How a Heat Pump Works | This Old House

[@ndeleonn]

I taught thermodynamics at the college level for over 35 years. The molecular dynamics for the cooling and heating of gases on expansion and compression are well understood and easily explained in the classroom. However, to put these scientific principles together for the purpose of heat exchange from the outside to inside or inside to outside and make it work in real life is absolutely genius. Richard Trethewey's explanation is simple to understand and masterful. Well done!

[@bryanc531]

I have been in the hvac field for about 15 years and this is by far the best way that I have heard the refrigeration cycle explained. Richard you are awesome

[@Rpotts1999]

12 years for me and I couldn't agree more

[@michaeljames3509]

You're still an apprentice.

[@Fkidd702]

5 years and same hahs

[@michaelheery6303]

And complex formula wow

[@paulriccio5333]

I just got a heat pump and the genius of this makes me feel better about the money I spent. I ACTUALLY understand it.

[@michaelm7874]

I’m in HVAC field myself for ten years and this guy explains it better than I’ve ever heard it explained

[@A_J502]

This Old House for the win! In all my years as an engineering student, this is THE BEST demonstration of heating, cooling, and basic gas law I’ve ever seen!

[@starshipgus8578]

I’ve worked automotive air conditioning all my life,but this heat pump system was somewhat complicated….until now.Thanks to you Richard,all it takes is a switching valve and some electronics.Now I can even explain it to someone else.You get the credit of course.

[@TheSpoonyluvin]

Richard really has a talent for teaching. You can tell that he enjoys explaining it, and also understands the concept so well that he can easily dumb it down for the rest of us.

[@nursecarmen]

I have found that the people that aren't able to dumb down a subject, either don't know the subject, or are full of it.

[@sceneryj]

I’m studying 1st year engineering and you’ve just done a better job of explaining half of the thermodynamics I need to know this semester than the (very expensive) textbook. Thank you!

[@oldtwinsna8347]

Richard is a certified elite grandmaster of heat pump systems.

[@zacharywestover217]

I just graduated USF with a degree in mechanical engineering. Should have watched this before my first Thermo class. Good stuff.

[@CDinkle]

Just getting into this material in my Thermo series for Mech E., and yeah, this video really brings it home in a way that's understandable.

[@matgggg55]

I’m a mechanical engineering student now and I’m taking thermodynamics this coming semester lol good thing I’m here lol

[@warrenwiz5]

There's a joke here about which college to attend, etc. But agree, these "basics" I feel like should be a preface into what textbooks show. In only a couple of minutes they give a very good explanation of how something works. There's also a comment regarding teachers and tuition, but it would quickly arrive at the Good Will Hunting summary of “...wast[ing] $150,000 on an education you coulda got for $1.50 in late fees at the public library.”

[@JT-Works]

Go Bulls!

[@modernhustle11]

You should stay away from refrigeration then if you think this guy knows what he’s talking about.

[@EmilioPanighetti]

Like listening to a good teacher, concisely and clearly explains thermodynamics with no-nonsense. Thank you

[@Lino44]

Finally a detailed explanation and in layman terms how these things really work. Thank you!!

[@kwpowell0412]

Great job Richard!! I just want to echo what a few other people have said. I have never been able to wrap my head around how a heat pump & Air conditioner work. And here in South Carolina....EVERYBODY has one. What made things so clear for me was not only did you break it down explaining it. You also had the visuals that everyone could see. Outstanding sir......you da man!

[@McRocket]

8:08 - Kevin O'Connor said it PERFECTLY, IMO. WOW. Thank you This Old House's Richard Trethewey .

[@AndrewJJ-0114]

I really enjoy Richard's cutaway models, they really clearly explain plumbing parts that I would never understand otherwise!

[@fernandomingo2398]

This video is pure gold. Never in my life HVAC has been so well explained. Thanks!

[@SLCKaled]

No fancy animations. Just pure old school wisdom!! LOVED THE EXPLANATION. Makes me realize how much real life examples like the canned air are so powerfully effective

[@johnmacward]

There is not a better explanation on KZbin for heat pumps than this one. That simple concept of ‘heat always goes to cold’ and that gases when compressed or decompressed can either get really hot (and in turn attract cold) or get really cold (and attract heat) was the little understanding piece I needed to put it all together.

[@ml9633]

You are amazing. I'm 64 and never understood this process, because nobody could ever explain it to me so well. Thank you so much :) Maurice

[@RayR]

The best explanation of a heat pump I've ever seen. Great job Richard. Your a great teacher.

