How to Install- GeoCool Series: Closed Loop System

To maintain your system’s manufacturer warranty, all installation work MUST be performed by a certified GeoCool installer, and any service repairs MUST be authorized by MRCOOL before proceeding. This ensures you remain fully covered and your system continues to perform at its best.

 

Be sure to check out this Preparation and Setup article before you begin!

For additional Product and Installation information- GeoCool Install Manual

 

When receiving your shipment, be sure to check for any shipping damage and verify the packing slip accuracy. If any damage is noticed, have the carrier note it on the delivery slip. Note: Smaller items like thermostats or temperature sensors might be packed inside the unit—so be sure to check carefully!

Always move and store units in an upright position to avoid potential damage. Do not stack units—proper care here ensures they’re ready for use when you need them.

 

System Installation:

Find the perfect spot for your unit indoors, where it’s easy to service and maintain (check out the image below for guidance). Ensure that air filter access and unit access panels are quick and effortless to reach. Create ample space for all essential connections—ground loop, well water, DHW, condensate, and electrical—so everything runs smoothly. If the unit is going in a closet, be sure to allow enough space for servicing and proper airflow to keep things running efficiently. In some cases, you may need a condensate pump to direct excess moisture to a suitable drain. And remember, never place the unit in a freezing area—keep it in a space that stays comfortably above freezing for optimal performance!

Caution on Installation:

When attaching ductwork to the unit, be cautious not to damage the air coil by drilling or using screws that penetrate the unit. Always be mindful of where your ducts connect to the system.

For more on ductwork

 

For closed-loop systems to operate efficiently, you'll need a minimum of 3 G.P.M. per ton if the ground loop is designed to maintain a temperature range between 32ºF and 90ºF. If the temperatures fall outside this range, more flow will be necessary to keep the system running smoothly.

For residential units, each one typically requires its own pump. The specific loop pump requirement will depend on the design of the loop for the particular application.

To ensure proper function, the ground loop piping system must be designed with easy access for purging the loop. It should also include isolation valves for purging both the inside plumbing and the unit itself. When purging the closed-loop system, a minimum velocity of 2 feet per second must be achieved in every branch of the loop to ensure the system is properly cleaned and free of airlocks.

The purge ports aren't just for cleaning—they can also be used for anti-freeze charging, making the system even more adaptable to various conditions!

 

Purging the Closed Loop and Unit:

Purging the closed loop and unit is a crucial step that should only be done after the system has passed the air pressure check and any leaks have been fully repaired. To ensure optimal performance, purging requires a high-velocity pump, and it’s important that this process is handled by the installing dealer or subcontractor.

For a clear understanding, refer to the picture below for a detailed piping example.

 

Freeze Protection:

The Freeze Stat is your unit's safeguard, ensuring the liquid-to-refrigerant heat exchanger stays protected from freezing. It works by monitoring the refrigerant temperature as it exits the water coil during heating mode. If the temperature drops below the freeze set point, the unit will automatically lock out to prevent damage—requiring a manual reset to get things running again.

 

On closed loop systems WITH ADEQUATE ANTIFREEZE, the tab labeled “ANTIFREEZE”
should be broken off, lowering the unit freeze setpoint to 20 degrees. Use a small pair of needle
nose pliers to break the tab (see image below). 

 

DHW Tank Preparation:

The DHW coil is a vented double-wall copper heat exchanger, perfect for potable water use. The DHW pump is installed inside the unit and connected to a fused terminal. Follow these steps carefully to prepare the tank:

1. Turn off the power supply (or fuel supply) to the DHW tank. Warning: If the power isn’t turned off before draining the tank, the electric heating elements will burn out—so be sure to disconnect power first!
2. Close the cold water supply valve to the DHW tank.
3. Attach a water hose to the tank drain connection at the bottom of the tank and drain it to an appropriate location, such as a drain or outside.
4. Open the pressure relief valve or a nearby faucet to relieve the vacuum inside the tank, which helps speed up the draining process.
5. Once the tank is empty, disconnect the hose and remove the DHW tank drain fitting.

Desuperheater Option Installation:

Install the desuperheater circuit, and make sure to include isolation valves and two boiler drain valves for easy tank draining and DHW system purging. These valves, as shown in the diagram below, also allow for pump servicing without draining the DHW tank.

