Carrier RHS, RVS, RDS006-060, RVR Unit Start-UpCooling Mode, Operating Limits - 50RHC,RVC Units

Operating Limits

ENVIRONMENT — This equipment is designed for indoor installation ONLY. Extreme variations in temperature, hu- midity and corrosive water or air will adversely affect the unit performance, reliability and service life.

POWER SUPPLY — A voltage variation of ± 10% of nameplate utilization voltage is acceptable.

UNIT STARTING CONDITIONS — Depending on the model, units start and operate in an ambient temperature of 45 F with entering-air temperature at 40 F or 50 F, entering- water temperature at 20 F or 50 F and with both air and water at the flow rates used.

NOTE: These operating limits are not normal or continuous operating conditions. Assume that such a start-up is for the purpose of bringing the building space up to occupancy temperature. See Tables 18 and 19 for operating limits.

When the disconnect switch is closed, high voltage is present in some areas of the electrical panel. Exercise caution when working with the energized equipment. Failure to heed this warning could lead to personal injury.

1.Restore power to system.

2.Turn thermostat fan position to ON. Blower should start.

3.Balance airflow at registers.

4.Adjust all valves to the full open position and turn on the line power to all heat pump units.

5.Operate unit in the cooling cycle. Refer to Tables 18 and 19 for unit operating limits.

NOTE: Three factors determine the operating limits of a

unit: (1) entering-air temperature, (2) water temperature and

(3)ambient temperature. Whenever any of these factors are at a minimum or maximum level, the other two factors must be at a normal level to ensure proper unit operation. See Tables 18 and 19.

Scroll Compressor Rotation — It is important to be certain compressor is rotating in the proper direction. To determine whether or not compressor is rotating in the prop- er direction:

1.Connect service gages to suction and discharge pressure fittings.

2.Energize the compressor.

3.The suction pressure should drop and the discharge pressure should rise, as is normal on any start-up.

If the suction pressure does not drop and the discharge pressure does not rise to normal levels:

1.Turn off power to the unit. Install disconnect tag.

2.Reverse any two of the unit power leads.

3.Reapply power to the unit and verify pressures are correct.

The suction and discharge pressure levels should now move to their normal start-up levels.

When the compressor is rotating in the wrong direction, the unit makes more noise and does not provide cooling.

After a few minutes of reverse operation, the scroll com- pressor internal overload protection will open, thus activating the unit lockout. This requires a manual reset. To reset, turn the thermostat on and then off.

NOTE: There is a 5-minute time delay before the compressor will start.

Unit Start-Up Cooling Mode

1.Adjust the unit thermostat to the warmest position. Slowly reduce the thermostat position until the compres- sor activates.

2.Check for cool air delivery at unit grille a few minutes after the unit has begun to operate.

3.Verify that the compressor is on and that the water flow rate is correct by measuring pressure drop through the heat exchanger using P/T plugs. See Table 20. Check the elevation and cleanliness of the condensate lines; any dripping could be a sign of a blocked line. Be sure the condensate trap includes a water seal.

4.Check the temperature of both supply and discharge wa- ter. Compare to Table 21. If temperature is within range, proceed. If temperature is outside the range, check the cooling refrigerant pressures in Table 21.

5.Check air temperature drop across the coil when com- pressor is operating. Air temperature drop should be between 15 and 25 F.

Table 18 — Operating Limits — 50RHC,RVC Units

AIR LIMITS	50RHC,RVC
	Cooling	Heating
Min. Ambient Air – db	45 F	45 F
Rated Ambient Air – db	80.6 F	68 F
Max. Ambient Air – db	110 F	85 F
Min. Entering Air – db/wb	70/61 F	50 F
Rated Entering Air – db/wb	80.6/66.2 F	68 F
Max. Entering Air – db/wb	95/76 F	80 F
WATER LIMITS
Min. Entering Water	50 F	50 F
Normal Entering Water	60-90 F	60-70 F
Max. Entering Water	110 F	90 F
Normal Water Flow	2.5-3.0 gpm per ton
LEGEND

db — Dry Bulb wb — Wet Bulb

Table 19 — Operating Limits — 50RHR,RHS,RVR,RVS,RDS Units

AIR LIMITS	COOLING (F)	HEATING (F)
Min. Ambient Air	45	45
Rated Ambient Air	80	70
Max. Ambient Air	100	85
Min. Entering Air	50	40
Rated Entering Air db/wb	80/67	70
Max. Entering Air db/wb	110/83	80
WATER LIMITS
Min. Entering Water	30	20
Normal Entering Water	50-90	30-60
LEGEND

db — Dry Bulb wb — Wet Bulb

NOTE: Value in heating column is dry bulb only. Any wet bulb read- ing is acceptable.

Table 20 — Water Temperature Change

Through Heat Exchanger

	COOLING		HEATING
WATER FLOW RATE (GPM)	RISE (F)		DROP (F)
	Min	Max	Min	Max
For Closed Loop: Ground Source or	9	12	4	8
Cooling/Boiler Systems at 3 gpm/ton
For Open Loop: Ground Water Systems at	20	26	10	17
1.5 gpm/ton

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