23
4. Check the temperature of both supply and discharge
water.
5. Air temperature drop across the coil should be checked
when compressor is operating. Air temperature drop
should be between –9.4 and –3.9 C.
Unit Start-Up in 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.
5. Air temperature rise across the coil should be checked
when compressor is operating. Air temperature rise
should be between –6.7 and –1.1 C after 15 minutes at
load.
6. 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 11. 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.
Table 11 — Coaxial Water Pressure Drop
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 direc-
tions with a high volume of water at a high velocity. Cleaning
and flushing the piping system is the single most important step
to ensure proper start-up and continued efficient operation of
the system. Follow the steps below to properly flush the loop:
1. Verify power is off.
2. Install the system with the supply hose connected directly
to the return riser valve. Use a single length of flexible
hose.
3. Open all air vents. Fill the system with water. DO NOT
allow system to overflow. Bleed all air from the system.
Pressurize and check the system for leaks and repair as
appropriate.
4. Verify that all strainers are in place. Carrier recommends
a strainer with a no. 20 stainless steel wire mesh. Start the
pumps, and systematically check each vent to ensure that
all air is bled from the system.
5. Verify that make-up water is available. Adjust makeup
water as required to replace the air which was bled from
the system. Check and adjust the water/air level in the ex-
pansion tank.
6. Set the boiler to raise the loop temperature to approxi-
mately 30 C. Open a drain at the lowest point in the sys-
tem. Adjust the make-up water replacement rate to equal
the rate of bleed.
7. Refill the system and add trisodium phosphate in a pro-
portion of approximately 0.5 kg per 750 L of water (or
other equivalent approved cleaning agent). Reset the boil-
er to raise the loop temperature to 38 C. Circulate the so-
lution for a minimum of 8 to 24 hours. At the end of this
period, shut off the circulating pump and drain the solu-
tion. Repeat system cleaning if desired.
8. When the cleaning process is complete, remove the short-
circuited hoses. Reconnect the hoses to the proper supply,
and return the connections to each of the units. Refill the
system and bleed off all air.
9. Test the system pH with litmus paper. The system water
should be in the range of pH 6.0 to 8.5 (see Table 2). Add
chemicals, as appropriate to maintain neutral pH levels.
10. When the system is successfully cleaned, flushed, refilled
and bled, check the main system panels, safety cutouts
and alarms. Set the controls to properly maintain loop
temperatures.
DO NOT use “Stop Leak” or similar chemical agent in
this system. Addition of chemicals of this type to the loop
water will foul the heat exchanger and inhibit unit opera-
tion.
11. Restore power.
Antifreeze may be added before, during or after the
flushing process. However, depending on when it is added
in the process, it can be wasted. Refer to the Antifreeze sec-
tion for more detail.
Loop static pressure will fluctuate with the seasons. Pres-
sures will be higher in the winter months than during the
warmer months. This fluctuation is normal and should be
considered when charging the system initially. Run the unit
in either heating or cooling for several minutes to condition
the loop to a homogenous temperature.
When complete, perform a final flush and pressurize the
loop to a static pressure of 275 to 345 kPa for winter months
or 100 to 140 kPa for summer months.
After pressurization, be sure to remove the plug from the
end of the loop pump motor(s) to allow trapped air to be
discharged and to ensure the motor housing has been flood-
ed. Be sure the loop flow center provides adequate flow
through the unit by checking pressure drop across the heat
exchanger.
NOTE: Carrier strongly recommends all piping connections,
both internal and external to the unit, be pressure tested by an
appropriate method prior to any finishing of the interior space
WARNING
Electrical shock can cause personal injury and death. Shut
off all power to this equipment during installation. There
may be more than one disconnect switch. Tag all discon-
nect locations to alert others not to restore power until
flushing is completed.
50HQP
UNIT
SIZE
L/s
PRESSURE DROP (kPa)
–1 C 10 C 21 C 32 C
072
0.6 8.3 6.2 3.4 2.1
0.9 22.8 19.1 14.5 12.4
1.3 42.7 36.5 29.0 26.2
096
0.8 45.4 14.5 11.7 9.0
1.1 68.1 36.5 31.0 24.8
1.5 90.9 64.1 54.5 45.5
120
0.9 56.8 27.6 22.1 15.2
1.4 85.2 59.3 49.6 37.9
1.9 113.6 100.0 83.4 67.6
