Operating instructions

5
Table 3 – Loop Side Flow Rates
Model Closed Loop Open Loop
Flow dP Flow dP
(gpm) (psi) (gpm) (psi)
G(V,H)18 4 0.9 2 0.9
G(V,H)23 6 3.0 3 0.9
G(V,H)29 7 3.9 4 1.5
G(V,H)36 8 5.5 4 1.3
G(V,H)42 10 7.8 5 1.7
G(V,H)52 11 5.2 6 1.6
G(V,H)59 13 6.0 9 3.1
G(V,H)67 14 7.0 10 3.8
G(V,H)98 22 3.8 12 2.5
G(V,H)120 26 4.5 16 3.0
Pressure/Temperature (P/T) ports should be installed in
the entering and leaving water lines 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 5). 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.
The purge pump can be used to pressurize the system to
an initial static pressure of 30-40 psi. Make sure the
system is at this pressure after the loop pipe has had
enough time to stretch. In order to achieve the 30 to 40
psi initial pressure, the loop may need to be pressurized to
60 to 65 psi. This static pressure will fluctuate from
heating to cooling season, but the pressure should always
remain above zero so circulation pumps do not cavitate
and air cannot be pulled into the system. (( For
information regarding earth loop installations contact your
local installer, distributor or factory representative.
B. Open Loop Applications
An open system gets its name from the open discharge of
water after it has been used by the heat pump. A well
must be available that can supply all of the water
requirements (see Table 3) of the heat pump along with
any other water requirements drawing off that same well.
The well must be capable of supplying the heat pump’s
required flow rate for up to 24 hours per day on the
coldest winter day.
Figure 2 shows the necessary components for water
piping of an open system. First, a bladder type pressure
tank with a "draw down" of at least 1½ times the well
pump capacity must be installed on the supply side of the
heat pump. Shut off valves and boiler drains on the
entering and leaving water lines are necessary for future
maintenance issues. A screen strainer is placed on the
supply line with a mesh size of 40 or 60 and enough
surface area to allow for particle buildup between
cleanings.
Pressure/Temperature (P/T) ports are placed in the supply
and discharge lines so that thermometers or pressure
gauges can be inserted into the water stream. On the well
water discharge side of the heat pump, a flow control
valve must be mounted next to the heat pump to regulate
the maximum water flow through the unit. A solenoid
valve is then installed and wired to the accessory plug on
the controller. This valve will open when the unit is
running and close when the unit stops. A visual flow
meter is then installed to allow visual inspection of the
flow requirements. The flow meter is useful in
determining when maintenance is required. (If you can't
read the flow, cleaning is required.)
Schedule 40 PVC piping, copper tubing, polyethylene or
rubber hose can be used for supply and discharge water
lines. Make sure line sizes are large enough to supply the
required flow with a reasonable pressure drop (generally
1" diameter minimum). NOTE: Do not use plastic
female fittings with metal male fittings, or fractures may
result in the female fittings. Always use plastic male into
steel female!
Water discharge is generally made to a drain field, stream,
pond, surface discharge, tile line, or storm sewer.
II CAUTION: Using a drain field requires soil
conditions and adequate sizing to assure rapid percolation,
or the required flow rates will not be achieved. Consult
local codes and ordinances to assure compliance. DO
NOT discharge water to a septic system.