6
1.6.2. Discharge Air Sensor (DAS)
A discharge air temperature sensor (19V99) monitors the supply air. This electronic
sensor’s probe is inserted into the discharge air plenum to gather air temperature
data for the zone control panel. “Figure 4. Discharge Air Sensor Installation” on
page 8 for location of the sensor.
TEMPERATURE/RESISTANCE CHART
TEMP ºF
RESISTANCE (OHMS)
30
34,566
40
26,106
50
19,904
60
15,313
70
11.884
80
9,298
90
7,332
100
5,826
Figure 3. Discharge Air Sensor
1.6.3. Thermostats
IMPORTANT
Use only Electronic thermostats. Mechanical or electro-mechanical thermostats
will not work with the Harmony III zoning system.
For all zones, use thermostats that are of this type:
• Electronic thermostat
• Single-stage
• Non-heat pump
• Non-power robbing
• Auto-changeover or non auto-changeover
• Lennox recommends that zone 1 thermostat (central [vacation] mode controller)
be programmable.
• Each thermostat must have a deadband between HEAT and COOL.
Recommended thermostats include:
•
ComfortSense
®
5500
(13H13) 7-Day Programmable Touch Screen Thermostat
- 1 heat / 1 cool
•
ComfortSense
®
7500
(13H14) 7-Day Programmable Touch Screen Thermostat
- 4 Heat / 2 Cool (configured for non-heat pump operation). When using this
thermostat, only Precision Mode dehumidification can be used wherein 2°F of
over-cooling is allowed. Also, it cannot reduce the blower speed because the
zone control DS signal controls the blower. Thermostat
D
terminal is not used.
•
iComfort M30 (15Z69
) 4 Heat / 2 Cool, Universal Multi-Stage Touch Screen
Thermostat.
1.6.4. Transformers
The dampers, zone control panel, zone thermostats and Humiditrol
®
Zoning
Accessory (if EDA is used) are powered by a single, field-provided 24VAC
transformer. Together, the zone control panel and thermostats require 10VA;
dampers require 10VA each. The transformer must have an adequate VA rating to
serve all components as described in the following table.
IMPORTANT
Up to 5 dampers per zone may be connected in parallel to the zone control panel
—not to exceed a total of six dampers for entire system.
Also, if more than 6 dampers are used, another transformer and isolation relay
will be necessary.
Table 5. 24VAC Transformer Selection Chart
Catalog
Number
Size
Description
VA LOAD =
Panel Plus
10P17
40VA
120/208/240VAC, 24VAC
3 dampers
10P87
50VA
120/208/240VAC, 24VAC
4 dampers
12P61
75VA
120/208/240VAC, 24VAC
6 dampers
83P74
_
Electrical Box (4-in. Square)
1.6.5. Dampers
Motorized 24VAC powered closed/spring return open dampers are standard for
the Harmony III zoning system. However, “power-open/spring-close” and “power-
open/power-close” dampers can be accommodated
1.6.6.
Remote Vacation Switch
The Harmony III zoning system control panel includes connections for an optional
remote vacation switch (see “Figure 2. Harmony III Zoning System Zone Control
Panel” on page 5). The same connections are also used for connecting an
optional Humiditrol
®
Zoning Accessory controller (see Humiditrol
®
Zoning Accessory
Installation Instructions for details).
NOTE:
If a remote vacation switch is connected for routing to a convenient location
for end user operation, be sure the switch (field-provided) is properly
labeled and instructions provided for proper operation.
IMPORTANT
Do not locate the remote vacation switch next to other house switches! The
recommend location is next to Zone 1 thermostat.
Summary of Contents for Harmony III
Page 80: ...80...
