There’s a lot to consider when upgrading your HVAC system, including how much heating and cooling capacity it should have to keep your home comfortable year-round. You want to keep your HVAC system’s overall size closely matched to your home’s size and climate control needs, otherwise you could find yourself wasting energy and money OR worse.
Unfortunately, many homeowners end up purchasing an HVAC system that’s often too large or too small for their homes to handle. In this video, we explain why oversizing or undersizing your HVAC system could end up being a major drawback for your home’s overall comfort and energy efficiency.
For more information on Griffin Air, visit https://www.griffinair.net/
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Unfortunately, many homeowners end up purchasing an HVAC system that’s often too large or too small for their homes to handle. In this video, we explain why oversizing or undersizing your HVAC system could end up being a major drawback for your home’s overall comfort and energy efficiency.
For more information on Griffin Air, visit https://www.griffinair.net/
For more information on New HVAC Guide, visit https://www.newhvacguide.com/
Hey guys before we get to the video, please click that subscribe button, hey guys, joshua griffin, air, serving the middle peninsula and the northern neck of virginia, and i wanted to do a video on one of the most controversial topics in the heating and air trade. And i'm going to do it, i'm going to talk about heating and air sizing, and you know before i get into all this. I do have a few disclaimers that i want to mention uh. The first thing is, i'm only going to be talking to you know you guys that are homeowners residential applications.
I know you folks that are up against industrial, commercial type challenges, it's a whole nother animal, totally different set of rules, and we're not going to be talking about any of that in this video. So we're only going to stick to residential stuff, and my other disclaimer is every market is different. Some of the things i'm going to run through is controversial, because every area is different. Every area of the country, every area of the world and you're going to see different types of challenges, meaning humidity and you know, sizing and other conditions like where the units are located and maybe what their atmosphere is subject to.
So that's the disclaimers and so we're going to talk about a couple different things. We're not just going to say you know. Air conditioners are too big or too small or whatever we're going to go through a list here and we're going to talk about things that i think that you know you need to know. Maybe some things to think about, but again because every area is different.
I would defer to your local expert, your local heating and air guy that does this for a living. I can tell you that there are folks that come into our market, where we're located in virginia and they'll oversize systems, or they won't understand that some of the challenges we're up against another area of the u.s i always hear about, is the northwest part of the United states, because the air is more of a cooler, uh, more humid, clammy type of feel, and so you guys have. You know, challenges that we don't have here. So let's go through this.
The first thing i want to just kind of touch on and again every area is different, but i want to just say in general, just starting out: if we're talking about heating and heating alone, you have a little bit more, i would say, play a little more Cushion than you will when we get to talking about air conditioning and some of that stuff, so what i mean by that is, i see systems all the time that you know for the heating. It's actually oversized for the space for one reason or another, and it's not the end of the world. Again, that's just a general rule of thumb. So if you know, if you have electric or some sort of fossil fuel being burned or, however you're heating your home, i would say that in general, if it has more btus than what that space calls for it's not the end of the world, and in fact I can think of certain applications where they intentionally oversize things. One thing that just comes to mind is mobile homes. We see mobile home furnaces, put in they're high static applications and we'll see them install really large heat kits in these. You know furnaces uh, they're straight electric and all that good stuff, but you know i think the thought process is. You know we're gon na be burning a bunch of electricity right here.
Let's heat the home as quick as we can and get that thing off. Uh. You know so it's not the end of the world is all i'm saying. If it's a little oversized uh, you know it's not the end of the world in general.
Another thing i would just say, is you know if you have other types of heating systems like radiant floor, hydraulic heating things like that again, i wouldn't lose sleep. I've even been on projects where you know they're building one wing of the house and they're gon na heat, that with this system and another wing, or something like that, isn't done yet and they're wondering you know if the system's gon na be oversized and heating, it Should be no big deal in most cases again, every market is different area. Every area is different. I keep saying that because it is, i would just defer, ask your local expert and see what they think.
