Operating instructions

8
drop of the condensate trap. Vented condensate traps are
necessary to break the negative pressure in the air
chamber and allow the condensate to flow. Construct
condensate traps to the following diagram.
Figure 3 – Condensate Drain - Horizontal and
Downflow Units Only
VI. UNIT SIZING
Selecting the unit capacity of a geothermal heat pump
requires two things:
A) Earth Loop Configuration and Design Water
Temperatures.
B) Building Heat Loss/Heat Gain.
A. Earth Loop Configuration and
Design Water Temperatures
Loop configurations include the open and closed loop
varieties. Heat pump capacity and flow rate requirements
vary depending on loop configuration (see Table 3).
1. Closed Loop Systems
Closed loop systems use a heat exchanger of high density
polyethylene pipe buried underground to supply a
tempered water solution back to the heat pump. Closed
loops operate at higher flow rates than open loops since
the entering water temperature (EWT) is lower. The loop
EWT supplied to the heat pump has a great effect on the
capacity of the unit in the heating mode. Earth loops in
cold climates are normally sized to supply a wintertime
EWT to the heat pump from 32
o
F down to 25
o
F, which
minimizes the installation cost of the earth loop and still
maintains proper system operation. The unit GPM
requirements and pressure drops for loop pump sizing is
available in Table 3.
When selecting the heat pump, choose a unit that will
supply the necessary heating or cooling capacity at the
minimum and maximum earth loop temperature
conditions respectively. Example; if a residential system
requires 45,000 Btu/hr to heat a house on an earth loop
system (designed for 32
o
F minimum wintertime EWT),
and 36,000 Btu/hr to cool the house on an earth loop
(designed for 77
o
F summertime EWT), a Gx52x-x-Txxx
GeoSource 2000 heat pump is required to handle the
loads.
2. Open Loop Systems
On an open loop system the design water temperature will
be the well water temperature in your geographic region.
Many cold climates are in the 50
o
F range for well water
temperature. If your well water temperatures are lower
than 50
o
F, for instance Canadian well water can be as low
as 43
o
F, the flow rate must be increased to avoid leaving
water temperatures below the freezing point. If well
water temperatures are above 50
o
F, as in some southern
states where well water temperatures are above 70
o
F, the
flow rates may need to be increased to dump heat more
efficiently in the cooling mode.
Varying well water temperatures will have little effect on
unit capacity in the cooling mode (since the well is
connected to the heat pump condenser), but can have
large effects on the capacity in the heating mode (since
the well is connected to the evaporator). If well water
temperatures are to exceed 70
o
F, special considerations,
such as closed loop systems, should be addressed.
B. Building Heat Loss/Heat Gain
The space load must be estimated accurately for any
successful HVAC installation. There are many guides or
computer programs available for load estimation
including the ECONAR GeoSource Heat Pump
Handbook, Manual J, and others. After the heat loss/heat
gain is completed and loop EWT are established, the heat
pump can now be selected using the specifications data.
Choose the capacity of the heat pump based on both
heating and cooling load.
VII. ELECTRICAL SERVICE
The main electrical service must be protected by a fuse or
circuit breaker, and be capable of providing the amperes
required by the unit at nameplate voltage. All wiring
shall comply with the national electrical code and/or any
local codes that may apply. Access to the line voltage
contactor is gained through the knockouts provided on
either side of the heat pump next to the front corner.
Route EMT or flexible conduit with appropriate 3-
conductor wire to the contactor.
NN WARNING - The unit must be properly grounded!NN
II CAUTION: Three-phase units MUST be wired
properly to insure proper compressor rotation. Improper
phasing may result in compressor damage. An electronic
phase sequence indicator must be used to check supply-
wiring phase. Also, the “Wild” leg of the three-phase
power must be connected to the middle leg on the
contactor.
When supplying power to external water pumps with the
heat pump’s power supply, use only impedance protected
motors. ECONAR PumpPAKs can be wired directly to
the contactor in the electrical box. The relay will energize