Water heating consumes more energy in the home than all utilities besides space heating, costing U.S. households about $500 every year and representing a significant chunk of the nation’s greenhouse gas emissions. The steep costs are maybe no surprise considering the evolution of water-heating technology has long remained stagnant.
For more than a century, storage tank water heaters have been the most common method of delivering instant hot water to homes. These tanks use gas or electricity to keep a reservoir of water constantly hot. When you turn the hot handle of a faucet, cold water enters the storage tank, forcing hot water to travel through a plumping system and to your sink, shower, or dishwasher. It’s an effective but somewhat inefficient system.
Getting instant hot water from the tap isn’t cheap.
Tankless water heaters are a more recent and efficient system. Instead of constantly storing hot water in a tank, these systems use electricity, natural gas, or propane to heat water only when you need it. They do so by passing water through pipes into a small unit that heats water, typically with a metal heating element — essentially a metal rod that gets extremely hot.
But both storage tanks and tankless water heaters have an inherent problem: the buildup of minerals. That’s because most heating elements only have two states: on and off. They can get extremely hot, which boils the water and causes rust and limescale to accumulate on the heating element. Just a tiny bit of buildup on an element can drastically reduce efficiency.
What if water heating systems eliminated heating elements altogether? That’s the driving idea behind Heatworks, a technology company that developed a smart tankless instant hot water heating system called the Model 3. The goal is to provide homes with hot water as quickly and efficiently as possible.
Innovativing tankless water heaters
The Model 3 has no metal heating element. It turns the water itself into the heating element. Inside the unit are electronic controls and pairs of graphite plates, which themselves don’t heat up, but rather act as electrical conductors that pass electricity through the water, heating it in the process. The company calls this Ohmic Array Technology, named after the German physicist Georg Ohm.
“Using graphite electrodes and electronic controls, we increase the energy state of the water molecules, so they move faster,” Heatworks noted on its website. “The faster they move, the more kinetic energy they have. This causes the molecules to begin to bounce off each other; that kinetic energy turns into heat. Through direct energy transfer, your water is heated instantly, within (+/-) 1 degree Fahrenheit of the temperature setpoint.”
The Model 3 is efficient not only because it heats water quickly, but also because users can control the temperature to which water is heated.
That means water doesn’t boil and minerals don’t build up. And because there are no heating elements — which wear out in traditional heating systems — the unit doesn’t need to have parts repaired or replaced. If a unit fails, as some of the earlier models did, the company sends customers a new one.
The Model 3 costs $999. Callahan told Freethink that savings on heating will cover the cost of the unit after 5 years of use. But the costs of installation — and getting people to rethink water heating in general — remain obstacles for Heatworks and other tankless water heater companies aiming to make the industry more efficient.
Changing how we heat water
The technology could reap big savings on utility bills and the environment over the long term, cutting annual heating costs by 40% (about $200) and saving 2,100 gallons of water each year.
Still, these devices require a lot of electricity — up to 100 amps — when they’re running. The electrical service in most U.S. homes ranges from 100 to 200 amps, meaning homeowners who want to install tankless water heaters would typically need to upgrade their electrical systems. The costs of labor, rewiring, and new electrical equipment can be steep. As such, it’s cheaper to install tankless water heaters in new construction.
No matter the price tag, the industry also has to convince consumers it’s worth their time to upgrade to new technologies.
“It’s difficult to get homeowners to change from the technology that they’re used to, especially in staid devices like water heaters, because they think of it as a utility: open the faucet, water comes out,” Callahan told Freethink. “There’s an education process to get them to understand that there’s a better, cheaper, faster, cooler way to [heat water].”
Tankless systems like the Model 3 aren’t the only new instant hot water-heating technologies aiming to reshape the industry. Solar-powered water heaters can reduce your utility bill by 50 to 80%, according to the U.S. Energy Department. Heat pump water heaters — which extract heat from the air, store it in tanks, and use it to heat water — are estimated to be at least twice as efficient as conventional systems, partly because they can store midday heat and use it later that night.
There’s not necessarily one best method for instant hot water. After all, solar-powered water heaters will generally work better in sunny locations, while heat pump systems will work better where it’s warmer. No matter the innovation, what’s clear is that the water heating technology of the 20th century needs some upgrades. Getting homeowners to upgrade their systems by appealing to utility savings could be the most efficient route to heating up water instead of the planet.