Specifications

GT-PCS Split Units - 60Hz Puron
®
Created: 29 Aug., 2013
10
Test individual horizontal loop circuits before backfi lling.
Test vertical U-bends and pond loop assemblies prior to
installation. Pressures of at least 100 psi [689 kPa] should be
used when testing. Do not exceed the pipe pressure rating.
Test entire system when all loops are assembled.
The following section will help to guide you through fl ushing a
unit with internal fl ow control.
Water Pressure Schrader Ports
The pressure ports built in to the unit are provided as a
means of measuring pressure drop through the water-to-
refrigerant heat exchanger. The water pressure ports are
schrader ports smaller than refrigerant schrader ports. They
are the same size as tire schrader ports. A digital pressure
gauge is recommended for taking
pressure readings through these
ports. The water fl ow through
the unit can be determined by
measuring the water pressure
at the “water pressure out” port
and subtracting it from the water
pressure at the “water pressure
in” port. Comparing the pressure
differential to the pressure drop in
Table 14 will determine the fl ow
rate through the unit.
Closed Loop Heat Pump Applications with Internal Flow Controller
Figure 5: Internal Flow Controller
Figure 6: Internal Flow Controller Pump Performance
Units with internal fl ow control come with a built-in variable
speed pump, an expansion tank, fl ushing ports and three-
way valves (used to fl ush the unit). The variable speed
pump is controlled by the Communicating DXM2 board
based on the difference between the entering and leaving
water temperature (ΔT). For operation outside of the normal
entering water temperature range (50° or 60°F - 110°F
for cooling, 30°F-70°F for heating) the DXM2 controller
may automatically adjust the control ΔT to account for
the abnormal entering water temperatures, maintaining
an appropriate fl ow rate for proper unit operation. When
entering water temperatures are abnormally low for cooling,
or abnormally high for heating, the DXM2 controller will
maintain a constant leaving water temperature which will
allow the unit to operate properly under those conditions.
The internal expansion tank helps to maintain constant loop
pressure despite the natural expansion and contraction of
the loop as the seasons and loop temperatures vary. The
expansion tank also helps to avoid fl at loop callbacks.
Pre-Installation
Prior to installation, locate and mark all existing underground
utilities, piping, etc. Install loops for new construction before
sidewalks, patios, driveways, and other construction has
begun. During construction, accurately mark all ground loop
piping on the plot plan as an aid in avoiding potential future
damage to the installation.
Piping Installation
The typical closed loop ground source system is shown in
Figures 4a. All earth loop piping materials should be limited to
polyethylene fusion only for in-ground sections of the loop and
it is also recommended for inside piping. Galvanized or steel
fi ttings should not be used at any time due to their tendency to
corrode. All plastic to metal threaded fi ttings should be avoided
due to their potential to leak in ground loop applications. Loop
temperatures can range between 25 and 110°F [-4 to 43°C].
Flow rates between 2.25 and 3 gpm per ton [2.41 to 3.23
l/m per kW] of cooling capacity is recommended in these
applications.
Digital Pressure
Gauge
0
10
20
30
40
50
60
0 5 10 15 20 25 30 35 40
Head (Ft.)
Flow (GPM)
GPM Head (ft)
0.0 44.7
1.0 45.4
2.0 46.1
3.0 46.8
4.0 47.5
5.0 47.7
6.0 47.1
7.0 46.1
8.0 45.3
9.0 43.9
10.0 42.6
11.0 41.2
12.0 39.9
13.0 38.7
14.0 37.4
15.0 36.1
16.0 34.9
17.0 33.7
18.0 32.5
19.0 31.3
20.0 30.1
21.0 28.9
22.0 27.8
23.0 26.7
24.0 25.6
25.0 24.5
26 23.4
27 22.3
28 21.3
29 20.2
30 19.2
31 18.2
32 17.3
33 16.3
34 15.4
35 14.4
36 13.5
37 12.6
38 11.7
GPM Head (ft)