The next thing i just want to touch on before we move on to air conditioning and heat pumps is dehumidifiers. I love dehumidifiers and talking about them, because i've seen a lot of misinformation out there. But again i would say, as a general rule, you cannot oversize a dehumidifier, you can undersize it and it just can't reach the humidity set point that you have it set at depending on the market and all the conditions and thought you know all those things like That but you can't really oversize a dehumidifier in most cases, because all it's going to do is it's going to remove that humidity. Get that set point.
You know where you have it set and should be no big deal. So let's talk about the big elephant in the room, one of the most controversial topics in the heating and air industry, and the reason i say it's controversial is i hear all the time and it's true with my experience as well - is most systems when we go To someone's home, their system is not sized properly for their house in our particular area. I see them oversized a lot, but you know you'll see different times when it's oversized or undersized it's not sized properly, and why does that matter? Well, in general, if a system is undersized for a home or space, then you know, obviously it's going to struggle to keep up in those extreme temperatures. So you know if you got a hot summer day and you got a two-ton system there and it should be a three-ton, it may struggle to.
You know, get that heat down and reach temperature and you might say well what do you mean by tonnage? All we're talking about is btu. So when you hear folks say: oh, that's a two ton system, four ton system, whatever all they're talking about is the capacity the btus that that system makes we'll send folks different proposals, sometimes and they'll, have different seer ratings and they'll say well. Will this system keep up well, they're, all the same capacity? You know we're giving you the properly sized system here also keep in mind. If we're talking about heat pumps, again, i've seen houses where the heat pump may be. You know undersized or too big or whatever and in heating mode, and you know you have those challenges, but then you get to air conditioning mode and you're back up against the same challenges that you do with straight air conditioning and so just keep that in mind. That all the heat pump is is a air conditioner that runs backwards in the winter time to provide heat right, and so in that summer time it still has the same challenges. If you undersize it, it won't reach temperature, that's undersizing! What happens if you oversize it uh? You know we talked about heating oversizing it and it'll heat the space really quickly and shut off, and that's not necessarily a horrible thing. Why is it such a big deal when we're talking about air conditioning? Well? The first thing is, it will make the system not dehumidify enough and in a lot of markets, especially the market that i'm in that's a big deal pretty much anywhere on the east coast.
That's a big deal, the further south you get the bigger of a deal. It is i remember years ago i worked for a property management company and we had a a property down in florida. That was having all these mold issues and they found out that it had to do with the air conditioning in the apartments and all this it was just a nightmare, and so all i'm saying is: if it's oversized, what happens, is the system will run cool the Space really quickly, it doesn't remove enough humidity from the space where heat meets cold right. So you got these hot walls, hot furniture.
All this heat and now you've cooled that space really fast. You're gon na have humidity issues, and you know you can remedy that with dehumidifiers and things like that. But hey. Why not size your system to start with properly right? So that's the first thing and then you know honestly, i think that's the biggest thing.
But if you're in a market where you know humidity is not an issue, it's dry air, you know maybe you're out in the west somewhere and it's basically a desert and that's not such a big deal. Then i would just say that you need to worry about it for short cycling and things like that. So you know if the system's oversized for the space it cools the space really quickly you're getting this short cycling instead of it's actually a lot of folks, don't realize it's less efficient for that system to be on off on off, rather than being sized properly on A hot summer day and just running for long periods of times, instead of having those spikes in energy, hopefully that makes sense you can oversize it and you can undersize it in a lot of markets. Now that we've said all that, i do have an exception to that rule, and that is we are seeing if you have a system that are, that is three things. Three things. First of all, it has variable, speed and or motor okay. Indoor fan motor is variable. Speed, the second thing is it's an inverter system, so your outdoor compressor can ramp up and down right and then the third thing is it's communicating system where they can communicate with one another.
I know we've actually installed some of those bosch products and some of those products that are coming out and i'm not saying, there's anything wrong with them. But you know, even though they're inverter technology and they're more efficient, you still have those same challenges of sizing and all that good stuff. But when we're talking about the three things i just talked about, the system is variable, speed, indoor inverter outdoor and then communicating then that system you can technically oversize it and it be okay, and what i mean by that is, if it's running at 100 capacity yeah. It's oversized, but it's rarely gon na do that.
