HVAC Heat Pump Basics
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- เผยแพร่เมื่อ 5 ส.ค. 2024
- In this video, HVAC technician Jesse covers some heat pump basics for beginners. The basics cover how a heat pump works and the operation of all components of a typical heat pump.
In the cooling cycle, the liquid line leads into the TXV where the refrigerant pressure rapidly drops and some flash gas is produced. From there, there's a short expansion phase into the evaporator, where the refrigerant absorbs heat from the space and boils. The refrigerant travels to the compressor via the suction line as a superheated vapor. The compressor rapidly raises the temperature and pressure of the vapor and sends the refrigerant to the condensing coil through the discharge line. The condenser rejects heat from the refrigerant and turns it back into a liquid. From there, the cycle repeats itself.
In a heat pump, you have all of the same basic components. However, the evaporator coil in cooling mode becomes the condenser in heating mode, and the condenser in cooling mode becomes the evaporator in heating mode. In the air handler, you will also have heat strips, which provide electrical backup heat. When the system goes into defrost, the heat strips also turn on to prevent the space from cooling too much. Heat pumps also have two metering devices: one for cooling mode and one for heating mode. TXV systems have check valves that allow the refrigerant to bypass the metering device that is not in use.
At the outdoor equipment, a heat pump has a defrost board, reversing valve, a common suction port. The defrost board is located in the same place as the low and high-voltage wiring underneath a panel, and it has a defrost sensor connected to the outdoor coil. The common suction port is located between the suction and liquid line coming out of the outdoor unit. A 4-way reversing valve has a solenoid that can slide the reversing valve and swap the suction and discharge lines when energized. That process reverses the flow direction and allows the heat pump to switch between heating and cooling mode. There will always be a common suction line and a common discharge line leading into the reversing valve.
There may also be an accumulator on the system, which prevents liquid refrigerant from getting into the compressor. In cooling mode, the refrigerant flows through the suction line and then passes through the reversing valve before the compressor. In heating mode, the refrigerant passes through the compressor before it reaches the reversing valve.
The defrost board depends on a defrost sensor to tell the unit when to defrost. (In this case, it's a pink wire.) In defrost mode, the defrost board will send a 24v call on the white wire to energize the backup heat inside (heat strips).
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Thank you! Great info. Looking forward to more.
I really appreciate Jesse taking us inside the condensing unit. Really helped me demystify where the lines are going once they're ran inside the unit.
Thank you so much for these videos. I struggle to pay attention, my mind will wander constantly as the instructor is teaching. These videos help me focus. Watching, listening and taking notes helps me retain the information better. Plus, I get to rewind when I become distracted. Thank for taking the time to educate me!
Same thing happens to me as well. Also, english being my second language is also the reason.
This is THE best HVAC channel out there. This dudes like a surgeon but only in the HVAC field....
Moved into a new-to-us house that had this system, from a home with a gas furnace, and had no clue how it all worked... now I do! thank you!
Ty brother! Informative, clear, loud and slow.
We need a troubleshooting sequence to figure out what went wrong with heat pumps, besides typical operation sequence. Like with furnace operation. Trace what's supposed to happen, and find the defects. Like stuck or worn out reversing valve. What would you see, how would you know? What would your pressures be like?
As a HVAC student I love your videos
Nice information guys. And since you guys put out the free videos I will do my part and not skip the commercials, only fair. Thanks.
when the system goes into defrost it simply goes back into cool mode with the fan cycled off so the head pressure can go up and then a signal is sent to the indoor board to turn on the heatstrip so it can warm up the cold air while its in defrost. And the main reason you want to have a high head preasure is so the hot gas can melt the ice around the outside coil.
Wow
Bam!
What's the reading on the hot line?? When it comes out
Good explanation exhibits what it's doing. How's the cycle sensed & actuated to defrost the iced outside coil? Time or by a temperature sensor?
The defrost terminator initiates and terminates defrost by temp.
Thank you very much for your teaching hope you guys make more of this. Heat pumps thanks 🙏
Amazingly clear and precise video. Incredibly thorough video. Thank you so much!
