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Heat Pumps Explained - How Heat Pumps Work HVAC
WEBVTT Kind: captions Language: en
00:00:04.670 --> 00:00:05.503 Hey there guys. 00:00:05.503 --> 00:00:07.650 Paul here from theengineeringmindset.com. 00:00:07.650 --> 00:00:10.060 In this video we're going to be discussing heat pumps, 00:00:10.060 --> 00:00:12.160 the different types and how they work. 00:00:12.160 --> 00:00:12.993 Coming up: 00:00:12.993 --> 00:00:14.200 How heat pumps work, 00:00:14.200 --> 00:00:15.500 air to air heat pumps, 00:00:15.500 --> 00:00:16.950 air to water heat pumps, 00:00:16.950 --> 00:00:18.360 ground source heat pumps, 00:00:18.360 --> 00:00:19.830 water source heat pumps, 00:00:19.830 --> 00:00:20.663 as well as animations 00:00:20.663 --> 00:00:23.021 and systems schematics for each of these. 00:00:23.021 --> 00:00:24.550 I just want to take a moment 00:00:24.550 --> 00:00:27.400 to thank our partner Danfoss for sponsoring this video. 00:00:27.400 --> 00:00:29.140 A critical aspect of heat pumps 00:00:29.140 --> 00:00:30.810 is how energy-efficient they are, 00:00:30.810 --> 00:00:32.960 and Danfoss has everything you need to make sure 00:00:32.960 --> 00:00:34.150 your heat pump is running 00:00:34.150 --> 00:00:37.940 at what they call 360 degree energy efficiency. 00:00:37.940 --> 00:00:39.670 They even built a heat pump website 00:00:39.670 --> 00:00:42.640 that has business cases, case stories, e-lessons, 00:00:42.640 --> 00:00:44.290 and they even have a fun diagram, 00:00:44.290 --> 00:00:46.080 similar to the ones you see on this channel, 00:00:46.080 --> 00:00:48.040 so you can see how it all comes together. 00:00:48.040 --> 00:00:49.670 Just click the link in the video description 00:00:49.670 --> 00:00:53.243 below to see what 360 degree energy efficiency is all about. 00:00:54.200 --> 00:00:55.510 Okay, the first thing we're going 00:00:55.510 --> 00:00:58.140 to look at is the air to air heat pump. 00:00:58.140 --> 00:01:00.470 These are the most common heat pump types. 00:01:00.470 --> 00:01:01.640 They often look very similar 00:01:01.640 --> 00:01:03.710 to a standard air conditioning split unit, 00:01:03.710 --> 00:01:07.580 with the unit located outside & another unit located inside. 00:01:07.580 --> 00:01:10.170 These can either work as a heating-only device 00:01:10.170 --> 00:01:12.420 or, alternatively, the more popular choice is 00:01:12.420 --> 00:01:14.600 to have a device which can provide both heating 00:01:14.600 --> 00:01:17.640 or cooling by making use of the reversing valve. 00:01:17.640 --> 00:01:20.100 We've covered reversing valves in our previous videos. 00:01:20.100 --> 00:01:22.970 Links to that can be found in the video description below. 00:01:22.970 --> 00:01:24.250 There are a few different ways 00:01:24.250 --> 00:01:26.370 to configure a reversing valve heat pump. 00:01:26.370 --> 00:01:29.040 I'll show you a simple, typical example. 00:01:29.040 --> 00:01:31.280 The main components we'll have in this type of system 00:01:31.280 --> 00:01:33.446 are the compressor, the reversing valve, 00:01:33.446 --> 00:01:36.650 the indoor heat exchanger, an expansion valve 00:01:36.650 --> 00:01:38.710 with a non-return valve bypass, 00:01:38.710 --> 00:01:40.305 a bi-directional filter drier, 00:01:40.305 --> 00:01:43.230 a sight glass, another expansion valve 00:01:43.230 --> 00:01:45.370 with a non-return valve and bypass. 00:01:45.370 --> 00:01:47.229 Then we have the outdoor heat exchanger. 00:01:47.229 --> 00:01:49.380 We also have a controller and a number 00:01:49.380 --> 00:01:52.900 of temperature and pressure sensors around the system. 