So if you have everything set up properly, that system's gon na at times, just barely be running cooling, the space, removing the humidity and keeping you comfortable and the way i can definitely tell you - is check out a lot of the ductless systems that are being installed Today and i'm not talking about those el cheapo ones, you can find online, i'm talking about the guys that are the best at what they do guys like daikon mitsubishi and then some of these other folks like fujitsu that are coming along. So a you know a great inverter system, communicating ductless system and we're seeing those you know work tremendously in spaces that technically it might be oversized and things like that now again, i know i'm throwing blanket rule of thumbs. That's why a lot of this stuff is controversial and all that good stuff. I'm sure someone will comment on this and you know i get heat in there guys all the time telling me why i'm wrong and that's fine, but i just i'm giving you a few things to think about when it comes to that stuff.
The last thing i'm going to say before we wrap up is ductwork again, there's so much misinformation out there. Ductwork sizing is probably just as important as the sizing of the system. You know - i don't think i mentioned, but if you're actually sizing a system for a home, doing a proper heat load calculation getting a contractor that you know knows how to do that and figures out the exact size that that home needs to be the same would Be true for the ductwork sizing it properly for the proper amount of static and proper amount of airflow, and all that good stuff uh. You know just real quick.
If a system has duct work, that's undersized, then you know you're going to have some more velocity through there, but the system is going to be cut down on capacity because the air can't move across that coil like it should, and you know imagine if you had To breathe - and you covered, you know, half your mouth or even three quarters of your mouth and you had to breathe through that small hole all the time same concept. So you got this fan motor trying to either pull air through a return. That's too small or push air into you know duct work. I always think about like garden hose. Imagine a garden hose. That's kinked right and it's you know you got all this pressure building up, so you know you might put your hand over the vents and if it's under size and say, oh, you know it's, it's blowing my curtains, but you. What you don't realize is you've actually lost capacity and, of course, nobody changes their air filters as often as they should, and you know now, you're losing even more capacity, and you know we've seen that a lot you know where folks are just not moving enough air Through there and they're having capacity issues they're having issues with the evaporator coil freezing up and things like that, and the last thing i'll say is if the ductwork is undersized, is it's just harder on that system? You know the fan motor, especially it's trying to it's. Trying to push all that air through there and it can't you know it's doing what it can but you're, putting a lot more strain on that system than what it should have been.
You know designed for if it's oversized uh now again we're talking about residential. So you can technically i when it comes to my returns, i'll oversize them a little bit because i'd rather be too big than too small, but when we're talking about the supply side and we're pushing air through that duct work that ductwork, if it's oversized it. Actually, it's almost like, if you were to try to if you took those deep breaths like right, you take a deep breath and that system's trying to push this air through this system with too big of duct work, the biggest thing is you're not going to get The velocity through those ducts that you should right so it's pushing air and you, but you don't, have the static. And then you start getting to some of these vents that are a little further away from the unit and things like that and you know you're not getting proper amount of airflow.
You have one of those homes that you know the one room is colder than the rest or warmer than the rest, or things like that. I can't tell you how many times that has to do with ductwork sizing either it's too big, too small something's wrong there and just getting that corrected, takes care of that you don't have to go, adding a ton, more duct work or adding a ductless unit to You know supplement it's just a matter of getting it sized properly and preferably sized properly from the get-go. So hopefully that makes sense if you have any questions or suggestions. Add them to the comments down below. I really appreciate you watching. Thank you with all that said. If you're in our coverage area - and you are in the market for a new heating and air system, give us a call we'll give you a free estimate, we'll give you a great warranty. The best warranty, i think in the area - and you know we'd love - to earn your business if you're, not in our coverage area but you're in the market for a new heating and air system.
Before you spend thousands check out my website, newhvacguide.com and the whole idea behind this website is just like a cpa would help you with your taxes. This is going to help you with the purchase of in a lot of cases, the third largest investment that you're going to make behind your house behind your car. A lot of folks, their heating and air system is the third largest investment with that said, we put so much information on there. I it's almost as if i wrote a book decided not to because it you know.
