You have the best videos for learning the proper techniques for HVAC repair and troubleshooting. Thank you for sharing.

Great video! Easy to understand, quick and to the point. Thanks for posting!

Been doing this 15 years ...best explanation ive ever heard.

Great video, just changed out my louvered door for full 6-panel door, & installed a 24x24 in the wall & 8x30 grill above the door to give 816 for my new 4-ton unit. My contractor tried to tell me that the 24x24 would be fine, but it was easy to add the grill above my new door. Looks much better. Sounds quite now Thanks!

thanks for schooling us with this quick, easy to understand, fun to watch tutorial. You're awesome.

Thanks for making this video.

David you are the greatest.... Thanks for sharing your knowledge.......

It's great that you've pointed out the problem that many customer's and even many contractor's don't seem to realize,. I was on a job recently that the return was so small that when the customer installed (pleated)1inch "High efficiency"filtersthey were pulled out of the R/A grill and up into the ductwork. The question I have is when you talk about 200 sq.in per ton, Are you taking into account the free area or "K" factor, because each one of those louvers is a restriction, and if you were to slide them all to one side and add up the area they take up, it's significant, one third or better of the grill's area, which is why the manufacturer's have to calculate the amount of free area for each Supply and Return Grille and register

@gaylefriedman3773

2 жыл бұрын

I had a 2.5 Ton Unit Residential A/C. I went to a 3 Ton Unit. Does this mean My grill is too small? I noticed an opening at the front side of grill. It doesn't close totally like before. Thank You!

Thanks for the video. I've been having issues with my old system and not 1 person mentioned to me that the size of the return needs to be increased. I have a 24"x16" 384 sq.inches when I need 600 for my 3 ton unit. This is half my problem

Great video David !! Take care, Brett

really like your video s.. appreciate the knowledge.. How would u size the proper flex return for that grill?

I hope you find this video helpful...thanks for watching from Jones Air Conditioning & Electric in Naples, FL!

great job.thanks for all your wisdom.you are planting seeds into million dollar business!!!

thank you man. i wish my contractors knew it when the did the job

thanks, outstanding lesson.

Building a home on my own. This will help. Thanks!

Good job David ...!!!.

You are the best thanks Mr jones

Thank you very much for a such valuable information. I have an open concept home and my living room is 16 feet tall. I have two ac units. One downstairs and one upstairs. If I need to add an extra return does it matter if it's at floor level or ceiling level? Thank you.

Thanks for explaining that.

thanks i have a test over this on Thursday and my teachers are horrible at explaining that. u just taught me more than my teacher did all class period

@jonesacnaples

7 жыл бұрын

thanks for the comment

Thanks for this video, but need another help please tell me how to calculate supply air grill size to consider supply cfm?

Thanks for nice advice.

well job sir.. proud of your skills..

Great video thank you!

I will work on it.. Thanks

Great video. Thanks

I hope it's a 2 million dollars a year. I will be here for support.

Hi David jones, thanks for the video, what I'd like to know is what type of duct are you using in your design, is it flex, metal or fabricated board?

Great series of videos, Dave! I have a quick question. I would like to finish my basement but I have one room where the return duct, leading to the furnace, is hanging down 9" and would make for a very unattractive bulkhead and low overhead. If this basement duct is 9" X 20" can I change that to 5" X 36" ? It's the same amount of square inches and those extra 4" of overhead room would really make a big difference to the look of the finished room.

I will, keep in touch. Thanks

great video you help me alot

Thanks for the video Its really helpful, I just want to as that you told Thumb rule for sizing Return Grill that 200 sq inch = I TR Is it standard of ASHRAE Or SMACNA??? Secondly is it valid for all type Units for example VRF Indoor , AHU etc??

Thanks, Brett

thank you, in hawaii and my ac is 3 ton , gettin gonly about 324sq in" return thats squealing, my poor ac is starving of air so im going to go install another grill,,,, does it matter how long the duct is ? thank you so much for you video ,helped me alot, i got quoted 710. to run a new return and a 12" duct about 20 feet. is that accurate? thank you again ! Sarah

Thank u sir very helpful video

very good video thank's!!!

Nice video David👍👍

@jonesacnaples

7 жыл бұрын

thanks

Thanks David

Excellent Tortola. I never had to replace an Air Conditioner Air Handler. Àlways a first!

You Rock! Thanks.

What if am using media filters? Calculations will be different. And if is for commercial installation also will be different. Had to consider the fresh air, so less static will be at the return grill.

My heating system is in a mechanical room. I have a large return grate in the wall outside of room next to the heater. There is a filter on the unit but no duct connecting the grate to the unit. Is it important to have this short run from grate to unit ran through duct? Probably 2 feet from the grate to the unit inside the mechanical room.

