Where I live in New England in the winter
it can get as low as -13 F (-25 C). During summer heatwaves, it can reach over 100 F (40
C). Many of our houses and homes weren’t built for that, and in the United States, we aren’t
exactly known for quality insulation. So how do we deal with heating and cooling our
homes? Well, some of you may already know I’m crazy about heat pumps, but I came
across a local company, called Flooid, that opened my eyes to the potential of cascading
heat pumps. The constant refrain that heat pumps can’t work in the cold isn’t true anymore
anyway, but this tech takes it to another level. But what’s a cascading heat pump?
And are our homes ready for them? I’m Matt Ferrell … welcome to Undecided. This video is brought to you by
Rocket Money, but more on that later. As I’m sure you could tell if you’ve seen just
one of my videos before…I’m constantly on the lookout for new and exciting tech advancements,
like some of the things I came across at CES this year. So when I stumbled upon a local
company here in Massachusetts that’s doing some interesting work with heat pumps, I had
to check it out in person. While cascading heat pumps aren’t a new idea, I haven’t seen
much about them in residential use cases, so this really piqued my interest. But what
is a cascading heat pump and why is Flooid’s version so special? To understand that, we
have to brush up on heat pumps in general. We’ve talked about heat pumps many times before,
so if you want to learn more about them check out some of those episodes. Here's a quick refresher.
A heat pump is essentially a refined series of heat exchangers, using a working fluid to move
heat around. Your refrigerator is already doing this, but it’s moving that heat in just one
direction (from the inside of the fridge to the outside). Thanks to a reversing valve, a
heat pump can heat or cool with ease. Because they’re just using a little physics exploit
to move heat around instead of generating it, they have a high coefficient of
performance (COP). At a high level, you get more heat energy out of the system
than the electrical energy you put into it. The higher the COP, the more energy efficient
the device. Another way to look at it, the higher the COP, the more money you can
save on your heating or air conditioning bill. What’s better than one heat pump? Flooid’s
answer is…drumroll please…multiple heat pumps working as one. It’s not a new idea, but their
implementation and flexibility of the system is pretty cool. The company refers to its use
of a group of heat pumps as a multi-cascading system. Each pump or loop has a different
working fluid with their own separate but overlapping operating temperatures. By working
together, they can accomplish more than an ordinary single loop heat pump. It’s not a
perfect analogy (at all), but it’s kind of like having multiple gears on your bike versus
just one. This is Mark Maynard, Chair & Director of Research for Flooid. He showed me around
Flooid’s lab in Easthampton, Massachusetts. “So this is going to start pumping out some
values very soon, and when it does, you'll see that we're at minus 11, which is lower than
almost anybody can do right now. But you'll see that our capacities are still high and our CLPs
will be very high also. So this will always save you energy… if you're above a COP of two or so,
it will most likely save you money as well. So the other advantage of this particular system is when
we're at low deltas, which is the majority of the heating season, which would be around 40 degrees,
30 degrees, that type of thing. Our capacities are 200 to 300 percent. So when it's normal heating
temperatures here in New England, we're not doing 100 percent capacity. We're doing 2 or 3, so our 2
ton system is acting like a 4 or 4 and a half ton, even a 5 ton system at times. But, it still
doesn't use any more electricity.” -Mark Maynard How do cascade heat pumps punch above their
literal weight class like that? You see, heat pump or loop #1 warms to a target
temperature on the upper end of its range, that’s when pump or loop #2 takes over. This
temperature is well within pump #2’s range, so it’s not very hard for pump #2 to take it
to an even higher temperature. We start with air that’s too cold for pump #2, and
pump #2 makes it hotter than pump #1 ever could by itself. Teamwork! Also very
confusing the way I just described that. If that’s still arcane sounding, think of it like
the lock on a canal. It’s hard to get your boat up stream, just like it's hard to heat a space up. A
lock can make this much easier by raising a boat up, and a loop can do the same with temperature.
A job that’s too big or inefficient for one lock or loop can be made much easier by having a bunch
of them working together. Each raising the boat, or the temperature, up. Then passing it onto
the next lock or loop to raise it up again in turn. And locks and loops are both reversible.
