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Geothermal Best Practices For Cold Weather Performance

Home Hacks Bryson Buehrer March 10 10 minutes reading time

A salt-encrusted car, icicles on the gutters, and air that hurts your face when you go outside. All of this can only mean one thing: winter is here, and here to stay. It's no secret that when the temperatures dip, many heating systems cannot keep up with the demand of the average home, especially those with poor insulation

Luckily, homeowners with a geothermal heat pump installed are more than well-equipped to handle a harsh winter. Geothermal offers many benefits over traditional air-source or combustion-type heating systems. Using the in-ground loop field, a geothermal unit (or "ground-source heat pump") is able to pull heat energy from the 45°F-70°F earth to heat your home at efficiencies of over 400%. It's a totally unique technology and is well suited for heating and cooling spaces when the weather gets rough. We'll always recommend that people insulate properly when constructing the home, but we understand that's not always feasible in the short term when the weather is about to turn sour. So, read on to learn 4 things you can do (or avoid) right now to get the best performance out of your geothermal system in cold weather!

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4 Tips to Optimize the Performance of Your Geothermal Unit in Winter

Temperature - set it and forget it!

In general, we love the features, functions, and capabilities of modern programmable thermostats. Every year, it seems that these often under-appreciated accessories become more and more compatible with the needs of the modern homeowner! What's not to love about that?
However, when we're talking about keeping your geothermal unit in tip-top shape and maintaining excellent savings, then we have to address the "programmable" portion of that name. In theory, it makes a ton of sense to keep the home cooler while you're away and warmer when you are home, right? In practice, the benefits of keeping your home cool while you're away are offset by the high demand on the system when the higher-temperature schedule kicks in. When transitioning from the "away" temperature to the "at-home" temperature, the backup heat may kick on if the home's temperature is too far below the set point. This turns on all stages of heat in order to bring the room back up to temp as soon as possible. If you let the unit run all day at a single temperature, it can handle the high heating demands of your home, but at a significantly lower stage.
Similar to how the gas mileage in your car diminishes when you're in the city or in stop-and-go traffic, the efficiencies of a geothermal unit come from its ability to keep things consistently comfortable throughout the day.

Keep Your Air Filter and Air Coil Clean

While we're talking about consistent comfort, that will be much harder to achieve without sufficient airflow through the heat pump. While the geothermal unit works to pull heat from the ground by way of the loop field, it's taking the extracted energy, using it to heat air up to your desired temperature and, in most cases, pushing that air through ductwork and into various rooms.

The low-resistance movement of air is only possible with a clean filter and a clean air coil. Restricted air flow will cause the unit's compressor to work harder to achieve the set comfort level, meaning a greater power draw by the unit.  By keeping the filter and the air coil clean, you can rest assured that you're setting your geothermal system up for success.

In a geothermal heat pump, the air coil is one of the most integral parts of the unit. All air, whether in cooling mode or in heating mode, passes through the coil and its temperature is modified by the component. For Enertech's heat pumps, many of our units are equipped with an all-aluminum "microchannel" air coil. A microchannel air coil consists of a network of multiple flat tubes through which refrigerant flows. To maximize heat transfer, aluminum fins are inserted between these flat tubes. These coils are lighter, more durable, and provide exceptional heat transfer! With all these tubes and fins, you can imagine how an irregular maintenance schedule can cause issues with airflow. All air that flows through the air coil must first pass through the filter, so a well-cared-for filter should prevent most issues. However, in a high-particulate environment (dust, pet hair, carpet, etc.) the filter may not catch 100% of the material, which then gets caught in the air coil.

We do not recommend homeowners attempt to clean the air coil themselves! This is a process that should really only be completed by an experienced professional. Not only is the air coil hidden behind the return duct and the air filter, it's housed within the unit. A microchannel air coil should be cleaned from the inside - a process that necessitates accessing the unit cabinet and safely removing the piece. If you're working on cleaning the filter and do catch a glimpse of a gummed-up coil, it's best to call the pros. A damaged air-coil from a DIY project gone wrong will be far more expensive than calling the right person in the first place!

When it comes to the air filter, its primary purpose is to stop airborne contaminants and particulate from reaching the complex inner workings of your heat pump. When the airborne debris that would have gotten stuck inside the unit is caught by the filter, then the filter has done its job. Over time, the debris builds up and, if not attended to, will cause the unit to overheat every time it starts up: this is known as "short cycling." Regular cleaning or replacement of the filter will help you avoid this all-too-common problem!

