Thread by @curious_founder

There's a lot of misleading claims on the internet about heat pumps in cold climates.

Many people think they stop working below 30 or 40F

But heat pumps can work efficiently as low as -25F.

So here's a thread debunking 3 myths about cold-climate heat pumps.

🧵 #energytwitter

Before diving into the myths, it's helpful to understand how a heat pump works on a cold day.

While it might not seem like it, on a cold day there’s actually some heat in the air outside.

That's true until the temperature reaches absolute zero (–459.67°F)

A heat pump basically captures that heat and moves it into your home.

So rather than create heat directly by burning gas or electricity, it uses a little energy to run some gadgets that *move* heat.

As a result heat pumps become a magic heating and cooling machine that effectively turn 1 unit of energy into 3 or 4 units of heat.

If you want to understand the science of this more, check out this video by @thisoldplumber and @ThisOldHouse.

For now, the key things to understand are:

1. Even on a cold day there’s energy in the air outside.

2. A heat pump moves that energy into your home.

3. The net result is a super-efficient heating system.

Alright, let's start mythbusting.

Myth #1 - Heat pumps don't have enough capacity to heat a home when it's freezing.

False.

As the weather gets colder, the energy required to keep a home warm (the load), goes up.

At the same time, the amount of heat that a heat pump can move into the home (the capacity), goes down.

But as long as the capacity is higher than the load, then a heat pump will work.

This is called the balance point.

In the example above, that's at about -7F.

For a well-insulated and sealed home, that number can go as low as -25F.

But of course, if you have a really leaky home or a bad heat pump, then you'll run into problems.

Most complaints about heat pumps not working in cold weather are the result of user error.

There are plenty of contractors out there that don't know what they're doing.

But if you know what you're doing, heat pumps can work well into negative temps.

Myth #2 - Heat pumps lose their efficiency advantage when the temperature drops.

In other words, heat pumps stop becoming a magic machine below freezing.

This is far from true.

The best way to see this is to look at the coefficient of performance (COP) of heat pumps at various temperatures.

As long as the COP is higher than one, heat pumps are the most efficient solution.

Take a look at the chart below that shows the COP of a @Mitsubishi_USA cold-climate heat pump during a series of tests in Alaska.

As you can see, until the temperature reaches -10 degrees fahrenheit, this heat pump would perform more efficiently than any other piece of equipment.

This is the case for virtually all cold-climate heat pumps.

Some of them can achieve COPs of more than one as low as -22F.

Even in extremely cold temperatures, heat pumps are incredibily efficient.

Myth #3 - It costs too much money to use a heat pump in a cold climate.

Once again, false.

Sometimes you'll hear contractors say, "When it gets cold your heat pump costs more to operate than X."

And some hours out of the year that might be true.

But for the most part, that's irrelevant.

What really matters is how much it costs over an entire month or year.

So let's look at some of that data.

According to @NREL, here's how much the average homeowner can save in some pretty cold states:

In fact, there are millions of homeowners across the country that could save $500+ per year by switching to a heat pump.

And many of them live in places that get very cold in the winter.

In most places, heat pumps are the most cost effective way to heat a home.

Alright that's all for now.

If you've read this far, please consider retweeting this thread to spread the word that heat pumps work in cold climates.

And if you want to dive into any of this further, here's the full article - carbonswitch.co/do-heat-pumps-…