Operating instructions

3
The GeoSource 2000 is designed to operate on either
vertical or horizontal closed loop applications. Vertical
loops are typically installed with a well drilling rig up to
200 feet deep or more. Horizontal systems are typically
installed with excavating or trenching equipment
approximately six to eight feet deep, depending on
geographic location and length of pipe used. Earth loops
must be sized properly for each particular geographic
area, soil type, and individual capacity requirements.
Contact your local installer or ECONAR’s Customer
Support for loop sizing requirements in your area.
Since normal wintertime operating entering water
temperatures (EWT) to the heat pump are from 25
o
F to
32
o
F, the solution in the earth loop must include
antifreeze. GTF and propylene glycol are common
antifreeze solutions. GTF is methanol-based antifreeze,
which should be mixed 50% with water to achieve freeze
protection of 10
o
F. Propylene glycol antifreeze solution
should be mixed 25% with water to obtain a 15
o
F freeze
protection. DO NOT mix more than 25% propylene
glycol with water in an attempt to achieve a lower than
15
o
F freeze protection, since more concentrated mixtures
of propylene glycol become too viscous at low
temperatures and cannot be pumped through the earth
loop. Insufficient amounts of antifreeze may result in a
freeze rupture of the unit, and can cause unit shutdown
problems during cold weather operation (when the heat
pump experiences the longest run time) due to loop
temperatures falling below the freeze protection of the
loop solution.
Flow rate requirements for closed loops are higher than
open loop systems because water temperatures supplied to
the heat pump are generally lower (see Table 1). Between
2.5 to 3.0 gallons per minute (GPM) per ton are required
for proper operation of the heat pump and the earth
coupled heat exchanger.
Figure 1 – Closed Loop Water Plumbing
Pressure/Temperature (P/T) ports should be installed in
the entering and leaving water line of the heat pump on a
closed loop system (see Figure 1). A thermometer can be
inserted into the P/T ports to check entering and leaving
water temperatures. A pressure gauge can also be
inserted into these P/T ports to determine the pressure
differential between the entering and leaving water. This
pressure differential can then be compared to the
specification data on each particular heat pump to
determine the flow rate of the system.
A PumpPAK that is individually sized for each
application can supply pumping requirements for the
earth loop fluid. The PumpPAK can also be used to
purge the loop system. The PumpPAK is wired directly
to the contactor and operates whenever the compressor
runs (see Electrical Diagram – Figure 7). If a
PumpPAK is not used, a separate pump can be used
which is energized with a pump relay (note: electrical
code will require a fused disconnect for pumps other than
PumpPAKs).
Filling and purging a closed loop system are very
important steps to assure proper heat pump operation.
Each loop must be purged with enough water flow to
assure a two feet per second flow rate in each circuit in
the loop. This normally requires a 1½ to 3 HP high head
pump to circulate fluid through the loop to remove all the
air out of the loop and into a purging tank. Allow the
pump to run 10 to 15 minutes after the last air bubbles
have been removed. Enough antifreeze must be added to
give a 10
o
F to 15
o
F freeze protection to the earth loop
system. This amount should be calculated and added to
the loop after purging is complete. After antifreeze has
been installed it should be measured with a hydrometer,
refractometer or any other device to determine the actual
freezing point of the solution. Remember that a low
antifreeze level will lock the heat pump out on low
pressure during wintertime operation.