Why CO2 Heat Pumps Are The Future Of Cooling

Correction:
3:26 Should have said "Gas burner efficiency" - it's not a COP

Video script and citations:

Get my achieve energy security with solar guide:

Follow-up podcast:

Join the Undecided Discord server:

👋 Support Undecided on Patreon!

⚙️ Gear & Products I Like

Visit my Energysage Portal (US):
Research solar panels and get quotes for free!

And find heat pump installers near you (US):

Or find community solar near you (US):

For a curated solar buying experience (Canada)
EnergyPal's free personalized quotes:

Tesla Referral Code:
Get 1,000 free supercharging miles
or a discount on Tesla Solar & Powerwalls

👉 Follow Me
Mastodon

X

Instagram

Facebook

Website

📺 YouTube Tools I Recommend
Audio file(s) provided by Epidemic Sound

TubeBuddy

VidIQ

I may earn a small commission for my endorsement or recommendation to products or services linked above, but I wouldn't put them here if I didn't like them. Your purchase helps support the channel and the videos I produce. Thank you.

[UndecidedMF]

Correction: 3:26 Should have said "Gas burner efficiency" - it's not a COP

[TofuInc]

To put into context old heat pumps used R22 that had a high side pressure just above 200psi, current heat pumps use R410a which have a high side pressure just under 400psi. CO2 would have a high side pressure above 1500psi for a residential heat pump or 1700psi to 2100psi in a water heating application. R134a which is currently used in heat pump water heaters has a high side pressure around 200psi.

That is a significant pressure increase. The higher the pressure the higher the failure rate on these systems. When R22 was phased out and manufactures started using R410a the leak rate on systems increased exponentially. Due to the complexity of the heat pump water heaters it's not economical to service them when they have a leak. Even when they are under warranty the manufacture opt to replace them.

Instead of always chasing efficiency, maybe we should take a step back and look at the waste stream we are creating. It takes a significant amount of energy and resources to build these. So if we are replacing the unit 2 to 3 times in the lifetime of a single less efficient unit are we really saving anything?

[Tilley]

As an industrial refrigeration tech that deals with ammonia and CO2 as well as residential and commercial air conditioners. The biggest problem I see with residential air conditioners going to CO2. Is similar to when the industry changed from r22 to r410. The head pressures doubled from 200 PSI up into the 400 PSI range. CO2 has to be even higher than that. Combine that with the industry trying to cut cost at every corner you will have a lot of failed condensers because of the high pressure until the bad apples are weeded out. You also probably won't have the lifespan on the equipment that you used to get on the older equipment that used a lower pressure refrigerant. I wish the industry would fully embrace ammonia as a refrigerant. It's natural to the environment so there's no pollution factor. It cools with much lower pressures, so it takes less energy to get the pressures you need and you're not trying to contain such high pressure is on the condensing side. There's just the part that it's toxic to humans. Just my opinion

[Orchardman]

Liquid CO2 cooling was used a couple of decades ago to cool datacentres that had equipment cabinets having a high heat load. The heat latency of liquid CO2 to the gas phase was much more efficient than at moving heat than water based cooling. It was implemented as a fan assisted heat exchange "radiator" mounted on the back of a standard equipment rack. The high pressures 50+ Bar?) needed to work with liquid CO2 meant that the pipework had to be thick walled stainless steel with close tolerance preformed pipe dimensions. I saw one in operation at Imperial College in London. Expensive to build, but allowed heat loads in rooms that could not otherwise cope.

[stephengentle]

I have a CO2 heat pump at home, it’s great. It’s timed to run in solar hours, and so far it’s probably been run over 98% from my own solar. Since it only uses 1/5th of my solar output, and only for two or so hours a day, it’s rare to get a day when it’s not entirely solar powered. So that’s a pretty huge cost and carbon saving!

[geekdomo]

We had our heat pump put in last year and its been AMAZING! Cheaper to run and in the summer it can make our Rochester NY home feel like a refrigerator. Wasn't cheap but well worth it. Would love a heat pump running on CO2

[brianbesold]

Great video Matt. Thanks for helping to get the word out about CO2 heat pumps and Harvest Thermal's collaboration with SANCO2. I noted that you described both HCFC and CFC refrigerants as having ozone depletion potential. Currently R-410a is used in the majority of residential ASHP systems. While it carries a high global warming potential (GWP 2088), the ODP of R-410a is zero. This is one reason we look forward to increased demand for CO2 systems (GWP of 1) and R-32 (GWP 675) as the next phase of refrigerants to be used in res. systems.

As a building performance contractor working in the Bay Area we are especially appreciative of Harvest Thermal's product as it more than doubles the potential space heating capacity of the SCANCO2 system when installed as a combination domestic hot water and space heating system.

[billleddy]

We’ve had a Sanco2 water heater for almost 3 years and it’s been working great. The reason we chose it was because it’s a split system with the condenser outside. Our water heater is inside the house and so having the condenser mounted on top of the tank as most systems I’ve seen would have required relocating the heater. That would have added significantly to our installation cost.

