Can You Use a Mini Split in EXTREME COLD? Heat Pump vs. Propane Cost Comparison with Thermal Camera

today we're going to be talking about heat pumps and more specifically mini splits when it comes to whether or not you should use them for heating and some of the aspects and pros and cons of using them for heating we're going to go through several different points including talking about the coefficient of performance now not all mini split units can heat but the majority of these days typically are also equipped as heat pumps and i'll explain that a little bit further in the video we're going to use a thermal camera and actually be able to visualize and see exactly what's happening when the unit is in heat pump mode so make sure you stay tuned for that basically in heat pump mode it's doing the opposite of what it would be doing in the cooling mode where normally you're pulling heat from the inside of the building and putting it outside in heat pump mode it's pulling heat from the outside and putting it inside and that's where the coefficient of performance is going to come into play here in just a minute many heat pumps will only heat efficiently down to probably like 20 degrees or so and it just really depends on the manufacturer but there are some units that can heat even colder for cold climates which is like the one that i have behind me here this one's by cooper and hunter and these guys have a feature called hyper heat where this unit will actually heat all the way down to 22 degrees below zero fahrenheit now you do lose some efficiency as that drops down and we'll talk about that in a minute but having the capability of heating down to those lower temperatures is really convenient when you want to have a one unit solution for your heating and cooling needs for a particular space now a great way to be able to visualize how an air conditioner or a heat pump works is to use a thermal camera that's what you guys are looking through right now as you can see the camera is looking at where there is heat and lack of heat instead of visible light right now obviously it's running in heating mode and you can see that because of that glowing portion right there that is warmer than the environment the way this thermal camera works is anything that's hot will show up kind of that bright yellow or orange color and then anything cooler will be the darker color so it's really nice because you can distinguish what exactly is going on so right over here on the edge you can see where that line set first comes through the wall that is actually showing up a little bit uh brighter than the surroundings even though it is insulated and then it's really bright right there where the coil is located right now that coil is acting as the condenser portion of the coil and not the evaporator like it typically would in air conditioning and that's the unique thing about many splits or heat pumps in general actually is that they can switch using either coil in the inside or in the outside unit to be either the condenser or the evaporator let's go outside and take a look at exactly what is going on on the outside unit look at that that's kind of cool so you can see the uh framing members from inside the building are transferring through to the outside where you can see that it's warmer where the framing members are and less warm in between where the insulation is thicker so right over here you can see the line sets coming out of the back of the garage and that is warmer than the ambient environment even though it is insulated now right here this is a really interesting view you can see that the coil that is uh inside of this outdoor unit is colder than the ambient environment because what's happening right now is even though right now it's like zero degrees it's actually like minus five degrees fahrenheit right now here in minnesota even though it's so cold outside it's still pulling heat out of the air so it's taking heat out of the air so coming into that coil it's probably like let's just say it's zero degree air and coming out of the coil is probably like minus three or minus five i'm going to hang out at minus 14.2 degrees we'll call it 14 below zero right now now let's see how cold it is coming out of this fan should be even colder than that because this heat pump right now is actually pulling heat out of the air so by taking heat out of the air outside it's going to drop this temperature from 14 below to probably even colder let's get this in the airstream here minus 15.8 right there minus 16 16 below zero oh man that's so cold so we're going from 14 below zero to 16 below zero so it's it's pulling two degrees of heat out of the air out here which is so weird it took me a really long time to wrap my head around the fact that you could pull heat out of air that is like freezing cold but you can so hopefully the thermal camera can help you kind of visualize exactly what's going on with this it's kind of a neat way to be able to understand the way heat is being rejected or absorbed in either the inside or the outside depending on the mode that the heat pump is in wasn't that interesting i love those thermal cameras you can do some really really cool things like how you saw the studs through the wall from the outside or the inside it actually even works as a stud finder because you can see where the studs are located even behind drywall it's really really neat so if you guys are interested in that particular infrared camera i will link it in the description along with anything else that's relevant to this video including this exact unit that i have here behind me for this little 24 by 22 foot garage here in minnesota now people tend to talk a lot about how efficient a mini split system is and they are very efficient or just heat pumps in general but you do need to understand the numbers behind that and not just claim that hey it's so efficient it's just amazing it runs out nothing it's just incredible a lot of that is emotion and not hard data that people are going off of so that's where we're going to understand the cop the coefficient of performance which is just a fancy way of saying the percentage efficiency of a particular unit so a cop of one one cop equals 100 efficient so that'd be like your space heater or even any resistance electrical heat is going to have a cop of one for the elements in and of themselves because every kilowatt of electricity turns into one kilowatt worth of heat being released into the space so a cop of one equals resistance heater which is obviously very inefficient in many ways and is also very expensive as at 13 cents per kilowatt hour which is about the price of electricity in my area that comes out to be about 38 dollars and 10 cents per 1 million btus and remember that here in a second because we're going to compare this to propane to kind of give us a baseline of what we're working with so now propane at one dollar and sixty cents per gallon which is the current pricing in my area i actually got propane for cheaper in the summer by using summer fill it was like a dollar a gallon approximately but at 160 per gallon with a cop of .95 because it's only 95 efficient because you have some exhaust going outside the building you end up with an 18.44 per 1 million btus for propane so obviously 1844 is much cheaper than 3810 for our electric resistance heating thankfully our heat pumps don't run at a cop of one otherwise it wouldn't make any sense to even have them because that would be the same as an electric resistance heater so the way they're able to achieve a cop of greater than one is that they're not actually using the electricity to create heat directly they're using the electricity to power the