How to heat (and cool) your home with heat pumps
Whether you’re ready to install a heat pump or just curious, this blog will answer all your questions. Maybe your neighbor recently got one installed, and you think it might be a good fit for you. Maybe your heating system is on the fritz and you’re doing your research on a replacement before it goes. Maybe you’ve heard about them in the news and wanted to understand the fuss. No matter what, this article has the answers on heat pumps for heating and cooling your home.
Use the table of contents to jump to the information you’re looking for. Or read on for a deep dive into all things heat pump. If you’re looking for information on heat pump water heaters, check out this article.
Chapter 1: How do heat pumps work?
Chapter 2: Is your home ready for a heat pump?
Chapter 3: Understand your home’s layout and heating system
Chapter 4: What are your home heating goals?
Chapter 5: The four types of heat pumps
Ductless heat pump
Ducted heat pump
Air-to-water heat pump
Ground source, or geothermal, heat pump
Chapter 6: What are the next steps on your heat pump journey?
How do heat pumps work?
Heat pumps run on electricity rather than fossil fuels or wood, like other common heaters in Vermont. They are 2-4 times more efficient than electric resistance heating. They can also often provide cooling in the summer. The reason they’re so efficient is that they move heat from one space to another, rather than creating it through combustion. It’s similar to how AC units work, but heat pumps can provide both heating and cooling.
Both heat pumps and fossil fuel heaters have whole-home and space heating options. While many homes have a central furnace or boiler, some homeowners choose to heat individual spaces with space heaters.
Fossil fuel heaters typically have just one central unit inside a home. Heat pumps have an indoor and and outdoor unit. Refrigerants run between these units, bringing heat and cooling between them. In the summer, a cold liquid refrigerant goes into the house. Since the refrigerant is colder than the air in the house, it absorbs heat from the home. That effectively cools the home. The warmed refrigerant goes back outside through a compressor, which heats it further. When the refrigerant is warmer than the outside air, it will reject that heat outside. The cooler refrigerant then passes through an expansion valve to drop the temperature. The process repeats, keeping your house cool even when it’s warm outside.
In the winter, the process reverses. The cold refrigerant is outside, absorbing heat from the outdoors. When it’s compressed and heated up, it rejects that heat into your home, warming your home. The cycle continues, keeping your home warm even when it’s cold outside. Modern heat pumps can work down to –20 degrees Fahrenheit or lower. They may start to lose efficiency or have lower output when the temperatures fall.
Heat pumps operate at significantly lower temperatures than fossil fuel heaters. They are so efficient in part because they only heat as much as is necessary. Combustion heaters provide extreme levels of heat which can quickly dissipate as it spreads throughout the house. Because traditional heating systems operate at higher temperatures than heat pumps, it’s not always possible to retrofit existing systems with a heat pump.
What's the difference between fossil fuel heaters and heat pumps?
| Heat Pumps | Fossil Fuels | |
|---|---|---|
| Energy source | Electricity | Propane, fuel oil, or natural gas |
| Temperature of heat | Low heat | High heat |
| Efficiency | High efficiency | Low-medium efficiency, depending on system |
| Equipment needed | Indoor and outdoor units | Indoor unit |
| Types of heating | Single zone and whole home options | Single zone and whole home options |
| How they work | Move heat using refrigerants | Create heat through combustion |
Is your home ready for a heat pump?
Your heat pump journey will be more successful if you know what your home needs before you get a heat pump. Your home needs adequate electric service to run a heat pump. Weatherizing your home will enable the heat pump to perform efficiently and cost-effectively.
Most homes in Vermont have 100- or 200-amp electric service, which is the maximum amount of amperage you can draw before tripping a breaker. Adding a heat pump will increase your home’s electric usage, so it’s important to know if you have enough electric service to cover the additional load. A heat pump contractor or electrician can evaluate your current electric service. If an upgrade is necessary, a professional can give you an idea of what the upgrade will cost. Some upgrades are simple, like adding a subpanel. If you have to increase the service size, that’s much more costly. Understanding what your home needs before you begin will avoid unwelcome surprises later.
Weatherization helps keep warm air in your home in the winter (and out of it in the summer). If you add a heat pump without weatherizing, you’re paying for some of that heat (and cooling in the summer) to escape outside. By weatherizing, you’ll maximize your investment in your home. Some contractors do both weatherization and heat pump work in Vermont. Use our tool to find an Efficiency Excellence Network contractor in your area who will help you take advantage of available rebates.
You might be ready to install a heat pump in your home if one or more of these apply:
- Your current heating and cooling system is not keeping you comfortable or is ready to be replaced
- You’re interested in reducing your fossil fuel use
- Your electric panel has sufficient space and service to operate a significant electric load
- Your home has been recently weatherized
Understand your home's layout and heating system
The layout of your home will impact where heat pumps can be installed and how much of your home they can heat.
