In this podcast, John Maher talks with Joseph Wood about gas furnace installation. They look at the benefits of gas furnaces and talk about the efficiency of new gas furnaces. Then, they discuss installation costs and considerations.
John Maher: Hi, I’m John Maher. I’m here today with Joseph Wood, president of New England Ductless, specializing in high efficiency, residential and commercial heating and cooling in Massachusetts. Today, we’re talking about gas furnace installation. Welcome Joe.
Joseph Wood: Hey John, thanks for having me on the show.
What Are the Benefits of Replacing Your Gas Furnace?
John: Sure. So Joe, why might a homeowner want to do a furnace replacement and replace their existing furnace with a gas furnace?
Joseph: The gas furnace market has changed a lot and is really at peak efficiency now. There’s some products on the market that are pushing past 98% efficiency. So there’s a lot of reasons why, if you look at something older, the average really all the way into the early 2000s was that things were sitting around 80% efficiency, which means approximately 20% of what you’re burning was going right up at chimney or right out the side of the building through the exhaust pipes.
The products that are on the market now at face value, if you purchase something that’s 97 or 98% efficient, that’s the efficiency that they’re rated at, but they also kind of have these like gas pedal sort of stages that allow them to turn on half load and three quarter load and so forth. So there’s a lot to be said for moving from something older and moving up to something new because the efficiencies are just through the roof.
What Does Fuel Efficiency Mean With Gas Furnaces?
John: And like you said, those efficiencies, what we’re talking about there is that fuel that you’re burning. How much of that heat that’s created from that burning is going directly into heating the house, as opposed to, like you said, going out of the exhaust, right?
Joseph: Yeah. They call that AFUE, the annual fuel utilization efficiency. So AFUE, the higher the number, the better. And 97, 98, those are kind of the peaks that you’re seeing on the market. And the remainder is what’s lost because obviously you’ve burned fuel, but they’ve gotten these things so efficient these days that when you burn fuel, you create a gas’s exhaust, the gas’s exhaust, they actually extract so much energy from it, it turns into a liquid condensate and goes back through a pump. So they’re really, the engineering in these things is amazing. They’re great products.
How Do You Know Which Type of Gas Furnace to Choose?
John: So how do I choose what type of gas furnace to install or even what brand and what size furnace I might need for my house?
Joseph: That last question is probably the most important part. I think that the era where neighborhoods were converted over from coal to oil and oil to gas, there wasn’t a lot of science being used at that time for sizing and people were kind of putting their right palm over their right eye, looking at the house from across the street and saying, ah, 100,000 BTUs ought to do for that. And then 10 to 20 years later, someone replaced another appliance and used the left hand on the left eye.
And they even upsized it from there. The truth of it is, is that most of the systems that we encounter in the wild are too big. So we do a calculation called a Manual J. It basically just kind of draws the home as if it were a shoebox. And then we put bad weather on the outside of that box and insulation in the walls and figure out how much heating and how much cooling you need.
And that’s really the only right way to size a furnace. Any other averages or approximations, they’re not very good. And it’s important because a furnace is sized for the very coldest day of the year. And the coldest day of the year by rule should only happen once. So the rest of the year, it’s too big. So you want a system not only to service you on the coldest day of the year, but you want to choose something at a minimum that is two stage.
And that would be like, your gas pedal has a low and a high, because almost all year you’re going to be on the low. And so that 97 or 98% efficient appliance could even probably poke above that at some points, because it’s just matching exactly what you need. And if you don’t choose something like that, the downside is, is and we’ll pick a number here, say, you bought a 100,000 BTU furnace, but you really only needed a 60,000.
The unit is going to turn on and shut off so abruptly. It’s called short cycling, and it basically beats up the furnace and it causes it to fail prematurely. So it’s really important that you pick the right size furnace. And though we represent a number of brands, the real truth of the matter is, and this is backed up by the Department of Energy and other people who are totally independent, it’s really all about the install. You need someone to do a great job when they put it in, size it correctly. And probably any brand from there will last a great long time.
What Is the Manual J Load Calculation?
John: And like you said, you don’t just go by the square footage of the house. What are some of the things, the factors that are involved in that Manual J load calculation that you said?
Joseph: Yeah. So, the quality of the windows, the storms, if there are any, the door sizing, are they hollow? Are they solid core? The insulation that’s in the walls, the attic, the rim joist, you even get into whether or not windows have insect screens on them because they shade windows or do they have, you see older homes that had awnings. Or maybe you’re in a wooded lot, but you’re about to clear it. And if you’re going to get some Southwest exposure, my last home, I remember, the backyard, it was like, you could get a suntan there in 10 minutes. So we have to look at all that stuff, because that kind of shoebox concept I was talking about, we’re also rotating the home and modeling it towards the orientation of the way the sun passes over, sort of like the companies that do solar. They have to determine how much time you’re going to get sunshine. So we do all that sort of stuff to make an accurate sizing for your home.