To prevent water from flowing backward when the pump is off, use a horizontal swing check valve. For lower DHW pressure drop, use 3/4 inch copper pipe.

Remove the existing drain port from the hot water tank and insert a standard dielectric fitting (thread the male end into the water heater drain port using a PTFE-based thread sealer). Then, continue with the installation as outlined. Insulate all desuperheater circuit piping to ensure efficiency.

 

Filling the Hot Water Tank:

1. Close the boiler drain valves and the isolation valves to the GeoCool system.
2. Open the cold water supply feeding the DHW tank.
3. Open a hot water tap in the building to allow any air to bleed out of the tank. Alternatively, you can depress the lever on the tank relief valve to release any air trapped inside the tank.
4. Once the building plumbing is purged, it’s crucial to also purge the air remaining in the GeoCool system and the plumbing between the DHW tank and the GeoCool system.

Important:

Simply purging the building plumbing with the isolation valves open to the DHW lines won’t purge the air from the GeoCool system, so be sure to address both areas to ensure proper flow.

 

Purging Air and Debris from the DHW Circuit:

It’s critical to purge all air from the DHW lines before running the unit to make hot water. Improper purging can result in air entering the pump, which will cause cavitation and damage the pump.

Units are shipped from the factory with biodegradable RV antifreeze inside the DHW coil. Fortunately, if the correct purging methods are followed, this antifreeze will be easily removed from the system without any issues.

Purging the GeoCool Hot Water Lines:

1. Attach a hose to boiler drain A and direct the hose to a floor drain or outside.
2. Close isolation valve A at the cold-water inlet on the DHW tank.
3. Open isolation valve B at the bottom of the tank and let the water flow out through the hose.
4. Let the water run for a few minutes while keeping an eye out for air exiting the hose. Once all air has been purged, close isolation valve B and open isolation valve A.
5. Allow the water to flow through the system and out the hose for about 5 to 10 minutes, checking for any remaining air in the hose.
6. To ensure there’s no air trapped anywhere, open both valve A and valve B to allow water to flow in both directions. Let the water run for about one minute.
7. Once purging is complete, close the boiler drain valve, remove the drain hose, and make sure both isolation valves A and B are fully open.

Low & High Voltage Connections:

🗲Always use caution when working with or around electrical wiring or connections!🗲

When running high and low voltage wire into the electrical box always leave
enough slack to swing out or remove the electrical box. The electrical box can be swung
outward by removing one screw from the unhinged side of the box. Then , if
desired, the box can be lifted to provide easy access behind box. This only
works if slack is left in the field wiring.

ALWAYS TURN OFF THE POWER TO THE UNIT BEFORE DOING THIS!!!

 

The electrical box cover features a small tab that, when rotated 90 degrees to a vertical position, will allow the cover to swing down on a hinge for easy access.

Main System Power:

• Wire sizing should be done in accordance with local electrical codes.
• The main power connects to the top of the contactor, labeled “L1” and “L2”.
• A green ground lug is also provided for the ground wire to ensure safe operation.

Pump Outputs:

• A terminal strip will be provided for each pump or water valve output that applies. Each terminal will be clearly labeled for easy identification.

Loop Pump (Closed Loop Systems):

• Inside the control panel, you’ll find a 230V fused terminal strip labeled “CLOSED LOOP PUMP” for the field-installed ground loop pump.
• If the fuse is tripped, an ORANGE LED will light up on the terminal, signaling that attention is needed.

Thermostat Wiring:

The thermostat will wire directly to the removable terminal block on the Dallas Board, which is labeled using standard thermostat lettering. (See the image below for a sample thermostat wiring diagram.)

For detailed installation instructions, be sure to consult the thermostat manual.

 

Dallas™ Microprocessor:

The Dallas™ microprocessor combines simplicity with advanced controls, offering a wide range of options to suit most installation scenarios. With the LED indicator board, both technicians and homeowners can easily check the unit’s status, making troubleshooting and monitoring a breeze.

System Safeties:

The Dallas board comes equipped with multiple built-in safety inputs, providing multiple layers of protection for the GeoCool unit.

 

Dip-Switch Settings:

The Dallas board features a set of 4 dip-switches, which allow access to various features. These settings should only be adjusted by a trained factory technician.

