My Heat Pump Story

Heating and Cooling with One Super-Efficient Appliance and No Direct Emissions.

Our furnace died. It had every right to. It had been installed when the house was built in 1948, and had heated that house for 64 years! Even in Los Angeles it can get chilly in winter, and some sort of heat is necessary for a few months each year, so for a while we heated the house room by room with a couple of electric, oil-filled radiators. Our electric bill was manageable thanks to our solar panels, but it was definitely a temporary solution.

The Search

Thus began the search for a furnace replacement. Our initial goal was simply to replace the now defunct antique, not being aware in 2016 of the climate impact of gas-fired appliances. Even that proved a challenge, as a new furnace could not replace the old one without opening walls in our 932 sq ft house.

As research continued, the idea of adding air conditioning took hold. As summers are getting warmer – even on the ocean-adjacent westside of LA – we decided to add AC to our plans, if we could manage it. As with a furnace, equipment size and location were a problem, and a central HVAC system was finally rejected when we realized that our old ducting would need to be replaced at significant cost.

The Solution

We were temporarily flummoxed until we came across a type of heat pump, the ductless, mini-split HVAC system. Friends had recently installed one with good results. A little research led me to realize that this solution was already widespread around the world, though less well known in the U.S. back in 2016. I knew little about it, but was soon impressed by what I learned.

Ductless, mini-split heat pumps include an outdoor compressor unit connected to internal, room by room wall units. They run entirely on electricity. The outside unit looks a bit like a slimmer version of an air conditioner unit. It is also virtually silent, especially in contrast to the lumbering noise of your typical AC unit!

These systems utilize a heat pump which heats and cools indoor air, depending on the season. Mini-splits are air-to air heat pumps, the most common of the two main technologies, the other being the geothermal heat pump. There are even portable heat pumps that can be used in apartments! I will discuss these and other options in more depth in my next blog, How to Heat Pump. Suffice to say that the mini-split, air-to-air heat pump was the one for us!

How Does a Heat Pump Work?

Rather like a refrigerator, heat pumps utilize the principle of thermodynamics to move warm air from one location to another. They literally pump heat in to heat, or pump heat out to cool. In winter, cold outside air is still warmer than the refrigerant inside the heat pump. (1) That relative heat from outside is drawn inside by passing the air over an evaporator coil, transferring heat energy from the air to the refrigerant. The refrigerant then passes through and heats a condenser coil, and that heat is then released indoors as a fan blows air across the coil. At the same time, any cool air is pulled from the indoor air and ejected outdoors. The process works in reverse during the summer months, working like a conventional air conditioner to cool a home,  moving warm air out while cooling recirculated indoor air. (2, 3)

It seems magical to me, but however it works, the mini-split heat pump has functioned brilliantly in our home. There are pros and cons, as with anything, but the pros have far outweighed and outnumbered the cons over the last seven years of heat pump happiness.

Pros

Among my favorite features of ductless, mini-split heat pumps are that they…

• Heat and cool a house with one system.
  • A traditional furnace only heats the air, requiring two major equipment systems to heat and cool a home.
• Heat and cool a house room by room.
  • You can vary the temperature from room to room, increasing energy efficiency.
• Are more energy efficient than other types of HVAC systems.
  • 50% more efficient than resistant electric heating systems (4)
  • Four times more efficient than gas furnaces because heat pumps move heat from one place to another rather than burning fuel to heat or cool air (5)
• Are extremely quiet, both indoors and out.
  • The main outdoor unit runs at a very low hum. Compared to a traditional air conditioning unit, mini-split heat pumps are virtually silent.
  • Indoor wall units are also very quiet, with only the noise of the remote-controlled fan.
• Dehumidify more effectively than traditional air conditioners (not an issue in LA!). (4)
• Produce no direct emissions as there is no fuel combustion.
  • The source of electricity will determine the overall emissions produced by running a heat pump system.
  • With home solar panels there are minimal associated emissions (relating to the back-up grid), and none at all with a home battery backup.
• Cost less over time, and sometimes even in upfront costs.
  • Our heat pump system was competitive with a gas-furnace and AC unit combo.
  • Heat pump efficiency keeps electrical bills low, and rooftop solar can bring the energy cost to zero for much of the year.
  • Heat pump systems vary in cost depending on location, existing home conditions, and system type.
    • Seek out experienced local contractors or electrification advisors
  • The 2022 Inflation Reduction Act already offers federal tax credits and will provide for state-administered rebates for heat pumps and a variety of energy efficient upgrades.
    • Once available by 2024, IRA rebates will be $2000 per household for heat pumps, and even more–as much as $8000–for low-and-moderate income households. (6, 7)
  • Many local utilities already offer rebates for efficiency upgrades like heat pumps
    • We received a rebate from our local utility for our heat pump installation

Cons

The main disadvantages of ductless, mini-split heat pumps are that they…

• Are aesthetically intrusive in indoor spaces, compared to ducted systems.
  • Wall unit size will vary depending on the dimensions of the room, but they are essentially rectangular boxes on your wall.
  • You may have limited choices as to where the wall units can be placed.
  • There are now options for locating wall units inside a ceiling or under the floor where possible. (8)
• Must have the main compressor unit located outside the home for air-to-air transfer, so placement is key for function and aesthetics.
  • A heat pump can sometimes take over the location of a pre-existing , exterior air conditioning unit.
• May require a circuit board upgrade depending on heat pump size and age of home.
• Require a little bit more maintenance than traditional furnace/central air combos.
  • Yearly professional cleaning is recommended to maintain all components and check/refill refrigerant as needed. (9)
  • More frequent indoor filter cleaning can easily be done by the homeowner.

Wrapping Up…

The ductless, mini-split heat pump has been a great solution for our house. It may be for yours too. Depending on your home and its geographic location, however, ducted air-to-air heat pumps or geothermal heat pumps could be a better match for your needs.

Whatever works best for your home, be assured that any type of heat pump will reduce your home’s energy use and associated emissions.  I’ll give an overview of other heat pump options, and their pros and cons, in a future blog…How to Heat Pump. Come back soon for that offering!

Sources

1. NPR – 6 Things to Know About Heat Pumps, A Climate Solution in a Box
2. Inside Climate News – International Commission Votes to Allow Use of More Climate-Friendly Refrigerants in AC and Heat Pumps
3. PBS Newshour – More Homes Using Heat Pumps as Cheaper, Greener Alternatives to Fossil Fuels
4. U.S. Department of Energy – Heat Pump Systems
5. Bloomberg News – Five Questions to Ask Before You Buy a Heat Pump
6. U.S. Department of Energy – Inflation Reduction Act of 2022 – What it Means for You
7. California Energy Commission – Inflation Reduction Act Residential Energy Rebate Programs in California
8. Consumer Reports- Heat Pump Buying Guide
9. Forbes – Heat Pump Vs. Furnace: Major Differences, Pros And Cons