26
Table 13 — Operating Limits — 50PCH,PCV Units
LEGEND
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 14. 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 Tables 15-25. If temperature is within
range, proceed. If temperature is outside the range, check
the cooling refrigerant pressures in Tables 15-25.
5. Check air temperature drop across the coil when com-
pressor is operating. Air temperature drop should be
between 15 and 25 F.
Table 14 — Water Temperature Change
Through Heat Exchanger
OPERATING LIMITS COOLING (F) HEATING (F)
AIR LIMITS
Min. Ambient Air – db 45 39
Rated Ambient Air – db 80.6 68
Max. Ambient Air – db 110 85
Min. Entering Air – db/wb 50 40
Rated Entering Air – db/wb 80.6/66.2 68
Max. Entering Air – db/wb 110/83 80
WATER LIMITS
Min. Entering Water 30 20
Normal Entering Water 50-110 30-70
Max. Entering Water 120 90
Normal Water Flow 2.5-3.0 gpm per ton
db — Dry Bulb
wb — Wet Bulb
WATER FLOW RATE (GPM)
COOLING
RISE (F)
HEATING
DROP (F)
Min Max Min Max
For Closed Loop: Ground Source or
Cooling/Boiler Systems at 3 gpm/ton
91248
For Open Loop: Ground Water Systems at
1.5 gpm/ton
20 26 10 17