00:01:52.900 --> 00:01:55.330 In heating mode, the refrigerant leaves the compressor 00:01:55.330 --> 00:01:57.354 as a high-pressure, high-temperature vapour 00:01:57.354 --> 00:01:59.950 and passes to the reversing valve. 00:01:59.950 --> 00:02:02.400 The reversing valve is positioned in heating mode, 00:02:02.400 --> 00:02:04.070 so the refrigerant passes through this 00:02:04.070 --> 00:02:06.340 and heads to the indoor unit. 00:02:06.340 --> 00:02:09.440 Cool air is then blown over the indoor unit's heat exchanger 00:02:09.440 --> 00:02:11.180 to remove some of the thermal energy 00:02:11.180 --> 00:02:13.340 and provide heating to the room. 00:02:13.340 --> 00:02:14.480 As heat is removed, 00:02:14.480 --> 00:02:16.810 the refrigerant will condense into a liquid. 00:02:16.810 --> 00:02:18.430 Having given up some of its energy, 00:02:18.430 --> 00:02:19.370 the refrigerant leaves 00:02:19.370 --> 00:02:22.270 slightly cooler liquid. 00:02:22.270 --> 00:02:23.390 The refrigerant then comes 00:02:23.390 --> 00:02:25.760 to the expansion valve and bypass. 00:02:25.760 --> 00:02:27.830 In this mode the expansion valve is closed, 00:02:27.830 --> 00:02:29.460 so the liquid refrigerant passes 00:02:29.460 --> 00:02:31.230 through the non-return valve. 00:02:31.230 --> 00:02:33.840 It then passes through the filter drier and sight glass, 00:02:33.840 --> 00:02:36.540 and then passes to the second expansion valve. 00:02:36.540 --> 00:02:38.800 It will then pass through this expansion valve 00:02:38.800 --> 00:02:40.354 because the non-return valve on this side 00:02:40.354 --> 00:02:43.460 is preventing flow in that direction. 00:02:43.460 --> 00:02:46.000 As the refrigerant passes through the expansion valve, 00:02:46.000 --> 00:02:47.700 the refrigerant expands in volume 00:02:47.700 --> 00:02:50.730 and turns into a part-liquid, part-vapour mixture. 00:02:50.730 --> 00:02:51.970 This expansion in volume 00:02:51.970 --> 00:02:54.420 reduces the temperature and pressure. 00:02:54.420 --> 00:02:55.890 We've covered how thermal expansion valves 00:02:55.890 --> 00:02:58.020 and electronic expansion valves work 00:02:58.020 --> 00:03:00.420 in great detail in the previous videos. 00:03:00.420 --> 00:03:01.260 Do check those out. 00:03:01.260 --> 00:03:03.840 Links are in the video description below. 00:03:03.840 --> 00:03:06.860 The refrigerant then heads to the outdoor heat exchanger. 00:03:06.860 --> 00:03:09.307 Here, a fan is blowing outside ambient air 00:03:09.307 --> 00:03:12.890 over the coil and adding heat to the cold refrigerant. 00:03:12.890 --> 00:03:15.420 The refrigerant boils at a very low temperature, 00:03:15.420 --> 00:03:18.570 and as it boils it will carry away the thermal energy. 00:03:18.570 --> 00:03:20.490 As an example, we know that water 00:03:20.490 --> 00:03:23.440 will carry thermal energy away as steam when it boils, 00:03:23.440 --> 00:03:24.710 and we know that it boils 00:03:24.710 --> 00:03:28.380 at 100 degrees Celsius or 212 degrees Fahrenheit. 00:03:28.380 --> 00:03:31.240 Well, if we then look at some common heat pump refrigerants, 00:03:31.240 --> 00:03:33.750 R134a for example, has a boiling point 00:03:33.750 --> 00:03:36.200 of minus 26.3 degrees Celsius 00:03:36.200 --> 00:03:39.540 or minus 15.34 degrees Fahrenheit. 00:03:39.540 --> 00:03:41.980 Refrigerant R410a has a boiling point 00:03:41.980 --> 00:03:44.410 of minus 48.5 degrees Celsius 00:03:44.410 --> 00:03:47.310 or minus 55.3 degrees Fahrenheit. 00:03:47.310 --> 00:03:49.580 So, it's very easy to extract thermal energy 00:03:49.580 --> 00:03:52.000 even at very low outdoor temperatures. 