In this podcast episode, John Maher talks with Jesse Corso from N.E.T.R., Inc. about the benefits and features of ductless heating and cooling systems. Jesse explains how these systems offer individual temperature control, energy savings, and easier installation compared to traditional HVAC systems. They discuss the suitability of ductless systems for different types of homes, the importance of proper sizing using a manual J calculation, and the additional features like air filtration and dehumidification. Jesse also covers the various types of indoor units and the factors influencing their selection, emphasizing customer preference and application. Finally, they discuss the maintenance requirements for ductless systems, recommending seasonal check-ups for optimal performance.
John Maher: Hi, I am John Maher and I’m here today with Jesse Corso, comfort consultant with N.E.T.R., Inc. a heating and cooling company in Massachusetts with a focus on ductless heating and cooling products. Today our topic is ductless heating and AC 101.
Welcome, Jesse.
Jesse Corso: Hi John. How you doing?
What are the Advantages of Ductless Mini-Split Systems?
John: Good, thanks. Yeah. So Jesse, what are some of the biggest advantages of ductless mini-split systems as compared to traditional HVAC systems maybe with ducts?
Jesse: I’d say one major advantage is that if you have multiple mini-split indoor units in the house, you have individual temperature control of each one. Whereas typically a central AC system or a ducted system, you’re looking at one, possibly two thermostats controlling that whole system. So, I would say that’s one advantage. If you’re not in a room, you can shut that unit off, shed that load and just focus on the rooms you are occupying at that time.
Mini-Split Systems Can Save You Money
John: Right. So maybe if you’re working from home or something like that, you can have just your office being heated or cooled and have the rest of the house not on, and that’s going to save you money because you’re not heating or cooling the entire house when you don’t necessarily need that.
Jesse: Absolutely. So you have second floor bedrooms, you have first floor living space, living room, kitchen, dining. You go to sleep at night up to your bedroom, you can shut the first floor off entirely, something like that. Now you’re shedding half your load of your house and just focusing on the bedrooms where you’re at for the night.
John: Okay. What are some of the other advantages?
Jesse: Other advantages would be if you had a house that’s got, maybe it’s got a finished basement, first floor, second floor, and even a third-floor finish attic space or something. Really, when you have no room to run that duct work, ductless can come in handy, you can install those units, no duct work needed. It just makes for a little bit of an easier installation instead of running, cutting open walls and ceilings to run that duct work throughout the space.
Does Ductless Heating Work in Any Type of House?
John: And so along those lines, will ductless heating and cooling work for any type of house, or are there types of houses where maybe it doesn’t work so well?
Jesse: I’d like to say we could make anything work in any type of house, but obviously some houses are easier than others. But I would say if you have a spot outside for an outside condenser, that’s a big thing. We need some exterior real estate to actually put an outside condenser.
Usually we can get pretty creative and make any application work. Where it gets really difficult is if you don’t have any exterior walls. If you’re in a brownstone in Boston or in a townhouse or something and you have a unit to the left of you, a unit to the right of you, if you’re, say, on the first floor of a multi-story building, a unit above, then it gets really tricky where we just have, it’s difficult to run the piping and whatnot. But we always do our best to try to figure out something. I’d like to say yes, we can make it work in almost every application.
John: But you’d say in most typical homes that people would have, certainly outside of the city, most homes would be able to have a ductless system?
Jesse: Oh, absolutely. Yeah.
John: Okay.
Jesse: Absolutely. Single-family homes, without a doubt. Multi-family homes that have any sort of exterior wall, yeah, most all those homes.
How Does Sizing Work for Ductless Systems?
John: Okay. How does sizing work for ductless systems? How many outdoor units and indoor units do I typically need? Does it just go by square footage or are there other factors involved in determining what size system I need?
Jesse: Well, so for sizing, there’s always the manual J, which is a load calculation for the home. It’s basically a calculation we perform that is going to tell you specifically how much cooling, how much heating you need for that space. So that’s always important. You have to look at the manual J to size your equipment. But with ductless, you have to take into account what space that individual ductless unit is serving. So if you have a primary bedroom on the second floor, you’re only going to put an indoor unit in that primary bedroom. It’s very important that you size that unit for not the entire load, but just for that one room individually.
And how we kind of lay that out is air flow. Can we get the air into that space that we’re trying to condition with that ductless unit? If the answer is yes, the air’s going to flow from where that head is on the wall or wherever it’s located into that space we’re trying to serve, then that, we will take that into our load calculation, that area, and we’ll figure out what size head we need from there, what size indoor unit we need from there.
What Factors Go Into a Manual J Calculation?
John: What are some of the things that are in that J load calculation, that factor into it? Obviously like the square footage and how open the room is. Like you said, if there’s air flow, do things like windows and insulation factor into that?
