York B2CH180 Heat Anticipator Setpoint, Checking Supply Airflow, Belt Drive Blower

035-18895-000-A-0902

HEAT ANTICIPATOR SETPOINT

It is important that the anticipator setpoint be correct. Too high a setting results in longer heat cycles and a greater temperature swing in the conditioned space. Reducing the value below the correct setpoint causes shorter “ON” cycles and may result in the lowering of the temperature within the conditioned space. Refer to Table 9 for the required heat anticipator setting.

TABLE 9 - HEAT ANTICIPATOR SETTING

HEATER		SETTING, AMPS
kW	TH1		TH2
18	0.29		-
36	0.29		0.29
54	0.29		0.29
72	0.29		0.29

CHECKING SUPPLY AIRFLOW

The RPM of the supply air blower will depend on the required airflow, the unit accessories and the static resistances of both the supply and the return air duct systems. With this information, the RPM for the supply air blower and the motor pulley adjustment (turns open) can be determined from the blower performance data in Table 4.

Knowing the required blower RPM and the blower motor HP, the setting (turns open) for the supply air motor pulley can be determined from Table 10.

BELT DRIVE BLOWER

All units have belt drive single-speed blower motors. The variable pitch pulley on the blower motor can be adjusted to obtain the desired supply air flow.

Note the following:

1.The supply airflow must be within the limitations shown in Table 1.

2.Pulleys can be adjusted in half turn increments.

3.The tension on the belt should be adjusted as shown in Figure 8.

Start the supply air blower motor. Adjust the resistances in both the supply and the return air duct systems to balance the air

FIG. 8 - BELT ADJUSTMENT

TABLE 10 - SUPPLY AIR BLOWER MOTOR PULLEY ADJUSTMENT

TURNS	BLOWER DRIVE RANGE (RPM)
OPEN*	180 UNIT
6	845
5	885
4	925
3	960
2	1000
1	1040

*Pulleys can be adjusted in half-turn increments. Do NOT close pulley below 1 turn open.

distribution throughout the conditioned space. The job specifications may require that this balancing be done by someone other than the equipment installer.

To check the supply airflow after the initial balancing has been completed:

1.Remove the two dot plugs from the blower motor and the fil- ter access panels shown in Figure 7.

2.Insert at least 200mm (8") of tubing (approximately 6mm (1/4") diameter) into each of these holes for sufficient pene- tration into the air flow on both sides of the indoor coil.

NOTE: The tubes must be inserted and held in a position perpendicular to the air flow so that velocity pres- sure will not affect the static pressure readings.

3.Using an inclined manometer, determine the pressure drop across a dry indoor coil. Since the moisture on an indoor coil may vary greatly, measuring the pressure drop across a wet coil under field conditions would be inaccurate. To en- sure a dry coil, the compressors should be de-energized while the test is being run.

4.Knowing the pressure drop across a dry coil, the actual air flow through the unit and clean filters, can be determined from the curve in Figure 9.

WARNING:Failure to properly adjust the total system air quan- tity can result in extensive blower damage.

After readings have been obtained, remove the tubes and reinstall the two dot plugs that were removed in Step 1.

NOTE: DE-ENERGIZE THE COMPRESSORS BEFORE TAKING ANY TEST MEASUREMENTS TO ENSURE A DRY INDOOR COIL.

	1.9	2.4	m3/s SUPPLY AIR		3.8	4.2	4.7
			2.8	3.3
	0.65			180 MBH			1.61
PRESSUREDROP(iwg)	0.55						1.36	PRESSUREDROP(Pa)
	0.45						1.12
	0.35						81
	0.25						62
	4	5	6	7	8	9	10

NOMINAL CFM (THOUSANDS) SUPPLY AIR

FIG. 9 - PRESSURE DROP ACROSS A DRY INDOOR COIL VS SUPPLY AIRFLOW

Unitary Products Group 13