- Open floor plan vs. multiple rooms. If you have an open floor plan, a single ductless heat pump can provide significant heating for your living space. If you have multiple rooms shut off by doors or walls, the heat from a ductless heat pump won’t reach those rooms. It may be easier to heat those rooms using your existing heating system or a central heat pump solution.
- One story vs. multiple stories. While heat rises in a home, a single ductless heat pump on the first story will likely not fully heat the second story. One heat pump on each level may be sufficient to reduce reliance on your fossil fuel heating system for much of the year.
Your existing heating distribution system will also impact your heat pump choice. If you choose a central heat pump system, the project will be significantly less expensive if you can use your existing heating distribution system. Part of what makes heat pump systems so efficient is that they operate at lower temperatures. Most heating distribution systems lose significant heat between the furnace or boiler and the living space. Heat pump distribution systems have to be more insulated so the heat is maintained into the living space.
- Ducted systems. In some cases, your existing ductwork can be used for a central ducted heat pump system. They must be designed and installed with a fan to move air through the ductwork. In many cases, the ducts will need to be altered or fully replaced.
- Radiators or Baseboard Heaters. In almost all cases, these systems are designed for extremely high temperatures. They will not work with an air-to-water central heat pump system.
- Radiant Slab. An air-to-water heat pump may work well with an existing radiant floor.
Different types of heat pumps work best in different layouts. Some heat pumps also require specialized distribution. Understanding your home will help you understand how heat pumps will work in it.
At the end of the day, your best resource will be an Efficiency Excellence Network contractor. Your contractor can look at your home with you and tell you what system will be the best fit.
Identifying your home heating goals
Vermonters choose to install heat pumps for several reasons. Identifying your goals will help you choose the type and number of heat pumps to install. Knowing your goals before you talk to a contractor will help you be satisfied once the project is complete.
I want to improve the comfort of my home.
Heat pumps can make your home more comfortable in the winter and the summer. A single ductless heat pump installed in your living space can provide comfort no matter the temperature outside. You’ll still rely on your central heating system to keep you cozy on the coldest days and to heat separate rooms in your home.
I want to save money on my heating bills or reduce my use of fossil fuels.
Depending on your current heating system, the layout of your home, and the heat pumps you install, heat pumps can help you save money and use less fossil fuels. In most cases, you’ll need more than one ductless heat pump to result in significant cost savings or fossil fuel use reduction. You’ll still have your central heating system for backup on the coldest days.
I want to replace my current fossil fuel heating system.
Ductless heat pumps almost always require backup heat. However, whole home heat pump systems (ducted, geo-thermal, or air-to-water) are a great solution for some homes and can fully replace a fossil fuel furnace or boiler.
The four types of heat pumps
Below are the four main types of heat pumps on the market. Your contractor will be able to advise you on how to meet your heating goals in your specific home. Understanding your options upfront will help you navigate that conversation.
Here’s an overview of the four types of heat pumps with simple ratings for their complexity and cost. Read each section for more detail about these ratings.
Ductless heat pumps are the most popular heat pumps in Vermont. Ductless heat pumps have been used for cooling in warmer climates for decades. Around 2010, manufacturers improved the technology to provide heating even in Vermont’s cold winters. Since then, they’ve only grown in popularity. Today tens of thousands of Vermonters have installed ductless heat pumps.
| Type of Heating System | Point source (the heat comes directly from the heater with no distribution like ducts or pipes) |
|---|---|
| Distribution | None |
| Home heating load | A single heat pump serves a single living space. Multiple wil llikely be needed to reach the whole home. |
| Cooling | Yes |
| Back-up system requirement | Yes |
| Types of equipment | Wall mount, floor mount, and ceiling mount |
What is a ductless heat pump?
A ductless heat pump is a single zone heater. That means it heats a specific space in your home. The heat pump emits warm air directly, without passing through ducts or pipes. Different models can be installed high on a wall, on the floor, or in the ceiling to fit your room’s configuration and your aesthetic preferences. In the summer, the heat pump can be used as an air conditioner to keep your living space comfortable.
You can install one or more ductless heat pumps in your home. A single heat pump improves comfort in a primary living space or large bedroom. For whole-home heating, multiple heat pumps are necessary. If you have two floors, you will need at least one heat pump on each level to provide heat throughout your home. Heat pumps are most efficient when each indoor unit connects to its own outdoor unit. While you can run multiple indoor units off the same outdoor unit, it will not be as efficient.
You may still rely on your existing heating system after installing heat pumps. Your existing system will likely do a better job of reaching closed-off rooms or distant corners of the house. Using your supplemental heat on the coldest days will help keep your home warm.
Who should install a ductless heat pump?
