We're going to talk about this whole weird, how to connect a dehumidifier and a dehumidifying piece of equipment together as a means of talking about some electrical concepts. Okay, so this is not something you're going to do very often, but this is a fairly i mean it's really not that complicated, but for the sort of thing you would wire up on low voltage. This would be one of the more complicated things, but if you understand how this works, it kind of goes a lot towards understanding the electrical circuits and the dehumidification circuit all right. So, let's start with the 9340 relay.

We've done this a lot, but i want to make sure that we're all clear on what this is in inside this relay. You have two sets of what we call dry contacts. That's the first thing i want to identify is what makes a dry contact different from an energized contact or all wet contact, even though nobody ever calls it a wet contact. That sounds weird.

Has anyone ever heard the term dry contacts before it's a it's? A really common term - that's used in controls, and it just means that, within the contacts, there's no connection to a power source, there's no connection to anything else. So within this relay you have three distinct or discrete layers in it. You have the coil, which is what energizes the con. The relay did, i say contactor, i might have said, contactor relay, which is just an electromagnet.

So when we energize the electromagnet, it pulls in a set of contacts just like on a contactor right, but on a contactor you only have one set of contacts and those contacts are normally open right, so the spring keeps them open, and then they close when the Electromagnet energizes in this relay, you have two sets of contacts and they have both normally open and normally closed positions, which means that when you are not energized in the electromagnet, you don't have 24 volts applied across the electromagnet. Then this set of contacts from four to five is normally closed. So if i took an ohmmeter - and i put it right here - it'd be beep without being energized. It's normally closed right and, if i go from here to here, i would have an open circuit with it de-energized now, when i energize it these contacts that were normally closed, guess what happens to them.

They go open right, they drop and the ones that are normally open. What do they do? They close right and the exact same thing happens up here. One to two is normally closed. One to three is normally open.

How do we know because there's a pretty diagram drawn right on the front? That's why i like to use the 9340 there's a lot of different types of relays out there, the 9380 ice cube relays rib relays. They don't all. Have these really nice diagrams drawn right on the front the way the 9340 is and the 9340 is great, because all the terminals are on top it's easy to access easy to wire up. That's why i like it, but anyway do we understand the three layers: coil electromagnet, one set of contacts normally open normally closed.

Second set of contacts normally open normally closed. So, in order for me to do anything with these contacts i have to, i have to wire them up to as a switch basically, so these are wired up as a switch, not basically, that is what they are they're wired up as a switch, and this is Wired up as a load with a load, you need to have a power supply and a common in order to energize or de-energize it right. What is turning that relay on and off power supply, something that energizes the 24 volts and the other side needs to go to common. That's how loads work right with switches they're in the circuit in order to turn something on or off so they make or break a circuit.

So we can see just right off the bat. We've got something that's energizing. The coil we've got something that is always energized, because it's normally closed, always energized, even when the coil is not energized, and then we have something that energizes when the opposite position occurs. So, let's zoom out all right.

So we're going to talk a little bit about basic dehumidifier wiring, how we would normally do this, so we have a normal ecobee here we have our acc plus and our acc minus. So how would we normally wire this up? If we didn't have all this mess here? What would we do acc, plus straight to dehume right and how does that work? So what causes the system to dehumidify you? You do not have voltage on dh. So when you do not have voltage on dh, the system goes into dehumidify mode, which just means what what does dehumidify mode mean on this system lowers the fan speed. That's it right, so might be 20.

Something like that, i don't know varies a little bit, but it's just going to drop the fan speed a little bit if we didn't have an ecobee at all or a nest or a you know, system any sort of thermostat that could control humidity. What would we have set up on this board? You have a jumper wire between dh and r, and what would that do? It removes the humidification by energizing dh all the time right. If dh is energized all the time, then the blower always runs at full speed. So quick note, if you ever replace a system or a thermostat that has a dehumidification mode with one that does not have a dehumidification mode, say you're at a house late at night you don't have the right thermostat you put a honeywell in.

You need to make sure that you put that jumper back between dh and r. Now, hopefully they left that little pin there right, which is a piece of cake. So you just take the pin and you put your jumper back what if they didn't leave it there. You can just as easily take a wire and connect, so dh energized, all the time equals not dehumidify, and so this is an opposite way of thinking than what we would normally think, because normally when we want something to be in its normal state, it's de-energized and Then we energize it to change its state right to change it to something else.

