Hey this is the HVAC school podcast and this is a short episode, episode number 28, the magic heat absorber, but before we get into the magic heat absorber, I want to thank our sponsors now: vac and navigable comm, air, Oasis, air, Oasis, comm, /go makers of great Indoor air quality products, air purifiers, find out more by going to air oasis, comm /go fill out the form, don't be afraid, it'll be okay and then also if you want to find out more about solder, weld products, I've been talking a lot about solder weld. You can go to products by proz.com products by pros com. We have some videos on there shown how to raise aluminum coils and how to use all the different products, especially their new HVAC kit, brazing kit, everything that you need to fix almost anything on an HVAC system. You can find inside that kit from solder weld so find out more there.

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It's a Viper Viper products by refrigeration technologies, great company. They make great products that you can trust alright. So let's talk about the magical heat absorber, because this is an area I'm actually starting to change. How I talk about air conditioning, especially with newer technicians, because they get overwhelmed and they think about pressures and weird ways and even saturation temperature.

They get overwhelmed by that and everything gets real, confusing and latent and sensible, and all that jazz and unfortunately, as much as I would love for everybody to be super techy and excited about all of these things. We were tasked as an industry with getting people on boarded more quickly than we have in past generations. We have a skills gap, any way you cut it and we need good people in the trade. We need them to learn things and pick it up quickly and understand it quickly and the easiest way to do that is through some simplified training where they can grasp the concepts quickly using analogy metaphor, things that they can get their head around.

And so what is the point of refrigeration? What are we trying to do and we'll put heat pumps aside for now, because in heat pumps we use the opposite process, but mostly what we're trying to do is we're trying to take the heat out of stuff. I mean that's, do with refrigeration and refrigerators and freezers. It's. What we do in air conditioning is we're trying to take the heat out of stuff.

Ventilation is a little easier for people to understand and heating. With a furnace you make fire make heat. That's kind of simple there's a lot to understand there still, but that's a different thing. So, on the refrigeration side of things, it's this whole idea of pulling heat out of something.

Obviously, electrical is a challenge for technicians vacuum, there's a lot of things to our industry, but this whole idea of pulling heat out of something that's kind of the core of what we're doing for a good portion of our industry. So how do you think about that? Well, the way that I've been teaching this lately that I think has been resonating a little bit more of my technicians is instead of calling things compressor, condenser metering device evaporator early on, we introduce them to the names. But then we change and we say the compressor - is the pressure increase or metering device? Is the pressure drop er, so they're opposite sides from each other pressure increase, er pressure drop er? Then you have the heat absorber and the heat rejector heat absorber is the evaporator coil, and that goes against what a lot of people found less cold. So how does it heat absorbing well yeah? But this very nature? Hot goes cold, that's another one of the basic concepts.

High temperature goes to low temperature. High pressure goes to low pressure. High humidity goes to low humidity. High altitude goes to low altitude.

We understand all those things that how energy moves. I've talked about that in the past, but if you start to think in terms of in the air conditioning system, we're trying to focus on that heat absorber, that evaporator coil and we've got to get it to an appropriate temperature and what is the appropriate temperature? We have to get it to in air conditioning. Let's just focus on air conditioning got any two things it has to be lower than the indoor temperature a obviously, if it's not lower than the indoor temperature, then it's not a heat absorber, because in order for heat to move out of the air into the evaporator Coil, it has to be a lower temperature. I know some of you guys are like this is the silliest stupidest thing I've ever heard in my life.

Bear with me here. I'm trying to help give you tools that you can use to explain to newer technicians who struggle with this stuff and then the next thing we're trying to do an air conditioning in especially in markets where we're wanting to remove moisture, which is a lot of the Us we want to remove moisture. We also have to control the dew point of that coil. So we have to control how much moisture we're removing by controlling that temperature.

The other thing we have to think about again with the temperature side is we don't want to go below 32 degrees unless we have some sort of defrost? So when you explain that all right on this heat absorber, we have to get it a certain temperature below the air going over it and the way that we do, that is by controlling the pressure and the amount of refrigerant in that evaporator coil. That's really it! We do that through the pressure dropper, the metering device controls that refrigerant flow going into there, and then that impacts the pressures, but we're really trying to hit a target on that evaporator coil and everything else that happens on the rest of that. We're really just trying to keep it as efficient as possible. We don't want excessively high head pressure.

We don't want excessive pressure, drops or anything weird going on, but the point is to create the proper temperature inside that heat absorber inside that evaporator coil in an air conditioning for most of the country that is 35 degrees below the indoor dry bulb temperature. That's pretty consistent, and so, if you have a 785 degree into our dry bulb temperature, then your coil temperature is gon na be about 40 plus or minus 3 degrees. But it's gon na be about 40. If technicians can get that and start by measuring, not only it would be preferable if they don't just measure dry bulb in the return, but they also measure wet, bulb and relative humidity.

So that way they can do target delta T in superheat, if that's appropriate, but getting them to start to a measure, indoor temperature and then be look for what the temperature is of that heat absorber in relation to that indoor temperature or box temperature. Whatever the case may be, if it's refrigeration, I think that's where we should start and then start to add in the other pieces. Now you add in the pressure increase or that's the compressor and how it works, and you add in the condenser and it has to reject heat and how that works. And now you don't want it to be any higher than it needs to be in order to reject the heat, but you also have to have high enough head pressure coming back in order to have the proper pressure drop across the metering device, then you kind of Work backwards, but I think getting technicians to understand the evaporator coil as a heat absorber understanding.

What the limitations are, what we're trying to achieve here. So it's got to be lower than the indoor temperature and the lower the better until you hit freezing that's a problem. Unless you have some sort of defrost controls like on a freezer cooler or something like that, and then you also have to think about the dew point of that coil in order to remove the appropriate amount of moisture. Those are the things you want to consider on that heat absorber, which is the evaporator coil there.

You go that's my short episode, so if you're new and you're like brand new to it and you're in school, that might be helpful to you for the rest of you who are experienced. Try next to me teaching you guys something teach them the evaporator coil. As the heat absorber focus on suction saturation as evaporator temperature and controlling that and relationship to indoor temperature, instead of starting backwards, looking at pressures and then moving into inside start by looking at the inside temperature and then work backwards and look at the temperature of your Evaporator coil and explain it as a heat absorber. So thanks for listening, we'll talk to you next time on the HVAC school podcast.

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