How to perform a quick load calculation

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[martysomoco]

Thank you for the most complete, most clearly presented, most thorough, most succinct, most helpful video on Manual J calculations on You Tube.

I have watched so many presentations by so many so-called "experts" (including ACCA board members and authors associated with ACCA).

Not a single one of those videos completely covers the process. All of them leave out some of the essential, necessary steps. None of them clearly provides enough specifics to actually do the Manual J analysis required by most jurisdictions for a new system install.

Many of the so-called "experts" and "trainers" ramble on about irrelevant or personal information for the better part of 1 or 2 hours

Typically, the presenters provide just enough information to get your interest and attention so that you will buy their book, pay for their services, or purchase parts or tools from their sponsors.

Thanks again!

[charlton]

I loved using those load calc tables, we were also an Airtime 500 contractor. Those calculations are the job so much easier when doing loads.

[stlwrkr]

Great explanation!! Thanks for breaking this down into such an easy to understand way.

[eagletek]

Thanks for sharing.This will greatly bless our up coming business fulltime.

[demondude]

Easy video, I am jsut starting in the HVACR field so this is good info

[tedjohnson]

Excellent tutorial, thanks for sharing this!

[lucdumouchel]

Have 2 questions. How do you calculate gains from ductwork.
And second: when it says number of people: I have a hall to calculate with about 60 people and 1 bathroom. Do I calculate only 1 bathroom or calculate 60 people?

[edithnogueira]

I suggested to pay a company to get the AC load calculations rather to install based to 1 ton every 400 sf. I have installed a 3.5 ton AC to a 1570 sf house and the size was wrong. All the AC contractor agreed the size was between 3 and 3.5 ton, but all of them were wrong. The AC turned on and off quick without completing the cycle, and not removing the humidity and not cooling, and therefore creating mold. A professional calculations done by engineering company specializing on this, shows that the correct size was 2 ton., could go up to 10% high in size. The AC was replaced, and the problem resolved.

[humbertodiaz]

Hello, i like your video. thanks for taking the time publish it. i have one question? you said that this worksheet is only for the part of US where you live in, but what does it have to be changed in order to use it in other parts or in other countries?

[KenTraining]

Can you help me

I am wanting to find CFM’s for rooms once I know the Btu/h
heating and cooling loads.

I have the Manual J8AE spread sheet and the CFM outputs seem
high to me and I wanted to see other calculations.

I tried the Sensible Heat Formula of CFM = Sensible Btuh / 1.1 * Delta T

But when I input those numbers I get higher CFM needed in

areas that have lower Btuh heat loss/gain.

Here is my example

Home is in Laguna Beach California

The area labeled 1st Flr Master Bedroom has a
heat loss of 9138 Btuh and a Heat Gain of 4807 Btuh

Manual J8AE want to provide 299 cfm for heating and less air
(244 cfm) for cooling

If I do the sensible heat formula CFM = Sensible Btuh / 1.1
x ∆ T, I am using 29 ∆ T for heating and 10 ∆ T for cooling

I get 286 cfm for heating and more air (437 cfm) for cooling.

This does not make sense to me with needing more cfm with less of a Btuh load.

Can you show me where I am thrown off?

[dennmillsch]

I'd love to use this accu-size sheet but it only allows a few specific construction parameters. Doesn't work for R40 walls, or R-60 ceiling or triple glazed windows with U factor 0f 0.15. It could be useful if it had adaptable formulas rather than specific multipliers for specific construction only.

[Alhabshan_m]

Hello,

thank you for your explaining.

Actually, I did understand how we get the total BTU/h heat gain. Can you please show me how we calculate it?

[jonathanavila]

Can I pay you to do a load calculation for me? Also how do you determine the region?

[dennmillsch]

Oops, at 02:00 you calculate 33 sq ft, however you entered 8 when it should have been 18, meaning it should been 43 square feet.

[IA-geet]

Many thanks for sharing that with us. I can't help but wonder, how exactly you developed this sheet. I mean how you come up with multiplied numbers?

[peerod]

I love the explanation but I would love to know where they are getting the multiplier factor so I can convert to my region.

[crownjewels]

Great video. If the average degree day for heating changes from 0 in your example to 25 then would the multipliers change also?

[barry]

Nice video where can I go to get a worksheet like the one you have.

[peterkalinin]

The formula is: 400 sf pet ton - for commercial and 500 sf per ton - for residential installations (8 ft ceiling).

[amokoikaw]

HOW DID YOU GET 70, 000 BTU and decided to get a 2 ton unit furnace? Thanks . . .