As soon as i do it's going to be outdated, new technology comes out, new, all kinds of information comes out, and so this website is like a book, but it's constantly being added and changed. So you know we even have a whole page called no-no's things to stay away from things that you want to avoid in your pursuit of purchasing a heating and air system, and we just have this step-by-step guide, so new hvac guide, dot com and lastly, please subscribe. If you haven't already, we really appreciate your support and stay tuned for more videos, tips, tricks and appreciate it. Thank you.
Any feedback on figuring out a ducted heat pump size in a new build ICF home. R60 attic insulation. One level, Atlantic Canada, slab on grade, 2250 sq ft. We’ve had contractors suggest anywhere from 1.5 ton to 2 ton. Most online calculators show that as very small for the climate and square footage but not sure how the ICF factors in. Trying to make the most educated decision.
I installed my own HVAC system this year central air worked great maybe a dumb question but the blower runs harder when the furnace runs than when the ac is on is this due to the ECM motor
I recently moved to Fl. and the ductwork in my house is the square or rec, and several rooms are not receiving good air flow. I was in the hvac business years back and we installed metal size being diminished the farther away from the unit, never had a complaint round air flow helps the room receive good flow.
Hey, question for you. We have a 2005 Norris singlewide. We got a new Train heatpump inside & outside unit with Train Cleaneffects whole home air purifier. I think it's a 3 ton the old original was 2.5 Ton. We wanted a powerful high end system cause we like the house super cold and don't want to wait for the temperature to get where we want it. We used to ran it 67 day and 59 night. We also installed new flooring and noticed it separating due to temp. differences. So we stopped doing that set it at 70° always and got a portable ac unit for the bedroom to keep it as cold as we wanted…well now the walls in bedroom seem mushy due to condensation. So would having a dehumidifier help? I feel like our house has low humidity though. How can I fix the situation? Would better insulation or something help? Thanks for any advice.
Sizing isn't my concern. What I find is this Carrier unit. It's small. 9,000 BTU. But they call it 42 SEER… I don't believe it. Are they just making up numbers? For my application, I need all the efficiency I can get. It's not a matter of cost. It's a matter of being utterly impossible if it uses too many watts. It's not a matter of "being worth it." It's a matter of "it can't be done unless it's silly-levels of efficiency." Which makes me a perfect target for made-up numbers…
Good video, I have a question. I have I have a metal garage 20'X12' 240 SF. It's all insulated with 1" foam except the garage roll up door. I want to install a mini split 9,000 BTU or 12,000 BTU?
My Townhouse had the original 1981 138,000 btu(60% efficient) furnace when I moved in 15 years ago. I did load calcs myself and ended up specifying a 66,000 btu (80%) efficient unit. So I essentially went from an 83,000 btu output unit to a 52,000 btu unit. My Contractor was not impressed. Well in the 14 years of ownership I’ve only had a few days(high single digit temps in the Mid Atlantic)where it could not quite keep up, which is exactly what a properly sized unit should do. To be fair I probably should have or could have gone up a size for the increased airflow for the AC given I have 3 floors. So furnace sizing can also be impacted by AC requirements.
The confusion lies in multi speed systems. For example 2000 sq feet for heat basic number is 80000 btu of heat based on 40 btu per sq foot. So if it is a 2 stage system i would size the heater at a 80,000/60,000 for an example. The problem is there is nothing comparable on the AC side coming from manufacturers when in comes to high seer multispeed compressors and hvac systems. In western Colorado desert climate witj average temps around 95 snd arid you can oversizeba system and it will run largely at the lower speed most of the time but on those days when it 105 the system can operate at 100 percent, not run all day and it gives more flexibility. So now that i say all of this i am a layman learned hvac in the navy working on aircraft. Have done a number of installs for family and myself and i am wondering if my logic is correct on both heating and air? Seemed to me once i did the cfm calculations for duct sizing and matched the blower speed to the system requirements to the whole house i felt pretty darn confident i had sized the unit correctly and checking my temps and gages on ac obviously to see i was operating correctly.
