WRONG! Misinformation on the internet about HVAC system sizing and what you should do instead.
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- Опубликовано: 24 авг 2024
- There is all kinds of information out there about HVAC system sizing. None of them replace having a proper heat load calculation performed. You should have a professional calculate the exact size you need.
A big percentage of heating and air conditioning systems are installed when the house is built sized wrong from the start. So even replacing the system with a new one may warrant having a proper heat load calculation done.
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I built my house in 2020. The ac guys came out and said were getting a 3 ton. Our house is 2300 sq ft, 1805 living. I told him that we should have at least a 3.5 ton and he laughed at me. I even offered to pay for the upgrade through our builder. Still, nothing. Had this big ordeal about it and had the 'experts' come out for a second opinion. Same conclusion. Four long, hot years later. We tossed the 3 ton and got a four. Best decision I ever made. I live in southern Louisiana by the way.
Yeah,these guys are being oversold on overthinking efficiancy!
Nice call, did you have to upgrade the copper from 3/8 to 7/8?
@@romeomazzaluna5516 3/8 TO 7/8? LIQUID LINE REMAINS 3/8 REQUARDLESS. suction should have been 7/8 for either.
My house is in N. Texas. It's *hot* in the summer. The house is a 2 story with around 1000sq/ft up and 1700sq/ft downstairs. The 3 most used lived in areas downstairs are the living room, large office and kitchen/breakfast area + lesser used dining room, spare bedroom a full bath and large entryway. Upstairs are 1 very large master BR + 2 other avg size BR's + smaller work out & 2 baths. The insulation isn't very good and none of the exterior walls have insulation. (pull the wallboard off, and there is a plastic sheet then brick. No foamed beams on underside of attic, nor any non liveable attic space.
WHen it came time to replace units, I went with a 16 SEER 4 ton dual speed variable fan downstairs and a 2 1/2 Ton single stage upstairs. It has been a *perfect* system and initially so did the company I hired to install it. Downstairs rarely runs on high speed - in fact, hardly know it's running. The 2.5 ton upstairs temp is set at 67* and cold air falls like crazy coming down the staircase in the large downstairs 2 largest areas. My 4 ton unit went out and the same company I used originally insisted that unti should be a 3 ton single stage. I adamantly disagreed due to how quiet the unit was, maintained perfect temperature. Relative Humidity downstairs runs 33-42% year round during warm months (70% of the time). *So, WHY is my HVAC guy so insistent on taking down from a 4 ton dual stage to a Single Stage 3 ton* ??? I can't for the life of me figure why he's so insistent on downsizing. ANY IDEAS OR COMMENTS??
An HVAC guy telling people they cant do it themself, ill just put on my surprised face.
Impossible conversation. Each house in each region will be so different. Windows, insulation, leaks etc. People really need to spend the extra money to have it surveyed first.
Surveyed by whom? The Hvac company?
Would really love to know thank you!
Please make video on step by step how to do heat load calculation.
😆
You need a heat load program
Every new house we do. I run a load calc. My problem is my state of nj has to be ran at 89 degrees. Even though we get days at 95. We in nj every company has to do there own load calcs. Even in replacement work.
I have a slightly larger system, and it works great. I would be more afraid of going too small... and having the thing run all day long just to pull the house down a few degrees. Mine will pull down to whatever I want it to, quickly. It gets up to 115f in the summer here. Dry heat. House is not real tight and thermally efficient. So... the larger unit works great. Specs would call for a 3 ton. I have a 4 ton. 1700 sq ft.
Where are you located at if don't mind asking?
Thanks for the response!! I have a 2.5 Ton and my AC struggles to lower the temp within a normal time i'm going to jump to a 3.5
Quility only hurts once.
We have a 2000sf mobile home with a 4 ton heat pump. It needs replaced I was thinking of a 5 ton but one with a 2 speed condensing unit. Were in texas and no shade 14 windows plus a sliding glass patio door.
I'm in South Central area of Arkansas (about a 100 miles Southwest of Little Rock) so our weather temps are pretty much identical. My recommendation go with a 5-ton 2-stage (or Variable Speed system if you can afford it) heat pump system. Personally after several quotes had 3 out of 7 HVAC guy who did my quote recommended me upsizing to a 5-ton system that was either 2-Stage or Variable speed system so i chose to go with a Trane 5-ton Variable Speed climate control system upgraded from a Trane XR13 Single stage 4-ton system that never shut off in the summer months. My nee Systemt barely runs more than 40% capacity except during the triple-digit hot summer days and even then it never operates above 80% capacity and it easely maintains whatever i set the temperature at. My recommendation at the very least get a 2-Stage oversized heat pump system if they say you need a 4-ton insist on a 5-ton 2-Stage heat pump system. it will run in 1st-Stage (which is equivalent to roughly a 3.5 - 4-ton system amp draw) about 80% of the year. By me doing that or at least something similar my electric bill literally dropped by more than half because unlike my old system this one does not run all day and all night when it's hot. You can thank me later.
