The hottest thing in HVAC, especially here in Massachusetts, is heat pumps. You are forgiven if you don’t really know what a heat pump is and you’re even more confused about why the words ductless and mini-split sometimes come up in the same breath.
HVAC is indeed a little confusing, so it’s not unusual for people to use the shortcut “heat pump” when they really mean a ductless mini-split heat pump. Let’s break it down.
First, a super quick physics lesson. There is no such thing as Hot or Cold, there is only a difference in how we perceive Heat or No Heat (and degrees therein). This is because heat is energy, and cool is the absence of that energy. Here’s how that applies to HVAC:
- Air conditioning is the process of removing heat from your house and putting it outside. It is not the process of adding cold to the inside of your house.
- Heating systems (furnaces and boilers) usually create heat by burning something (combustion). That is the process of adding heat to the inside of your house.
Photo by Preethika Anbalagan on Unsplash
A heat pump is a piece of technology which moves heat from a source to a destination.
- Air conditioners are heat pumps! They move heat from inside your home to the outside.
- Furnaces and boilers are not heat pumps! They generate heat by burning a fuel source and push it around your house via ducts.
- A two-way heat pump replaces both by moving heat from outside to inside — even in a cold Boston winter in addition to its normal function of moving heat from inside to outside.
Ducted HVAC (central heating and cooling) uses ductwork in your walls, ceiling, and attic to move hot or cold air around your home.
There is usually one “air handler” — the part which actually moves the air — per air conditioner or furnace in the home. The air handler for air conditioners ejects the heat in the house to the outside. The air handler for furnaces blows the heat the furnace created into the ducts to move around the house.
Ductless HVAC — a.k.a. a mini-split — forgoes all of that bulky, leaky ductwork and uses small tubing to pass air from the unit outside to the rooms inside. Ductless HVAC is perfect for small homes, old homes, and sometimes as an addition to an existing ducted HVAC system. Learn about good places for mini-splits.
The mini-split is the air handler, and you have one in each room where you want climate control instead of one for the whole house. Instead of a central thermostat, each mini-split sets its own temperature.
All mini-splits have a heat pump outside the house (or apartment) – some are only air conditioners and may be called ductless air conditioners or mini-split AC instead of mini-split heat pumps.
Some mini-splits have two-way heat pumps which provide heating in addition to cooling. In climates with cold winters, like Boston, a mini-split without a two-way heat pump won't be sufficient for year-round comfort. You would need to rely on your existing heating setup.
The main reason you might choose a heat pump over an air conditioner + furnace combination is that one heat pump can do both heating and cooling, so there’s no need to have both an AC and a furnace.
Ductless Mini-Split Heat Pump Systems are Energy Efficient.
Each component in the very long name of these systems contributes to their overall energy efficiency — especially when compared with central or ducted HVAC.
Ductless is energy efficient. Ductwork in homes is notoriously hard to maintain. It needs to be cleaned regularly to maintain its efficiency (and it rarely is). The materials used to connect different sections (usually actual duct tape), breaks down over time. Between these two issues, ductwork is leaky. The EPA estimates 30% of a central HVAC system’s inefficiency comes from the ductwork alone.
Heat pumps are energy efficient. Unlike a furnace which needs a tremendous amount of energy (whether electric, natural gas, propane, or oil) to produce heat, a heat pump simply moves heat from the outside to the inside (even when it’s cold outside).
Mini-splits are energy efficient. Throughout the day, each room in a house is a different temperature based on which way its windows face, which side of the house it’s on, and whether or not there are shade trees surrounding the room.
Instead of adjusting the whole house to make a cold or hot room more comfortable, mini-splits let you control just the room which needs adjusting. Hot person in a hot room? Adjust the temperature down in just that room. Cold person in a cold room? Heat up just that room. Much less energy is required to heat or cool one room than a whole house.
Ducted mini-splits are less energy efficient. There is such a thing as a ducted mini-split. Those ducts lose a lot of energy through leaks, so these models are less efficient and therefore less popular.
Pushing Energy Efficiency Even Further
Beyond the inherent energy savings, there are ways to save even more energy with a ductless heat pump mini-split system.
- Use the auto setting on the mini-split. It will manage the desired temperature on its own in the most efficient way possible.
- Adjust where the air flow points. Blowing the hot or cold air from the mini-split right onto yourself isn’t the best way to get the most out of the system. By directing the air slightly away from you — either or lower or higher — the unit will be more efficient.
During the summer, direct the air above where the people are. During the winter, direct the air below where the people are. - Maintain your mini-split regularly. Like central HVAC, mini-splits have air filters inside which need to be cleaned regularly to maintain their maximum efficiency.
Upfront Costs and Financial Incentives
While ductless mini-splits heat pumps offer significant long-term savings, the initial cost is typically higher than a non-heat pump system. The costs come from the heat pump itself, the mini-splits, and the costs go up if you’re installing a multi-zone system with more than one heat pump (usually in large houses).
To help offset the upfront costs of switching from central HVAC to mini-splits, there are financial incentives available to Boston area residents from the state of Massachusetts and from the federal government.
Mass Save: this program offers rebates on the whole cost of your system, plus rebates on upgrading your insulation. If you are low income, you may be eligible for even bigger rebates. For any amount you spend that isn’t rebated, you can also get a o% interest HEAT loan to make affording the switch easier.
Federal Tax Credits: The federal government also offers tax credits to help bring down the cost of installing energy-efficient appliances in your home — especially heat pumps. The credits can be used again and again if you make improvements over time.
Is a Heat Pump Worth It?
For those seeking a year-round home comfort solution and the potential for significant energy savings, a heat pump mini-split is a compelling option. The initial investment can be recouped over time through lower energy bills, and financial incentives can further sweeten the deal.
In Chelmsford, many residents can leverage Mass Save rebates and incentives to further offset the cost of installing a ductless mini-split system.
By consulting with a qualified Chelmsford HVAC contractor specializing in mini-splits, you can determine if this innovative technology is the right choice for your home comfort needs.