Amazing guy

How do you measure cold air return for filter

Sir can u pls explain about slots calculation of linear plenum

Can you make a video on how to size diffusers? Do you size grills with return ducts in the same way you size grills with no return ducts

hey. i have a question .recently i had installed 2.5 tonn rheem unit for heat and AC and there is only 1 return duct which is 12 by 14 and followed by 16 by24 main return built in unit filter. can it provide enough air volume for this unit? so it can work properly

The house we bought has three returns with filters at each return. The air handler itself has a place to put a filter. Is it better to have the filters at the returns, is it better to just have a single filter at the air handler or does it not really matter? I question if all the filters add restriction, making the return more inefficient (they appear sized right for 3 ton system, 2 - 12x24 and 1 - 12x12). Thanks.

what about size of the flex in the grill

Thank you so much

What about converting to a 4 inch deep filter does that change the math...4x the filtration area or is the math just about the opening? Thanks

I live in a mobile home that has a 3.5 ton heat pump on it. My furnace sits in the hallway, and the door/grill is the only return I have because it free pulls from there. The opening of the grill only measures 17” x 23”, which is way too small for a 3.5 ton system. My calculations using this method bring me to the conclusion that I could just cover up that door somehow, and install a 24” x 30” filter grill. Would that work in this situation?

Hi David, my AC is 3.5 ton unit while the furnace is 4 ton unit. The house is about 2,500 sq. ft divided into 3 zones and I have only 2 returns with the total of 744 sq. inches. Do you think having another return will help the air flow since one of the zone now has much lower flow? Thanks in advance.

Is cutting the register necessary if I have wood studs where the register needs to go?

How about sizing supply registers?

Do all air returns have to be that size.. ie adding a return in a bedroom?

David, what size of duct should I put for on those return grills?

I have a 16x20 grill on 3 ton. Iam trying to put my own unit in and all the runns. My house is only less than 2000 square feet house one story with 2 bathrooms 3 bedroom s. All my rooms are about 14 x14 except my bathrooms and laundry room their 7x8. Whats the best size duck's do i need 6 in or bigger

Thank you

What is general rule for supply grill ?? Or any formula

I got a new return grille 20x20 and it's alittle smaller than my current old one and the filter is snug also I've searched for wider dimensions but none that goes to 23 on the outside, It's not in yet I need help on what to do

Thanks for the great information. Could an AC start forming ice on the coils if it is starving for air? My 4 ton unit has 1 return duct register of 13x21.5 sq inches (280 sq inches) approx I've had the HVAC tech stop by and check for refrigerant leaks, or issues with the TXV and they all look good. He is recommending to add additional return air registers in the house to help with reducing the ice buildup.

@wcollins7557

8 жыл бұрын

If you get this reply, ice on the indoor coil is EXACTLY what you should expect from a unit that is starving for air. If more warm air was flowing over the coils, they would be kept above freezing. The engineers who design these units assume that the indoor coil will soak up as much heat as the outdoor coil can dissipate.

@DW-vl2wi

7 жыл бұрын

Niyati Abhi Gupta Hope you didn't have that done. All you needed was to increase the size of the existing return duct. Literally splice it, and add to it. Having just a couple extra feet that the air has to travel can make the difference, especially a couple degrees in which 33°F at the coil would not create ice. Either that or he was actually talking about a dump or bypass... oh well.

what would be the effects of having an undersized return? I've only got a 24×18 return so obviously that needs to be enlarged, tech never mentioned it, learning on my own at this point. I've had major sweating issues with my air handler, I've done everything to treat the attic and it stays under 90°f up there. Could the small return be contributing to the sweating issues?

Does the 200 sq inch rule work for just a heating system as well? I don't have ac (tons) just heat. Not sure what the BTUs are but the unit puts out quite a bit. Thanks

how did you come up with 200? basic rule of thumb number just curious

Hello! Great video one question how would you translate this into cfm's? Example I have a 4 ton unit with only an 8x12 grill it's freezing up and flowing ice into the ducts. I know I need more air but honestly I would like to understand the difference between cfm's and free air. Thanks in advance

@3beltwesty

7 жыл бұрын

OK here is a back of the envelope swag:) : (1) Old rule of thumb is 400 cfm per ton thus 4*400 =1600 cfm. ( cubic feet of air per minute) (2) Grille area minimum = 4 tons *200 inches squared is 800 sqin . 800/144= 5.56 sqft too. (3) For fun the air velocity is 1600 cubic feet per minute / 5.56 sqft = 288 ft per minute. Ok 288/60 = 4.8 ft per second.

So if i have a 2 ton a/c unit would i need 400 square inches of return a/c grille space? If i am suppose to have 400 square inches for a 2 ton a/c unit will a 25 x 16 return a/c grille work since it comes out to 400 square inches?

I wanted to apologize about the Monkees and the pirate comment. I have been watching HVAC videos and started watching yours, good stuff, God bless.

Someone capped a floor return for a 3 ton unit. It has been pulling crawl space air into a open flash pan under house, then out to the packaged unit. I believe I will have to have a 20 x 30" filter grille installed in the floor

I have 4 ton roof packaged unit with 20x30 intake. Seems to be working fine with 600 inches. What do you think?

what is difference in R22 vs R410A return inches per ton>?