👍👍👍👍 nice explanation I don’t work on many heat pumps here in Iowa nice refresher.
What a great explanation, well done.
Some of the best explained info ive ever heard. Thanks so much for the careful consideration of " wording"/ terminology because its very easy to become complacent of wording leading to a total misunderstanding of functions for those who are wanting and trying to be good techs but that are just not quite there yet. Great job guys!!
you said a mouth full there my friend i am 66 and retired for a long time ,,,,,i always said everything can depend on HOW A TEACHER explains certain things ,,,they can understand it well OR cause a big f,,,,ing mess LOL ,,,,,enjoy the new year
wow ! nice review for this retired old man lol ,,,,,,well done guys ! now in 2020 first day ,,my heat pump is running in north florida ,,,,,not like miami or ft laud here at all for just little over 4 hours away ! thank you
ill give this 5 star. very good explanation.finally no more intros direct to the point.
Really, what is up with that??
Thank you so much for sharing this teaching video.
We’re starting to see alot more of these up in Connecticut. Thanks for the video!
Loved the video. It was very informative and he nicely explianed the concept practically.
this is a great channel to watch, learned a lot. keep it up with a good content....
great information. thank you so much!
Really help I use to always wonder how did the heat pump work, but it’s amazing how the coils make that switch. 3 main things that he spoke was reversing valve defrosting board the common suction line how they rotate depending if it heat or cold air
Great video and good detailed explanation.... keep this video coming
Thank you for your clear explanation and good luck always
Love these videos. Excellent description of the system and the process.
Glad you like them!
Would like to see a video on pressure drop on line sets / sizing
Thanks for the videos, great work!!!
Pretty helpful thanks sir for simplifying it made a little easier to understand
Wow this is a lot. Thank you for the information very much needed
Very helpful video - thanks for posting! :D
Thanks!! Good video.
Thank you got great information on Heat Pump system.....
Great explanation!
fantastic job
Thank you so much what you shared for us.
Heat pumps are krazy tight and mind blowing yo.
That’s what I’m Really Really realizing now
Good video!
very informative. thanks.
Great video Guys
Nicely done
I see you have Comfortguard on that system. Good info.
Thanks a lot for this video 👏👏👏👏🇻🇪.
Here in Colorado, heat pumps are usually connected to a furnace for a dual-fuel setup because NG is far less expensive and efficient compared to heat strips. If you buy an efficient enough heat pump, it will be less of a problem or requirement of NG furnace. But I love my Bryant Evolution Heat pump and high-efficiency Bryant Evolution furnace. The cost of electricity is skyrocketing but our solar panels produce plenty of power during the day to run the heat pump completely.
Relly nice explained
great video.
That was nice!
Good teaching master
Good stuff guys thanks
Hi sir any jobs in air conditioning technician s plzzz information
Thank you for helping educate people who have to know EVERYTHING due to corrupt tech companies who only want to sell units and not repair. There should be a law. I went through four last time I had an issue and finally fixed with blower motor instead of $6500 replacement. Those liars are killing your industry.
It's all fun an games until an untrained homeowner gets electrocuted since they neglected essential safety procedures prior to working on the system since they became an HVAC guru via TH-cam over night....
@@factfactory575 No one suggested DIY on HVAC, or other major systems, or even tolerating unlicensed repair guys. But since most 'servce calls' and 'repair techs' are just salesmen, it's good to have knowledge to find the right, licensed guy (one who doesn't carry or sell systems).
Very true, I work for an HVAC wholesale company.
realy great info
Thanks 👍
I like how he just starts off saying most of us know this then glossing over it like we already know lol my dude we're here watching this video because we know almost nothing.
No point in learning about a heat pump if you don't understand how a AC unit operates first, that would be the first step. He really should have mentioned that but this content is for their students, not really directed at the public.
