load calcs and duct work question

[AllTemp]

Originally posted by detroit_pierogi
What do you guys think about trying to do our own load calculations, like with the free trial program that is advertised at the top of this site ?

Hey, didn;t I advise you to do this days ago on anotehr thread?

GREAT IDEA!

Thats a pretty good offer if I say so myself. Download it and have some fun with it!

Lets us know how you did...

[framehvac]

Originally posted by AllTemp

Originally posted by detroit_pierogi
What do you guys think about trying to do our own load calculations, like with the free trial program that is advertised at the top of this site ?

Hey, didn;t I advise you to do this days ago on anotehr thread?

GREAT IDEA!

Thats a pretty good offer if I say so myself. Download it and have some fun with it!

Lets us know how you did...

Ok AllTemp your ad is just wrong in so many ways you should have to pay money for a ad like that.Why didn't I think of that?

[professor hvac]

There arte many things that can change over the years since the last time the heating and air have been replaced! If the insulation has settled or been added to, then the cooling load would be different. If there have been any updated windows, doors, or even the color of the roof!

Then again if you go by the equipment that is being replacesd, you are asumming that the last guy that installed the system did everything right and did a load calc on the house and did it right!!!

Many contractors don't like to run loads on every bid they give because it takes a lot of time and time is money! I usually told customers that the estamate was also an estamate on the size and it should be in the ball park and if they were interested in my estamate then I would run a load calc from that point!

I never would start a job without doing a load calc on it first!

[pstu]

>>But you have a working system that can tell you far more than heat loads. You have Real world testing of a known sized system.

Thank you Jax, for pointing out something very logical. I still have the highest respect for all the educated experts who advocate the ACCA calculations (Manual J, D, etc.), I think they have a lot to teach us. I do think another valid area of inquiry is how to get the most out of a system being *already* installed. For example all the measurements you can make which are not available prior to building, starting with the obvious "does it make you comfortable?". Of course measurements are less subjective and help any two people communicate better.

In the end, if we have a brain like Lstiburek and enough time to figure things out, I expect the ACCA methods to generally agree with after-the-fact real world testing. But at the present, I would need somebody to explain a lot of details.

Best wishes -- P.Student