Carrier ZONEKIT4ZCAR ÐHeating System Option Vs. Type of Heater Used, Starting the Hvac Equipment

Table 3ÐHeating System Option Vs. Type of Heater Used

HEATER TYPE USED	HEAT PUMP	TWO STAGE	DUAL FUEL	FAN ON
				FOR COOLING ONLY
	SYSTEM TOGGLE:	HEAT PUMP	SYSTEM SWITCH:
IN SYSTEM				TOGGLE:
	T-6	TOGGLE: T-26	S-7
				T-9
Single-Stage Heat Pump	On	Off	0oF (off)	Off
Two-Stage Heat Pump	On	On	0oF (off)	Off
Heat Pump/Furnace Dual	On	Off	10 to 60oF	Off
Fuel
Two-Stage Heat Pump,	On	On	0°F	Off
Furnace Dual Fuel*
Furnace Heat Only	Off	Off	0oF (off)	On or Off
Strip Heater Only	Off	Off	0oF (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 4ÐAvailable Heating and Cooling Stages Vs. System Type

TYPE OF HVAC	COOLING STAGE 1	COOLING STAGE 2	HEAT STAGE 1	HEAT STAGE 2	HEAT STAGE 3	HEAT STAGE 4
EQUIPMENT USED
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.

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

10change has reset the Comfort Setpoints.