Comfort-Aire HBH Series 1/2 to 5 Ton - Manual (Page 15)

Heat Controller, Inc. HBH/V COMPACT IOM Instructions
Ground-Loop Heat Pump Applications
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 Figure 13. All earth loop piping materials should be
limited to polyethylene fusion only for in-ground sections
of the loop. Galvanized or steel fittings should not be
used at any time due to their tendency to corrode. All
plastic to metal threaded fittings should be avoided due
to their potential to leak in earth coupled applications. A
flanged fitting should be substituted. P/T plugs should be
used so that flow can be measured using the pressure
drop of the unit heat exchanger.
Earth 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.
Test individual horizontal loop circuits before backfilling.
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.
Flushing the Earth Loop
Upon completion of system installation and testing, flush
the system to remove all foreign objects and purge to
remove all air.
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. 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
2 for the amount of antifreeze needed. Antifreeze
concentration should be checked from a well mixed
sample using a hydrometer to measure specific gravity.
CAUTION! The following instructions represent industry
accepted installation practices for closed loop earth coupled
heat pump systems. Instructions are provided to assist the
contractor in installing trouble free ground loops. These
instructions are recommendations only. State/provincial
and local codes MUST be followed and installation MUST
conform to ALL applicable codes. It is the responsibility of
the installing contractor to determine and comply with ALL
applicable codes and regulations.
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 (antifreeze 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.
CAUTION!
CAUTION!
Type
Minimum Temperature for Low Temperature Protection
10°F [-12.2°C] 15°F [-9.4°C] 20°F [-6.7°C] 25°F [-3.9°C]
Methanol
100% USP food grade Propylene Glycol
Ethanol*
25%
38%
29%
21%
25%
25%
16%
22%
20%
10%
15%
14%
* Must not be denatured with any petroleum based product
CAUTION! Ground loop applications require extended range
equipment and optional refrigerant/water circuit insulation.