Gas Furnace Efficiency Compared to Other Types of Fuels
John: Okay. And what kind of energy efficiency does a gas furnace have versus other types of fuels?
Joseph: Yeah, as far as anything that’s in the quote unquote fossil fuel realm, a gas furnace brings the highest efficiency. And so that I was saying 97, 98%. The products that are available in propane, they can match the efficiency. In fact, you can take a gas for instance, just simply convert it over to burn propane.
The problem with propane, however, is just a very expensive fuel. It’s I think more expensive than oil. The last time I checked. So of anything that you would have, be it propane, electric, oil, or natural gas, natural gas would be your cheapest. And that even includes, I mean, everything that’s going on in the world, the cost of gas has risen and they’re still quite efficient to own and operate.
How Much Does Gas Furnace Installation Cost? What Factors Affect the Cost?
John: And what’s the typical cost for a gas furnace installation? And what are some of the factors that might increase or decrease that cost?
Joseph: So a furnace on average, I’d say probably in the six to 10 grand range, and I’m thinking about something where this is a, we might call it central air, it attaches to your duct work, but the factors that would affect that, some of them are code based. They changed in the state of Massachusetts for this calendar year, the exhaust material, which a lot of people used on high efficiency furnaces for probably the last 30 years, they used PVC drain piping. And there was the spat going on of the drain manufacturer saying, Hey, we didn’t really approve it for that and for this and for that.
So the board came out and mandated that you need to replace that piece of pipe with a new type of material, either schedule 80 CPVC or there’s some other thing called polypropylene, but that can add significant expense, say it ran across a basement ceiling and you’ve got to open the ceiling.
Other factors, if you need to modify ductwork and a lot of homeowners, they get into the concept of thinking about their furnace. They’re not really, and all that thing does is create heat effectively and then blow it through duct work. But really home’s comfort is about much more than just heating. We have to add humidity, we have to remove humidity.
We have to filter the air. We have to bring fresh air into home. So we’re looking at systems, we’re at least looking at all of those things to find out because we don’t want to be guilty of going into a customer’s home. Being asked to quote a new furnace, quoting it and then leaving and then not having considered any of the other components of comfort, because they’re all there, whether or not we discuss them so.
Joseph: There’s a lot that goes into it and we like to make sure we talk about all of it.
John: Right. So it’s not enough that, oh, they’re warm enough, but it can’t be super dry or your hands are getting chopped and cracked over the winter because the air is so dry. So…
Joseph: Exactly. And you think about it this way, the older appliances, I kind of reference how they’re on or off. They didn’t know any speeds in between. So there are customers that have moved from those old on-off appliances, which turn on like a blast furnace, like an incinerator and hot air is like dumping out of the vents immediately. And they’re like, oh it’s on.
Then, they move to a more efficient appliance. The goal of that appliance is not to pour the air out of the duct work at temperatures that are almost too hot to touch. They pour them out at milder temperatures. So the usage changes from a real on-off to a more constant temperature management. Because that’s what these really smart appliances will do, is keep temperature rather than change temperature. That’s the goal.
John: Right. And that’s where they gain that efficiency.
Steps Involved in Gas Furnace Installation
John: Yeah. So what’s involved, what are some of the steps involved in a gas furnace installation and how long does it typically take?
Joseph: Yeah, I mean, so you got to do a new gas furnace, permits and inspections are of course important, the sizing. Once that stuff is out of the way and you’re ready to actually start a job, you’re going to deal with disconnecting the electrical, disconnecting the gas, disconnecting the intake and exhaust vents. And then of course removing the appliance itself.
Sometimes it could sit underneath an air conditioner. Sometimes it’s directly attached to duct work, but that’s going to need to physically be removed and recycled. And then kind of the reverse process goes on, but then whatever you might be adding as far as higher quality air filtration, reconnecting to the duct work. So there’s sheet metal work, gas fitting work, plumbing work, electrical work.
And it’s a lot to do, but on average, we’re trying to make sure that most of our installations like this are done inside of a day because you have to keep in mind, we’re doing some of these things on an emergency basis in the middle of winter. So we have no goal to make any of these processes go longer than possible. But of course you never want to try to move so quickly that you’ve cut a corner. So I think we’ve got a nice balance with that. And usually inside of a day, we try to get our clients taken care of.