Hank Hill Heat Pumps

The future of air conditioning is spelled 'propane.'

With the northeast baking under a heat dome this week, it seemed like a good opportunity to talk about how what I call “Hank Hill Heat Pumps” can bring down the costs of staying cool —except there are obscure regulations preventing Americans from being able to buy them. Here’s how we can fix this and keep you cool in the summer for less.

Buckle up for some King of the Hill Meets Political Economy.

The AC Hero was right there all along. Image Credit: Neatoshop.

The Problems with the Old ACs and Heat Pumps

There’s a measurement here that you need to know: GWP (global warming potential). Carbon dioxide is the reference point. It has a GWP of 1, so anything over 1 heats up the planet even more than carbon dioxide, anything less than 1 heats it up less than carbon dioxide.

HFC 410a (HFC is for hydrofluorocarbon), which is the refrigerant that the vast majority of U.S. air conditioners (ACs) and heat pumps use, has a GWP of 2,088. That’s not a typo. It has more than 2,000 times the global warming impact of an equivalent amount of carbon dioxide. While they are not released in the same quantities as carbon dioxide, they do gradually enter the atmosphere through gradual leakage from use and wear, improper end-of-life disposal, and from any damage the equipment sustains over time, and with a GWP that high, even small amounts cause significant environmental damage.

In 2020, the American Innovation and Manufacturing (AIM) Act mandated a gradual phase down in the use of these HFCs and does so in a stepwise fashion. This was intended to give industry time to transition instead of forcing them to do it all at once. Keep this stepwise thing in mind, because it’s causing a problem that we’ll get to later.

Image Credit: Ecotope.

To comply with this law, the HVAC industry is transitioning to using newer synthetic chemical refrigerants that are referred to as HFOs (HFO is for hydrofluoroolefin). These refrigerants have GWPs in the 450-700 range, so a marked improvement over HFC 410a, but still pretty high. And these synthetic compounds are pretty expensive to produce (more than $40 per pound).

But what if there were a better refrigerant that we could use for heat pumps and ACs? What if it were both much better for the environment and cheaper to produce? Wouldn’t it be great if saving consumers money and taking climate action went hand in hand?

Hank Hill to the Rescue…

For those of you who somehow missed it, King of the Hill was a hit TV show in the 2000s and in it, Hank Hill famously sells propane and propane accessories (it’s a frequently recurring bit in the show).

Well, guess what? That potentially magic refrigerant that’s better for the environment and cheaper- it’s **propane.** Specifically R290, a refrigerant grade propane. Remember those GWPs that were 2,088 and then for the “better ones” were 450 to 700? The GWP for R290 propane is 0.02. That’s it. It has essentially zero global warming properties. 450 times carbon dioxide (at best) versus 0.02 times carbon dioxide. With those kinds of numbers, environmentalists can give the trees a break and start hugging propane cylinders!

Image Credit: Author’s using Reve.

On top of the low GWP, it’s cheap!Refrigerant-grade propane costs about $7 a pound to produce, and that price is likely to come down a lot as economies of scale are achieved (combustion propane which is already done at scale can be produced for about $1 a pound). So it’s already a lot less expensive than the HFOs and set to gain even more of a cost advantage. If King of the Hill were remade today, Hank might not just brag about propane’s performance on the grill but also about how it can keep your house cool for less money too.

An Extremely Brief History of Refrigeration and Flammability

A smart reader might be asking at this point: why haven’t we been using ACs and heat pumps with refrigerant-grade propane all along? Well, propane is highly flammable and so, for a long time, it was considered by regulators to be too volatile to use in ACs and heat pumps. And, to be fair, back in the early days of refrigeration, given the rudimentary technology available, the flammability of the gas itself was a big deal. One of the earliest demonstrations of refrigeration was at the World’s Fair in Chicago in 1893…..it caught on fire and killed 17 people. As refrigeration took off, CFCs which were terrible for the ozone, (but people didn’t know that) but which were much less flammable became the industry standard.