Hello, I am wondering what the drawbacks would be to putting the compressor in a shed? Specifically an uninsulated 8' x 8' x 9' open eaved (32 sq ft of open soffit vent)) building on an 8" concrete slab. This would be in a 95% heat situation but in very high humidity. I am thinking of all the corrosion, leaf/needle accumulation, as well as snow. Since the unit is just coated steel and the fins are so close together avoiding having them foul up would help the unit's longevity immensely. This is a 17' line set that I have another two layers of insulation over the top of the original. i started it up two days ago (45 degrees night and day 100% humidity) and am seeing a lot of condensate coming off the bottom of the casing which has a drain installed leading outside. I installed it up off the floor about two feet on a wood shelf with 4x4 legs drilled into the concrete. The issue is it makes enough water to keep the wood soaked and a puddle on the floor (although that drains out the door it will be an ice rink in the freezing weather). I am hoping to protect the unit from the wind and rain/snow that accumulates here in a temperate rain forest and coastal winds. I have found the plastic drain fitting is proud of the bottom enough to always have a layer of cold condensate in the bottom which condensates on the bottom side of the bottom in a major way. I am thinking of spray foaming between the shelf and the bottom with low expansion canned foam to stop this happening? As the temperature outside drops I can't see it doing anything but becoming a block of ice building up from the bottom? What are your thoughts? I have not found this addressed anywhere else. Thanks. Doug
I see. The flibjabber encapsulates the mobibblybob at the same time the jigglydiggly sucks out the whammyjamjibblybop. Got it!
Good video. Any chance on getting a video on multimeter basics in the field?
good info
Can this be used with an existing heating/cooling system i.e. existing furnace/AC kicks on in extreme cold/heat otherwise heat pump is on? Also does system have a backup so it works when power goes out?
Hi, I just want to leave rough in lines in my new construction for now between air handler and outside heat pump unit. Should I leave just two half inch copper lines or do I need anything else. I will leave two 5 conductor low voltage wires and ac wiring as well. Also do I need to insulate those copper lines?
nice description of the systems and operation, can you clean up those wires with some wire ties so it is easier to see what the components are
What is the transformer on outside unit for. Does this supply the 24V to the inside of the house as well.
The evaporator is referred to as the indoor coil and the condenser coil as the outdoor coil to eliminate confusion, indoor fan, outdoor fan... when d3aling with heat pumps.
whole suction line have to be insulated?
in the indoor unit we have two coils and a directional valve? One for cooling and one for heating? Or Is there one and the same element that performs two functions?
Does the compressor run during the Heat cycle just like during the Air Conditioning cycle? Will the electric consumption be just as high in the winter as it is in the summer?
Took me a while to understand that the heat pump is also the reversing Valve. I was looking for an actual pump or anything like that until I got my thoughts together
The bypass for either heating or cooling occurs at the reversing valve?
Yes and No. The reversing valve only selects the direction of the refrigerant once it leave the compressor. For heatpump mode It simply sends the liquid to the outdoor coil so It can absorb heat there then takes the heat to the indoor coil and a fan blows the warm air into the conditioned space.
I live in North California we don't get snow here when installing this or wiring this should wire the defrost wire or just bypass it
I have an 8-year-old Bryant 213B heat pump & Bryant gas furnace. This morning (at 35 degrees outdoors) I upped my thermostat from 64 to 69 degrees. The heat pump and furnace fan came on and ran for just a couple of minutes. Then, due to the call for 5 degrees of heat all at once, the Aux gas heat was initiated which makes sense. I heard the gas burner fire up and the vent pipe got hot. My concern is this: I could hear that my heat pump was still running. I learned that the 2 units (HP & gas furnace) should never run at the same time. I suppose it could be that the HP is possibly running in a different mode, such as defrost or possibly in some way that would not be harmful, but I don't know. So, I immediately dialed back the thermostat to shut it down. I don’t know how to confirm if this is a ‘dangerous’ situation or not. I don’t know if the heat pump is supposed to ‘run on’ in some otherwise safe mode temporarily. I am afraid that if I let it run on just to see if it eventually shuts down I might do damage in the meantime. The fact is that it may have been doing this all along but since I installed a new thermostat recently I am being hyper-vigilant now. I am very confident that my thermostat wiring and setup is correct. I would feel better if I knew that the HP is supposed to behave like this under these conditions. Can anyone comment on this if you happen to know?