Having issues with an oversized central AC in Minnesota. System was short cycling on and off every 5 minutes in moderate heat. Replacing the original round Honeywell mercury thermostat with the new Honeywell round non-mercury thermostat helped. We also added a delay on break timer to the condensing unit, and set it for 10 minutes. The temperature needs to be set to 66 degrees to get adequate humidity removal. With the new thermostat and timer, we get about 3 on and off cycles per hour, vs 6 to 7 cycles per hour before the modifications. Sometimes the air handler comes on in 8 minutes, but the condenser is held off for a full 10 minutes. The house is much more comfortable, and we are attempting to save wear and tear on the condensing unit by avoiding excessive on and off cycles. Is this reasonable or would you have done things differently?
Im in Hampton Roads, VA. My place has a old 2.0 ton unit (from 2001) but it struggles (1800 sqft) on hot days it does hit thermostat temp. I had a quote from HVAC company to a 2.5 ton system and 2.5 vap coil. Should a 3.0 ton be used instead?
Nice informative video. Have a question, I live in the Midwest and could get really hot and humid in the summer. My house in the main floor is around 2000 sq ft. My unit is a 3 ton ac/furnace 2 stage. It working good except for one room that has a cathedral ceiling, I am guessing 15 ft high. Only one register but no return. It gets really hot in the summer. I cut off the bottom of the door but still really hot in the afternoon. My question is do I need a return vent or supply vent, or both? The room is comfortable in the winter. Thank you. Are you in Barrhaven ?
Trying to get a new gas high efficiency furnace here in Massachusetts. My old one is a 96000 btu furnace with pvc flue. 2500 sq ft house , built in 1995. Why am I getting some companies say I need 80,000 BYU’s and some say 100,000.? Old one seems ok.
Never heard some one use so many words to say absolutely NOTHING. Not a CLUE about how to size a Heater or air conditioner for your house. A bunch of Obnoxious NOISE with out saying anything about how to size. What a Waste of time Ignorant and Obnoxious!!! Why can't you shut off the NOISE and explain how to calculate the size of the system??? Are People to stupid?? You should be fined and made to pay listen to this B S NOISE!!!!!!!!!
I live in a 3600 sq. ft. home in Arizona so it is hot. I have a 2 ton unit which covers my master bedroom, closet and bath and my 4 year old Lennox unit does not adequately cool. There are 2 vents (10 in vents) in master and it cools fine but the bathroom has a little 6 in vent and so does the closet and closet blows barely anything so it is stifling in there; and the bath is the same; just blows slightly more air. We had Lennox rep who installed system and they said it is working properly but it is miserable especially in summer. We have solar panels on our home and our bills are still over $200 a month and that is keeping our units at 78 during the day; even if you turn it down in the afternoon the thermostats will not reach 75 or 76. I am miserable. Our old trane units in a much larger home cooled within minutes? What to do? I am aware the builder uses units and not square footage and the air flow is not cool. It is a long summer here. Some neighbors have had to reduct ($2000) and had to order new larger units.
This is helpful. Thanks. Wish you worked Montgomery Co in MD.
Awesome video! Quick question I live in Canada on the West Coast. My house is built in late 80s 2 storey home, We are looking to add Central AC to the main floor 1450 sqft (3 beds, kitchen, living, dining, hallway) one contractor said I would require a 2.5 ton one said 3 ton is it safe to go for 3 ton if I choose a dual-stage system to prevent cycling? Service area Orleans??
You are just trying to get work , because you are not saying anything that can be used for the home owner. Service area Ottawa??
Just changed my ac unit I had a 4 ton and it was struggling and my thought was bigger size and I got a 5 ton Goodman but now I’m realizing I made a huge mistake reading on it and kinda bummed 2000sq ft 2 story I’m in Houston it gets hot my 4 ton was old and it was on all day and night so my thought was in need a bigger unit the guy said okay what ever you want and now I’m stuck between what can I do? Add a dehumidifier but I did for the reason that my light bill was $500 I was like I need it replaced it ASAP then I did it the house is cold but now I’m thinking of solutions.. any thoughts? Just dehumidifier I read that I can add a duct to the garage to get rid of some and add a dehumidifier?
How much BUT for 75 ³ m (5X5x3) to make it cool ?
