System information

ManualsBrandsClimateMaster ManualsHeat PumpGT-PX Indoor Split Series

Geothermal Applications

Carrier: Turn to the Experts.

Heat Source/Heat Sink

The heat source/heat sink for geothermal systems is determined

based upon the speciﬁ c application. Where water quality is

good and a sufﬁ cient quantity of water is available, an open

loop (well water) source/sink is a very cost effective solution.

Otherwise, one of the three types of closed loop applications

may be a better choice. In any case, operating costs are

very similar, since the source/sink and heat pump are sized

according to the heat loss/heat gain of the home. All residential

applications (open or closed loop) require extended range

equipment. Carrier Geothermal residential series equipment is

standard with insulated water and refrigerant circuit insulation,

designed for low temperature operation.

Open Loop Systems (Well Water)

Typical open loop piping is shown in Figure 3 and 3a. Shut off

valves should be included for ease of servicing. Boiler drains

or other valves should be “tee’d” into the lines to allow acid

ﬂ ushing of the heat exchanger. Shut off valves should be

positioned to allow ﬂ ow through the coaxial heat exchanger

via the boiler drains without allowing ﬂ ow into the piping

system. P/T plugs should be used so that pressure drops and

temperatures can be measured. Piping materials should be

limited to copper or PVC SCH80. Note: Due to the pressure

and temperature extremes, PVC SCH40 is not recommended.

Water quantity must be plentiful and of good quality. Consult

Table 1 for water quality guidelines. The unit can be ordered with

either a copper or cupro-nickel water heat exchanger. Consult

Table 1 for recommendations. Copper can be used for open loop

ground water systems that are not high in mineral content or

corrosiveness. In conditions anticipating heavy scale formation or

in brackish water, a cupro-nickel heat exchanger is recommended.

In ground water situations where scaling could be heavy or where

biological growth such as iron bacteria will be present, an open

loop system is not recommended. Heat exchanger coils may over

time lose heat exchange capabilities due to build up of mineral

deposits. Heat exchangers must only be serviced by a qualiﬁ ed

technician, as acid and special pumping equipment is required.

Desuperheater (HWG) coils can likewise become scaled and

possibly plugged. In areas with extremely hard water, the

owner should be informed that the heat exchanger may require

occasional acid ﬂ ushing. In some cases, the desuperheater option

should not be recommended due to hard water conditions and

additional maintenance required.

Table 1 should be consulted for water quality requirements. Scaling

potential should be assessed using the pH/Calcium hardness

method. If the pH <7.5 and the calcium hardness is less than 100

ppm, scaling potential is low. If this method yields numbers out of

range of those listed, the Ryznar Stability and Langelier Saturation

indices should be calculated. Use the appropriate scaling surface

temperature for the application, 150°F [66°C] for direct use (well

water/open loop) and DHW (desuperheater); 90°F [32°F] for

indirect use. A monitoring plan should be implemented in these

probable scaling situations. Other water quality issues such as iron

fouling, corrosion prevention and erosion and clogging should be

referenced in Table 1.

Vibration

Isolation Pad

Unit Power

Disconnect

High and low

voltage

knockouts

Pressure

Tank

Shut-Off

Va l v e

Boiler

Drains

Flow

Regulator

Water In

Water Out

Water

Control

Va l v e

Optional

Filter

P/T Plugs

To Thermostat

Figure 3: Typical Open Loop Application

For use on applications using external source for ﬂ ow

Heat Source/Heat Sink

Internal Motorized

Modulating Valve

Water Out

Shut Off

Ball Valves

for Isolation