2:02 Nice..Balance point what is the balance point for Florida?... curious...and HHD? I would assume high balance low HHD
Nice in comfortable
What happens when it's very cold outside how take heat on temperature colder ..? It's normally head pump running and doesn't stop on this colder days
endothermic and exothermic state changes through the manipulation of pressure. three way valve position determines the direction of flow. Come to Canada boys, we'll get yall learned up. those valves are called suction and liquid line service valves by the way.
🙄🇨🇦
Can you provide us with your heat pump videos on youtube I am sure we could learn a lot from your wealth of knowledge.
I thought they were two position valves. Inny or outty, like belly buttons.
Gooooooood
I installed a Carrier heat pump system a few months ago. Heating and cooling functions are fine so far. But there is a wild constant humming sound from the bottom of the unit (transformer?) when the system is not working. Is this normal? Thanks.
Unfortunately that is normal in my experience. But I am no electrical expert.
Probably the contactor. It might have gotten wet or have insects in it.
Do these also have a reheat coil?
Do the fans blow the same direction or do they change in respect to the coils absorbing and dissipating heat?
they always blow the same
I have a heat pump and a gas furnace. The company I work for does this a lot here in Indiana.
What is the reason for doing that? I want to know, thanks
Sounds easy enough.
Just graduated HVAC trade school and have a buddy that's having an issue with his outdoor heat pump unit. Says he hears his outdoor unit run randomly in cool (lives in las vegas about 70 degree weather currently). He noticed it because his unit is right next to his bedroom. Thermostat is set to off the times that this has happened and the said he didn't feel any air coming out of his Vents. Told him to check for any schedules on the thermostat and there was none aside from it already not calling for it because the tstat is off. What are some possible things that can cause this. When I went I didn't see anything out of the ordinary and it happens randomly.
Great explanation, but isn't this a long way round just to say that the system swaps the coils, and bypasses the expansion valve that is not in use? Then it has a back-up electric heater inside and a fan-kill option outside to get the coils hot enough to defrost. I was hoping for an explanation of some of the engineering, I guess, like if the suction line is still larger, what effect does that have coming off the compressor in heat mode, etc.
I couldn't ever figure out what went wrong except to replace a worn out reversing valve. What could be worse besides a compressor burn out?
I always thought heat pumps made a lot of sense to me, the system literally is pumping heat... it takes heat from either inside or outside and pumps it from one space to the other
Yes. Heat flows to where it's cooler the way water flows downward due to gravity. A pump uses energy to work against these.
Can you please do one on a commercial carrier unit
Common suction is also referred to as "true suction"
Hi my name is Jose I am from Los Angeles ca I watching your videos and I loved but you never told about water source heat pump please if you have any time to talk about water source
Jesse....you're awesome. Just one minor detail....please allow me to remove the "bar code sticker" (@ 9:39) from your shirt collar so you can be all comfy....
COOLING CYCLE is a just cycle in a HEAT PUMP SYSTEM
HEATING CYCLE orREVERSE CYCLE is just another cycle in a HEAT PUMP SYSTEM
HEAT PUMP is any SYSTEM that allows you to capture energy from point A and take it to point B as that happens through a thermo-dynamic process we call this energy heat
In the end of the day HEAT is only a label that we use to talk about energy so whoever is listening to us understand that we are talking about energy transference in a thermo-dynamic process
There are many other language traps in HVAC like “cold retention” and so on..
They have been around for decades!
Please make vidio tutorial how to repair heat pump error 29.. thank aboat it Mr
Watching a bunch of HVAC videos and computer programming videos because... 21st-century.
The strips are only 24v? Or 220v?
Heat strips are 220v. They work like the heating element in a waterheater.
@@TanTan-ni4mg it's actually more like a toaster
You're kidding, right?
