Sequence of Operation

Step 5ÐInstall Barometric Bypass Damper

NOTE: The barometric bypass damper is a critical part of the WeatherMaker Two-Zone System for control of minimum airflow and noise reduction. It is recommended that the bypass be installed.

The bypass should be installed according to local codes and SMACNA standards. Be sure the bypass is properly supported.

For proper installation, refer to the Installation Instructions pack- aged with the barometric bypass.

Failure to properly install the bypass damper can cause permanent damage to the HVAC equipment. For single-speed furnace applications, the bypass air must never exceed 25 percent.

→Step 6ÐInstall Leaving Air Temperature Duct Sensor

Locate duct temperature sensor in main supply trunk after heating and cooling coil and before the bypass damper and before the first branch. The duct sensor must be radiant shielded to prevent heat from affecting the correct air temperature.

1.Drill 1/4-in. hole at location in supply trunk where sensor will be installed.

2.Insert sensor in hole and use as template to mark 2 mounting holes.

3.Drill two 1/16-in. holes to accept No. 6 screws through pre-drilled holes in duct temperature sensor back plate.

4.Use 2 No. 6 sheet metal screws to mount duct temperature sensor to unit.

5.Connect sensor to 2-conductor wire using provided wire nuts. (See Fig. 12 for connection to equipment controller.)

→Step 7ÐInstall Heat Pump (HP) Temperature Sensor

The HP temperature sensor is required in all heat pump/fan coil installations. It is not used in dual fuel (heat pump/furnace installation.) It measures the indoor coil temperature. The sensor is to be installed downstream of the indoor coil, but before the electric heaters. It can be installed through the wall of the fan coil or may be located entirely inside the fan coil near the blower inlet. Anchor firmly in place with cable ties so that it cannot interfere with the blower wheel. To activate the HP temperature sensor, remove factory supplied resistor from HP terminal block and replace with sensor leads. When activated, the HP temperature sensor has built in LAT set points of 50°F and 45°F in the cooling mode, and 105°F and 110°F in the heating mode. This is non-adjustable. (See Fig. 12 for connection to WeatherMaker Two-Zone center.)

Step 1ÐSequence of Events for a Normal Heating or Cooling Cycle

The thermostats will determine if active heating or cooling is required. If so, the WeatherMaker Two-Zone System will perform the following:

· Make sure all zone dampers are fully open.

·Energize HVAC equipment fan.

·Energize heating or cooling equipment. The equipment may be a compressor, furnace, strip heater, etc.

·Set zone damper to the open or closed position based upon individual zone demand.

·Energize additional stages of heating or cooling if the thermostat demand warrants.

·Turn off heating or cooling equipment when all zones are satisfied.

·Open all zone dampers when equipment is turned off (after 90 sec delay).

This is the basic sequence of operation for the WeatherMaker Two-Zone System. The actual control of the dampers, HVAC equipment, and system fan will change with the configuration of the system. Depending upon the configuration, WeatherMaker Two-Zone can control heat pumps, furnaces, and dual fuel applications, (dual fuel will require a third party relay interface).

Step 2ÐSelection of a System Mode

The first step in any heating or cooling cycle requires Weather- Maker Two-Zone to receive an input from any thermostat located in a zone. WeatherMaker Two-Zone will then prepare to operate the heating or cooling equipment as requested by the thermostat. (See Fig. 12.)

Step 3ÐPre-Positioning Dampers and Starting System Fan

In order to minimize noise and enhance system operation, Weath- erMaker Two-Zone maintains fully open zone dampers prior to starting the system fan or the heating/cooling equipment. The intent is to provide the HVAC equipment with unrestricted ductwork and to reduce pressure surges. WeatherMaker Two-Zone also fully opens the dampers whenever a heating or cooling cycle is completed (this is done after a 90 sec delay). All zone dampers will remain fully open until the next heating or cooling cycle.

The other reason for opening the dampers is to provide unrestricted ductwork to other equipment which is not directly controlled by WeatherMaker Two-Zone. One example may be a Heat Recovery Ventilator. If WeatherMaker Two-Zone is not actively controlling the HVAC system, then it must not impose any control influences (such as closed zone dampers) on the system and prevent proper operation of other devices.

Only the zone 1 thermostat controls continuous fan operation. When the zone 1 thermostat has the fan selector switch in the AUTO position, the fan will operate only when the heating and cooling equipment is operating. When the zone 1 thermostat has the fan selector switch in the ON position, the fan will operate continuously. Zone 2 will not control this.

Step 4Ð HVAC Equipment Connections

The WeatherMaker Two-Zone relay outputs are shown in Table 1. The Y1 and Y2 contacts are used for the compressor contactor only. WeatherMaker Two-Zone operates the heat pump by ener- gizing the compressor contactor and controlling the reversing valve through the O 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 WeatherMaker Two-Zone are shown in Table 1.

Table 1ÐAvailable Heating and Cooling Stages Versus System Type

TYPE OF HVAC	COOLING STAGE 1	COOLING STAGE 2	REVERSING VALVE	HEAT STAGE 1	HEAT STAGE 2	REVERSING VALVE
EQUIPMENT USED			O			O
Single-Stage Heat	Y1	Ð	Energized	Y1/W1	W2	De-energized
Pump

2-Stage Heat Pump	Y1	Y2	Energized	Y1/W1	W2	De-energized
Cooling Only, any	Y1	Y2	Ð	W1	W2	Ð
Heater Type