this post was submitted on 01 Aug 2023
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Reverse-cycle ACs have had >100% heating efficiency since the 1990s. America just seems to take forever to embrace anything environmentally friendly (reverse-cycle AC, solar hot water, rooftop solar, etc…).
It wasn't until somewhere in the last 15 years that air type type heat pumps, as opposed to ground loop, could cope with the cold temperatures in the northern states without having to fall back to resistive heating for weeks at a time.
When you have to run resistive heaters the electrical usage skyrockets and makes a heat pump system vastly more expensive to operate.
If you live in a cold State, Zone 6 or higher, then you need to be careful when purchasing an ASHP to make sure that it has an HSPF of 10 or greater. If it doesn't then you'll be paying big electrical bills trying to keep your home warm. Those units are also more expensive to purchase than a regular Heat Pump like you would run down under.
Frankly nowhere in Australia experiences cold anything like what I do on a yearly basis. The coldest temperature ever recorded anywhere in your country was a mere -9f. Here in the United States there's quite a few places where that is a common daytime high temperature in the winter, even in the lower 48. There's quite a few places even in Zone 5, see previous map, that will get to -9 and stay there for days at a time.
It's not uncommon for overnight lows in Zone 6+ to hit -20f and temperatures even lower are definitely possible. At my house in Wyoming last winter we touched -40f / -40c for a some hours one night.
Air type heat pumps simply could not handle those kinds of temperatures until relatively recently. That's why so much of the US doesn't have them already. They just didn't work during the winter in northern half of the country.
More expensive than a heat pump without a backup/additional electrical resistance heater. Not more expensive than an electrical resistance heater on its own.
That's what's so strange about this, in most cases a heat pump would be replacing a non-reversible AC and an electrical resistance heater or gas-fueled furnace. And in nearly every case, even with the need for a backup/additional resistance heater, you're still saving money. And it's not like any of this is new technology, it just took forever for it to become popular in the US.
> 100% efficiency doesn't mean much when you consider that the generation and distribution of electricity is not efficient. It wasn't until recently that heap pumps became efficient enough to beat onsite burning of fuel.