[oakld]

It's a common practice to pair a heat pump with PV solar and use excess of the sun to heat 300 to 500 L tank for hot water and even some heating, if the days are sunny during the winter. Not exactly dedicated system, but it accelerates the ROI calculation dramatically.

[coolbrotherf]

My father is an expert in HVAC technology and I asked him about this video and he had a few thoughts. One thing he mentioned is that the positives mentioned for residential systems are exaggerated a bit, as the cost of the installation of the system doesn't really ever pay for itself because after the the savings catch up, it's already breaking down and costing hundreds if not thousands to fix, completely offsetting any savings it creates. Companies always try to entice us with impressive sounding marketing, but it rarely as perfect as they say.

He said it can be good if you can build a home with the system from the start, but if you have a standard system that is already working fine, don't worry about it.

For commercial usues it does make a lot of sense though as the higher efficiency is ultilized more effectively for much larger buildings.

[loneIyboy]

I have spent an unreasonable amount of time thinking about heat pumps and thermal batteries, and now Harvest Thermal does precisely the system I had been imagining for months now. Bless their hearts.

[patrickjkavanagh]

Matt I'm currently design/building a four family apt building and am exploring ways to potentially be the utility provider for the building. The further I drill down I realized thermal storage is the piece that brings it all together with respect to hvac, hot water, etc. This is a fantastic piece to that puzzle. A further integration/improvement would be adding PVT solar panels to this set up, as the hot water could be dumped in this same water tank / thermal battery to supplement it further. I haven't found a PVT supplier in the US, but there are several abroad; DualSun (FRA), several Chinese, and some Dutch if I recall correctly. A further improvement is using a ground source heat pump (geothermal) vs air source. This is far less practical though per installation and cost though.

It's frustrating how much better the options are in the commercial space vs residential, thanks for shedding some light on that. I found the most efficient set up to be a ground-sourced heat pump that, in a multi-unit apt building mind you, could not only heat and cool each space, but also transfer heat/cool from one unit to another (as opposed to from the ground (or air in an air-sourced set up). This is even more efficient than moving from ground/air. Problem is, it requires 3phase electric. Also impractical from an installation/cost perspective.

[mjears]

Congratulations, Matt! It’s very touching to see your studio transition starting, and how you’re feeling about it. Best wishes!

[robwoodcock]

I worked with a team that put heat pumps into pubs to chill cellars/ heat water. Brilliant idea that needs to be expanded to lots of other areas that need cool products / people and hot water !

[m.e.]

Thanks Matt.. this is a very interesting topic for me.

[Powertampa]

One of the biggest annoyances with heat pumps in general is that they are almost always tied to installation providers. I have been trying to find data sheets and price listings for heat pumps, especially here in Europe, for a while now and it's almost impossible to find just the compressor unit and a heat exchanger unit prices, even for large manufacturers like Mitsubishi. I don't get this whole situation either, because you can just buy a mini split and install it yourself, but the moment it gets above 5 tons in capacity or thereabouts the listings just vanish it seems.

[donscott]

Thanks and very interesting. I head the Swedes were working on CO2 HP several years ago but have not heard of anything until your presentation. I installed a Mitsubishi Mr Slim Zuba Central unit in 2010 and have saved over $22, 000 in energy costs since its installation. Two years ago I replaced my 22 year old electric Hot Water tank (domestic hot water) with a Rheem Prestige heat pump hot water tank. It only used 500 kWh last year and my total home energy costs continue to fall and now charge my Leaf at home with no additional household energy use. From what I understand the global warming potential equivalent GWPe of 410a refrigerant is in the thousands so that may be the most attractive aspect of CO2 systems (which of course would only be GWPe of 1). I suspect the problem will be reliability of such high pressure systems and the additional component. But a very interesting potential and thanks for bringing it to light.

[RyuukoKobayashi]

Definitely going to keep this in mind when I get closer to a heat pump install at the end of next year. My current water heater may only be a few years old, but its a gas unit installed by the prior owner. Running on gas is enough to put it on my "hit list", and doing it at the same time as a heat pump and looping them together in a smart system sounds like it makes a lot of sense to me.

[nerophon]

Air-to-water heat pumps are the standard design in the UK, since HVAC overall is rare. Our summer temperatures have tended never to be high enough to require cooling. Most housing stock uses wall-mounted water-based radiators to provide heating, sometimes augmented by underfloor heating where the flooring is appropriate. The big problem with this setup is that there is no way to bring fresh filtered air into the home. Also, most of the wall-mounted radiators aren't large enough to work well with the low deltas of most air-to-water heat pumps. As such, the journey towards Passive House will be long and arduous for the majority of UK homeowners.

[mrbuckmeister]

I have a heat pump water heater and we use a heat pump for heating and cooling. Especially living in a hot climate I have often thought about having one heating cooling loop to for example take heat from our fridge and move it into our water heater or even just outside. It has to be better than heating up our house only to have our AC heat pump move it outside.