option 1
S
Lennox Gas Furnace with VSM only (G60UHV, G61MPV,
G71MPP, SLP98, SL280V, E296V).
S Lennox Condensing Unitas described in table 3.
Option 2
S
Lennox Air Handler Unit with VSM only (CBX32MV,
CBX40UHV, CB31MV, CBWMV).
S Lennox Heat Pump Unitas described in table 3.
Option 3
S
Lennox Gas Furnace with VSM only (G60UHV, G61MPV
G71MPP, SLP98, SL280V, E296V).
S Lennox Heat Pump Unit as described in table 3.
NOTE − Limited variations to condensing units described
herein are detailed on Page 38.
Table 3. Condensing units / Heat Pump units
No. of
zones
Comparative Zone
sizes
Lennox Condensing Unit or
Heat Pump
2 *Equal Single or Two−stage
2 *Unequal Two-stage only
3 or 4 Equal or Unequal Two-stage only
*Equal zones would have very similar total ducting lengths with CFM
requirements within 10% of average CFM per zone. Unequal would
have less similar ducting length and greater variances from average
CFM (see table 2 example).
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