• First 2 switches: Factory-set according to the unit's tonnage, matching blower CFM’s with the correct compressor size.
• 3rd switch: Allows the installer to select a slower CFM in cooling mode, slowing the fan to increase dehumidification.
• 4th switch: Reserved for future use, enabling the board to incorporate a variable speed flow center or a modulating electronic water valve.

Limit Switches:

The Dallas board includes independent inputs for both low limit and high limit switches.

• Auto-reset high limit switch: Trips at 550 psi and shuts the compressor down for 5 minutes once the switch resets. The RED light labeled "HIGH PRESSURE LIMIT" will blink when the switch trips and turn solid RED once it resets.

  • If the switch trips 3 times in 30 minutes, the board will lock out the compressor. A blinking red light will indicate the lockout status. To reset the lockout, power must be cycled, but only after identifying and correcting the cause of the trip. Failure to do so can damage the unit and void the warranty!

• Auto-reset low limit switch: Trips at 75 psi and shuts the compressor down for 5 minutes after the switch resets. The RED light labeled "LOW PRESSURE LIMIT" will blink when the switch trips and turn solid RED when it resets.

  • If the switch trips 3 times in 30 minutes, the board will lock out the compressor. As with the high limit, a blinking red light indicates the lockout status. To reset, power must be cycled, but only after identifying and correcting the cause of the trip. Failure to do so can damage the unit and void the warranty!

Condensate Overflow Switch:

The unit comes with a normally closed (N/C) float switch, which is factory installed in the unit’s internal drain pan. If the condensate line becomes clogged, the float switch will be activated, shutting the compressor down.

• A RED light labeled "CONDENSATE FAULT" will illuminate on the LED board.
• Once the drain pan empties, the light will turn off, and the compressor will be allowed to resume operation.

DHW Option:

For units equipped with a DHW pump, it will not be energized until the compressor has been running for 5 minutes.

• The pump will shut off whenever the tank temperature reaches 135°F to prevent overheating.

Water Flow Control:

The Dallas board is designed to control either a loop pump/flow center for closed-loop applications or a 24Vac water valve for open-loop applications.

• A 230Vac fused terminal strip is provided for loop pumps.
• A 24Vac 3-position terminal strip is provided for water valves, with connections for common, N/O (normally open), and N/C (normally closed)

Thermostat Selection:

The Dallas board is compatible with any 24Vac “relay” type heat pump thermostat (up to 3 heat / 2 cool, depending on options). The thermostat will be wired directly to the removable, labeled Dallas board plug for easy installation.

(See the image below for wiring details.)

LED Indicator:

Located on the front post of the Geocool unit, the LED indicator provides real-time unit status to both the homeowner and technician.

• BLUE light: Indicates unit power is on.
• GREEN light: Shows that the compressor is running.
• RED lights: Indicate fault statuses:
  • High Pressure Limit Switch
  • Low Pressure Limit Switch
  • Freeze Protection
  • Condensate Fault

This simple yet effective system makes it easy to monitor and troubleshoot the unit.

 

Dec-Star ECM Blower – Variable Speed Blower:

GeoCool sets a new standard in comfort and efficiency by integrating Dec-Star ECM Blower Motor Technology into our equipment. This variable speed blower, paired with the Dallas microprocessor, ensures:

• Even temperatures throughout the space
• Improved indoor air quality
• Precise humidity control
• Quieter operation
• Lower utility bills

Features and Benefits of the Dec-Star:

• High Efficiency Blower (HEB) housing with an impeller driven by an Axial Flux BLAC motor and full-featured Sinusoidal EON motor control technology.
• Operating speed range from 250 to 2400 rpm, offering exceptional flexibility.
• 4-pin Serial and 16-pin Thermostat and PWM input for seamless control.
• Variable speed, constant torque/constant airflow ECM motor for optimal performance.
• UL & cUL recognized system for enhanced safety and reliability.
• Saves 15% - 35% in energy consumption compared to standard blowers with traditional ECM technology.
• Meets or exceeds next-generation regulations, including FER/SEER levels.
• Unique blower system removes the motor from the blower inlet, eliminating restrictions and significantly improving system efficiency.
• Patented HEB design maximizes blower housing CFM per input watt for superior performance.
• Balanced airflow from both inlets, providing uniform output unlike traditional systems that restrict airflow.
• Improves heat transfer and reduces the occurrence of hot spots.
• Reduces pressure drop across the unit, leading to more efficient operation.
• Shaft-less rotor system allows for a hub-less impeller, reducing wear and tear.
• Standard triangle motor mounts with welded brackets provide added durability and stability.
• Heavy-duty welded aluminized steel ensures the blower assembly is built to last.