A ductless heat pump might be right for you if one or more of these apply:
- You are looking to improve comfort in your primary living area in the summer and winter
- You have an open floor plan
- You want to offset your existing heating, and you’re open to installing more than one heat pump
Ducted heat pumps are newer than ductless heat pumps. They use the same heating technology. Rather than emitting the heat directly into your room, it is distributed through ducts. There are two types of ducted heat pump systems: central and compact. Central will feel like a furnace with central air conditioning. Compact can heat individual rooms that may be hard to heat in other ways.
| Type of Heating System | Central or compact |
|---|---|
| Distribution | Ducts (may be compatible with existing ductwork, but will likely need some upgrades) |
| Home heating load | Whole home (central) or individual rooms (compact) |
| Cooling | Yes |
| Back-up system requirement | Yes |
| Types of equipment | No (central), Yes (compact) |
What is a ducted heat pump?
A ducted heat pump generates heat in a central compressor. The heat is then distributed through ducts. The compressor can be large enough to distribute heat throughout the house. Typically these would be installed in an unfinished basement, similar to a furnace. Or you can use a compact ducted heat pump to heat one or two smaller rooms. In this case, the heat pump might be installed in an unfinished attic above smaller bedrooms.
Central ducted heat pumps can fully replace your existing heating system. If you currently have forced hot air heat, you may be able to use your existing ductwork. In most cases, the ductwork will need some upgrades to carry the lower temperature heat without losing too much on the way to your living space. The installation and upgrade could require significant work throughout your house, making this a higher cost option than ductless heat pumps. It may make sense to wait until you have a larger renovation planned.
Like ductless heat pumps, ducted heat pumps can provide air conditioning in the summer. The cool air would travel through the same ducts, providing central air and comfort all year round.
Who should install a ducted heat pump?
A ducted heat pump may be right for you if one or more of these apply:
- You are looking to replace your fossil fuel heat
- You are hoping to add central AC
- You have a house with many closed off rooms
- You have a single story home with an unfinished basement
- Your home already has or can accommodate ductwork
- You’re planning a full home renovation in the near future
If ducted heat pumps are a replacement for your furnace, air-to-water heat pumps replace your boiler. Like boilers, the system heats hot water and distributes it to provide heat throughout the house.
| Type of Heating System | Central |
|---|---|
| Distribution | Radiant flooring or specialized radiators |
| Home heating load | Whole home |
| Cooling | Only if ducts are added |
| Back-up system requirement | No |
What is an air-to-water heat pump?
Air-to-water heat pumps use refrigerants to heat water. The water is distributed throughout your house to provide comfortable, efficient warmth. If ductwork is added, the heat pump compressor can also provide cooling in the summer.
Like central ducted heat pumps, air-to-water heat pumps can fully replace your existing heating system. An air-to-water heat pump may also be able to provide your domestic hot water, depending on the system’s design. If you currently have radiant flooring, you will likely be able to use the existing distribution system. Unfortunately many existing distribution systems are designed for higher temperature water. Technology like cast iron radiators or baseboard heaters are not compatible with air-to-water heat pumps. The piping can be complicated with these systems. It will likely be most cost-effective to pair installation with an existing large-scale renovation.
Who should install an air-to-water heat pump?
An air-to-water heat pump may be right for you if one or more of these apply:
- You are looking to fully replace your fossil fuel heating system
- You already have compatible distribution, like radiant flooring
- You are planning a large-scale renovation in the near future
Ducted, ductless, and air-to-water heat pumps are all considered “air source” heat pumps. They pull hot air molecules from the outside air. Ground source heat pumps use the same principles, but pull the heat from the ground. They can pull heat from the earth or underground water. Ground source heat pumps are highly efficient to operate. However, their complexity and upfront cost make them challenging for many Vermont households.
| Type of Heating System | Central |
|---|---|
| Distribution | Specialized ductwork, radiant flooring, or radiators |
| Home heating load | Whole home |
| Cooling | Only if ducts are added |
| Back-up system requirement | No |
What is a ground source heat pump?
Like air source heat pumps, ground source heat pumps have an outside unit and an inside unit. In this case, the outside unit is buried underground. The earth or underground water maintains a more stable temperature throughout the year. That means it takes less energy to create either heat or cooling. That helps contribute to their high efficiency.
Once inside, the heat from the indoor unit is distributed throughout the house. Ground source heat pumps can use the same distribution systems as either a ducted heat pump or an air-to-water heat pump. If the household wants cooling, ducts must be added.
The excavation necessary to bury the outside unit makes ground source heat pumps the most expensive option. Due to their size, they work best in larger homes with the right site for drilling.
Who should install a ground source heat pump?
A ground source heat pump might be right for you if one or more of these apply:
- You are looking to fully replace your fossil fuel heating system
- You have a larger home
- You are planning a major renovation or new building
- You have enough space on the property to complete the drilling and excavating
What are the next steps on your heat pump journey?
Now that you understand how heat pumps work, the different types of heat pumps, and where they work best, you’re prepared to move forward. If you feel like a heat pump is the right fit for your home, reach out to a contractor. Share your home heating goals and let them help you find a solution. Your contractor will work with you to take advantage of available rebates and ensure you’ll be satisfied for years to come.