For ACs and heat pumps, propane’s flammability just isn’t a problem anymore. This is why, in 2022, the International Electrotechnical Commission (IEC), the international body that sets standards for home appliances, voted to allow hydrocarbons like propane to be used as refrigerants for the first time. The U.S. was part of the IEC vote in 2022 and voted for this change. It’s also important to note that these hydrocarbons have been used in the EU safely for decades now. Americans have already used propane safely for their grills and do so with larger quantities of propane than would be present in ACs and heat pumps. And, propane is already in use as a refrigerant in supermarket refrigerators. As one observer put it, “the refrigerant future is spelled propane.” Hank Hill couldn’t have said it better himself.

An important term to understand at this point in our story is “charge limits.” These are just the maximum amount of a refrigerant that can be safely stored in an AC or heat pump. At a technical level, what that IEC vote did was raise the charge limits for refrigerants such as propane R290 and others like it such that using them would become feasible. Under the new IEC rules, you could now store up to 988 grams of R290 in ACs and heat pumps.

Other countries are quickly updating their building standards to allow for heat pumps and ACs that use these hydrocarbons like propane. Companies in the EU, for example, are racing ahead in developing and building these new ACs and heat pumps.While they are off to the races building cheaper, greener ACs and heat pumps, we are not.

Those 2020 Regulations, and Other Regulations, Stand in the Way

Here in the U.S., we have two hurdles in the way. The first is UL 60335-2-40. That UL standard functions as a federal standard on heat pumps and ACs and it has a charge limit for propane R290 of only 114 grams, making R290 heat pumps and ACs almost totally unviable.

OK, so then the next question one might ask is “how do we change UL 60335-2-40?” Well, there are two problems there. The first is institutional.

• Updating the UL is technically complex,

• The UL was designed specifically with synthetic refrigerants in mind

• The UL has to collaborate with and receive guidance from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Building codes, EPA rules, and UL standards all reference ASHRAE's technical guidance.

• UL is ultimately legally liable for their standards, so it has an interest in moving very slowly (arguably too slowly in this particular case)

• These standards making processes usually have multiple rounds of comments, technical review, and voting anyway.

The second problem is that the Standards Technical Panel (STP) — the entity responsible for updating the UL — has a heavily skewed voting composition.

Image Credit: Ecotope.

There’s no one voting member there from the government, only one member there for consumers, and only two from commercial/industrial users. Meanwhile, the producers and supply chain firms have a combined 34 voting members. As one report puts it, “Due to the current composition of the STP and the process UL uses to update its codes, UL 60335-2-40 over-represents the interests that benefit from restricting the use of A3 refrigerants like R290. This unfortunate outcome poses substantial and unnecessary economic and health risks.” (emphasis mine). While it would be too simplistic to say this is the only reason the UL isn’t being updated quickly, it is clearly not helpful and a significant (and somewhat infuriating) additional impediment.

Meanwhile, those regulations from the 2020 AIM Act cause a problem too. The stepwise reduction that I showed you earlier combined with the sluggish movement of the UL means that the industry is going through costly transitions each time. First they had HFC 410a but had to shift away from the HFOs (that’s the step we’re at now.)As the GWP limits tighten later this decade they have to make another costly transition, and then later at an eventual final phase they’ll probably end up using propane R290 anyway, with several extra steps, extra costs to consumers. All of this reduces American competitiveness, and creates more global warming than necessary.

How We Get You a Better, Cheaper Heat Pump to Stay Cool in the Summer

I have two ideas for how we fix this. First, Congress could amend the Clean Air Act to explicitly authorize the EPA to accept International Electrotechnical Commission (IEC) safety standards as equivalent to UL standards for natural refrigerant applications. The U.S. has already voted to approve these international standards so this wouldn't require new safety research, just formal recognition of standards we've already endorsed.

Second, Congress could also expand the EPA’s AIM Act authority to actively promote ultra-low GWP refrigerants rather than just restricting high-GWP ones. This could include directing EPA to fast-track approval processes for equipment meeting IEC hydrocarbon safety standards.

The bottom line: Congress can give Americans access to the same safe, cheap, climate-friendly cooling technology that the rest of the world is already using, that Hank Hill would definitely approve of.

-GW