No isolation
2 windows
The ceiling exposed to the sun
My house is 1100 sq ft with 7.5' ceilings and 111 years old. I live in SW Missouri with high heat and humidity. I am getting a heat pump split system Trane xr15 2.5 ton with an S9X1 furnace. Would a 2 ton system be better?
I used the coolcalc website to do a manual j calculation; Using my address in San Antonio, TX, the "outside design conditions" temp range by default is between 31 and 96f. This results in a load calculation of about 36k btu for cooling. But, we regularly hit 100+ in the summer, sometimes reaching up to 110. If I put 110 as the high for the temp range it calculates around 47k for cooling.
Would we be better off getting a 4-ton unit to handle those hotter days or could it be too much for most of the time when it is below 100 and cause those humidity issues?
Great Video ! Question what happens if my contractor sizes my air conditioner by rule of thumb(sq ft only) instead of doing a proper load calculation
Thanks for sharing this, I live in East coast I have two storey house 2100 sq, I hired a contractor to install HVAC and recommend me putting 5 tone AC, I'm concerning if is to big for the size of house? Are you in Kanata ?
Shoot we’ve been using daiken for the first time on this hotel job. There’s only 3 of us and it’s a new brand to us but it’s made this massive hotel job easier for some reason.
How do you do your heatload calculations to determine unit sizing?…
Thanks Josh. I'm in northern Virgina and am replacing my existing HVAC; 35 yr old single family home, around 1800 sf, new windows & siding. My current maintenance company proposed to replace my old 3-ton AC / 100-BTU (2 stage) furnace with the same sized equipment (AFUE is 80). For the second proposal, the contractor came to the house and said the current furnace was larger than I needed, and proposes to install a 3-ton AC / 80-BTU (2 stage) furnace (AFUE=80). The second guy was correct when he guessed that my current system probably didn't kick into stage 2 hardly at all in a normal winter. Any thoughts to share? Why should I go with the 100-BTU furnace if the second stage is rarely used? Service area Nepean??
I live in Kansas. Getting ready to have hvac system replaced. Little over 1800 sq ft home with partially finished basement and 10-11ft vaulted ceilings on main level. Currently have a 3 ton system that is original to the home when built in 2003. Should I go with a 3.5 ton or stick with a 3 ton system? Our current ac has never worked great since we moved in 2016, but that could have been because it wasn't working properly, not necessarily because it's undersized. Thanks
I live in south Texas. My house is 840 sqft. 2 bedrooms. I got quoted a 3 ton. Is this the right size.
I live in a 1,049 sq ft condo in Georgia that previously had a 2 ton regular A/C condenser and air handler/coil. Just had a company quote me a 1.5 ton Daikin DZ14SA0181 Heat Pump condenser with a 2 ton Goodman AWUF250816 air handler/coil. Does matching a 1.5 ton condenser with a 2 ton coil seem right? I was also originally interested in the Daikin Fit but they said it wouldn't work in my condo because the air handler I would need would be too big to fit in the utility closet. I was surprised they didn't make a wall hung air handler yet for the Fit. Also, thanks for all the videos you put out. I'm really learning a lot about HVAC and find it fascinating…
What have you seen with the reliability of an inverter heat pump vs just a two stage? The first seems to have higher efficiency, but is there an increased rate of failure? The higher cost doesn't bother me so much as the potentially higher repair costs down the line. If that is covered in your guide, I don't have a problem getting it now. I'm not in the market, but my units are old, so I could be, unexpectedly.
I'm in Maryland in a 2.5 story 1800 sq. ft. drafty stone home built in the 1840's. The primary heat is radiant and I have a 2.5 Ton system that was installed in 1997 that is rusting out. I've had two estimates for a ac and heat pump system in the past two days. One for $8800 for a 2 Ton Carrier system and one for $7500 for a 2.5 Ton Goodman system. The guy that spec'd the 2 ton said that the 2 ton is plenty and I could go to a 1.5. The other guy said he would prefer to put in a larger 3 ton in but because of the limited space he would have to put in a 2.5 ton. Two questions, one are these prices reasonable and two which system sounds more appropriate for my situation. Thanks
I have a choice between lennox 2 stage heat pump or brysnt 2 stage heat pump, which should I go with? Thanks in advance