York D1EE 060 Heat Anticipator Setpoints, Checking Supply Air Cfm, opera, dflece tionforcevalue.s

035-12046-003-A-0204

HEAT ANTICIPATOR SETPOINTS

It is important that the anticipator setpoint be correct. Too high of a setting will result in longer heat cycles and a greater temperature swing in the conditioned space. Reducing the value below the correct setpoint will give shorter “ON” cycles and may result in the lowering of the temperature within the conditioned space. Refer to Table 10 for the required heat anticipator setting.

CHECKING SUPPLY AIR CFM

The speed of the supply air blower will depend on the required CFM, the unit accessories and the static resistances of both the supply and the return air duct systems. With this information,

TABLE 11 - BELT-DRIVE SUPPLY AIR MOTOR PULLEY ADJUSTMENT

TURNS	BLOWER DRIVE RANGE (RPM)
OPEN*	3 TON	4 TON	5 TON
5	780	790	850
4	842	856	924
3	904	922	998
2	966	988	1072
1	1028	1054	1246
0	1090	1120	1220

*Pulley can be adjusted in half-turn increments.

the speed for the supply air blower can be determined from the static resistance and blower performance data on Tables 3 thru 6.

Knowing the required blower RPM and the blower motor HP,

the spe d setting for the d rect-drive supply air motor can be

determin

d.

CAUTION

Procedure

radjustingblttension:

1Loosennu(D)fromthemotormount.

2Neverlosnnuts(C)fromeachotherwhilelooseningnut(D).

3Adjustthete

sionbyturningbolt(B).

nsioning

4Donotlosfo

thefournuts(topandbotom)(A);unlesadditional

ditanceisrequired;immediatelyre-tigh

ntheseboltifs

losened.

atthe

5Ueabelt.s

tensionchecker

applyaperpendicular

rcetoonebe

midpointofthespanasshwn.to

Thedeflctionforceshouldbeappite l

d

untilaspecificdeflectiondistanceof4mm(5/32")isbtained.fo

Todtetermine

thedeflectiondistanceomnormalposition,useastraightedgefrom

sheave

sheaveasaefefr

renceline.Therecommendeddeflectionforce

isasfollws:to

H

GT

EN

AN

SP

E

RC

FO

FL

DE

Tnsionnewbeltsat

(A)

(C)*

(D)

(B)

max.deflction

rcerecom*NEVERenddforthebeltLOOSEN

sction.Checkthebelthtensionat

easttwtimesfo

duringthefirst24hoursof

opera

.Anyre-tenioningshouldfallbetweenthemin.andmax.

dflece tionforcevalue.s

6.Afteradjusting,re-tightennut(D)againstthemotormounttakingcarenot toloosennuts(C).

FIG. 7 - BELT ADJUSTMENT

The setting (turns open) for the optional belt-drive supply air motor pulley can be determined from Table 11.

OPTIONAL BELT-DRIVE BLOWER

All units with belt-drive blowers have single-speed motors. The variable pitch pulley on the blower motor can be adjusted to

obtain the desired supply air CFM. Refer to Table 7 for blower motor and drive data. The tension on the belts should be adjusted as shown in Figure 7.

Start the supply air blower motor. Adjust the resistances in both the supply and the return air duct systems to balance the air 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 air CFM after the initial balancing has been completed:

1.Remove the (two) ￿￿￿ " dot plugs from the holes located on the filter access panel side of the unit.

2.Insert at least 8" of 1/4 inch tubing into each of these holes for sufficient penetration into the air flow on both sides of the evaporator 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 assure 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 CFM through the unit can be determined from the curve in Figure 8.

	0.7
	0.6	060
(IWG)	0.5
		036
		048
DROP	0.4
PRESSURE	0.3
	0.2
	0.1

0

750 1250 1750 2250 2750 3250 3750

NOMINAL CFM

FIG. 8 - PRESSURE DROP ACROSS A DRY EVAPORATOR COIL VS SUPPLY AIR CFM, WITHOUT AIR FILTERS

WARNING:Failure to properly adjust the total system air quan- tity can result in poor system performance.

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

Unitary Products Group 13