Upflow HVAC: Filters, Drains & Float Switches

 So this is a common HVAC system, what we call an upflow, because the air goes up. So this is where the components are, the heating elements are, and this is where the filter goes and the evaporator coil. So a few things to notice. Number one, this should always be clean, which it is wonderful. The filter size is right here.

The direction of the airflow is very important, especially for some filters. But this should always be clean. You should always replace these every time you do a make ready. Get it ready. They. It's always recommended to change them every month or two or three months. And this is the evaporator coil. This should always be clear and clean, and a good practice is to clean this during the make ready process.

So now as air blows through this, the condensation in the air, we'll collect, go down the coil. And into the drain pan right here. Something that's very helpful that prevents a lot of service calls, especially in the summer, is to put a drain tablet in there and it prevents sludge and slime from building up and algae inside that drain pan.

And then it will just consistently go down the drain instead of back up. So you can put one in here, make sure it doesn't go down the drain. But the way this works is the water will run down, settle in this drain. Come out here. And then go down to the drain. Now right here, this is a float switch. So if the drain pan fills up and the drain line gets clogged.

So this is clogged. The drain pan fills up. The water level in here will get high enough that it interrupts the power to the thermostat or to the controls, and then your system will no longer work. So if you have these, just always remember that if nothing works, to check this first and make sure that the drain line is clean.

And as a technician that's been in the field, this is one of the most common scenarios. In the industry in the summer, because everything's hot, it's running. The condensation gets dust, the dust turns into slime and algae, and then pieces will get stuck in the drain. So this is the coil. Keep this all clean, keep it free of debris.

Try to keep the entire area free of debris. Let's take a second look at the bottom part of this, because I spoke earlier about the drain. So here's the drain line, the main drain line that comes outta this. And it goes to a trap, which it's supposed to. So this will collect with water so no gas can get up into the system.

And it's, uh, something that's common in many plum systems that have plumbing attached to them. And of course, this will be the second one, which is attached to the float switch to shut down the AC system. If this drain pan fills up because this line is clogged, then the water will fill up. Go in here. And then lift the float switch and turn that off.

So that's how this works. This is the main drain line that this is actually connected to a drain, which is very smart to do. And then this is secondary. So when this gets clogged, if this backs up, that lifts the float switch and shuts, shuts it off, and it turns off the entire system and it's supposed to do that.

So this is something that you should always look for when you're on a service call. Change the filters often, and this is a float switch and you just put these in, make sure the arrow goes in the direction of the air. Yes, it is important and put it in, and the type of filter that you buy or install is totally up to you.

But these are probably the most common. They're what we call the base model filters, and they're usually not too expensive, but they're hands down. The most important thing that you can put in a system every single time it gets a little dirty.