Tim Schultz joined us recently for Dual Fuel Rural Ground Source Heat Pump add-ons on our Weekly Wednesday Free CEU webinar Series.
If you missed this session, want to rewatch it, or share it with a friend or colleague, you can now do so, as the recording is available below. In addition, Max answered some of the remaining Q&A below, and your question may have additional follow-up below.
Participants primarily learned about hybrid or dual-fuel geothermal systems that integrate ground-source heat pumps with existing fossil fuel heating systems, often using an existing well as the water source. Many noted this was an entirely new concept for them, appreciating the potential to reduce heating costs, fossil fuel use, and carbon
emissions while improving efficiency and comfort, especially for rural homes. They learned that such systems can run simultaneously, do not always require new wells or large loops, and can provide steady indoor temperatures even in cold climates. Several respondents highlighted the 80/20 efficiency concept—using geothermal for most heating needs while retaining fuel systems for extreme cold. Some also mentioned
learning about real-time monitoring, design tradeoffs, and water quality issues like iron bacteria. Remaining questions and curiosities focused on system sizing, decision factors, design challenges, and the complex tradeoffs in hybrid setups, such as when and how to best use dual systems and optimize efficiency in various climates.
Questions and Answers
Q1: Are you able to share rough installation and operating costs for a typical home in MI?
A1: Before incentives, systems are typically installed for between $14K to $16K.
A1: Before incentives, systems are typically installed for between $14K to $16K.
Q2: Will the lack of the current incentives be discussed in depth?
A2: While the 30% federal tax credit is going away at the end of the year, there are a growing number of incentives at state and local levels, as well as from individual utility providers. Some of these incentives are in the thousands of dollars and, based on the typical price of a Well-Connect system, make up for the 30% federal tax credit expiration.
A2: While the 30% federal tax credit is going away at the end of the year, there are a growing number of incentives at state and local levels, as well as from individual utility providers. Some of these incentives are in the thousands of dollars and, based on the typical price of a Well-Connect system, make up for the 30% federal tax credit expiration.
Q3: Do you need any special thermostats for operating both systems simultaneously or can the existing thermostat handle this?
A3: The Well-Connect thermostat controls both the Well-Connect geo heat pump and the existing furnace (2 stage heating and 1 stage cooling thermostat). The existing furnace’s thermostat is kept in place but turned down to about 50 degrees to serve as a backup. The homeowner only needs to operate one thermostat to control the home temperature.
A3: The Well-Connect thermostat controls both the Well-Connect geo heat pump and the existing furnace (2 stage heating and 1 stage cooling thermostat). The existing furnace’s thermostat is kept in place but turned down to about 50 degrees to serve as a backup. The homeowner only needs to operate one thermostat to control the home temperature.
Q4: Why aren’t all retrofits done like this?
A4: Great question! If a home has a well, a Well-Connect should be considered, though it isn’t necessarily the best option in every situation (mainly if there isn’t a 2′ x 3′ spot to put the heat pump).
A4: Great question! If a home has a well, a Well-Connect should be considered, though it isn’t necessarily the best option in every situation (mainly if there isn’t a 2′ x 3′ spot to put the heat pump).
Q5: How can both systems operate at the same time when the heat pump produces a much lower outlet temperature compared to the furnace? What is the system arrangement?
A5: The Well-Connect heat pump has its own fan and operates independently of the furnace. Both can operate simultaneously, with the furnace typically needed only about 10% of the winter months.
A5: The Well-Connect heat pump has its own fan and operates independently of the furnace. Both can operate simultaneously, with the furnace typically needed only about 10% of the winter months.
Q6: I have a WaterFurnace Series 7 with a variable speed compressor and blower. Does oversizing matter as much?
A6: Well-Connects are available in 1.5t and 2.5t sizes, which means they tend to be on the small side for most homes, delivering more even heat and better dehumidification. The extra cost and complexity of variable speed technology doesn’t tend to have great value in this application; they’d be running at or near full speed most of the time anyway. If you already have a variable speed unit, that’s ok, but it likely isn’t running at its full capacity very often.