Does some heat pump have burners
I assume that you are talking about the air handle or furnace. Yes, as backup or emergency heating, there can be either gas fire or electric elements that can be in place.
Yes some heatpumps are equiped with 2 or even three ways to heat. In the HVAC/R industry me call them dual-fuel or multi-fuel systems. Ive seen one with heatpump for primary , electric for back up, and natural gas for a third source. Ive also seen pellet fuel burners on ground source heatpumps. Its all in what makes economical sense.
So like, what's the point of one line being big and the other being small if you literally run it in reverse???
I think "taking heat from outside air" confuses people. The heat transferred into the house comes from the compression. Outside air just needs enough heat to boil off the refrigerant in the outdoor coil.
You are confusing heat and temperature. The heat absolutely comes from the outside air. The temperature increases during compression.
@@HVACS the refrigerant evaporated from the outside air is still below 40. Cool vapor prevents overheating from the compressor, right? Heat of compression will be about 100-120, right? After the heat exchange in the indoor coil, air from the register around 90. Not confusing temp and heat as latent heat isn't really a factor in heating mode. I'm no professor, but you need enough outside heat to boil in the outdoor coil. All sensible heat should come from compression, no?
The term "heat pump" originates from physics and thermodynamics. "Heat" = thermal energy, thus even environments that feel cold still contain heat. It's "cold" to us humans, because we have limited ranges of temperature we tolerate and like to live and feel comfortable in.
Thermodynamically, heat will flow from where it is higher to where it is lower:
- in the absence of some force/energy opposing that flow
- and if there's a path for that thermal energy to flow
What are some of the things that oppose/slow down that flow? Thermal insulation is one. Physically, they're ways that increase that flow path thus slowing down the overall heat transfer from warmER to coldER.
Another one is a heat pump, a system that opposed that thermodynamic flow, pretty much at the cost of energy (adding heat to the larger overall system).
Air conditioners, refrigerators, even furnaces (in a sort of roundabout way), are all heat pumps. ACs are easier to conceptualize because people already understand what they accomplish (even if vaguely). They're just fixed in the direction in which they pump heat, which is why ACs aren't used in the off-seasons.
A heat pump, as in the appliance, is thus "just" an AC that can operate bidirectionally, pumping the heat in either direction as well. If you took a small 5k btu window ac unit and flipped it around in the winter, you could have a really poor man's "heat pump" (appliance), in effect "air conditioning" the already cold outdoors even further. Purpose-designed heat pump appliances are accomplishing the same with some additional components, and likely design + engineering so that coil systems can serve as both condensers and evaporators.
In the summer, it costs energy, in the form of additional heat to the net thermodynamic system of home indoors + outdoor environment, to effect a cooler area such as a home. But in the winter, this works in our favor, outputting more heat than energy that is put in, because the difference is heat being taken from the colder outdoors.
Engineering-wise, there's more to it.
ACs aren't generally designed to cool the cool side to below ~60F because they're for human comfort, so they are heat pumps designed for efficient operation in that temperature range.
A refrigerator is a heat pump designed to cool down to lower temperatures, below freezing in the case of freezers, partly due to the heat pumps used, partly due to also having an insulated box.
A heat pump (appliance) has to be able to efficiently extract heat from an outdoor environment that's potentially closer to that of the refrigerator than that of the above AC example. So not only is it more versatile an appliance in that it's usable during both heating and cooling seasons, it also needs better engineering for the reversibility of heat pumping direction but also for extracting heat in colder temps during the heating season. This is where features like Hyper Heat come in.
Vrf system explanation
Jessie, lose that wedding ring before you lose a finger, no woman is worth that, LOL!
Anyone have a customer with a new install go out and use a fire extinguisher after watching a defrost cycle?
I haven't but I can guarantee it has happened. I have heard my dad talk about people calling about their ODU being on fire.
If its warm outside, shouldn't be even warmer inside? Why the need for a heat pump then?..
Only 1 unit to heat a whole house ..?
Not discharge muffler it is filter dryer
Getting ready for the CEC 2026.😅