heater. The electric strip heat is much more expensive to operate
when comparing cost per unit of heat. Because auxiliary stages of
heating tend to be more expensive to operate, Comfort Zone
attempts to keep number of stages at a minimum.
CONFIGURATION OPTIONS FOR EQUIPMENT
OPERATION
Comfort Zone has several configurable options which allow it to
control different types of HVAC equipment and change the
manner in which the equipment is controlled. This first group must
be set given the type of HVAC equipment installed. These include:
1. Heat Pump Operation (Rotary Position T-6).
2. Two-Stage Heat Pump (Rotary Position T-26).
3. Dual Fuel trip temperature (Rotary Position S-7).
4. Auto Fan Off For Heat (Rotary Position T-9).
The second group modifies the way the HVAC equipment is
controlled. These include:
1. Comfort Trend Staging (Rotary Position T-8).
2. System Mode Reselect (Rotary Position T-22).
3. High/Low Temperature Limits Enabled (Rotary Position
T-10).
4. High Temperature Trip Limit (Rotary Position S-6).
5. Dx Sensor (Rotary Position T-27).
6. Smart Start (Heat Pump Strip Heat Economy Feature)
The first options which must be set are based upon the type heater
or heaters used. These are shown in Table 3. The only option
which appears to impact cooling operation is Two-Stage Heat
Pump which implies the availability of 2 stages of cooling. In
reality there are no changes to cooling control scheme.
Comfort Zone assumes that there are always 2 stages of cooling
present. These are connected to the Comfort Zone Relay Pack on
the Y1 and Y2 contacts.
RELAY PACK TO HVAC EQUIPMENT CONNECTIONS
Given system configuration, Comfort Zone can determine number
of heating stages that it will actually control and which relay
outputs will be used to control each stage of heat. Comfort Zone
can control up to 4 stages of heat depending upon system
configuration.
For cooling only applications with any type of heater, Comfort
Zone will only control 2 stages of heat. If system uses a heat pump,
then Comfort Zone will control 3 stages of heat. The additional
stage is heat pump compressor contact. The auxiliary heat is still
2 stages. If system uses a 2 stage heat pump, then Comfort Zone
will control 4 stages of heat, 2 stages for heat pump and 2 stages
for auxiliary heat.
The Comfort Zone Relay Pack outputs are shown in Table 4. The
Y1 and Y2 contacts are used for compressor contacts only.
Comfort Zone operates heat pumps by energizing compressor
contacts and controlling reversing valve through Reversing Valve
(RV) relay output. The W1 and W2 contacts are always used for
heat sources. These are heating only units such as furnaces, strip
heaters, etc. The relay outputs for Comfort Zone 1.4 are shown in
Table 4.
Under no circumstances may the W1 and Y1 contacts on the
relay pack be jumpered together. This is a common practice
for many heat pump installations but will cause improper
operation of the Comfort Zone (1.4 or greater) system.
STARTING THE HVAC EQUIPMENT
Once Comfort Zone selects a mode, controller will use configu-
ration options to modify control of HVAC equipment. The
controller first selects number of stages of heating and cooling that
may be applied to building load. The "available" stages are
determined by Reference Zone temperature demand and are shown
in Table 5.
Using Table 5, if Reference Zone has a 2.3°F demand, then
Comfort Zone may use 2 stages of cooling or 2 stages of heating.
The HVAC equipment may not have 3 stages of heat or even 2
stages of cooling. The table is only used to determine what
equipment Comfort Zone is allowed to turn on at any given time
during a heating or cooling cycle. Actual operation of stages
depends on other variables as well.
Normally Comfort Zone will start equipment operation when it has
a demand of 1.5°F or greater. In some cases, Comfort Zone will be
facing a demand greater than 1.5°F when a mode is starting. This
can occur when user changes setpoints in a zone or if a schedule
change has reset the Comfort Setpoints.
Table 3—Heating System Option Vs. Type of Heater Used
HEATER TYPE USED
IN SYSTEM
HEAT PUMP
SYSTEM TOGGLE:
T-6
TWO STAGE
HEAT PUMP
TOGGLE: T-26
DUAL FUEL
SYSTEM SWITCH:
S-7
FAN ON
FOR COOLING ONLY
TOGGLE:
T-9
Single-Stage Heat Pump
On
Off
0
o
F (off)
Off
Two-Stage Heat Pump
On
On
0
o
F (off)
Off
Heat Pump/Furnace Dual
Fuel
On
Off
10 to 60
o
F
Off
Two-Stage Heat Pump,
Furnace Dual Fuel*
On
On
0°F
Off
Furnace Heat Only
Off
Off
0
o
F (off)
On or Off
Strip Heater Only
Off
Off
0
o
F (off)
Off
* Refer to 2-speed heat pump Installation and Start-Up Instructions for details regarding 2-speed heat pump operation. It is recommended that heat pump control board
controls operation of this equipment and not Comfort Zone.
Table 4—Available Heating and Cooling Stages Vs. System Type
TYPE OF HVAC
EQUIPMENT USED
COOLING STAGE 1
COOLING STAGE 2
HEAT STAGE 1
HEAT STAGE 2
HEAT STAGE 3
HEAT STAGE 4
Cooling Only, any Heater Type
Y1
Y2
W1
W2
--
--
Single-Stage Heat Pump
Y1
--
Y1
W1
W2
--
Two-Stage Heat Pump
Y1
Y2
Y1
Y2
W1
W2
For cooling applications, the second stage of an air conditioner is not necessarily more expensive to operate than first stage. But additional cooling can drive down the
efficiency of a 2-speed air conditioner and longer use of first stage alone tends to deliver better humidity control in moist climates. Again, because of these advantages,
Comfort Zone will attempt to minimize use of second stage cooling. This is not as great of a concern for a heating application, because the majority of small air
conditioning systems sold today (5 tons and below) are single-stage cooling only.
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