[@bopal93]

I have seen many videos of how an air conditioner works, but this is the best explanation I have ever seen. Now it totally makes sense

[@ReverendRandy]

Great to watch two intelligent minds teaching us very important lessons on how to save energy and be comfortable. Thank you for sharing! Peace

[@nicolasroberge2829]

I installed a Carrier Infinity mini split heat pump last spring. It is amazingly comfortable for cooling AND heating. Amazing technology!

[@rockinrobin322]

What size house did you install this on

[@nicolasroberge2829]

@@rockinrobin322 I installed two separate 12000 BTU units on each apartment of a duplex. Each unit is 1500 square feet.

[@aprilm9551]

Another question: What's the winter weather like where you installed this? How cold can it get, and does the system work all winter to heat? I'm in Iowa, zone 5b. Probably a heat pump would not work in the very coldest months, I'm thinking.

[@nicolasroberge2829]

@@aprilm9551 Winter is harsh here. -30 in the dead of winter.

[@aprilm9551]

@@nicolasroberge2829 Nicolas, thanks so much for the reply and info! It means a lot to have real world feedback about something, so not just having to rely on advertising or general stats. OK, -30 (Celsius, I'm assuming) is a bit colder than it ever gets here, so I just may be looking into getting a mini split heat pump and will check out the Carrier brand.

[@mulimotola44]

I've been trying to understand this theory FOR YEARS! Finally a great explanation that anyone can understand! I love the examples that explain the compressor and the expansion valve with the can. Thank you so much! This is the best video on the subject by far!

[@bertblue9683]

A great explanation for anyone, especially for guys like me that grew up being told how awful heat pumps are. It's a hard reputation to overcome.

[@AD-CAN]

Man I love this channel. You save my life by explaining complex thing in human language. I am so grateful. THANK YOU!

[@jpellet2744]

This is a truly inspired explanation of the principles and mechanics of heat pumps and hvac systems. Thanks!

[@VictorQuesada-bl1xk]

That was fantastic. Thank you so much for that clarity!

[@vincentdemmink4544]

Well explained! Even though English is not my native language, I could completly understand it!! (power of good explaining)

[@rickcarson9423]

I live in California and just bought a new home in Florida which has a heat pump, a/c combination. I love this video because I kind of understood that it worked the opposite of a/c, which I understand how a/c works, but this really cleared it up. I'll find out how well it works when I get into my new home in two weeks! Thanks Richard! I watch ALL the This Old House line up. Have watched for decades.

[@harleyb.birdwhisperer]

How’s that working out for you? (Still in CA)

[@rickcarson9423]

We've been here one year now and there really was no prolonged period of cold last "winter". It's really like a long summer and a short mild fall. There was one week in December, I think, some rare, freak, week-long cold snap hit and it got down to 29° on two or three non consecutive days but maintained daytime temps around 60°-70°and nighttime around 40° and no problem. But we rarely use the heat. It's a Carrier unit. Electricity is cheap here (0.9 cents per kwh) and that's good because you need the a/c ALL the time! Our house is all electric. Our monthly bill averages around $180-200. Thanks for asking and good luck in California. I mean that sincerely. We're born and raised Central Valley. 60 years. We fled the lunacy. Sold our home, left our family and friends and we didn't look back lest we turn into pillars of salt! Lol! We love our new home and the people. Hope you and Pete live long and prosper...

[@TheresNoAntidote]

This is something we take for granted daily. This process is insane! Human being invented this? Mind blowing

[@bulkbur6312]

king richard! being in the hvac field myself i can say that the future of comfort is exciting. i love seeing how you explain things. i want to be like you when i grow up 😀

[@mondavou9408]

Thanks for taking the time to build that model, it made it very easy to understand. Well Done!

[@stolas666]

That's the most brilliant video on the internet! A paroxysm of masterclass !

[@tannernewton8543]

Sometimes when i'm sad I come find this video for the 1000000th time, its that good

[@TheDataMaestro]

I might have to watch this a dozen times before it sinks in.

[@donchiva2222]

I agree, the explanation wasn't very good. He talks too fast and skips too much by not giving context.

[@jakefromstatefarm142]

Which brings me to my next point dont do drugs

[@AlecDinkleshit-yo5np]

@@donchiva2222he was making a joke cause it uses heat sink technology.

[@ktyoung67]

Holy Moly I always wondered how that worked! I need a new heating/cooling system for my home wanted to try and demystify the whole heat pump thing. Excellent explanation I am not mechanically or engineered minded at all and I understood this.

