Install Geothermal Heat Pump in the Attic

Dan Frawley

Dan Frawley

Where do you put your geothermal heat pump if you are building a home with a crawl space, or it is slab on grade and you do not have a large enough mechanical room?  Where do you put your geothermal heat pump if you are retrofitting your home for geothermal HVAC and have no room in your basement or existing mechanical room?

These, among others, are very important questions to ask before you begin your geothermal installation.  The location of the heat pump is crucial to know before you even put your project in the hands of the engineers and designers here at Eagle Mountain. Placement affects pump pack size, supply and return size, etc.  Where can you locate the heat pump?  An option is in a space that is normally used for storage, the attic.

The problem with this answer lies in whether or not your attic is a conditioned space or not.  The general rule of thumb for a geothermal heat pump is that it must be placed in a conditioned space.  The solution to the problem of placing a heat pump in an unconditioned attic is, what we call here at Eagle Mountain, a hot box.

Hot Box

Hot Box

The “Hot Box” can be essentially a 2×4 framed container that is sheathed in plywood with a removable top to create easy access for service. Once the container is built around the heat pump, you lay insulation across the attic floor and around the outside of the box.  This creates a conditioned space for the heat pump to sit in, essentially making that space part of the house, or heated space.

This “Hot Box” solution allows for two things.  First, it allows the heat pump to be placed in a conditioned space for optimal performance and efficiency.  Secondly, it allows the attic to remain unconditioned to conform to the outdoor temperature.  This is important, especially in winter, if ice damage is a concern.  Also, the attic will not be comfortable in the winter and then uncomfortably warm in the summer.  It is also important to note that piping from your geothermal loopfield to the heat pump must be insulated and contain the correct propylene glycol mixture for geothermal systems.

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