HVAC Ductulator 1

[lovelorn8888]

hey I have a question lets say im not so good at math,, is the going to hurt me really bad in HVAC?? im going to school right now for it.... oh and why am I the only young guy in my classes? LOL

[DrZarkloff]

@lovelorn8888 If you can do basic adding, subtracting, multiplication, division and fractions, you'll be just fine.

[lovelorn8888]

@DrZarkloff yeah I can LOL But some of the math is harsh... more like the Formulas

Like I hate trying to figure out how many BTU's it take to say cool meat thats 70 down to like say 5 or whatever Thats what always gets me

[rsurfer9]

You had me confused because you said .25 friction rate and went with .05 friction rate to 800 cfm, and mine wasnt matching up.

[jjpjjpjjp1]

If a furnace is rated at .03 ESP, where on the chart do you line up the chart?? AND... how come there is 2 scales for friction loss on the ductulator????? This stuff always concerns me. Is it .05 on the lower scale or is it .1 on the lower scale for friction loss???

[paunocuh]

Anyone have ductulator in Java for mobile?



[waters65]

ductulater ;  in a sentence . would you like to duct now or i could just duct u later

[orbtaybal]

If you have an iPhone you can get a series of programs..

HVAC Buddy (superheat/subcooling calc) .

PT Buddy (has like 700 refrigerants)

HVACDuct (ductalator)

I'm new school, card board calculator!? no way! :-D

BTW, I work on computer room air conditions so you can see how I'm a techie.

[DrZarkloff]

@orbtaybal Thanks for the info. I'll check to see if any of these programs are downloadable through my htc Droid.

[co2x3]

Excellent info Doc Z this clip is why i choose a ductless system yes a 2 ton r410a inverter condensor. whos got time to run ducts in your home when you could go ductless. very good info though keep em coming

[mithrander013]

Very good I like it what are you going to do next? You said it the sad thing is that most of them have not learned the basics when it comes to air flow.

[V8Jagnut]

cool. interesting.

[DrZarkloff]

@V8Jagnut Thanks.

[tstatech]

I realized after I reread my comment to you that it sounded like I was bustin your balls. I apologize. I just thought that you gave just enough information for newbies and a lot of oldies to get the wrong idea about duct design. You did you use the word design when you probably should exchange the word design with sizing.

It would have been nice if you would have been a good idea to touch on velocity limits that would at least keep the rule of thumb guys closer to the ball park.

[THEHVACTECH101]

Is the correct way to find the friction lost of a system is to use a magnehelic gauge????

[tstatech]

@THEHVACTECH101 No, this is a common misconception. Friction Rate is not the same as Static Pressure. You are measuring static pressure with your magnehelic gauge or monometer. You can go one step further and measure velocity pressure with your gauge if you have a pitot tube. Static pressure is like that in a balloon. Total pressure = static pressure + velocity pressure

Friction rate is a way to assign a scale of resistance per 100' of equivalent feet of duct.

[THEHVACTECH101]

@tstatech Thanks for clearing that up

[MinTrinidad]

@tstatech @comfortaircompany you guys are right. It is not that simple as Dr Z puts it, Fan curves , static pressure, duct type( losses), cooling method (VAV, Cooling coils etc.), velocity etc all need to come into the picture.

[DrZarkloff]

@MinTrinidad Thanks. It's funny how some people think they can design a duct system with just a few minutes of instruction.

[MinTrinidad]

@DrZarkloff I hate duct sizing. But keep up the good work.

[DrZarkloff]

@MinTrinidad Thanks

[ibunregistered]

I like the calculator at efficientcomfort net (free is 4 me). I try to figure these things out before I get to the job.

Do you use that if you suspect incorrect sizing problems?

I bet most of your work is on sheet metal duct.

[DrZarkloff]

@ibunregistered Thanks for the info. I usually just consult my ductulator.

[ComfortAirCompany]

Yes Dr Z is wrong because he is over simplifying duct sizing, but the sad and unfortunate truth is that it won’t matter in most circumstances if you use his over simplified methods of calculating duct sizing. If you’ve been in this industry long enough you’ll know that even hacks (I’m not calling Dr Z a hack) can produce working systems. Properly sizing ductwork will only affect its efficiency and noise levels. I use Manuel D and I don't cut corners, but nobody see anything but price.

[DrZarkloff]

@ComfortAirCompany I was just showing a couple of handy and simple ways to use a ductulator. Duct design is best left to the pros. Even I'd have a duct specialist design duct for my home if I were to upgrade my a/c to a two stage system.

[ComfortAirCompany]

@DrZarkloff

Ya you're doing great.

We techs typically only need to know rules of thumb like 300-400 cfms per ton, but designer and installers should learn a lot more. The sad fact is that most of them haven't learned even the basics that you were teaching.