[@modernhustle11]

To be honest, you still don’t understand it because he has no idea what he’s talking about 😆. He is a meme to us legit hvac guys

[@oisinofthefianna3246]

When in heating mode you will always be constrained by the amount of latent heat in the ambient air, regardless how advanced the control system is. When needs outstrips available sensible heat in the air back up must kick in (electric usually).

[@MikeInPlano]

Ask yourself if you really want to be running your air conditioning compressor year-round. Keep in mind how high your electric bill is in the months when your A/C is running. Do you really want that to be your electric bill 12 months of the year? There's a reason why the vast majority of homes use some form of fossil fuel (gas, oil) to heat them. It's much less expensive, and as others point out in the comments, much more efficient than a heat pump. Even electric heat will cost you less than a heat pump. No thank you!

[@tinysand3517]

love the fact that Richard always dissect his mock ups. Make it simple to understand. Great job

[@impsquared]

Richard best teacher on this planet by a long mile!

[@alonzogonzalez3062]

This show must never go away!

[@mikewalker344]

Finally an explanation of heat pump technology I can wrap my head around. Thank you!

[@simonslocombe5942]

Brilliant video Richard... the workshop, presenter and you my friend should be given an award for creating this one. Taking the simple principal of a air conditioning unit and reversing it to create a heat pump... Please do your best to get sponsored/funding/support to create more videos on heat pumps... by far the most effective and efficient is the ground source heat pump giving out over 400%... so for every 1KWh of electricity used, you get 4KW of heat... Just let you know there are massive incentive's by the UK Government to install and develop these thermodynamic systems... Not only are you helping out us electronics engineers and technicians, you are helping to save this planet...

[@johnmurphy8083]

I have a ground source pump here in Massachusetts, and it's simply brilliant! At the push on a display, switch from heat to cooling. No fuss, no muss

[@TheArfdog]

Thank you Rich for explaining the actual mechanics of how the coolant flows and what actual mechanical device allows it to change to different modes, instead of all the other videos about heat pumps simply stating "you just run it in reverse to change from cooling to heating"....

[@wisconsineaglesfan7925]

Best explanation on the subject that I've ever heard. Made it really easy to understand. Thank you!

[@DizzyDeeds66]

He lost me in a couple of places but I was able to get the overall gist and this was really helpful. I'm in the process of trying to figure out how to bring an almost 100-year-old house that still has no air conditioning and an oil burner heat and hot water system into the 21st century. The consultants that I've had come to the house have suggested this type of system (natural gas is not available where I am to convert to and I'm trying to get off the fossil fuels anyway). This was all new to me and this video was really helpful in my understanding of how a system like that would work in the house. Thank you!

[@treeskier58]

An old house, you would be better off spray foaming the place to seal up all leaks. The kicker with heat pumps in the winter is that they are still making heat with electricity by compressing the gas. The industry wide coefficient of performance (COP) usually given as 200 to 300% gives the general public the idea that they are getting free energy. Is this more efficient than resistance heating, yes a little. But a wood stove or a gas heater is more efficient in the overall scheme

[@evakaral1647]

Richard, thank you for explaining the operation so aptly; even I, a non-techi can understand it. Brilliant!

[@stevefiorito5379]

This kind of system whether in a residential unit or a mobile vehicle (car) works off of the principle of "latent heat" where heat energy (not temperature) moves due to a change in the "state" of a substance. From a gas to a liquid (condensation) or from a liquid to a gas (evaporation).

[@12345anton6789]

Steve Fiorito just compare how long time it takes to bring 1 kg of water to the boiling point, and how long time it takes before all of that water becomes steam. Keeping the same effect kW on the cocker all the time. Then its easy to see that phase conversion is where most of the energy is

[@Slowhand871]

I have had a new heat pump for 4 months now ..all winter. A few things. Our Bosch heat pump (5ton) works down to the teens and we went off NG so we do have heat strips. When you put your hand over the register it feels cool not warm. This is because it’s just heating up to (67-72) so it feels cool on your skin vs 140 that your old furnace heats up to. Our multi level house was too cold in the basement or too hot in the upstairs. We got a Honeywell thermostat with remote sensors so thermostat on main floor sensors in basement and upstairs. Our house is much much more evenly heated. You just set your thermostat to a temperature in the day and at night. It too much effort to do what you use to do on for 2-3 hrs in the morning off during the day on in the evening . I have ours at 67 at 6 am and 59 at 9:30. Our combined bill is $15 month less so not the massive savings I was hoping for but now it’s a much much better/even temperature and we will have AC. Costs I was quoted 19k But I have a HVAC friend sell me the outside Bosch condenser for 3k cash I bought all the parts and air handler for just under 3k 5ton)from his connection wholesale house I paid my friend $2500 to help me install it and another guy $400 to add another guy refrigerant. I installed a 50 amp breaker for the heat pump and a 60 amp breaker for the air handler/heat strips (these supplement the heat pump when it’s very cold) ideally the heat pump operates most efficiently at 45-55 degrees. My thoughts are these I would not have switched unless I got the good deal . Our old furnace was 24 years old and we will be selling the house soon so a new heating system was need . AC is now available. Adding enough supply on your panel can be expensive so plan on that maybe add space on it if you are doing other electrical work so you will be ready . Get an estimate now so you can get use to the cost. I’m glad to have done another part on my end to reduce my personal emissions. Cheers.

