Ground-Loop Applications - Heat Controller HBH Series Installation, Operation & Maintenance Manual

IOM Manual
Ground-Loop Heat Pump Applications
� CAUTION! �
CAUTION!
!
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.
CAUTION!
� CAUTION! �
!
CAUTION! Ground loop applications require extended range
equipment and optional refrigerant/water circuit insulation.
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 9. 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.
Table 2: Antifreeze Percentages by Volume
Type
Methanol
100% USP food grade Propylene Glycol
Ethanol*
* Must not be denatured with any petroleum based product
HBH SERIES
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; however your local sales manager should be
consulted for the antifreeze best suited to your area. Low
temperature 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 low temperature 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.
Low Water Temperature Cutout Setting - CXM Control
When antifreeze is selected, the FP1 jumper (JW3)
should be clipped to select the low temperature
(antifreeze 10°F [-12.2°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.
Minimum Temperature for Low Temperature Protection
10°F [-12.2°C] 15°F [-9.4°C]
25% 21%
38% 25%
29% 25%
13
Heat Controller, Inc.
20°F [-6.7°C] 25°F [-3.9°C]
16% 10%
22% 15%
20% 14%