compressor in the outside unit and the fans and controls that are involved in the heat pump and what that allows is it allows the unit to actually move the heat from the outside of the building into the building so it's pulling heat out of that really cold air which is surprising just like we finished looking at in that thermal camera video and depending on the indoor temperature and the outdoor temperature that cop is going to fluctuate now the cop data i have written out here you can see that it's based on the indoor temperature being 70 degrees and then you can see the outdoor temperature ranging across and the different cops that the unit is able to achieve now the cops are going to be different for different models and manufacturers of mini splits or heat pump units so you're going to want to obtain the actual data for your particular unit but this should be fairly similar to most modern mini split heat pump systems with that data we're able to extrapolate that the minimum cop that this heat pump needs to achieve or this many split system needs to achieve is 1.9 so we need a 1.9 cop before this mini split is able to equal or be better than the price of propane now obviously that's influenced by the current prices of electricity and propane so you have to keep that in mind so if your prices are different i'm going to link to a website that is really cool i've used it a whole bunch throughout the years that allows you to put in the different pricing of different energy sources for heating your home and you can calculate out all of this information yourself so that link will be in the description so in order to achieve that cop of 1.9 the outside temperature is going to need to be above probably about 6 degrees fahrenheit so anytime that it's below six degrees fahrenheit it's probably a little bit more expensive to use the heat pump versus burn propane but the vast majority of places in the united states have very few days that are under six degrees and that is a really important thing to keep in mind because even though below six degrees it's cheaper for me to burn propane the vast majority of the year i'm not going to be below that temperature so for a few days for it to be a little bit more expensive it's totally fine with these hyper heat units from cooper and hunter those things can go all the way down to 22 below zero or 20 minus 22 degrees fahrenheit which is very very impressive now when the temperatures are more mild and you only need a little bit of heating the heat pump becomes extremely efficient with a cop of 3.21 at 54 degrees fahrenheit so at 3.21 you are spending approximately 10.99 per million btus versus propane which would have been 1844. so you can see that running your heat pump when the temperature is just mildly cool outside and you just need a little bit of heat is extremely efficient and cheaper than burning propane at a dollar sixty a gallon when your heat pump is running at colder temperatures there are a couple of things that are needed in order for that to continue to operate properly and the first one is that the unit is going to have to go through more frequent defrosts because basically what's happening is that outside coil is now the evaporator coil and is going to be colder than the outside air so that it can absorb heat from the outside when that happens though the coil is going to be below the dew point of the air which will cause moisture to freeze onto the coil so the unit actually will have to switch back into air conditioning mode and heat up that coil outside so the water can melt off the coil so that it can continue to operate in heat pump mode now in extremely cold temperatures the ice will build up in the bottom of the unit so on these hyper heat units from cooper and hunter and many others have an electric element located in the bottom of the unit that will help to defrost and get all of the water to drip out of the unit and that is one of the reasons why your cop drops down so low when you're looking at those lower temperatures the unit is now in defrost mode you can see right up there it has df displayed on the front of the unit so let's go outside and take a look at it this is basically where the unit is going to run in air conditioning mode for a little bit in order to melt the coil off on the outside unit because as the unit pulls the heat from the outside that coil is going to be below the dew point of the air even though the air is super frigid and it's going to accumulate some ice and it needs to melt that off let's go take a look and see what that's like right now and i can feel that coil is warm definitely above freezing at the moment and it's probably been dripping water out the bottom right there that's the drain location and this whole bottom actually feels warm right here it's working just like it's supposed to obviously the fan's not running you wouldn't want to run the fan for this part of the process because the fan would uh only pull the cold air in so it's gonna it looks like it's about done defrosting actually at the moment so once it's done doing that then it'll switch back in the heating mode which will then start putting the heat back into the building again at 22 below zero which is the coldest that this particular unit will work the cop is 1.29 so it's just barely a little bit better than running an electric resistance heater plus the output of your unit also drops as the temperature drops outside you're going to go from let's say having a btu output of 24 000 down to an output of 10 000 btus so your heat output does drop some as well so just things to keep in mind and those are good reasons why you might want to have a backup propane heater not only because if you have some kind of an issue that you need to repair on your mini split but also just to supplement those really cool days if we get a polar vortex that comes in at 34 below zero or 30 below zero here in minnesota the heat pump might have a little bit of a hard time keeping up it probably won't freeze up the building or anything but it might not be able to maintain 70 degrees for example so in summary mini split systems are an excellent all-in-one solution where you just want to put one thing in it can do both heating and cooling take up minimal space you don't have to run duct work all those things we talked about those pros and cons in another video so i'll link that here at the end of this one when you're armed with this information you can make very informed decisions based on your climate based on the cost of your utilities both electric and propane or natural gas that website that i told you about earlier that's underneath this video in the description also allows you to calculate your cost of natural gas or coal or burning wood all those different things you can go through the pros and cons of which fuel you want to use for heating your particular building if you guys want to keep learning with me about mini splits in particular i put a couple of related videos right here on the screen this one is one where we discuss the pros and cons of a mini split system in general especially versus like a ducted system and then this one down here will be some installation videos if you click on this video up here you get to see me wearing shorts jeans shorts which apparently are not fashionable in most of the world but somehow i was unaware of that and i guess maybe that was why they were on clearance in the first place

Channel: Benjamin Sahlstrom

Views: 306,951

Keywords: mini split heating, heat pump, hyper heat, cooper & hunter, how does a heat pump work, hvac training, heat pump vs gas furnace, thermal camera

Id: n00qcO3iIR0

Length: 16min 0sec (960 seconds)

Published: Thu Feb 11 2021