System sizing is multi factor. Not just climate zone but, also the number of occupants, windows, ceiling height, number of occupants, IT equipment especially high end custom gaming PCs, appliances, and the insulation. Whenever you are building a house from scratch, it is worth it to hire an MEP engineer. Also having dampers on the branch take offs can ensure proper air distribution so all rooms are heated and cooled evenly.
Number occupants should never be factor. Houses are sold all time and occupants numbers change
Also orientation of the house… N, E, S, W
An occupant adds about 400 BTU heat generation. There is no way that this affects sizing for residential work. Commercial with large crowds is another thing.
Fortunately here in the St Louis metropolitan area, St Louis County provide a worksheet ( one of the best I've ever worked with). From a normal size house plans, say 2500 square feet it takes about a half an hour or so to complete.The big Builders still get around it a little bit by using the same worksheet for each house model they may have, even though the house may face a different direction ( it's close but we still find some under size systems ). We are also required to put a cold air returns in every room but the bathrooms or kitchens . The St Louis County worksheet is so good, all the surrounding counties and the City of St Louis honor it. I just wish code enforcement would require two systems for all two story houses but they still let the builders get by with one large unit.
That’s pretty cool. They seem to have the stuff together better than a lot of other areas.
Instead of 2 units for a 2-story house, how about a 2-zoned system?
@@lapk78 ,VRF heat pump zoning works pretty good as long as it is a manufactured approved zoning system. Around here we mainly use Natural Gas furnaces and it puts the temperature rise way out of whack when you use zoning systems. Even the zoning systems approved by the manufacturer are hard to dial in. I prefer two separate systems, damper systems seems a little Mickey Mouse to me , plus if one goes down you still have the other.
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the problem is that the professionals are not doing the load calculations and they're easy to fudge to get the size the contractor wants to be put in. sizing by runtimes is very good if equipment is working properly.
Definitely agree on contractors. Some can’t do one if they need to
The HVAC industry is such a rip-off. I was sold a 4-ton unit, but the shipping crate said it weighed only 335 pounds.
Outrageous!
Unbelievable
I hired an engineer to perform an HVAC load analysis. Says I need a 24K btuh system. Are all 24K systems pretty similar? I usually install Diakin or Fujitsu units myself then hire a pro to check and charge it.
Here in brutal Phoenix AZ I don't care what the chart says...upsize half or 1 ton everytime!
You don’t have to worry about humidity issues as much as some
Sooo how do you find out what the proper tonnage for a residential? Like, measuring the square footage to find the BTU’s, CFM, Airflow (I.e. latent heat). Manual J
Manual D for proper duct sizing
Yes sir!
Great video. Do you have anything for apartment buildings?
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 , does have 2 zones temptrol, 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.
96k would be pretty much the same as a 100k if you're comparing.
?
I don’t know the answer to your question. It’s like asking why some people recommend white bread and others recommend wheat bread. I was simply letting you know that there isn’t much difference between a 96,000 BTU furnace and a 100,000 BTU furnace.
Perhaps you can ask one of them why someone else is recommending a different size and why they are recommending what they are recommending. Someone that knows what they’re doing will know why they’re recommending the size that they are recommending.
From my understanding it would be their difference on recommended BTUs per Sq/FT. 35BTU per Sq/Ft= 87500BTU, 40BTU per Sq/Ft= 100000BTU and so on. Colder the climate higher BTU per Sq/Ft
Who does the survey? The hvac company?
I am curious for a 2-story house if the downstairs should have a much larger furnace and the upstairs a much larger A/C ? For my house the downstairs has the larger A/C and the upstairs struggles to remain cool.
Keep in mind the upstairs has to deal with the heat from the attic. If you want to aid the upstairs unit in remaining cool you could check the attic insulation level and add more. It like buying a cheap cooler that only keeps the ice solid for a few hours versus a Yeti or good one that last days. The difference is the insulation. So consider the same thought with your home. The walls are hard to upgrade after drywall is installed but the attic is really easy. Also is the largest contributor of heat. Lost local stores will let you rent the attic insulation blower machine with a few bags purchased there to blow more in. That would be the easiest first step and it'd help the house overall!
I need a 25 ton unit! If this summer is anything like last summer then yeah…hook up 5, five ton units!
Just be sure to hook up the electrical to my neighbors home!
Hi Josh - do you service Miami, Florida?
Did you find a good A/C company in Miami?
Manual J
Yes!
Have you ever heard of cool calc manual J and if so what are your thoughts on it?
I've heard of it. I have a friend that uses and likes it
Is there a map for Canada I may be able to see?
I'm not sure. The map was referenced in the video because they aren't accurate. :-)
Do you know of anyone in NOVA that can do a proper heat load calculation?
I know someone not in NOVA that can maybe help.
@@NewHVACGuide sent you an email
MY HOUSE WAS BUILD IS 1984 BUT HAS NEW WINDOWS AND INSULATION 2 STROY I 20 YEAR YORK REPLACED THE TRANE CONDENSER FROM 1985 IN 2006 AND ICP FERNUS REPLACED THE TRANE IN 2009 THIS HOUSE NEVER HAD 2 SYSTEMS
Waisted time. Didn’t leen nothing from here just bla bla bla
Sorry pal
Useless info bro!!!!
Sorry pal
blah blah blah. is all I heard after the 1st few seconds