A6: Well-Connects are available in 1.5t and 2.5t sizes, which means they tend to be on the small side for most homes, delivering more even heat and better dehumidification. The extra cost and complexity of variable speed technology doesn’t tend to have great value in this application; they’d be running at or near full speed most of the time anyway. If you already have a variable speed unit, that’s ok, but it likely isn’t running at its full capacity very often.
Q7: Which unit fan is operating? Furnace or heat pump?
A7: The Well-Connect heat pump has its own fan and operates independently of the furnace. Both fans can operate simultaneously when the furnace is needed.
A7: The Well-Connect heat pump has its own fan and operates independently of the furnace. Both fans can operate simultaneously when the furnace is needed.
Q8: Will buildings that have countywide water available be discussed?
A8: Most homes served by a municipal water system aren’t a good fit for a Well-Connect. This is mainly due to the cost of using metered water and typically colder water temperatures. Personal wells supply free and ‘earth-heated’ water.
A8: Most homes served by a municipal water system aren’t a good fit for a Well-Connect. This is mainly due to the cost of using metered water and typically colder water temperatures. Personal wells supply free and ‘earth-heated’ water.
Q9: Are GRECs (Green Renewable Energy Credits) available for offsetting cost?
A9: As we understand GRECs, they are available in certain states like Maryland but not in all areas.
A9: As we understand GRECs, they are available in certain states like Maryland but not in all areas.
Q10: Can you talk more about operating costs for GL systems? Are there increased costs associated with open loop systems (increased fouling, etc.) and the need for additional filtration?
A10: Open loop systems are slightly more efficient than closed loop systems due to the steady incoming water temperature. If the household water is good enough to drink, it’s likely good enough for Well-Connect. High sediment or iron bacteria require attention from a well driller before installation. Maintenance mostly involves keeping the spin-down sediment filter clean; advanced cleaning is rarely needed.
A10: Open loop systems are slightly more efficient than closed loop systems due to the steady incoming water temperature. If the household water is good enough to drink, it’s likely good enough for Well-Connect. High sediment or iron bacteria require attention from a well driller before installation. Maintenance mostly involves keeping the spin-down sediment filter clean; advanced cleaning is rarely needed.
Q11: What are the water quality issues for the heat pump?
A11: See answer 10 above.
A11: See answer 10 above.
Q12: What is the life of the heat exchanger given the use of raw well water?
A12: 20+ years. The heat exchanger is made out of cupro-nickel, which is corrosion resistant and designed for raw well water. Water only flows through the heat exchanger for seconds, minimizing mineral buildup.
A12: 20+ years. The heat exchanger is made out of cupro-nickel, which is corrosion resistant and designed for raw well water. Water only flows through the heat exchanger for seconds, minimizing mineral buildup.
Q13: Are there any options that don’t involve forced air?
A13: Prototype water-to-water units exist but aren’t commercially available yet. Many homeowners want AC or more efficient AC, which is only available with water-to-air models.
A13: Prototype water-to-water units exist but aren’t commercially available yet. Many homeowners want AC or more efficient AC, which is only available with water-to-air models.
Q14: Can you keep the same thermostats and just set the heat pump a few degrees higher than the furnace?
A14: Yes, that’s one way to do it if the systems aren’t formally integrated. The Well-Connect includes a relay that allows a new thermostat to control both the Well-Connect and furnace, which is the recommended configuration.
A14: Yes, that’s one way to do it if the systems aren’t formally integrated. The Well-Connect includes a relay that allows a new thermostat to control both the Well-Connect and furnace, which is the recommended configuration.
Q15: I have to filter my well for sulphur, magnesium, etc. Will that affect the system?
A15: Water quality is important. Hard water isn’t generally an issue, but iron bacteria can be. A flow test is recommended before installation to ensure sufficient water and check for excessive sediment or contaminants.
A15: Water quality is important. Hard water isn’t generally an issue, but iron bacteria can be. A flow test is recommended before installation to ensure sufficient water and check for excessive sediment or contaminants.
Q16: Can your system support a high pressure/volume or high pressure/velocity HVAC system?
A16: We have not installed our system in this application.
A16: We have not installed our system in this application.
Q17: Is there a well volume that permits the system to return water to the well, creating a closed loop using a large well volume?
A17: Yes. Vertical Standing Water Columns are used in many installations. 60 to 100 gallons of water column per ton of heating capacity is required.
