Comfort-Aire HEH Series 2 to 5 Tons - Manual (Page 15)

15
Heat Controller, LLC. HEV/H SERIES Installation, Operation & Maintenance
GROUND-LOOP HEAT PUMP APPLICATIONS
Table 3. Antifreeze Percentages by Volume
Type Minimum Temperature for Freeze Protection
10°F [-12.2 °C] 15°F [-9.4 °C] 20°F [-6.7 °C] 25°F [-3.9 °C]
Methanol 25% 21% 16% 10%
100% USP food grade Propylene Glycol 38% 30% 22% 15%
Table 2: Antifreeze Percentages by Volume
Low Water Temperature Cutout Setting
CXM Control
When antifreeze is selected, the FP1 jumper (JW3)
should be clipped to select the low temperature (an-
tifreeze 13°F [-10.6°C]) set point and avoid nuisance
faults (see “Low Water Temperature Cutout Selection” in
this manual). NOTE: Low water temperature operation
requires extended range equipment.
pressure is reached. Open the return valve and a
pressure surge will be sent through the loop to help
purge air pockets from the piping system.
4. Notice the drop in fluid level in the flush cart tank
when the return valve is shut off. If air is adequately
purged from the system, the level will drop only 1-2
inches (2.5 - 5 cm) in a 10” (25 cm) diameter PVC
flush tank (about a half gallon [2.3 liters]), since
liquids are incompressible. If the level drops more
than this, flushing should continue since air is still
being compressed in the loop fluid. Perform the “dead
head” procedure a number of times.
Note: This fluid level drop is your only indication of air in
the loop.
Antifreeze may be added before, during or after the
flushing procedure. However, depending upon which time
is chosen, antifreeze could be wasted when emptying the
flush cart tank. See antifreeze section for more details.
Loop static pressure will fluctuate with the seasons.
Pressures will be higher in the winter months than during
the cooling season. This fluctuation is normal and should
be considered when charging the system initially. Run the
unit in either heating or cooling for a number of minutes to
condition the loop to a homogenous temperature. This is
a good time for tool cleanup, piping insulation, etc. Then,
perform final flush and pressurize the loop to a static
pressure of 50-75 psi [345-517 kPa] (winter) or 35-40 psi
[241-276 kPa] (summer). After pressurization, be sure
to loosen the plug at the end of the Grundfos loop pump
motor(s) to allow trapped air to be discharged and to insure
the motor housing has been flooded. This is not required
for Taco circulators. Insure that the Flow Controller provides
adequate flow through the unit by checking pressure drop
across the heat exchanger and compare to the pressure
drop tables at the back of the manual.
Antifreeze
In areas where minimum entering loop temperatures drop
below 40°F [5°C] or where piping will be routed through
areas subject to freezing, antifreeze is required. Alcohols
and glycols are commonly used as antifreeze; however
your local sales manager should be consulted for the
antifreeze best suited to your area. Freeze protection
should be maintained to 15°F [9°C] below the lowest
expected entering loop temperature. For example, if
30°F [-1°C] is the minimum expected entering loop
temperature, the leaving loop temperature would be 25 to
22°F [-4 to -6°C] and freeze protection should be at 15°F
[-10°C]. Calculation is as follows:
30°F - 15°F = 15°F [-1°C - 9°C = -10°C].
All alcohols should be premixed and pumped from
a reservoir outside of the building when possible or
introduced under the water level to prevent fumes.
Calculate the total volume of fluid in the piping system.
Then use the percentage by volume shown in Table
1 for the amount of antifreeze needed. Antifreeze
concentration should be checked from a well mixed
sample using a hydrometer to measure specific gravity.
Table 1: Approximate Fluid Volume (gal.)
per 100' of Pipe
Fluid Volume (gal [L]/100’ Pipe)
Pipe Size Volume (gal) [L]
Copper
1” 4.1 [15.5]
1.25” 6.4 [24.2]
2.5” 9.2 [34.8]
Rubber Hose 1” 3.9 [14.8]
Polyethylene
3/4” IPS SDR11 2.8 [10.6]
1” IPS SDR11 4.5 [17.0]
1.25” IPS SDR11 8.0 [30.3]
1.5” IPS SDR11 10.9 [41.3]
2” IPS SDR11 18.0 [68.1]
1.25” IPS SCH40 8.3 [31.4]
1.5” IPS SCH40 10.9 [41.3]
2” IPS SCH40 17.0 [64.4]
Unit Heat Exchanger Typical 1.0 [3.8]
Flush Cart Tank
10” Dia x 3ft
[254mm x 0.9m]
10 [37.9]
DXM2 Control