It’s important to know up front what you’re looking to get from your heat pump. Some common reasons people switch to heat pumps are cost savings, comfort, reduced environmental impact, convenience, and aesthetics. Be sure to share your goals with your installer. It’s also helpful to know if the heat pump will be the only heating system, the primary system, or a supplemental system.
The primary drivers of heat pump costs are the number of indoor units installed and the complexity of installation. Costs can be reduced by maximizing the space that each indoor unit heats and cools, as well as by selecting locations that are easy for installers to access.
Indoor unit location
- Heat rises — while an indoor unit might deliver some heat to the floor above, it won’t send any heat to the floor below. Likewise, cool air from a first floor unit in air conditioning mode will not cool any floors above it.
- Air flow is tough to predict and every building is different. In general, open spaces tend to be easy to heat and cool from one indoor unit, while it can be challenging for heat to go through a doorway. In addition, a room with a door that is typically closed will not benefit from a heat pump located outside the room.
- The interaction with existing thermostats can be tricky. If an existing thermostat (for example, for a boiler) is going to end up in a space heated by a heat pump, then that boiler thermostat will never fall below its setpoint and will never ask for heat. As a result, other areas served by the same zone (such as bedrooms served by the boiler but not by the heat pump) may become cooler than desired. If you are not adding multiple heat pumps to cover the entire boiler zone, consider moving the boiler thermostat to another part of the boiler zone during your heat pump installation.
Indoor unit types
There are four types of indoor units:
- Wall units are by far the most popular. They are the most efficient and, because they are mounted high on a wall, they can heat or cool a large area. That said, they are also the most noticeable.
- Floor units are mounted on the wall down by the floor. They are less conspicuous, but are not as efficient and their airflow can be obstructed by furniture.
- Ceiling cassettes are mounted above the ceiling and only their vents can be seen. They are nearly invisible, but are less efficient and may not be able to distribute warm and cool air as far as a wall unit. These are typically installed in attic floors or above suspended ceilings.
- “Ducted ductless” indoor units are ceiling cassettes that connect rooms. The most common configuration is a vent in a hallway ceiling that takes in air, and 2 to 3 ceiling vents that supply warm and cool air to adjoining rooms.
Outdoor unit locations
Ductless heat pump outdoor units can be up to 60 feet away from their indoor units, so there’s a lot of flexibility as to where they are installed. Here are some considerations:
- Aesthetics – This consideration is highly personal but important. It can take a while to get used to seeing a heat pump, especially at first. Careful planning can minimize the visual impact of your outdoor unit.
- Unobstructed airflow – Although it’s tempting to tuck units into tight places for aesthetic reasons, it’s important to remember that they heat and cool based on outdoor air. The more access they get, the better they’ll work. Avoid shrubs, places prone to snow drifts, and structures that may block airflow.
- Door/window/walkway interference – It’s best to avoid installing the outdoor unit where it could interfere with the operation of a door or window. In addition, outdoor units release water when they defrost in the winter, which can form icy patches. Be sure to pick a spot where that won’t be an issue.
- Roof runoff – If the outdoor unit is going to be installed under a roof drip line, then be sure the unit is equipped with a rain cap.
- Serviceability – Keep in mind ease of service when selecting an installation location.
Line sets – Indoor units are connected with outdoor units by two insulated copper pipes and one wire. It’s easiest to hide them in a closet, basement ceiling, attic floor, or outside wall, but sometimes they can be hidden in a wall. These decisions affect both costs and aesthetics.
Condensate drain line – When heat pumps are in air conditioning or dehumidification mode, they produce condensate. This water needs to be drained, such as to a garden or downspout.
Code Requirements – As with most residential and commercial equipment installations, it’s best to consult with your installer to ensure code compliance. These requirements may impact installation costs.