[tstatech]

@ComfortAirCompany I agree, It is my experience that it is a prerequisite to be a installer before you become a service tech. Sadly most installers are little more than box cutters. The guys I learned from 20 years ago are still using rule of thumb to size equipment an ducts.

The best installers come full circle from installer to tech and back to installer.

[DrZarkloff]

@ComfortAirCompany Thanks. It's more like 400 to 450 cfms per ton.

[ComfortAirCompany]

@DrZarkloff Well I trust your knowledge over my own, but I've never seen matched units put out over 400cfm per ton. But I guess that why I hate rules of thumb; they always change depending on who I ask. Thanks for the insight, keep the videos coming.

[tstatech]

@ComfortAirCompany You can say that again.

[Nutintoitbut2doit]

Dr. Z thats a sheet metal ductulator not one used for flex, Manual J and D are the best way to go.

[DrZarkloff]

@Nutintoitbut2doit I knew that I was going to get busted on that one. Duct design isn't as simple as some people might want it to be. By the way, my ductulator has got me through some spots where I had to go from rectangular duct to round flex.

[Nutintoitbut2doit]

@DrZarkloff Yes it will help you out in most jobs like replacing a duct or two, it is good to know how to read a ductulator not many techs know how, I like to use duct software that has both J & D in it. But I'm no duct expert, I know enough to be dangerous lol.

Keep up the good videos Dr. Z

[tstatech]

DrZ, you are totally disregarding velocity and velocity limits.You also need to lay out your duct system on paper and refer to manual D equivalent lengths to determine the longest supply and return paths. You deduct pressure losses and you are left with available static pressure. You also need the blower table or fan curve from the manufacturer's technical data to determine the balance point between the duct curve and blower curve. Then you get friction rate.Get ACCA Manual D and give it a read

[tstatech]

@tstatech Manual D is for residential duct design and is based on equal friction. When doing residential design you are limited by the blower in the furnace or air handler. When doing commercial design you can use the static regain method because you can get different motors and shivs.

[DrZarkloff]

@tstatech All I did was touch on a few uses of the ductulator. I don't even plan on going into everything there is to know about duct design in just a few minutes. Please don't get the wrong idea. Duct design should be left to the pros.

[robw1031]

You should probably make some adjustments when using flex duct i.e. most ductulators are for sheet metal duct (smoother surfaces). There are some flex duct calculators/ ductulators available. I can't remember but there is also a ROT you can follow as-well. It's been so long since I used a ductulator as I now have a phone app for that. LOL

[DrZarkloff]

@robw1031 WOW! Where can I get that phone app? I have a Verizon htc phone.

[tstatech]

@robw1031 The ROT I have heard is to increase the size to the next size when reading a sheet metal ductulator when using flex or ductboard.

If you pull flex straight and tight it will perform nearly as well as metal.

The ductulator from ACCA has flex, duct board and duct liner.

[swampfoxgt]

The .1 rule of thumb and sizing flex using sheet metal friction rates are both bad practices, do so at your compressor's peril lol

[DrZarkloff]

@swampfoxgt Every manufacturer has it's own specs.

[tstatech]

@DrZarkloff Yes but typically you should shoot for a maximum .5" water column design static on the blower. Usually unless it is a small simple system you will find that you will go into the grey area between .5" and 1" of water column. Be ware most blowers will stall before you get to 1" water column. ECM motors are making it easier and will compensate for some design error but the same rules apply. They will fail as you approach 1"

[tstatech]

@tstatech YouTube doesn't work correctly. I was trying to reply to swapfoxgt above this comment labeled as if I was replying to DrZ.

I see all sorts of ways I would change YouTube not to just work better but to work correctly. Sorry guys didn't want to go off on a side tangent but come on.

Also want to apologize to DrZ for causing him any grief with my original or subsequent comments.

DrZ you are on cool tech. I have learned a thing or 2 from your videos. Great videos. keep it up.

[67tr876]

Holy carrier this is cool ! looks like it helps a lot !

[DrZarkloff]

@67tr876 Thanks

[eggman9713]

Ahh ye olde ductulator. I use a small pocket sized one all the time at work for designing systems.

 If you really wanted to be technical, the word "Ductulator" is trademarked by Trane I believe. Mine is from Carrier and is a "Duct Calculator." but of course I call it a ductulator.

[DrZarkloff]

@eggman9713 I didn't know they made pocket size. Is it hard to read?

[eggman9713]

@DrZarkloff Not for me. Looks like the numbering and whatnot is similar to the large one you showed, with maybe a tad less accuracy. And mine is a slide type, rather than a turning type. Much easier to use when marking duct sizes on plans.