You can use a series of locks to get a boat easily downhill, and you can use a cascade
heat pump to easily cool your house, too. This kind of teamwork means that cascading
heat pumps can be more energy efficient than a single-loop heat pump. It lets them handle bigger
buildings or spaces that need a lot of heating or cooling, such as large commercial or residential
buildings. If we can accomplish that by adding an extra loop, what would happen if we
added even more loops? If we went… loopier? Speaking of loopier, I got thrown for a loop
when I recently discovered that I was being charged for a video streaming service I hadn’t
used for months. Have you ever had something like that happen? Well, today’s sponsor, Rocket Money,
can help with that. Rocket Money is the personal finance app that helps you cancel subscriptions,
lower bills, and manage your money better. After I signed up for Rocket Money, the app highlighted
that long forgotten subscription of mine, told me when it was set to renew again, and even
offered to help me cancel it right within the app with just a few taps. I didn’t have to worry
about dealing with customer service. Rocket Money has helped save its customers up to $740 a year,
with over $500 million in canceled subscriptions. They can even help you lower your bills just
by uploading a photo of your bill, like your cellphone bill, and tapping a few buttons. Rocket
Money will negotiate your bills for you to get you the best rate. I’ve also been using the app to
set myself a new budget to help keep spending in check. It’s automatically monitoring my
spending, putting those expenses into categories, and letting me know when I’ve exceeded my limits.
It’s absolutely fantastic. Take control of your finances today. Go to Rocket Money.com/undecided
to get started for free. Thanks to Rocket Money and to all of you for supporting the channel.
Now, let’s loop back to getting loopier. What happens when we add even more loops to our
heat pump system? Each additional loop makes the system’s range larger, and thus makes its
flexibility and efficiency even better. Remember, Flooid’s system isn't a single, or even double
loop, but a multi-cascading system. This gives them that impressive degree of flexibility,
allowing their system to effectively heat or cool temperatures beyond HVAC units and even other
heat pumps. We’ll talk exact stats in a moment. But first, we have to deal with the superheat
refrigerant issue… a significant challenge for all heat pumps (really, their compressors), one
that can even destroy them if we’re not careful. What is the superheat refrigerant issue? Put
simply, the working fluid or refrigerant is only supposed to return to the compressor in vapor
form. If liquid refrigerant hits the compressor, it will kill the compressor. How does that happen?
If we want a specific air outlet temperature, then our compressor needs to hit and maintain a
specific, corresponding refrigerant flow rate. But it's hard to stay perfectly on target. So,
our little compressor is constantly adjusting its speed to be as close to the goal as possible.
In doing so, it often overshoots the goal speed (and temperature!) and then has to back off. As
a result it backs off too much and undershoots the goal, so it has to rev back up and ends up
overshooting the goal again. Round and round it goes, overshooting and undershooting
in a vicious cycle called oscillation. How about an example? Let’s say we want to
cool air, and our theoretical refrigerant boils into a gas around 200 F (about
93 C). The cooling takes place in the evaporating coil - where warm air flows over
the coils and our refrigerant absorbs heat, evaporating into vapor. We want to keep the
inside of this coil to at least 200F, so our refrigerant remains a gas when the compressor
sucks it up. If we have too little refrigerant, it creates too large of a superheat, meaning
we aren’t cooling the air very effectively. More importantly, the hot refrigerant can damage
the compressor. If we have too much refrigerant, we will flood the compressor with liquid,
which, again, kills the compressor. Our compressor is constantly trying to
balance between these two extremes. This balancing act creates that oscillating
sine wave. What’s so bad about that? Well, there’s a space in the lower part of the
sine wave where conditions are right for liquid to start forming in the compressor.
