Carrier PTV, 50PTH Unit Start-UpCooling Mode, Unit Start-UpHeating Mode, Water Temperature Change

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 proper 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 19. 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 water. Compare to Tables 20-23. If temperature is within range, proceed. If temperature is outside the range, check the cooling refrigerant pressures in Tables 20-23.

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

Unit Start-Up Heating Mode

NOTE: Operate the unit in heating cycle after checking the cooling cycle. Allow 5 minutes between tests for the pressure or reversing valve to equalize.

1.Turn thermostat to lowest setting and set thermostat switch to HEAT position.

2.Slowly turn the thermostat to a higher temperature until the compressor activates.

3.Check for warm air delivery at the unit grille within a few minutes after the unit has begun to operate.

4.Check the temperature of both supply and discharge water. Compare to Tables 20-23. If temperature is within range, proceed. If temperature is outside the range, check the heating refrigerant pressures in Tables 20-23.

5.Once the unit has begun to run, check for warm air deliv- ery at the unit grille.

6.Check air temperature rise across the coil when compres- sor is operating. Air temperature rise should be between 20 and 30 F after 15 minutes at load.

7.Check for vibration, noise and water leaks.

Table 19 — 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

Table 20 — Typical 50PTH,PTV,PTD026 Unit Operating Pressures and Temperatures

ENTERING		WATER	FULL LOAD COOLING WITHOUT HWG ACTIVE							FULL LOAD HEATING WITHOUT HWG ACTIVE
WATER			Suction	Discharge	Super-	Sub-	Water	Air	Suction		Discharge	Super-	Sub-		Water		Air
		FLOW					Temp	Temp							Temp		Temp
TEMP (F)			Pressure	Pressure	heat	cooling			Pressure		Pressure	heat	cooling
		(Gpm/Ton)					Rise	Drop (F)							Drop		Rise (F)
(EWT)			(psig)	(psig)	(F)	(F)	(F)	DB	(psig)		(psig)	(F)	(F)		(F)		DB
	30	1.5	118-128	159-179	25-30	9-14	16.7-18.7	19-25	73-	83	273-293	6-11	3-	8	5.9-	7.9	16-22
		2.25	118-128	146-166	25-30	7-12	12.3-14.3	20-26	75-	85	275-295	6-11	3-	8	4.2-	6.2	17-23
		3	118-128	132-152	25-30	7-12	7.9- 9.9	20-26	78-	88	277-297	6-11	3-	8	2.7-	4.7	18-24
	50	1.5	128-138	186-206	18-23	8-13	16.3-18.3	19-25	102-112		302-322	8-12	6-11		8.9-10.9		22-28
		2.25	128-138	172-192	18-23	6-11	12.1-14.1	20-26	106-116		303-323	8-12	6-11		6.7-	8.7	23-29
		3	128-138	158-178	18-23	6-11	7.8- 9.8	20-26	110-120		305-325	8-12	6-11		4.5-	6.5	23-29
	70	1.5	136-146	281-301	7-12	7-12	15.7-17.7	19-25	128-138		330-350	10-15	8-13		11.3-13.3		27-34
		2.25	136-146	267-287	7-12	5-10	11.6-13.6	19-25	134-144		332-352	10-15	8-13		8.5-10.5		28-35
		3	136-146	253-273	7-12	4- 9	7.6- 9.6	19-25	141-151		334-354	10-15	8-13		5.8-	7.8	28-35
	90	1.5	139-149	368-388	6-11	7-12	14.9-16.9	18-24	162-172		367-387	14-19	10-15		14.4-16.4		33-41
		2.25	139-149	354-374	6-11	5-10	11.0-13.0	18-24	166-176		372-392	15-20	10-15		10.8-12.8		34-42
		3	139-149	340-360	6-11	5-10	7.2- 9.2	18-24	171-181		377-397	17-22	10-15		7.1-	9.1	34-42
	110	1.5	143-153	465-485	6-11	7-12	13.9-15.9	17-23	—		—	—	—		—		—
		2.25	143-153	450-470	6-11	5-10	10.2-12.2	17-23	—		—	—	—		—		—
		3	143-153	433-453	6-11	5-10	6.5- 8.5	17-23	—		—	—	—		—		—
			LEGEND
DB	— Dry Bulb
HWG — Hot Water Generator

—— No heating operation in this temperature range

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