Bard W5RV1, W6RV1, W3RV1, W5LV1, W3LV1, W6LV1 LEAD/LAG Sequence, Cooling Sequence

COOLING SEQUENCE

Compressor Operation

The cooling capacity of the WV series is controlled by loading or unloading the compressor. On a call for cooling, the unloader solenoid is energized for one second to ensure pressure equalization in the compressor. The compressor contactor, RLY 2, is then energized and the compressor will start. A PI control loop then calculates the compressor capacity needed to reach set point and modulates the compressor . Modulation range is from 20% to 100% capacity. Modulation is accomplished by a pulse width modulated signal from OUT 8 which energizes the solid state relay (SSR) and energizes or de-energizes the unloader solenoid. The required compressor capacity is calculated every 15 seconds.

20% load means 0 VDC for 3.0 seconds and 5 VDC for 12.0 seconds from OUT 8.

30% load means 0 VDC for 4.5 seconds and 5 VDC for 10.5 seconds from OUT 8.

40% load means 0 VDC for 6.0 seconds and 5 VDC for 9.0 seconds from OUT 8.

50% load means 0 VDC for 7.5 seconds and 5 VDC for 7.5 seconds from OUT 8.

60% load means 0 VDC for 9.0 seconds and 5 VDC for 6.0 seconds from OUT 8.

70% load means 0 VDC for 10.5 seconds and 5 VDC for 4.5 seconds from OUT 8.

80% load means 0 VDC for 12.0 seconds and 5 VDC for 3.0 seconds from OUT 8.

90% load means 0 VDC for 13.5 seconds and 5 VDC for 1.5 seconds from OUT 8.

100% load means 0 VDC for 15 seconds and 5 VDC for 0.0 seconds from OUT 8.

Outdoor Temperature Sensor

A sensor probe projects out the bottom of the ECU control box into the outdoor section, and this provides input for the outdoor fan sequences below 55F and above 115F described under Outdoor Fan Motor Operation.

Discharge Temperature Sensor

This sensor is mounted on the compressor discharge line and protects the compressor against overheating. It opens at 250F and closes at 200F.

HEATING SEQUENCE

On a call for heating, if the space temperature falls 1°F below setpoint, the first stage of heating, RLY 4, will cycle ON. If the space temperature falls 3°F below setpoint, the second stage of heating, RLY 5, will cycle ON. Indoor Blower airflow is maintained at the Rated unit airflow at all times during heating.

Control
Device		Normal	Abnormal
Indoor	Red LED	lit, Green LED	No Red LED, and no Green
Motor	flashes long and short
			flashes when 2-10Vdc is
Blower	flashes when Fan is called
			present from Signal to
Control	for, 2-10Vdc from Signal to
			Common. Jumper is on P.
Board	Common. Jumper is on P.
Outdoor	Red LED not lit. Green long		Red LED lit, and no Green
Motor	and short flashes when 2-
			flashes when 2-10Vdc is
Fan	10Vdc present from Signal
			present from Signal to
Control	to Common on board.
			Common. Jumper is on P.
Board	Jumper is on P.
	Red LED lit when 24Vac		Red LED not lit. 5Vdc not
5Vdc	present. 5Vdc present at		present at solid Red and
Power	solid Red and solid Black		solid Black wires.
Supply	wires. Both jumpers on Half.		Both jumpers on Half.
	3A 250V fuse.		Check 3A fuse.

LEAD/LAG SEQUENCE

The digital controllers can be used for dual units used in a redundant application by using the scheduling function as follows:

1.The controllers should be mounted side by side so that they are in the same temperature zone.

2.The time setting on both controllers need to be synchronized to the same time of day. NOTE: there is a 72-hour time retention if power is removed. If power off-time exceeds 72 hours, the time clock in each device must be reset to match. The exact time is not important as long as both controllers are set the same unless it is critical to control the time of day when the units swap operating positions.

3.Set one controller #1 to be Occupied for a 12-hour period and Unoccupied for the other 12-hour period. Set controller #2 so that it is exactly the opposite. Unoccupied for the 12-hour period when #1 is Occupied and Occupied when #1 is Unoccupied.

4.Set Occupied cooling setpoint the same for each controller, and Unoccupied the same for each. 4°F difference is suggested.

5.Set controllers to “Auto” mode of operation. Example:

1.Both Unit #1 and #2 have Occupied setpoint of 74°F and Unoccupied setpoint of 78°F

2.Unit #1 set for Occupied from 1:00 a.m. to 1:00 p.m. & Unoccupied from 1:00 p.m. to 1:00 a.m.

3.Unit #2 set for Unoccupied from 1:00 a.m. to 1:00 p.m. & Occupied from 1:00 p.m. to 1:00 a.m.

4.Every 12 hours the units will swap position as being the lead unit, and the lag unit is available for back up operation at the higher temperature should the situation ever arise.

Manual	2100-538E
Page	17 of 23