LOAD CALCULATION

[Backspin]

Hey Guys,

Need your opinion... Here goes.... Being doing heating/a/c service/ installation for a number of years. Currently teaching HVAC at a 2-year tech college.

Done heat/cool calculations many different ways: (1) guess-a-ments, (2) rule of thumb, (3) manual-J, (4)short form, (5) computerized, and etc. All seem to work fine.

Finding out most of my students are saying they (companies) don't use manual J, or computized system.

I've asked my co-workers, HVAC advisory members they all say keep teaching the Manual J. ( I think becuase they are my friends and like me).

My idea is that this gets the students informed, increase their vocabulary and awareness regarding installation and sizing. Cann't pass a mechanical contractor exam with knowlegdge.

What do you say? What's the majority using? What is best in the "real world"
Concentrate particular on Manual J or teach something new and fast?

Looking for suggestions

[weathered]

I think it is important that students learn how heat loss and gain works, i.e. where it comes from, how glass direction has a large influence on gain etc.

You need to teach how heat loss and gain works. Now, once they understand the principals, then they need to know how to calculate it and that is where Manual J comes in. You could teach them right from ASHRAE Fundamentals, but you would lose most of them, Manual J is just a simplified method of ASHRAE.

Once they know how to do a manual Manual J calculation, it would be nice if you could show them how to do it on a computer.

I recommend HVAC-Calc for this. I spoke to an instructor who used another program and he said that he spent too much time trying to teach them how to run the program, losing sight of the end goal about teaching them about heat loss and gain. I suggested he give HVAC-Calc a try, which he did and now he uses it. You can get it at http://www.hvaccomputer.com - I believe he was very happy with their school site license pricing.

There are no rules of thumb or quick methods that are reliable. The only way to do it easily and quickly is to have a good computer program.

[dwahlman]

I currently teach at a two year college also. I have been teaching heat load calculations utilizing the Manual J forms, but have also been using the HVAC-Calc programs. I use primarily the residential HVAC-Calc program, but am trying to implement the commercial program into my curriculum also. It is very user friendly, and the reports are easier to read than the manual J. I have also found that the HVAC-Calc has the ability to direct students to things they may have overtly missed, (.ie floors and a ceiling in a room.)where the manual J can not compensate for human error. The HVAC-Calc programs are very precise also, I have used it for sizing our carpentry house projects, and I have not missed one load yet. The students also find that just after a few minutes of instruction, they can produce accurate heat loads also. I do not know for sure, but I know several of my "former" students have tried other programs, but have stated they preferred the HVAC-Calc program over others.

Hope this helps. If you have any questions feel free to e-mail me at: dwahlman@gwmail.nodak.edu

[Backspin]

Thanks guys,

I agree....We had mulitple copies of the Manual J software for DOS, they don't run on Windows or network systems. Spent two years without it... Then Manual J came out with a Windows base program.

But I am considering purchasing the new HVAC-Calc program that I have been test driving.

Any more inputs are welcome.

[TraneMan]

Buy it Buy it,its a great program
My 2 cents

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[AllTemp]

HVAC-Calc , I'd never consider another load calculation program

Cruise the HVAC Computer Website or better yet drop them a call, you be impressed!

I've posted on this topic in this forum before look for some of those threads, their quite informative...

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MDamron
http://www.alltemp-hvac.com

[Backspin]

Hey guys,

Its me again. Well the "check is in the mail"... (as if you haven't heard that before)

I had to a chance to talk to Don from HVAC Computer Systems. It looks like we are going to give the load calulation program a try and intergrate it into our class w/ Manual J.

Don is a great guy and the cost was much lower than I expected.

Thanks for your inputs and thanks HVAC Computer Systems.

[KMD]

I agree with ACBOB I think the kids need to know how to do and understand how to do a calculation by hand before trying the software programs. ASHRAE information is correct but it is to technical and very hard to follow, I have taken a lot of heat transfer classes in college and the colleges love to use ASHRAE standards but I would always return to my ACCA library,(manual J, D etc..) where it is written in english. And for the masters test you cant use a program to do a manual J you must do it by hand so keep on teaching the manual J by hand. I do agree if your in the business your a fool to do the calculation by hand it is too time consuming and easy to make a simple math error.

[jason_c]

gosh that would have been a tremendous help if id had that during ref. school.