[@nomadland99]

THE best explanation I have seen for any heat pump (AC, air source, geothermal). Well done!

[@mikepurewal5816]

Hi from Canada. This video and audio explanation of Heat Pump/AC was amazing. The concept was explained very well. Thanks to great mentors like him.👍

[@lkw5699]

I love watching these explanations. Love this show. Richard and Tom are the best.

[@SurferBum1002]

Best explanation I've found explaining how heat pumps work. Thank you!!

[@Bgkim1113]

thank you very much. you showed me a vaque understanding of heat pump of me made so clear. you are one of the best instructor who I ever have met.

[@ElectricFuture]

This was an excellent video. Great explanation and demonstrations.

[@scott.howell]

Finally, after a week of runaround and sophisticated jargon, I heard just what I needed. Thanks, and I believe I am now a "This Old House" super fan.

[@garywright8846]

Great video I’ve been in HVAC many years and this guys explains it all so well. Brilliant well done.

[@gregoryroscow5846]

Best explanation I've come across of how a heat pump works. I like the way it begins with the basic question, "How do you get heat into your house when it's cold outside?"

[@joshuasmith1215]

That was probably an easier and better explanation than like anything I've been watching to learn about this stuff. I think I truly understand the fundamentals of these systems now.

[@99andycat]

Great explanation...First time I've got close to understanding how these things really work and are controlled.

[@burningkarma]

Love my heat pump. I live in an open concept home (living area/kitchen in center, bed rooms on the outside) in Maine and have a ceiling cassette model positioned in the center of the house. Other than some nights of extreme cold, the unit does a great job on its own keeping the house up to temperature. My only other source of heat is electric which I will usually only turn on during those cold nights when the heat pump can't quite keep up. The two sources work well together. So with no gas, oil, etc my electric bill stays under $200 per month most of the time during the winter months. It's been equally as efficient to use for AC during humid summer days.

[@Matt-rz9fh]

Can I ask how many square feet your house is and what size are your indoor and outdoor units? We have all electric heat and curious what are electric bill will be with a heat pump vs getting a gas furnace.

[@jacked-666]

@@Matt-rz9fh No reply? Where I live in order to have a heat pump use must have a back-up heat system. I've heard that heat pumps aren't all that great in the cold north east. I'll stick with my oil system.

[@tylornunn1447]

That is by far the best explanation I have every seen on the refrigeration cycle. I have a question though, does this increase the amount of condensation being produced in the evap coil?

[@davidreis6431]

What a good explanation. Nothing like someone who knows what they are talking about, and able to communicate it for the average person. Thanks.

[@Jimmyjimjimjim]

Hands down one of the best explanations.

[@HrdRockFan]

Best explanation I’ve heard… and not likely to forget again. Thanks!

[@ltcameron1]

The best explanation I have ever seen. Really well explained. Thanks

[@neverbyluck]

This is an amazing and simple explanation. For the first time this concept makes sense! Thanks very much!

[@davidmurray6070]

Incredibly well explained. I definitely learned something new today. Also, love the passion with which Richard shares the knowledge.

[@paularubina3778]

I love this, thanks !!

[@arturomontalvo2963]

Richard can get a job in any school as a instructor. He knows his stuff

[@andrewl8251]

This explanation is simply priceless.

[@randydogs61]

Am getting a heat pump in Nov, thanks to Richard , When you need it explained the This Old House professionals. its that simple.

[@shangobunni5]

What a great explanation! THANK YOU for this very informative video. I’m looking into getting a heat pump, and this really helps me to understand more about how they work.

[@georgejones5431]

Very true very good on every explanation

[@candidone8544]

I've been a longtime fan of TOH and this segment is as good as any they've had...excellent! My personal surmise is how the use of known gas compression/expansion effects are used much like mechanical gearing, which can upgear or downgear by design. It's the reversibility where full spectrum versatility of heat pump tech resides. Awesome!

