Installing the external unit of your heat pump in your unused crawl space may seem like a tempting idea. It is an efficient use of wasted space and keeps an eyesore out of your well-maintained yard.
However, there are precautions to take when considering placing a heat pump in a crawl space. Make sure to consider all the pros and cons before going with this option.
Crawl spaces are not code-prohibited locations for heat pumps. Heat pumps can be installed in crawl spaces only if the manufacturer permits this location and if it is very well ventilated. Heat pumps will be pointless in encapsulated crawl spaces. The best and safest locations for heat pumps are well-ventilated and open.
The IRC on Heat Pumps
International Residential Code (IRC) applies through the USA and in other areas around the world. The code does have information about heat pumps, but it does not explicitly regulate their use in crawl spaces.
Heat pumps are referred to by the IRC in Sections M1403.1 and M1407.3. Section M1403.1 indicates that heat pumps must be regulated and labeled within the appropriate guidelines. Similarly, M1407.3 states that they must be labeled with the correct specifications to be located within 4 ft of duct heaters.
While the IRC does not prohibit the use of heat pumps in crawl spaces, doing so will not be a code violation. However, you’ll want to check your state and city codes to see if there are any relevant regulations for this situation on a more local level.
Manufacturer Guidelines Are Important
If there are also no specific regulations regarding heat pumps in your local codes, your next place to look is the manufacturer’s guidelines for the heat pump. Check if the guidelines specifically prohibit or warn against installation in crawl spaces or enclosed spaces. If they mention crawl spaces, you have your answer.
Most heat pumps will have at least general instructions for where to install the unit. The installation instructions may list a variety of locations or they may just provide a list of prohibited/allowed conditions (e.g., do not place the heat pump in direct or full sun).
Follow these guidelines to the best of your ability, and make sure you are not placing your heat pump in a crawl space if the manufacturer specifically recommends not to.
Some Manufacturers Design Pumps for Crawl Spaces
Sometimes, it’s not about the appliance, it’s more about the model. For example, electric heaters and dehumidifiers can be installed and effective in crawl spaces if they are designated as crawl space heaters and dehumidifiers, but a regular dehumidifier and a regular space heater are not going to do well in the same location.
Similarly, certain heat pumps are designed specifically for crawl spaces. While other heat pumps may or may not be applicable for use in this location, you can be assured that these heat pumps are correct for the job.
Horizontal heat pumps are designed to be wider and shorter than the traditional tall and slim heat pump. Since there is no difference in the internals of this version, they have essentially just taken the original heat pump and placed it on its side. However, it is essential to ventilate your crawl space well if you are going to install a heat pump there.
Arguments for Putting Heat Pump in Crawl Space
Installing a heat pump into a crawl space can improve the aesthetics of your home and give you more space to do with as you choose.
A heat pump is a large, clunky-looking metal box that is usually painted a dull grey color. It is meant to achieve a purpose rather than look attractive. Generally, the external unit of a heat pump would be installed in your yard somewhere, likely behind your house against the side or back wall.
Rather than having it take up space in your yard, where everyone can see it, using a crawl space can be an effective way to hide the eyesore. This is also a great way to use wasted space and keep all the usable space to yourself.
Are Heat Pumps Effective in Crawl Spaces?
Although there are arguments for placing a heat pump in a crawl space, there are also several significant disadvantages to this method. Most heat pumps will be much less efficient in these locations even if the crawl space is vented.
Although there are arguments for placing a heat pump in a crawl space, there are also several large disadvantages to this method. Most heat pumps will be much less efficient even if the crawl space is vented.
Heat pumps use the energy from the surrounding air to heat the house. If there is limited air supply to the crawl space the crawl space temperature will drop and this will drastically reduce the heat pump’s efficiency.
Heat pumps are effectively pointless in encapsulated crawl spaces, where the supply and loss of air are restricted.
Putting a heat pump in a crawl space makes it far less convenient to access. When it inevitably needs maintenance, as all devices do at some point, its inaccessibility will become a real pain in the butt.
There can also be dangers to keeping your heat pump in a crawl space. If a crawl space is not ventilated properly, it can lead to a build-up of radon gas, which raises risks of birth defects and cancer in those exposed to it.
Mold is a large concern with having your heat pump in a small crawl space. Since there is so much heat in a small area, the likelihood that mold will gravitate towards the moist and warm environment is high. This mold can cause unhealthy air to pump through your home if things are not ventilated well enough.
Best Locations for Heat Pumps
The ideal location for a heat pump is well-ventilated and open. Make sure there are no plants growing right next to your heat pump location. Give around a foot and a half of the distance between the heat pump and any plants surrounding it.
Precautions should be taken to prevent the heat pump from overheating in the summer. If you live in a sunny, hot climate, place your heat pump in the shade so that heat does not become a problem causing it to work harder.
Additionally, consider where snow will collect in the winter and try to place the heat pump somewhere where it will not be buried.
If you have a pool, you need to make sure to leave some distance between the pool and the heat pump. General guidelines recommend at least 6 ft of space.
People living in coastal regions must consider the impact of the sea air on their heat pump. Salty sea air can cause a heat pump to break down over time. People in these regions should make sure to install a ground-source heat pump to avoid corrosion.
If you are moving your heat pump to its new location, then check out my article on heat pump transportation.