Heat pumps work by using refrigerant and a compressor to move energy against a temperature gradient. If you put 1 kWh of energy into a heat pump, you get 3-5 kWh of heating in your home. But this isn’t breaking the laws of physics because heat pumps don’t make heat, they move it around. The extra 2-4kWh gets absorbed from the outdoors, even when it is cold outside. The low pressure refrigerant in the outdoor heat exchanger is colder than the outdoor air, so it has to absorb energy. After the compressor the refrigerant in the indoor heat exchanger is hotter than the indoor air, and energy flows into your home. This happens in a continuous cycle. A great feature in this system is a reversing valve that allows the flow of refrigerant to be flipped and your heat pump becomes an air conditioner.
There’s a big push to end fossil fuel use in US homes by electrifying all end-uses, and heat pumps are a critical part of this. Space heating is 50% of the average homeowners energy consumption, and makes up 10% of overall US energy use. Recognizing the importance of heat pump adoption, the recently passed Inflation Reduction Act contains $4.3B in heat pump rebates for low and middle income families, and a $2000 tax credit that applies to everyone. Heat pumps can also save homeowners on their monthly utility bills vs. heating with natural gas, propane, fuel oil, and electric resistance. And thanks to the popularity of vapor injection systems, heat pumps now work well even in the cold climates of the Northeast.
Quick technical aside on vapor injection systems - this is an improvement to the basic vapor compression cycle. Gas from the condenser outlet is injected halfway into the compression process. This increases the compressor efficiency, increases the mass flow rate of refrigerant through the compressor, and also lowers the discharge temperature. The result is higher system efficiency, higher heating capacity, and the ability to operate across large temperature gradients (say -15F outside temp to 72F in your home) without exceeding the discharge temperature limit and damaging the compressor.
I’ve spent my career building and designing thermal systems—first in aerospace, then at Tesla working on Model 3 and Semi Truck, and most recently in vertical farming. I got really excited about residential heat pumps when I realized that we’re about to go through a huge transition where the 80M single family homes in the US replace their furnaces with heat pumps.
But the products on the market today have a number of shortcomings. The homeowner experience sucks because the integration of thermostat, heat pump equipment and air quality systems is terrible. Nothing works together well, and the best thermostats are not fully compatible with inverter driven heat pumps. In addition the process of getting a heat pump is painful, including finding a trustworthy contractor, sorting out financing, and wading through rebates. And finally contractors struggle with installs because of the difficulty of properly sizing the system, and understanding if your duct work is compatible with a heat pump
I wanted to approach home heating and cooling from a product design approach, improve the end-to-end experience for homeowners and make a product that was compelling beyond its climate motivations. Electric Air is building a thermostat as well as heat pump equipment (air handler and condenser) and a contractor web-app.
Better air quality is achieved through a thermostat with PM2.5 and CO2 sensors, as well as an air quality module on the air handler that controls HEPA filtration, fresh air intake and modification of the home’s humidity. The thermostat algorithm combines demand-response with weather and time-of-use rate plans to reduce monthly utility bills through pre-cooling and pre-heating. Unlike a Nest or Ecobee, the thermostat will be able to run the heat pump in variable speed mode. A more powerful air handler blower and contractor software enables more ducted installs - no wall units required. The most common heating system in the US is a natural gas furnace connected to ductwork, with the hot air ultimately coming out of vents in each room. This heat pump is a great replacement for the furnace and air conditioner in these ducted systems. The same software used for ducts also helps contractors perform simple load disaggregation (turn a utility bill into a thermal load calculation) to properly size a heat pump system. In addition there’s actually some industrial design going into the outdoor condenser, meaning you don’t have to hide it in an alley. And finally homeowners can purchase this system online. We help with financing and rebates, and connect them with a contractor to do the actual install.
How come no one’s doing this? Heat pump manufacturers are bad at making consumer products like thermostats and the thermostat manufacturers are IOT companies that don’t have the know-how to wade into heat pump equipment manufacture. For heat pump manufacturers, their end customer is largely HVAC contractors, and not homeowners. Also selling direct means disrupting their current distribution strategy which normally involves selling to regional distributors, and sometimes straight to contractors. Getting this right is a big systems integration problem that the current players are ill equipped to handle.
While we don't have any physical prototypes at the moment, we have the industrial design and also largely understand how this will be built. The core technology risk is quite low, it's really about executing the scope well and also finding the right product that homeowners find compelling. I'm working on building traction via preorders (https://electricair.io), and will start building hardware once fundraising is complete, likely in the next few weeks.
What issues have you had with your existing heat and cooling, and do you have any interesting stories around a heat pump install or use? I would love to hear your ideas, experiences, and feedback on any and all of the above!
by Andrey
Azimov