00:03:52.000 --> 00:03:53.510 We've covered how refrigerants work, 00:03:53.510 --> 00:03:54.780 also in previous video. 00:03:54.780 --> 00:03:56.320 Again, links to that can be found 00:03:56.320 --> 00:03:58.260 in the video description below. 00:03:58.260 --> 00:04:00.360 So the refrigerant picks up the thermal energy 00:04:00.360 --> 00:04:03.390 from the outside air and leaves the outdoor heat exchanger 00:04:03.390 --> 00:04:05.089 as a low-pressure, low-temperature, 00:04:05.089 --> 00:04:07.360 slightly superheated vapour, 00:04:07.360 --> 00:04:09.380 and then heads back to the reversing valve. 00:04:09.380 --> 00:04:11.450 The reversing valve then diverts this 00:04:11.450 --> 00:04:13.980 to the compressor to repeat the cycle. 00:04:13.980 --> 00:04:16.530 If this system is then switched into cooling mode, 00:04:16.530 --> 00:04:19.610 the system then acts like a normal split air conditioner. 00:04:19.610 --> 00:04:21.450 The compressor forces the high-pressure, 00:04:21.450 --> 00:04:24.640 high-temperature vapour refrigerant into the reversing valve 00:04:24.640 --> 00:04:27.800 The reversing valve diverts this to the outdoor unit. 00:04:27.800 --> 00:04:29.210 The fan of the outdoor unit 00:04:29.210 --> 00:04:31.790 blows ambient air across the heat exchanger. 00:04:31.790 --> 00:04:33.570 This air will be a cooler temperature, 00:04:33.570 --> 00:04:36.610 so it carries the thermal energy of the refrigerant away. 00:04:36.610 --> 00:04:39.810 The refrigerant condenses as it loses its thermal energy. 00:04:39.810 --> 00:04:41.430 00:04:41.430 --> 00:04:42.360 00:04:42.360 --> 00:04:45.210 00:04:45.210 --> 00:04:48.160 It then heads to the expansion valve, but this is closed, 00:04:48.160 --> 00:04:50.730 so the refrigerant passes 00:04:50.730 --> 00:04:52.810 It then passes through the sight glass 00:04:52.810 --> 00:04:54.900 and the bi-directional filter drier. 00:04:54.900 --> 00:04:57.130 The next non-return valve is then closed, 00:04:57.130 --> 00:04:59.690 through the expansion valve. 00:04:59.690 --> 00:05:01.114 As it passes through the expansion valve, 00:05:01.114 --> 00:05:02.510 the refrigerant changes 00:05:02.510 --> 00:05:04.870 to a part-liquid, part-vapour mixture, 00:05:04.870 --> 00:05:07.450 which causes it to drop in pressure and temperature. 00:05:07.450 --> 00:05:10.100 It then flows into the indoor heat exchanger. 00:05:10.100 --> 00:05:13.820 And in here, a fan blows the warm indoor air over the coil. 00:05:13.820 --> 00:05:15.450 This causes the heat to transfer 00:05:15.450 --> 00:05:17.079 from the air into the refrigerant, 00:05:17.079 --> 00:05:20.300 and so the refrigerant boils and takes its heat away. 00:05:20.300 --> 00:05:22.030 The refrigerant leaves the indoor unit 00:05:22.030 --> 00:05:23.980 00:05:23.980 --> 00:05:26.180 slightly superheated state and flows 00:05:26.180 --> 00:05:27.620 into the reversing valve. 00:05:27.620 --> 00:05:28.880 The valve diverts this back 00:05:28.880 --> 00:05:31.620 00:05:31.620 --> 00:05:33.600 Air to water heat pumps: 00:05:33.600 --> 00:05:35.510 These units work in a very similar manner 00:05:35.510 --> 00:05:37.030 to air to air heat pumps, 00:05:37.030 --> 00:05:38.640 but without the reversing valve. 00:05:38.640 --> 00:05:41.180 The high-pressure, 00:05:41.180 --> 00:05:42.360 leaves the compressor, 00:05:42.360 --> 00:05:45.260 but this time it heads into a plate heat exchanger. 00:05:45.260 --> 00:05:47.360 On the other side of the plate heat exchanger, 00:05:47.360 --> 00:05:48.470 water will have been cycled 00:05:48.470 --> 00:05:50.086 through a hot water storage tank. 00:05:50.086 --> 00:05:52.870 Cooled water enters the heat exchanger from the tank, 00:05:52.870 --> 00:05:54.456 and as it passes through the heat exchanger, 00:05:54.456 --> 00:05:57.120 it absorbs heat from the hot refrigerant. 