My house has a 5 ton unit and the return grill is 20x25 , so I need to add one more grill correct?

very good infomation , When you say generally 200 sq. in. , could or would there be any reason for a change

@fleurdebreezeacheatingllc2573

2 жыл бұрын

The right way

Mr David, I currently have a 2.5 ton unit. I'm stepping up to a 3 ton. My return air is 274 sq inches. Should u install another 275 sq inch return grill? Does my ductwork have to be taken into account? Thanks

What duct work would the 600 sq in grille plunem?

How much can you oversize the supply and return ?

, , when putting the air grill back onto the wall doesn't make a difference if the slots are facing down or up?

It's same for supply grill also?

Sir,how to design Register per square inch

Question, does the design of the air return flex matter? Square versus round? Also, if a return is closer to the air handler does that mitigate the need for the rule of thumb 200" per ton? :-)

Correct!!

@coollasice4175

10 жыл бұрын

Good info.

How about without the filter? How do you calculate that?

Dave, Im considering starting my own business. Im a journeyman sheet metal mechanic with my local. Work is slow and i mainly worked on commercial projects. Whats the biggest difference between residential and commercial work?

Awesome Dave, but could you also address R/A duct size.

does your general rule of 200 sq inches per ton take into account the k-factor of the grille?

I have a 5 ton unit I know I need a thousand square inches of return grill right now I only have about four hundred square inches and I am whistling I change the blower motor for the guy and that's when it saw that whistle he said it never whistled before if I open up another return give another 600 square inches do you think I'll take care of my problem ty for all your videos

@jonesacnaples

7 жыл бұрын

you are on the right track

@yolandagarza7840

6 жыл бұрын

David r I

Residential is sometime harder. Going behind some one else can be tough. But you can make your money faster. I would try that less starting Capital. Good luck.

We always need to have a laugh I.am always joking around. Thanks for watching.

thank you

My system has an appropriately-sized grill but immediately inside it is a much smaller round duct. I'm amazed by the widespread incompetence in the HVAC industry.

I'm in Texas, been in a.c. field 18yrs (and still don't know everthing, no a.c. guy should ever tell you this) anyways I've always divided for gas units by 144 and electric by 215 not 200 ,that's per Airflow icb, is this correct?

What about calculations 20x30=600x2 cfm=1200/400cfm per ton=? Is this ok calculation?

Yes you can, it will be ok

QUESTION: What if you have a 2 or 4in filter? Does that “take away” square inches? Doesnt a bigger filter create more static pressure and affect the return numbers?

I have a question. My return is fed through in between the walls , so the cavity is like 32 x 3.5 inches, Due to the placement of the main floor support beam ( 2x 8) it chokes of the cavity from like 3.5 inches down to about 1.5 to 2 inches . and comes back to 3.5 inches x 32 . The grille size for my air handler is correct but this " choking " does it matter or doesnt it, since because after passing passing the support joist it comes back up to 3.5 inches wide? Thx in advance

@nicholashartzler2205

7 жыл бұрын

This starts to make things really really complicated.

My house is 1800 sq ft what size unit do I need and what size return

@jonesacnaples

7 жыл бұрын

if you have a 3 ton let say you need at least 18 inch, then a 10 in another part of house make sure your return grills are large enough for the air flow look at my video on sizing

Loved your video,lots of good information! I currently have 4 ton unit with a24×24 air filter. I plan to replace the unit and have received some quotes with 4 and 5 ton units. The 5 ton unit quote indicated the reason for a5 ton was because of living room ceiling of 15 feet, is reason enough to go with a 5 ton unit?.

@roccoVAL

2 жыл бұрын

no you're wayyyy off

@1227Masher

Жыл бұрын

Have them do a manual J calculation. That will take into effect total heat load. Remember - you are conditioning cubic footage not square footage. The number of windows, insulation, shade, etc all come into play. And yes - I realize your comment is six years old - this is for anyone that finds this later…

hey sir ...why we divide area of return duct by 200?

@MAGAMAN

2 жыл бұрын

To get the "tons". The number you get will tell you how many tons the opening is good for. For example, I have 588, which divided by 200 is 2.94, so I am good for a 2.94 Ton AC unit. I have no idea what the size of my unit is because I can not find any markings on the unit in my house. I am going to assume it is probably 2.5 according to Sq foot/ton calculators on the internet.

Good demo and video sir. I think my return is very undersized, but I don't see any adverse symptons. I have a 3 ton unit with an 18x18 return mounted in an 18x18x20 plenum, connected with a 12in x 3 foot flex to the unit. According to the calculation that's liike 1/2 the size needed? Yet there is no whistling or even observable wind noise, and airflow seems to be excellent. THe return is in the tongue & groove hallway ceiling so its hard to make it larger.

@malabarspyder

10 жыл бұрын

I should also mention- the air-handler opening itself is about 20x20 that that's only 400 in2 - sized for a 2-ton unit. So even if I went to 24x24 return grille, it reduces to 20x20 at the handler? ALso the 12in flex area is pi x 36 =~ 113in2 ! - sized for a 1/2 ton!

@rowhsv

9 жыл бұрын

Malabar Spyder Yes, but the air-handler opening and the flex duct do not have filters in them, so the air freely flows through them. To insure adequate air flow through the filter, the area of the filter must be greater than that of the duct and air-handler opening.