Once again, that would be bye-bye compressor. As so often happens in engineering, this creates
a cascading (pun intended) problem. If your system isn’t well optimized, it’s going to overshoot
the working fluid’s happy place by a lot, creating greater oscillations or waves and
more chances for fluid build up. Even worse, this oscillation can build, called resonance,
meaning the overshoot and the undershoot can become larger with each cycle. Every
heat pump has to deal with this issue. Then how do heat pumps avoid this? The safest
method is to dial up the temperature of their entire cycle so the lowest portion of the sine
wave is almost always above the working fluid’s preferred temperature. However, turning up the
heat on a system like this costs extra energy, equating to poor COP and energy efficiency.
The tighter you dial in that sine wave and the control systems around it, the less of an offset
you’ll need, which means a more performant system. That’s exactly what the Flooid team
says it's done. They’ve developed very tight control software that closely
manages the superheat of the vapor, limiting it to a single degree of variance.
This solves the super heat issue without having to burn extra energy. The control system
also optimizes the cascading system as a whole, micromanaging each loop and ensuring the
most efficient use of loops and cascades. Using software to optimize your HVAC system
like this has been around since the 1980s, but it contributes to Flooid’s great performance
and opens the door to some neat tricks. For instance, Flooid can deliberately make
their first loop slightly less optimized. Seems counterintuitive, so why would you
do that? Because it can make the second loop so good at its job, it covers for
the inefficiency of the first loop. It also lets Flooid customize their
heat pump to the situation at hand. “But basically this is our technology and we,
as you can see, we can tailor the technology to virtually any situation … we can do what no
other company can do, we can do 100 percent boiler replacement for baseboard hot water. We can
do steam… and we can do more…” -Mark Maynard And while Flooid’s customizability and the control
software are good (though not necessarily unique), it’s their performance range that
really piqued my interest. For example, most heat pumps struggle in the cold, and
need back up around -15 F (-26.1 C). However, Flooid has a cold climate system capable of
handling temperatures as low as -32.5 F (-35.8 C). I personally got to see it take -31 F (-35 C) air
and warm it all the way to 77.9 F (25.5 C), with a COP of 2.3. They also have a system that prefers
temperatures between 10 F to 120 F (about -12.2 C to 49 C). That’s perfect for temperate regions
like Virginia. In recent tests, their device was able to hit a COP of nearly 4 in milder
temperatures, even while running at 50% power. Also, being a heat pump and all, it works in
reverse too. Taking extreme temperatures of around 110 F (43.3 C) and cooling them down to
a much more comfortable range. Again, all while maintaining a COP of 2 or more. Flooid claims the
system can handle really extreme temperatures of up to 130 F (54.4 C), and their president, Ben
Schwartz, told me they’ve tested it all the way up to 140 F (60 C). Working at crazy high temps
like that does cause Flooid’s COP to dip below 2, though if it's that hot outside, we’ve
got some bigger problems. For comparison, you average residential air conditioner hits
a COP of 2.3 to 3.5 in mild temperatures, really start to struggle above 90 F (32.2 C),
and flat out won’t work above 115 F (46 C). At higher temperatures of 110F+, Flooid can
maintain a COP around 2. If you are trying to get 1000 kWh of cooling, you can expect
to pay about $10 more per 0.1 drop of COP, with costs exponentially increasing if it
drops below 1. So a worst case baseline of 2 provides a good buffer in summer months
where heat spells are becoming more common. This all sounds fantastic, so there
has to be a cascading heat pump catch, right? While it’s not a specific to heat pumps,
Flooid is about to begin their pilot process. As we know from a lot of other technologies, this is
a precarious point for startups. So many pieces of tech work phenomenally under lab conditions
but fall apart when the rubber meets the road in real-life application. Because of this, finding
the kind of funding to get something like this off the ground can be very challenging.
