So next we have our air handler and evaporator, or what we call indoor coil. So if you notice on a gas furnace, we had the evaporator coil on top. Now when we get to heat pumps, we'll see that the blower's on top, and then we have the evaporator coil. As far as heat transfer goes, same operation.
I'm moving air across the coil, I'm either adding heat to it or taking heat out of the air. The blower's still moving air across it, whether I push the air across the coil or pull the air across the coil. A heat pump though, we're going to be talking later about auxiliary heat.
And if I'm adding more heat to the air, that needs to be done after. So we're going to have to have that evaporator coil before the blower for most manufacturers. So here we have our indoor coil. Now in air conditioning, we call this an evaporator coil because the refrigerator is evaporating. And we call the outside unit a condensing coil because the refrigerator is condensing.
And a heat pump, we no longer call it condensing coil and evaporator coil. And the reason is, is in heating mode, this is not an evaporator, this is a condenser. In air conditioning mode, this is an evaporator. In heating mode, this is a condenser. We no longer call it the condenser outside because in AC mode it is a condenser, but we go to heating mode, it becomes an evaporator.
So what we do is we call it the outside unit, or outside coil, and the inside unit, or inside coil, because this coil changes its job depending on what mode it's in. So indoor coil, so this is our indoor coil. very important things about this coil we need to take a look at.
For one is here's our drain line. They've manufactured this coil to have a natural slope to it. You don't need to lean this unit to make it drain right.
You need to make sure this unit's installed level. The manufacturer's already taken into account how to make that drain line so it flows out correctly. Now the other thing we look at is we have two ports right here for our drain. The lower of the port is going to be our main drain line.
The auxiliary port if we pull this off The auxiliary port is actually halfway blocked off in there, and that's because we want the water to mainly be flowing from this main port. Now, as that water is draining, it needs to come through a trap, and this trap is actually not deep enough for what we need. So we need to make sure we have enough drop across and back up for this, and we'll talk about that in another video.
We need to make sure that we have a drain trap. If we have a T on this side for cleanup, that's great, but we need to make sure that we have a cap on it, and there must be a... a vent seat on the other side. Now some people like to put their float switch here.
And not necessarily wrong with that, but we wanna make sure that we adjust our float switch, our safety switch, so that this float is sitting down as low as it can be. If you see this float switch, I can actually adjust this, the height of this. And if we look at it now, I'm sitting a lot higher, which means I have to have more water in there before this float finally shuts it off.
So what I wanna do is, have this to where it's its lowest possible point without already causing a problem. So if we adjust this, now my float switch is going to be sitting right here at the bottom. So if I get any water in this auxiliary switch, this is going to shut the system off.
And what happens is the water fills up here, this comes up, a little sensor breaks the 24-volt wire, it shuts off the thermostat, so the whole system shuts off. And we want to do that so we don't flood the customer's floor. Other people like to buy... I'm a big fan of them as well. They make other tees that go in here and this same contraption goes right here I'm a big fan of those but you have to make sure that we adjust this correctly What I like about this is if it stops up It's still gonna to break the float switch and what I also like about it is I can pull this This device out and I can get to the drain line to clean it now Everybody has their own opinion on what's going to be better.
It's kind of like Ford Chevy Dodge Toyota If you have a truck and you're moving, it's going to be important to you. The other details about which one's better is going to be personal preference. If your boss wants to install them here, install them there, adjust it properly.
If your boss likes the ones installed here, put them there, but make sure you adjust it properly. Six, one, half a dozen, the other, if you ask me. We want to make sure that we do have a float switch.
Not having a float switch, now that's a big deal. We want to make sure if that water overflows, we're protected. The other thing, if you notice, there's also these drain plugs here as well. What this is, is what we call a multi-positional coil.
This coil's made with this, I can buy this one unit, lay it on its side, and it also works as a horizontal position for, say, an example, an attic system or under a house. So when this unit's water drains off, it'll build up in this drain pan, and this drain pan is sloped to where I'd have my primary and my secondary drain. So if we open this up, grab a...
tool for this. If we open these factory plugs up here you'll get to see that one will be partially blocked and one will be full flow. So this one is blocked.
There's a block in it. So if it's laying on its side, I would take and put these two plugs in this pan. This one, since it's halfway blocked, would be my overflow switch.
This one that's full flow would be my main drain line. But since this is an upflow unit, I don't have to worry about that. I can just simply leave that plug in. Leave this plug in so I'm not pulling attic air or air from under the house in.
And we're set to go. Now also with drain lines, you want to make sure that the drain line is glued. All connections must be glued and I really prefer and strongly recommend that you primer and glue all these fittings.
So that we make a good secure... good secure connection. What I like to do is put a little piece of rubber hose right here from like a heater hose for a car that goes over that three quarter inch pipe and some hose clamps.
That allows that rubber to absorb vibrations. So if somebody drops something on this the rubber will allow it to give. This one is installed straight into the connection and glued.
Which is fine, except if something was to fall on this, it could not only break this PVC, but it could very well break this drain pan. And this drain pan is a pain to change. We gotta take all the refrigerant out of the system, we have to cut the refrigerant pipes, we have to pull this evaporator or indoor coil out completely, put a new pin under it, slide it back in, re-braze the lines, change the filter dryer.
Pressure test it, pull the vacuum, and then recharge it. So we don't want to break these lines. So by putting a little piece of rubber right there, I allow it to absorb those vibrations.
If somebody was to drop something, the rubber would give, and it's unlikely that it would ever crack that drain pan. The problem with this one is if I needed to pull this coil out because it's glued so close together, I'd have to cut the fitting out to get this apart. And then I'd have to redo all these fittings.
Where if we did have a piece of rubber, we could undo the hose clamps, put a screwdriver in there to break the seal. And we could... you could pull that pipe separate.
So I'm a huge fan of that rubber adapter on there. We'll talk about that in another video when we do drain lines. So this particular coil here, the indoor coil is all aluminum. Some use aluminum and copper combination, but same thing, I send the refrigerant, if it's in cooling mode, my refrigerant goes this way through my tubes, saturation, boil it from a liquid vapor, superheat it, all the tubes come back together as one.
Back to the compressor. Now in heating mode, my refrigerant is running in the opposite direction. So I'm sending hot gas here.
Hot gas is going through the coil, de-superheating, changing from a vapor to a liquid through most of the coil. The last little bit sub-cools it through my sub-cooled liquid line to the outdoor unit. So it's very simple, but there's a lot of very important information all tied in this one section. And most all heat pumps, we need the evaporator coil to be below my auxiliary heat. So it's usually going to be below the blower.
That makes some other conditions we got to worry about is humidity. If we leave moisture on this coil between seasons, you can have a better bacteria growth, which causes what they call a dirty sock syndrome. And then when this coil starts getting warm, that moisture will get warm, more bacteria growth, and sometimes it can cause an odor in the house.
A whole other subject for the dirty sock syndrome, and there's many different solutions for it. But we also can end up with more moisture in our blower, which can mean more growth. So a lot of times we'll have to do more maintenance on it. We may have to clean that blower more often. But a great solution to all those situations is a UV light right here.
This particular brand has given us a nice little knockout. We can knock this hole out and our ultraviolet light the bulb can go right through that hole, the bulb can mount right here, and we can shine that light on the underside of this evaporator coil or inside coil and that will keep growth from happening on this coil, make the system last much much longer.