Carrier AQUAZONE 50VQP084-300 User Manual

Page 35

Table 15 — 50VQP Unit Operating Limits

LEGEND

*Requires optional insulation package when operating below the

dew point.

†With antifreeze, optional extended range insulation and low tem-

perature cutout jumper clipped for antifreeze.

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 an elevated level of 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 16. 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. If temperature is within acceptable range, proceed. If

temperature is outside the range, check the cooling refrig-

erant pressures.

5. Check air temperature drop across the coil when com-

pressor is operating. Air temperature drop should be

between 8 and 14 C.

Table 16 — Water Temperature Change

Through Heat Exchanger

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 wa-

ter. If temperature is within acceptable range, proceed. If

temperature is outside the range, check the heating refrig-

erant pressures.

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

11° C and 17° C after 15 minutes at load.

7. Check for vibration, noise and water leaks.

Flow Regulation —

Flow regulation can be accom-

plished by two methods. Most water control valves have a flow

adjustment built into the valve. By measuring the pressure drop

through the unit heat exchanger, the flow rate can be deter-

mined using Table 17. Adjust the water control valve until the

flow of 0.09 to 0.13 L/s is achieved. Since the pressure con-

stantly varies, two pressure gages may be needed in some

applications.

An alternative method is to install a flow control device.

These devices are typically an orifice of plastic material de-

signed to allow a specified flow rate that are mounted on the

outlet of the water control valve. Occasionally these valves

produce a velocity noise that can be reduced by applying

some back pressure. To accomplish this, slightly close the

leaving isolation valve of the well water setup.

Flushing —

Once the piping is complete, final purging

and loop charging is needed. A flush cart pump of at least

1.5 hp is needed to achieve adequate flow velocity in the

loop to purge air and dirt particles from the loop. Flush the

loop in both directions with a high volume of water at a high

velocity. Follow the steps below to properly flush the loop:

1. Verify power is off.
2. Fill loop with water from hose through flush cart be-

fore using flush cart pump to ensure an even fill. Do

not allow the water level in the flush cart tank to drop

below the pump inlet line to prevent air from filling

the line.

3. Maintain a fluid level in the tank above the return tee

to avoid air entering back into the fluid.

4. Shutting off the return valve that connects into the

flush cart reservoir will allow 345 kPa surges to help

purge air pockets. This maintains the pump at 345 kPa.

5. To purge, keep the pump at 345 kPa until maximum

pumping pressure is reached.

6. Open the return valve to send a pressure surge through

the loop to purge any air pockets in the piping system.

7. A noticeable drop in fluid level will be seen in the

flush cart tank. This is the only indication of air in the

loop.

AIR LIMITS

COOLING (C)

HEATING (C)

Minimum Ambient Air db

Rated Ambient Air db

Maximum Ambient Air db

Minimum Return Air db/wb

18/15

Maximum Return Air db/wb

43/28

WATER LIMITS

Standard Unit
Minimum Entering Water*

Maximum Entering Water

Extended Range Unit†
Minimum Entering Water*

–1

–6.7

Maximum Entering Water

db — Dry Bulb
wb — Wet Bulb

WATER FLOW RATE (GPM)

COOLING

RISE (C)

HEATING

DROP (C)

Min

Max

Min

Max

For Closed Loop: Ground Source or
Cooling/Boiler Systems at 3.9 L/m per kW

5.0

6.7

2.2

6.1

For Open Loop: Ground Water Systems at
2.0 L/m per kW

10.0

12.8

3.9

11.1

WARNING

To avoid possible injury or death due to electrical shock,

open the power supply disconnect switch and secure it in

an open position before flushing system.