Recommended GeoCool Start-Up Procedure

Before starting the unit, verify the following items are addressed.

Startup Checklist:

• Closed-loop system: Ensure the loop and unit are purged of air, and all valves are open.
• Methanol/Propylene Glycol: Ensure at least 20% methanol or 25% propylene glycol is purged into the loop and properly mixed.
• Flow Rate: Verify that all piping meets the designed flow rate and that all valves are open.
• Open-loop system: Ensure well pressure is between 25 PSI and 50 PSI and that all valves are open.
• Hot water loop: Ensure all air is purged from the hot water loop lines and all valves are open.
• Supply grills: Confirm all supply grills are installed and unobstructed.
• Return ducts and grills: Ensure they are installed and unrestricted, with a filter properly in place.
• Service panels: Ensure all service panels to the air chamber are closed and securely fastened.
• Electrical check: Confirm supply voltage is correct and matches the nameplate.
• Fuses and wiring: Verify fuses, breakers, and wire sizes are correctly matched.
• Low voltage wiring: Ensure all low voltage wiring is completed, including thermostats.
• Leveling: Ensure the unit is level for proper condensate drainage.
• Access panels: Confirm service/access panels are in place with sufficient clearance for front and side servicing.

Start Unit:

1. Reinstall all panels and ensure they are securely fastened.
2. Turn on the main power to the unit.
3. Adjust the thermostat up or down to activate the system. You may experience a time delay of up to 5 minutes.
4. Check blower operation to ensure the blower is running.
5. Check compressor operation to confirm the compressor is running.
6. Verify water flow to ensure the correct flow is being achieved.
7. Check hot water loop circulation (if applicable) to ensure water is circulating properly.
8. Set thermostat to the desired temperature for optimal comfort.
9. For well water systems, the water flow should typically be 2 GPM to 3 GPM per ton.
10. For closed-loop systems, check the temperature of the water in and out. There should normally be no more than a 10°F to 12°F difference in temperature.

Refrigerant System:

To maintain sealed circuit integrity, do not install service gauges unless unit operation appears abnormal.

• Compare the temperature changes on both the air side and water side with the Operating Parameters tables found in Section 17.0 in the install manual.
• If the unit’s performance is outside the recommended ranges, and both airflow and water flow are confirmed correct, then gauges should be installed by a qualified technician.
• Superheat and subcooling numbers should be calculated. If these are outside the recommended ranges, an adjustment to the refrigerant charge may be necessary to optimize performance and efficiency.

Preventative Maintenance

Your GeoCool Water Source Heat Pump is designed for minimal maintenance, giving you more time to enjoy its efficiency. However, to ensure it continues running at peak performance, there are a few simple steps you can take!

For ultimate peace of mind, we recommend having your system inspected once a year by a trained service professional. Many of our trusted dealers offer Preventative Maintenance Checks, keeping your system in top shape and helping you get the most out of your investment.

Don't miss out—keep your system running smoothly and efficiently all year long!

• Air Filter: A clean air filter is essential! Change it about once a month—or sooner if needed—using a high-quality filter. Neglecting this can lead to costly air coil cleanings during your preventative maintenance checks. Keep it fresh for top performance!

• Visual Check: Take a few moments every so often to check your unit. Look for any signs of water around the base and listen for any unusual sounds. Catching small issues early can prevent bigger problems down the road.

• Closed Loop Systems:
  Important: If your unit uses a ground loop system, make sure the antifreeze solution stays at a minimum of 20% methanol or 25% propylene glycol. This ensures the refrigerant stays at the right temperature and prevents internal freezing. Failure to maintain proper antifreeze levels could result in severe damage—and that’s not covered under warranty!

• Fan Motors:
  Your fan motors are permanently lubricated, so no need to worry about extra lubrication. However, they should still be checked annually for wear during your preventative maintenance inspection. Keeping an eye on these can ensure smooth operation for years to come.

• DHW Plumbing:
  If maintenance or replacement is needed for your hot water tank, make sure the DHW plumbing is properly purged of air. Always consult your installing dealer for proper procedures, especially before draining the hot water tank.