A17: Yes. Vertical Standing Water Columns are used in many installations. 60 to 100 gallons of water column per ton of heating capacity is required.
Q18: We have a small clubhouse with a 7-ton HVAC system and high utility costs. Is a vertical closed loop system the only geothermal option?
A18: If the water is metered, it probably isn’t a good fit for any open loop system, including Well-Connect (see answer 8).
A18: If the water is metered, it probably isn’t a good fit for any open loop system, including Well-Connect (see answer 8).
Q19: Is the flow rate variable to minimize wasted water?
A19: Well-Connects are single stage/fixed capacity machines, so the water flow rate is constant. A pressure-compensating flow restrictor delivers the correct amount of water. The next generation will have a 2-stage compressor with variable flow.
A19: Well-Connects are single stage/fixed capacity machines, so the water flow rate is constant. A pressure-compensating flow restrictor delivers the correct amount of water. The next generation will have a 2-stage compressor with variable flow.
Q20: Is there a separate well pump in the unit?
A20: The Well-Connect ties into the existing household water supply. It uses the existing well pump, similar to other household appliances. The only pump in the Well-Connect is for condensate in cooling mode.
A20: The Well-Connect ties into the existing household water supply. It uses the existing well pump, similar to other household appliances. The only pump in the Well-Connect is for condensate in cooling mode.
Q21: Can you discuss renewable energy credits?
A21: Maryland has good availability of renewable energy credits, but not all states do.
A21: Maryland has good availability of renewable energy credits, but not all states do.
Q22: Is any geothermal installation discussed for city/municipal water availability?
A22: No, because of the high cost of water to run the system and suboptimal water temperatures.
A22: No, because of the high cost of water to run the system and suboptimal water temperatures.
Q23: Can the well system work without a furnace, using another fan coil?
A23: Yes, it is a stand-alone/self-operating heat pump with its own blower and can operate without a furnace. An electric ‘duct’ heater is sometimes installed in series, but minimizing electric resistance heating is recommended.
A23: Yes, it is a stand-alone/self-operating heat pump with its own blower and can operate without a furnace. An electric ‘duct’ heater is sometimes installed in series, but minimizing electric resistance heating is recommended.
Q24: Does this system work in hot/humid climates with groundwater temperatures around 68 degrees?
A24: Yes, it works well in southern climates with warmer groundwater. Efficiency and capacity in heating mode increase, while cooling mode efficiency is still better compared to air source equipment.
A24: Yes, it works well in southern climates with warmer groundwater. Efficiency and capacity in heating mode increase, while cooling mode efficiency is still better compared to air source equipment.
Q25: Where does the cooled water go?
A25: Discharge water is returned to the ground, typically via drain tile, ditch, sump pump discharge, or—in some cases—a standing column well. Condensate water is pumped out separately.
A25: Discharge water is returned to the ground, typically via drain tile, ditch, sump pump discharge, or—in some cases—a standing column well. Condensate water is pumped out separately.
Q26: Is a backflow prevention device installed on the well piping to prevent contamination?
A26: While not always necessary, backflow prevention devices are installed where local regulations require them.
A26: While not always necessary, backflow prevention devices are installed where local regulations require them.
Q27: What is the estimated installation cost for running the return water pipe to the existing well?
A27: This depends on the site and should be determined on a case-by-case basis, ideally with an experienced standing column installer.
A27: This depends on the site and should be determined on a case-by-case basis, ideally with an experienced standing column installer.
Q28: What does it cost to pump the well water to 40 psi, which is more than required for running it through the heat exchanger?
A28: Pumping power depends on site specifics. Generally, it takes about 200 watts for a 1.5 ton unit and 300 watts for a 2.5 ton unit. Some have tried dual-pressure controllers, but simple single-setting pumps are generally preferred.
A28: Pumping power depends on site specifics. Generally, it takes about 200 watts for a 1.5 ton unit and 300 watts for a 2.5 ton unit. Some have tried dual-pressure controllers, but simple single-setting pumps are generally preferred.
Q29: Will this system work in the Southwest, where water is scarce and pressure is low?
A29: Probably not. The system is better suited for areas with high water tables and high-yielding wells.
A29: Probably not. The system is better suited for areas with high water tables and high-yielding wells.