In this case, the normal state requires dh to be energized and when we drop dh, when we remove power from dh, that's when it goes into dehumidify mode anyway. So what we would have to do now in order to make this work properly because of my jacked up uh diagram - is that, rather than wiring this up to uh energize to not be in due mode, we would energize this to be in due mode. So when you, when it energizes now that will force it into dehu mode, so we energize this this coil, you see it goes from acc, plus to one side of the the coil back to common on the other side of the coil. That makes the circuit, and by making the circuit, then that forces it out of dehumidify mode acc plus, is just an accessory terminal on ecobee, and so you program it the way you want to.

You basically tell the thermostat, and this is common with modern thermostats. This is how nest works and ecobee you tell it what that terminal does, and in this case we're going to tell it that when we want to dehumidify, we leave the terminal de-energized, that's how we would normally set them up. Okay. So if you were going to set this up without this mess, that's how you would set it up, acc plus to dh, and you would set it up with unenergized, to dehumidify energized to not dehumidify to run full speed, because that's all we're saying we're saying blower Run full speed, blower not run full speed, blower run full speed, equals, add 24 volts to dh, blower run less than full speed, you drop dh and then it ramps down okay.

So the way this is wired when this thermostat says we do not want to dehumidify. Now it energizes like it normally would it energizes this coil, it's 24 volt coil, it pulls in the contacts. These go open. Sorry, these go closed because they're normally open it.

Energizes these go closed. You energize dh, which keeps it in full speed. You energize for full speed and now these because these were normally closed. Sorry, these were normally closed.

This is 24 volts from the dehumidifier transformer back to dehumidify call on the dehumidifier. Then these that were normally closed now or yeah these, because yeah these that are normally closed, now go open in order to not run the dehumidifier, because again the thermostat is saying: do we need to pull humidity out or don't we and when we need to pull Humidity out, what do we do? We turn the dehumidifier on and we do what to the system fan speed. We dropped our blower speed right in the case of the dehumidifier. We have to take the 24 volts from the dehumidifier transformer and energize the dq terminal.

To turn it on to turn it on for normal operation, with no dehumidifier it's going to do just like it would normally do it's going to energize the acc plus terminal energizing. The acc plus terminal is going to open these contacts, which keeps the dehumidifier off. But let's break it down to what i need you to know, how does the relay work? Coil two sets of contacts dh being energized equals full fan, speed, dh, being de-energized equals less than full fan speed less than full fan. Speed means dehumidify, pulls more moisture out.

Dh energized equals full fan speed. If you don't have a thermostat, that's controlling it, then you need to have a jumper in place between d, h and r. So that way, it's always in full fan speed. We understand what how the relay works.

Basically, we understand that part now, where it gets complicated, is dehumidify mode for a dehumidifier and dehumidifier mode, for an air handler are opposite for a dehumidifier. You energize dh with 24 volts in order to make it run in a air handler you de-energize dh. In order to make it go into dehumidifier mode, so that's why we're doing this we're also doing it, because we have to isolate because a lot of people say well. Why do you need? Why do you need the relay like it's? Well, we showed why you need it because they're opposite modes, but the other reason we need.

It is because we need the dry contacts, because this has a separate transformer. You can't mix the 24 volts from one transformer with the 24 volts from another transformer, so the dehumidifier has its own transformer. The air conditioner has its own transformer on the dehumidifier. All we're doing is 24 volts out 24 volts back into dq.

That turns it on. If it was me, i'd probably do it opposite so that it's not always energizing right? That, probably would be why so, let's just say: if to do it, the way that bert's saying we would set up the thermostat so that way it operates in the opposite way, and then we would connect them in opposite. So this one would be on the open contacts and, and the system would be on the closed contacts and actually that's what i'll do is i'll create a version that shows the other way. So that way that i think that will make it make a little bit more sense, but the point is is that these are opposite in terms of what makes them operate into humidify mode this to illustrate, because again, how often are you going to do this? Not very often, and when you do, you know, call somebody and you'll figure it out.

It's not a big deal that you remember. Did you memorize this? What's the big deal is that you understand what the dh terminal does you understand what a relay does, so you can see why this is why this works in this way. So when you run into a thermostat and you have to configure it for dehumidification mode, just remember - i got to make sure to set up these terminals to tell them the right thing and it's not energized to go to dehumidification mode. It's stay energized all the time and then de-energize to go to dehumidification mode, make sense cool.

I think i repeated the same thing about 50 times there. That's the whole class uh. Thank you for your time and have a great week thanks for watching our video. If you enjoyed it and got something out of it, if you wouldn't mind hitting the thumbs up button to like the video subscribe to the channel and click, the notifications bell to be notified when new videos come out, hvac school is far more than a youtube channel.

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