Trane Axiom GEH006, Manual

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28 WSHP-PRC001-EN
Boiler/Cooling Tower Application
In a boiler/cooling tower application ( Figure 37 ), the closed water-loop, along
with multiple water-source heat pumps are utilized in a more conventional
manner.
Typically, a boiler is used to maintain closed-loop temperatures
above 60 F, and a cooling tower is used to maintain
closed-loop temperature below 90 F. All the units
function independently, either by adding heat,
or rejecting heat, or moving heat from the
closed water-loop. Because the heat
from a building is being rejected
through a cooling tower, the system
is more efficient than air cooled sys-
tems.
The boiler/cooling tower system pro-
vides a low installation cost to the
owner when compared to other sys-
tems, and is the most common applica-
tion. It also allows the owner to add units to
the condenser water loop as needed.
Ground Coupled Application
Systems that utilize the ground-coupled (geothermal) design are also applied to
a closed water-loop, along with the multiple ground-source heat pumps.
With the ground-coupled (geothermal) system, heat is exchanged with the earth
by either moving heat into the earth, or absorbing heat from the earth. Water
temperature ranges vary from 25 F to 105 F depending on climate, and season.
Because the ground-coupled system does not use the fluctuating outside-air
temperature, the geothermal heat pumps are capable of using less energy.
The choices in earth-loop coupling consists of a vertical (
Figure 38 ), hor-
izontal, or a pond-loop design. Each of these options offer different
system design characteristics. The vertical and horizontal loop
systems can be designed to provide the same fluid temper-
atures under a given set of conditions.
Operating and maintenance cost are lower
because an auxiliary electric/fossil fuel
boiler and cooling tower are not re-
quired to maintain the loop tempera-
ture in a properly designed system.
Because the ground loop is made of
chemically inert, non-polluting, high
density polyethylene pipe, the loop
is environmentally responsible. The
heat pumps use HCFC-22 refrigerant,
which has a low ozone depletion poten-
tial. Because the closed-loop system does
not require a heat adder, there are no C02 emis-
sions. Less power is consumed by the system, thereby
reducing secondary emissions from the power plant. Therefore, the
ground-coupled system offers advantages not seen by other HVAC system types.
Application
Considerations
Figure 37: Boiler/cooling tower
Figure 38: Vertical bore ground loop
application
application