Jesse: Yeah, definitely. Square footage is big. Installation values of the house. I’m always constantly asking, do you know the installation values of your home? That it’s important to have an accurate knowledge of what that might be. How much glass doors and windows that are glass, that’s going to make a big difference. Type of window. It might be single pane, double pane, all sorts of. What kind of floor is above? What kind of floor is below? Is it an unconditioned attic or a conditioned space above? So that all comes into account when you’re taking that load calculation, that manual J.
Do Ductless Systems Have Other Features?
John: Okay. And then beyond just heating and cooling, did ductless systems have any other additional features that they offer? Maybe air filtration or dehumidification? Are there other things that are advantages of a ductless system?
Jesse: Yes. So every ductless indoor unit has filters on it. So they’re always going to be filtering air anytime they’re moving air through the unit. And then most, for manufacturers, I don’t know if 100% of the manufacturers offer this, but most manufacturers offer a mode that it’s called a dry mode, dehumidification mode. So you can have heating mode, cooling mode, fan only just moving air through those filters, and then you would have a dry mode as well if you wanted to dehumidify the space, take out some moisture.
John: So, the dehumidification mode kind of tries to dehumidify the air without necessarily heating or cooling it. Is that kind of the idea?
Jesse: Yeah. So the way we can dehumidify is actually to cool the air. So what the system will do is it will do its best to de-cool the air. So this is where it gets tricky, right? It’s not a dedicated dehumidifier, so it’s going to end up cooling that air a little bit by removing the moisture. That’s how it removes the moisture from the air. It will do its best not to cool that air, keep that discharge air temperature as high as possible. But when you have a standalone dehumidifier or something like that, they have reheats in them to heat that air back up. So they make sure they are not going to make that space too cold while bringing that humidification level down.
Ductless units do not have that reheat function, so they tend to make the space a little colder in dry mode, but not as cold as it would be if it was trying to maintain a cooling temperature set point.
John: Right. So you’re not putting the temperature at 68 degrees or something like that and really, really cooling the room down. It’s going to do its best, like you said, to dehumidify it without cooling the air as much as it can.
Jesse: Exactly. But the whole way to dehumidify is to cool that air and wring some of that humidity out of it. So just the sheer nature of dehumidification, it ends up cooling it a little bit.
How Do You Determine What Type of Ductless System You Need?
John: Right. Right.
When you’re looking at in term going back to the sizing of the systems, I know that you can just have one outdoor unit with one indoor unit, but I think you can also have systems where the outdoor unit can power multiple indoor units. And then you have even other systems like cassette systems that go in the ceilings. And then you have some ducted type of systems where you have an air handler in the basement or in the attic and then just have a little vent in the ceiling or the floor. How do you determine, well, what are the different types of units that I might need for this house?
Jesse: Right. So there’s a lot of different types, and there are single zone systems, like you said, where you have one compressor outside or condenser outside to one indoor head. And there are multi zones manufacturers that we offer. You can have up to eight indoor units on one outdoor condenser.
And then, within that indoor unit realm, there’s a bunch of different kinds, like you were just stating ceiling cassettes, wall mounts, high wall mount, low wall mount, ducted units, all that.
Basically, how we would go out and design a system and determine what was best for the space, it all has to do with obviously what’s the customer prefer. Do they want to see the units on the wall? Do they want a sleeker look where the unit is hidden in the attic and just have the vent coming through? So it all has to do with obviously customer preference, but a lot of it also is application, what’s going to work for us.
If there’s no unfinished attic to run duct work, it’s going to be hard to do a ducted system on the second floor. So application and what the customer actually wants, those are the two considerations.
When you’re doing maybe a high wall ductless unit, do we have 31 and a half inches of width on the wall to put a unit? If not, okay, then we might have to go to something that’s recessed in the ceiling or something that’s low on the wall, looks like a radiator. So what can possibly be done and what does the customer want are the two driving factors.
What Maintenance Does A Ductless System Require?
John: Okay. And then finally, what about maintenance on ductless systems? What maintenance is required and how often should it be done?
Jesse: So, I would say the maintenance is, it all depends on how you’re using the system. If you have a ductless system and you use adjuster air conditioning, then I would say a once a year annual maintenance is good for you, maybe in the springtime before you fire up that AC. If you’re using them for heating and cooling, both seasons, heating and cooling season, I would say twice a year maintenance, maybe one in the spring, one in the fall basically before you’re gearing up for that heating or cooling season.
Also, if you’re just using it for heat, we have customers who might not use the AC much at all a couple of weeks out of the year. So they could probably take that down to one annual maintenance before the heating season.
John: All right. Well, that’s good advice and great information. Jesse, thanks again for speaking with me today.
Jesse: Yeah, thanks John.
John: And for more information, you can visit the N.E.T.R. website at netrinc.com or call 781-933-NETR. That’s 781-933-6387.