00:05:57.120 --> 00:05:59.385 The water will then leave at a much hotter temperature 00:05:59.385 --> 00:06:00.500 and flow back 00:06:00.500 --> 00:06:03.390 to the hot water storage tank to repeat this cycle. 00:06:03.390 --> 00:06:05.560 As the refrigerant gives up its heat to the water, 00:06:05.560 --> 00:06:08.270 it will condense and it will then leave the heat exchanger 00:06:08.270 --> 00:06:11.300 lower-temperature liquid. 00:06:11.300 --> 00:06:12.960 We've covered how heat exchangers work 00:06:12.960 --> 00:06:14.110 in our previous videos. 00:06:14.110 --> 00:06:15.290 Links to these can be found 00:06:15.290 --> 00:06:17.300 00:06:17.300 --> 00:06:18.490 The refrigerant then passes 00:06:18.490 --> 00:06:20.259 through the filter drier and the sight glass, 00:06:20.259 --> 00:06:22.460 and then into the expansion valve. 00:06:22.460 --> 00:06:24.310 The expansion valve causes the refrigerant 00:06:24.310 --> 00:06:26.575 to become part-liquid, part-vapour state. 00:06:26.575 --> 00:06:29.070 It'll be at a low temperature and pressure. 00:06:29.070 --> 00:06:31.175 outdoor heat exchanger, 00:06:31.175 --> 00:06:33.140 where the outdoor ambient air 00:06:33.140 --> 00:06:35.160 causes the refrigerant to boil. 00:06:35.160 --> 00:06:37.480 The refrigerant then leaves at a low-pressure, 00:06:37.480 --> 00:06:40.140 low-temperature, slightly superheated vapour 00:06:40.140 --> 00:06:41.839 and is then sucked back into the compressor 00:06:41.839 --> 00:06:44.090 to repeat the entire cycle again. 00:06:44.090 --> 00:06:46.230 The hot water tank then provides hot water 00:06:46.230 --> 00:06:49.789 to the radiators, sinks, and showers within the building. 00:06:49.789 --> 00:06:52.000 Ground source heat pump: 00:06:52.000 --> 00:06:54.470 There are two main types of 00:06:54.470 --> 00:06:57.300 that being the horizontal and the vertical type. 00:06:57.300 --> 00:06:58.930 Both essentially work the same, 00:06:58.930 --> 00:07:00.500 it's just how they access the heat 00:07:00.500 --> 00:07:02.320 in the ground that varies. 00:07:02.320 --> 00:07:04.190 We'll look at when to use the different types 00:07:04.190 --> 00:07:06.770 as well as the pros and cons to these in our next video. 00:07:06.770 --> 00:07:09.650 This video, we're just gonna focus on how they work. 00:07:09.650 --> 00:07:12.530 Ground source can be used for heating air or water. 00:07:12.530 --> 00:07:14.650 In the air type system, the heat pump can 00:07:14.650 --> 00:07:16.180 also have a reversing valve 00:07:16.180 --> 00:07:18.580 and then supply either heating or cooling. 00:07:18.580 --> 00:07:20.800 In both cases, the outdoor heat exchanger 00:07:20.800 --> 00:07:21.827 can be a plate heat exchanger 00:07:21.827 --> 00:07:23.821 with the refrigerant passing on one side 00:07:23.821 --> 00:07:26.170 and a mixture of water and antifreeze 00:07:26.170 --> 00:07:27.810 cycling on the other side. 00:07:27.810 --> 00:07:29.860 The water and antifreeze mixture is forced 00:07:29.860 --> 00:07:32.280 by a pump around the pipes within the ground. 00:07:32.280 --> 00:07:34.360 This will allow it to pick up the thermal energy 00:07:34.360 --> 00:07:37.480 in heating mode and bring this to the heat exchanger. 00:07:37.480 --> 00:07:39.528 The refrigerant on the other side of the heat exchanger 00:07:39.528 --> 00:07:42.108 absorbs the heat because it has a very low boiling point, 00:07:42.108 --> 00:07:44.823 so as it boils it carries the heat away, 00:07:44.823 --> 00:07:47.090 which can then be used within the building. 