How a Ground Source Heat Pump Works

​

A ground source heat pump operates on the same refrigerant cycle as a conventional air conditioner, but exchanges heat with the ground instead of the outdoor air. A buried loop of piping circulates fluid that absorbs or releases heat depending on the season.

In winter, the fluid absorbs heat stored in the earth and carries it to the heat pump, where it is concentrated and transferred to your home's air distribution system. In summer, the process reverses: the system removes heat from your home and deposits it into the cooler ground.

At depths below the frost line, Iowa ground temperatures remain between 50 and 55 degrees Fahrenheit throughout the year. That thermal stability is what gives geothermal systems their efficiency advantage. A standard air-source heat pump works against outdoor temperatures that can drop below zero in an Iowa winter. A ground source heat pump always has a temperate, stable heat reservoir to work with.

Coefficient of Performance (COP) Efficiency in geothermal systems is measured by COP, the ratio of heat energy delivered to electrical energy consumed. Most ground source heat pumps operate at a COP between 3.0 and 5.0, meaning three to five units of heating or cooling energy are delivered for every one unit of electricity used. No combustion-based heating system can match that ratio.

​

Ground Loop Configurations

​

The ground loop is the buried pipe network that connects the heat pump to the earth. Loop design depends on your property's land area, soil conditions, and budget. 72

Degrees evaluates each site before recommending a configuration.

Horizontal Closed Loop

Horizontal loops are buried in trenches typically four to six feet deep. They require more land area but generally cost less to install than vertical systems. For rural Iowa homeowners with acreage, a horizontal loop is often the most economical choice. Trenches can be placed in fields, along fence lines, or in open lawn areas.

Vertical Closed Loop

Vertical loops are drilled straight down, often to depths of 150 to 300 feet per borehole. They require a smaller surface footprint, making them suitable for properties where horizontal trenching is not practical. Drilling costs are higher, but the smaller disturbance to your landscaping and yard is often worth it.

Pond or Lake Loop

If your property includes a pond or is adjacent to a suitable body of water, a submerged loop is an efficient and cost-effective option. Water transfers heat more readily than soil, so pond loops can perform well with less installed footage.

Open Loop

An open loop system draws groundwater directly from a well, passes it through the heat pump for heat exchange, and then returns it to an aquifer or discharge point. Open loops are efficient where water quality and supply are adequate and local regulations permit. 72 Degrees can evaluate your well and determine whether an open loop is a viable option for your property.

Efficiency, Energy Costs, and Savings

Heating, cooling, and water heating together account for roughly 70 percent of a typical home's energy bill. A ground source heat pump addresses all three.

Because geothermal systems deliver more energy than they consume, homeowners who switch from propane often see substantial reductions in annual operating costs. Propane prices are volatile and typically higher per BTU than electricity, which makes the efficiency ratio of a geothermal system especially favorable in rural Iowa where natural gas is not available.

Desuperheater for Hot Water Many geothermal systems include a desuperheater, a component that captures waste heat from the refrigerant cycle and uses it to pre-heat domestic water. During peak heating and cooling seasons, a desuperheater can offset a significant portion of your water heating costs at no additional operating expense.

Longevity and Maintenance The indoor components of a ground source heat pump are protected from weather, ice, and UV exposure that degrade outdoor HVAC equipment. Ground loops, once installed, carry manufacturer warranties of 25 to 50 years and typically require no maintenance. Indoor equipment life expectancy is generally 20 to 25 years, compared to 15 to 18 years for conventional systems.

Federal Tax Credit

Under the Inflation Reduction Act, residential geothermal heat pump installations qualify for the Residential Clean Energy Credit, which covers 30 percent of total system and installation costs through 2032. The credit steps down to 26 percent in 2033 and 22 percent in 2034 before expiring.

For a system with an installed cost of $20,000, a 30 percent credit represents $6,000 in direct federal tax reduction, not a deduction. This is one of the most significant residential energy incentives currently available, and it applies to both new installations and replacements of existing equipment.

Iowa utilities may also offer additional rebates for high-efficiency geothermal systems. 72 Degrees can help identify what incentives apply to your project.

Is Geothermal Right for Your Iowa Home?

Ground source heat pumps perform well across a wide range of Iowa properties, but some situations are a particularly strong fit.

You heat with propane. Propane is expensive on a per-BTU basis and subject to price swings. Geothermal eliminates combustion fuel costs entirely and replaces them with the lower, more predictable cost of electricity. Homeowners who switch from propane typically see the largest operating cost reductions.

You are building or replacing a system. New construction is the easiest context for geothermal because loop installation can be coordinated with other site work before landscaping and finish grading are complete. System replacement is also a natural entry point, particularly when an aging propane or electric resistance system is due for retirement.

You have land area available. Rural Iowa properties with acreage are well suited to horizontal loop systems, which are less expensive to install than vertical drilling. Even modest land areas can accommodate horizontal loops with careful layout planning.

You want long-term operating cost certainty. Geothermal removes dependence on fossil fuel pricing. Your heating and cooling costs become a function of your electricity rate, which is more stable and more predictable than propane or fuel oil markets.

The Installation Process

A geothermal installation at 72 Degrees begins with a site evaluation. We assess soil conditions, available land area, well access if applicable, and your home's heating and cooling load to size the system correctly. Undersized systems struggle in deep cold snaps; oversized systems cycle inefficiently and increase wear.

Loop installation is completed by a drilling or excavation crew. For horizontal systems, trenches are opened, pipe is laid, and backfill is restored. For vertical systems, boreholes are drilled and grouted. Once the loop is in the ground, the indoor heat pump unit is installed and connected to your existing ductwork or a new distribution system.

Most installations are completed within three to five days depending on site conditions and loop type. After startup, we verify system operation and walk you through controls and maintenance expectations.