[@sonklam2304]

Man, I just finished the fundamentals of Thermodynamics course ( mechanical engineering major) but didn't really understand much about this until now. Wow, exceptional well explanations.

[@StarWarsCosplay]

This is brilliant. I have never understood this until now.

[@kszatmary]

This is the best explanation for the layman. Other videos I've seen on this topic were too technical for my non-mechanically inclined brain. This video was perfect. Thanks.

[@ceeemm1901]

Fantastic explanation and so simple, just following basic laws of physics.Thanks.

[@TheBoomtown4]

In all my years of teaching thermo heat value stochiometric binary engineering, this is by far the best carrot diaper tuna carburetor camera suspension banana! Thanks!

[@ronhamm]

Great explanation of a complicated system.

[@aprilm9551]

What a fantastic explanation. Thorough and detailed, and I was able to understand everything. Not that I remember it all, but it certainly makes sense to me now. And, previously I was confused -- as are many people -- as to how a heat pump can cool, but now I see it is all just a matter of moving heat around, in one way it heats a space, and move it the other way and it cools.

[@erlanisy4481]

Awesome demonstration of how it works. Great and easy to think. Thank you.

[@GunnyPhillips]

Those who intimately know their craft can impart it to others in easily understood terms. Great job and many thanks!

[@dharmawanindrathaher5989]

Wow. Just wow. You brought this mystery down to an easily understandable treat!

[@fessit]

Thanks. I studied refrigeration in college over 4 decades ago. Things have come a long way since then.

[@MatthewWilliams-b1m]

Thankyou for explaining this in such a understanding presentation .

[@efficientmewithsomto8020]

You’ve got it perfectly explained, I love the the enthusiasm

[@waltervasquez1488]

Best video ever about heat pumps.

[@CMRHM]

Sir, you guys have just made a best demonstration regarding refrigeration cycle, thank you!

[@bb57365]

Outstanding explanation of a complicated subject.

[@bkohatl]

Thanks Richard and Kevin, you make the mysterious understandable.

[@brianscheuermann9862]

Thank you for explaining that in a way that even I can understand! I knew the principal of it but not how it actually worked.

[@jaredsilvers2782]

Thermodynamics is the coolest thing I wish everyone was given the opportunity/ability to understand it. It completely changed my understanding of the natural and unnatural world. It took me getting to the advanced level of engineering courses in college to be taught it. I was a relatively lazy college student, pretty average for an engineering student, but I got an A+ in thermodynamics(notoriously hard course), and that was because A. I had a great teacher and B. It was absolutely fascinating I couldn't get enough of it.

[@timefly4221]

This video is amazing! We are having our old, dying A/C system replaced with inverter heat pumps so that we have more flexibility to heat with oil or electricity depending on temperatures and costs. I looked into the technology quite a bit before making the decision, and I generally understood that heat pumps are air conditioners that can also “work in reverse” and they’re very efficient in mildly cold conditions. But this is such a great explanation of the details.

[@talkingbeers]

Such an astonishing coach! Simple crisp memorable - genius at work I love this show!

[@surendersingal9122]

Great demo on showing us expansion n reversing valve mystry demo.

[@TheNephilim101]

WOW ! 😱 What an amazing explanation and illustration ! Thank you 🙏

[@lauriebeaman6315]

Should've explained the liquid and gaseous states of the refrigerant and what happens when it absorbs or rejects heat.

[@ElijahLynn]

Yeah, I found the explanation pretty lacking in detail.

[@ep9360]

Some folks are never satisfied, even when its free to them.

[@ep9360]

Go take a dump Laurie and Elijah

[@iatsd]

Why? What would that add to the video? He's explaining the process so people understand what's happening. The state changes in the refridgerant simply aren't important for that level. Do you want him to explain how the logic board controller works too when it's deciding on the pressure cycling from second to second??

[@woodtool2882]

Thanks Richard, you're the best.

[@youngyeller]

he explained it well, but its still mind boggling. I have a heat pump system and it does work well.

[@joeyavicoli8132]

Does it work down to negative degrees Fahrenheit and if so can it keep inside around 70 degrees on those days?

[@CheloRoja]

Thanks for that explanation in detail and also with a visual effect👍

[@snowy800123]

I never heard of a heat pump until we had a warm summer and I was looking for a cooling solution. I got a pump installed which solved the heat. Then, come winter, my power bill was $260 versus $400 for comparable size houses running on baseboard heaters. This thing pays for itself no time here in Canada.