00:07:47.090 --> 00:07:49.454 In the air type system, there can be a reversing valve. 00:07:49.454 --> 00:07:52.040 This will allow the refrigeration system 00:07:52.040 --> 00:07:54.380 to pull unwanted heat out of the building 00:07:54.380 --> 00:07:57.640 and transfer this into the water-antifreeze mixture. 00:07:57.640 --> 00:07:58.950 This water will then be pumped 00:07:58.950 --> 00:08:00.300 around the pipes in the ground, 00:08:00.300 --> 00:08:02.630 and it will transfer the heat into the ground, 00:08:02.630 --> 00:08:05.757 thus returning cooler, ready to pick up more heat. 00:08:05.757 --> 00:08:07.940 Water source heat pumps: 00:08:07.940 --> 00:08:10.610 Water source heat pumps come in two main variations, 00:08:10.610 --> 00:08:12.260 closed and open loop. 00:08:12.260 --> 00:08:15.140 The closed loop sends a mixture of water and antifreeze 00:08:15.140 --> 00:08:17.710 to collect thermal energy from a pond or river, 00:08:17.710 --> 00:08:20.230 and transfers this through 00:08:20.230 --> 00:08:21.580 The same water is then sent round 00:08:21.580 --> 00:08:23.400 again to repeat the cycle. 00:08:23.400 --> 00:08:25.960 Open loop pulls in fresh water from an aquifer 00:08:25.960 --> 00:08:27.820 or from a river and pumps this 00:08:27.820 --> 00:08:30.180 into the heat exchanger to collect the heat. 00:08:30.180 --> 00:08:31.170 Once it passes through, 00:08:31.170 --> 00:08:33.810 it is then released back into the same water source. 00:08:33.810 --> 00:08:36.730 In a closed loop type, a water and antifreeze mixture 00:08:36.730 --> 00:08:39.257 cycles around the pipes to collect the thermal energy 00:08:39.257 --> 00:08:41.670 and bring this to the heat exchanger, 00:08:41.670 --> 00:08:42.962 where the refrigeration system will 00:08:42.962 --> 00:08:46.460 then would absorb the energy and use it for heating. 00:08:46.460 --> 00:08:49.230 Alternatively, it will dump the building's unwanted heat 00:08:49.230 --> 00:08:51.170 into the water-antifreeze mixture 00:08:51.170 --> 00:08:53.060 to provide cooling for the building. 00:08:53.060 --> 00:08:55.810 The unit then works the same as a ground source heat pump. 00:08:55.810 --> 00:08:59.030 In an open loop type, the water is pulled in via a pump 00:08:59.030 --> 00:09:01.380 and sent directly to the heat exchanger. 00:09:01.380 --> 00:09:03.540 The heat exchanger then pulls the thermal energy 00:09:03.540 --> 00:09:04.580 out of the water, 00:09:04.580 --> 00:09:07.300 or it dumps the unwanted heat into the water. 00:09:07.300 --> 00:09:09.420 The water then passes through the heat exchanger 00:09:09.420 --> 00:09:12.003 and returns to the source some distance apart. 00:09:13.190 --> 00:09:15.340 Before I wrap things up, I just want to thank 00:09:15.340 --> 00:09:17.940 Danfoss one last time for sponsoring this video. 00:09:17.940 --> 00:09:20.090 Don't forget to check out their heat pump solutions 00:09:20.090 --> 00:09:23.120 by clicking on the link in 00:09:23.120 --> 00:09:24.780 Okay guys, that's it for this video. 00:09:24.780 --> 00:09:26.060 Thank you very much for watching. 00:09:26.060 --> 00:09:27.820 And I hope you enjoyed this and it has helped you. 00:09:27.820 --> 00:09:30.510 If so, don't forget to like, subscribe, and share. 00:09:30.510 --> 00:09:32.450 Leave your questions in the comment section below 00:09:32.450 --> 00:09:34.520 and follow us on Facebook, Instagram, Twitter, 00:09:34.520 --> 00:09:37.290 and of course, theengineeringmindset.com. 00:09:37.290 --> 00:09:39.957 Once again, thanks for watching.
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