If they can make it out of this stage, Flooid has a path to make cascading
heat pumps more affordable. Here’s Mark. “...everything here is off the shelf … so there's
no new technology here other than what we do. Everything is, the industry already builds,
already makes, and already has available. So it's not like we have to wait for the industry to
start manufacturing new equipment.” -Mark Maynard Using readily available parts should avoid supply
bottlenecks and help lower manufacturing costs. Because their custom control system operates
efficiently even at very low temperatures you shouldn’t need to spring for a backup heat
source. This goes back to the “heat pumps don’t work in the cold” myth. They do, but as they
get farther from their ideal temperature range, they can struggle to keep up with our heating
demands in an energy efficient way. That’s why so many heat pump systems are hybrid. They include
things like resistive heat strips to supplement heat for those handful of days where outside
temperatures outstrip the system’s ability to keep up. If a heat pump can handle temps down to -30
or -40 F (that’s -34.4 or -40 C) with a high COP, then hybrid systems go away. That could
save space, time, emissions, and money. Another thing that should help with the
price is certification. Lots of tax rebates are available for homeowners looking
to upgrade to a certified heat pump. While the initial upfront cost is there,
the tax rebates can sweeten the deal. “We are ready to certify our cold climate
air to air, our temperate climate air to air, and the boiler, the forced hot water
boiler. We're ready to go to certification, but it's expensive. We're a very small company,
so when funds become available, then we're going to certify it. Once we're certified, then
you'll be able to get rebates...” -Mark Maynard Speaking of boilers, Flooid also showed me a
system that could replace your gas boiler. The versatility of heat pumps and cascading heat pump
systems has incredible potential. Flooid isn’t alone. Several companies are offering cascading
systems, like the ground source heat pump from Kensa, or the air-slash-water source heat pump
from Clade ES. And it’s just not just newer, nimbler companies coming at space-heating
from this angle. Even HVAC old guard Trane has a similar air and water source cascade
heat pump. However, many of these systems are literally just daisy chaining separate heat
pumps together, so multiple, large boxes, and condensers on the outside of the building.
Mark drove home the point to me that their system is tightly integrated and doesn’t need
multiple separate boxes and condensers. “If you want to see what an actual
unit would look like. In your house, we can come over here. This is that system. In the
size that it would be. And this would literally, you would take your furnace out. You would
put this in, and this will do the heat and air conditioning of your house. This would stay
in your cellar, and only a very small system would go outside. But it would completely replace
your furnace and air conditioning.” -Mark Maynard That’s a much more elegant solution than I’ve
seen elsewhere. All of this leads me to the big question, if cascading heat pumps are already out
there (setting aside Flooid’s specific approach), why aren’t they everywhere? Well there’s no
single, easy answer. It’s partly because simpler, cheaper, single heat pumps have
only recently become mainstream. It’s going to take time before the upgrade gets
its foot in the door. There’s also cost issues. In previous videos we’ve noted that the big thing
standing in the way of heat pump proliferation is their cost. Even with rebates, they’re
expensive. And up until now cascade heat pumps, with their more powerful and complex technology,
are appropriately more expensive. As such, you’re more likely to find cascading
heat pumps in places with specific, intense demands that are also able to
absorb the cost. Places like hotels, hospitals, semiconductors plants, and
even some types of textile manufacturers. Even with its customizability, a cascading
heat pump isn’t necessarily the best fit for every job. Flooid’s 2-ton system might punch
as hard as a 4-ton system for less money, but if your needs are satisfied by a traditional
single loop system, it all comes down to cost of ownership. Flooid says you should come out ahead
on that front with theirs, but your mileage might vary. A study from the University of Ontario's
Institute of Technology (UOIT) has shown that cascading isn’t always the most efficient
option either. In extreme lows and highs, you might be better off just running two identical
heat pumps instead of a cascading tandem system. It could also just be a matter of economies
of scale. Most of the other companies doing cascaded heat pumps are gearing
them for commercial properties, not residential homes. This might be
because commercial properties tend to be newer construction with modern insulation.
There’s also some additional incentives out there for commercial spaces. Some of which, like
the oh-so-evocatively named 179D tax deduction, offer savings per square foot, so the
incentives are stronger for larger spaces. So while multi-cascading systems aren’t
a new technology, they are new to the residential market. If Flooid can make their
small, flexible, compact design accessible, it could make a big splash in that
market, and even open up some new ones. But what do you think? Would you be
interested in a cascading heat pump for your home? Jump into the comments and let
me know and be sure to listen to my follow up podcast Still To Be Determined where we’ll
keep this conversation going. And thanks to all my patrons for your continued
support. I’ll see you in the next one.
