Hey this video is about something that every technician who's worth their salt does whenever they walked by a condensing unit, and that is to throw their hand over the condensing unit and see how much heat it's rejecting. Now, from a very realistic standpoint that heat that you're feeling coming out of the top of the condensing unit, that is the heat that it's absorbed in the evaporator core from the inside, as well as the heat absorbed in the suction line, picked up to the suction Line as and heat of compression inside that compressor, all the heat gained within that compressor, in addition to that as well, so it's all of the heat in the system has to be rejected in that condenser. First by D, super heating inside the condenser, so bringing it down to the condensing temperature and then through condensing all of that refrigerant, but all that heat is literally coming out the top of that condenser. So I encourage you to do that.

I encourage technicians to feel their way through the system. Listen to the system. I don't want you touching discharge lines because I don't want you hurting yourself with that. Whenever I go to a system that I suspect there's a problem within its running, I throw my hand over top of that condenser and if I don't feel a lot of heat being discharged, I get an indication that there could be something wrong with the system.

Also, if I throw my hand over the top and the air is hotter than I'm used to that's generally an indication that the system may be either overcharged or it may have a dirty condenser coil. Those are two common things that can result in having more heat. Coming out of the top, then I would expect high load in general can also cause it on the inside. But you kind of start to pick that up over time by just throwing your hand over the top of it.

But you can do this with temperature probes and you can gain a little bit more information now disclaimer here when we measuring the temperature difference between the air going into the condenser coil and the air coming out of the top of the condenser coil. That is highly variable system to system. So there's not like one number you can hit. I've often said that it's about half a CTO, a that's not always the case.

I mean that there are cases where you'll see a fairly new system and you'll still have about a 20 degree differential between the air going in the air coming out, and a lot of it has to do with exactly where you're measuring a lot of it has To do with Radian gains from the Sun and the same rules apply that when the sun's beating on a temperature probe, it's going to read a higher temperature, and so that makes it kind of inaccurate. But it just kind of gives you a quick and dirty way of seeing how much heat is this rejecting, especially if you can compare it to other similar systems. So we do a lot of commercial maintenance on a lot of self storage facilities where they have idea. Nicoll systems all the way down the row, if you measure that outlet air temperature and every one of these identical systems and compare them to each other as long as you know, the majority of them are charged properly and running properly.

When you see that outlier either higher air temperature coming at the top or lower, that's actually a really good indication of operation. But in that case you have the advantage of having something to compare to. When you walk up to a unit that you don't have a history with, you can't use that single indicator to say yay or nay. It is or isn't working, but just from a very simple standpoint: here's how you do it! You put one probe outside of the Sun measuring the outdoor air temperature, and you put another probe outside of the some measuring the discharge.

Air temperature and that temperature differential is generally going to be between will give you kind of a rough number of between 8 and 20 degrees differential for a typical modern system, and maybe even a little more than that on a refrigeration unit or on an older system. And the higher that differential is the greater the indication that either you have high load on the system, meaning the system is moving a lot of heat. That's an indication. Obviously, if you're moving more heat from the inside, then it's gon na be hotter air coming out of the condenser on the outside, or maybe you have a dirty condenser coil, something like that.

Maybe the wrong: can that's a fan motor or a blade that isn't the right blade. You shouldn't have to say this, but there's a lot of cases that we run into this nowadays, where people have made inappropriate alterations. But just looking at that temperature differential can be a really nice indicator and it's a nice thing for you to start measuring, especially if you work on the same pieces of equipment over and over again, because all of the heat that was absorbed in the evaporator inside Is rejected in the condenser outside and you're going to see that in the form of a temperature differential from the air entering that condenser coil to the air, leaving that condenser coil very simple, but hopefully that helps you get your head around! That concept a little bit more thanks for watching.