If the problem seems severe or you're experiencing more issues than just a dirty filter, it's best to call a professional. However, if you're prepping for cold weather and want to perform some basic maintenance, that's great! It's best to perform all of this cleaning, on the filter and the air coil, before it gets bitterly cold. To clean the filter, follow these steps.

  1. Confirm that your filter type is meant to be cleaned. Some filters should be replaced each time.
  2. Turn the unit off from the thermostat, NOT the breaker.
  3. Remove the filter. A screwdriver may be needed.
  4. Vacuum the filter. Use a soft brush attachment. Sharp or hard plastic accessories can bend, pierce, or otherwise damage the filter's mesh.
  5. If a deeper clean is needed, fill a vessel with one part water and one part white vinegar, and soak for an hour. Rinse the filter gently with cool, fresh water.
  6. Replace the filter. Wait until after it has sufficiently dried, if necessary.
  7. Turn the system back on at the thermostat.

Remember, if you suspect deeper issues with your system, the unit hasn't been professionally serviced in an especially long time, or if you're simply uncomfortable with performing the filter maintenance, don't hesitate to call a local geothermal technician! If you're not sure who to contact, we can help with that

Keep Ductwork Sealed And your vents clear

This one might seem obvious, but it's equally important as any other step in this process. It's again an issue that stems from airflow, where suboptimal airflow causes longer unit runtimes and generally inefficient operation. Giving your ductwork a basic once-over and walking through the home to check that vents are clear can result in some massive improvements in the efficiency of your geothermal system.

According to Energy Star, around 20% to 30% of the air that moves through a duct system is lost due to leaks, holes, and poorly connected ducts. In cold weather, this wasted heating potential can massively effect your geothermal heat pump's ability to bring your home up to temperature. If your home has a basement with exposed ductwork in the ceiling, you may be able to repair some poorly joined or leaky ducts yourself! If you're doing this DIY repair make sure you purchase temperature-resistant duct tape, typically with a highly-reflective foil backing. The adhesive on standard grey duct tapes may fail over time as the ductwork heats up. If you suspect significant leakage in your ductwork, you'd be right to call a technician to take a look! 

The same concept goes for vents - of all types - in your home. There are three basic types of vents in your home. Supply vents provide conditioned air to your spaces, return vents pull air back into your system for reconditioning, and exhaust vents remove air from the home without return (like in an oven range vent, bathroom fan, or clothing dryer). Ensuring that all of these different vents are clear is vital to the performance of your geothermal system, as it all comes down to... you guessed it! Airflow. Be mindful of furniture if some of your supply or return vents are on the floor, and be equally cognizant of leaves, soil, or snow blocking the external portions of your exhaust vents.

Don't Mess With The Breaker

One of the most common problems that we receive calls about is when the homeowner attempts to reset their geothermal unit by flipping the breaker. Often times, homeowners do this when they notice their unit running almost all day, even though the home has come up to the desired temperature. 

Geothermal is actually at its most efficient when it's able to keep the home at a single set point (the temperature at which the thermostat is set), and the homeowner sees the greatest savings when the unit does this. At one set point, the unit can continually make small adjustments to the home's temperature over time as opposed to reaching the set point, turning off, and kicking back on to rapidly account for the new temperature swing. When the unit is turned off at the breaker, it loses the ability to keep your home at that consistent level of comfort.

Shutting down the unit at the breaker brings similar issues to setting a temperature schedule at the thermostat, as noted at the beginning of this article. The variation in demand on the unit causes it to activate all heat stages, even the supplemental electric strip heat, to bring your home up to temperature, resulting in a loss of efficiency and savings. 

Aside from setting a single set point for your geothermal unit, your installer should also ensure that the thermostat is programmed to stay in one heating stage until it reaches the desired temperature in the home. Many thermostats tell the geothermal system to downstage, or to reduce the total output, as the home reaches the set point. In general, it's more efficient and cost-effective to keep the unit in a higher stage until the desired temperature is reached in the home. All of this can be set within the thermostat, and a trained installer should know the best practices for setting your thermostat and your home up for total success!

If you're wanting to learn more about getting the most out of your geothermal system, download our FREE guide to maximizing the performance of your geothermal heating and cooling system!



Bryson Buehrer
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