HVAC Load Calcs

[MandJ]

We're building a new house just outside of Knoxville, TN. It's taken over two weeks for us to get the load calcs faxed to us from the HVAC subcontractor on this project. He apparently doesn't do them himself but gets them from someone else.

Anyway, now that we have them, how do we go about evaluating them to see if he is proposing a properly sized system? He's proposing a 5-ton system which he has told our builder is "a bit oversized" in case we want to finish some of the unfinished areas in the future.

We'd prefer not to figure the load calcs ourselves, but either provide the necessary information for someone to do another calculation to compare to these or forward the calcs we received to someone for review. If any of you pros are willing to provide such a service or know of someone who will, we'd really appreciate it.

[jchunter]

Here is a link to a simpler load calculator that you can use to get a feel for your house's heating and cooling requirements:
http://www.mrhvac.com/ and click on "Load Calculator" on the bottom of the page.

[MandJ]

Here is a link to a simpler load calculator that you can use to get a feel for your house's heating and cooling requirements:
http://www.mrhvac.com/ and click on "Load Calculator" on the bottom of the page.


Thanks. I gotta tell ya, though, that if that is a simpler load calculator then I would hate to see a difficult one. ;)

We'd really like to find someone who can take our plans and window schedule and do the calculations for us or at least check them for accuracy against the information already provided to us (and of course, we're willing to pay a reasonable fee for their time).

[dcmcm5]

I provide the full design process from the Manual J8 Load Calculations, Manual S equipment selection, Manual D duct design, flow balancing, testing, etc. Obviously the testing and balancing is out given that you are about 12 hours East of me, but the other items can be done remotely. Most of my work is done in the same climate zone as Knoxville. I am a licensed Professional Engineer and have a Class B HVAC license and would be happy to help you. I use the Wrightsoft RightSuite software and have done many residential and commercial designs.

[skippedover]

Before you put too much doubt on the installing contractor, you might ask for a copy of the calculations. It's unfortunate you had to wait so long but on the other hand, at least the company was willing to have the calcs done. That's a step in the right direction.

When sizing equipment, there is no breakdown between 4-tons and 5-tons. So if your system called for 4.5-tons, everyone would put in a 5-ton system. That would, of course, make it slightly oversized. We do load calcs for every system we propose but we're in the northeast and are not familiar with your local design criteria. In that respect we'd probably not be the best ones to run that load for you. :)

[MandJ]

Before you put too much doubt on the installing contractor, you might ask for a copy of the calculations. It's unfortunate you had to wait so long but on the other hand, at least the company was willing to have the calcs done. That's a step in the right direction.

When sizing equipment, there is no breakdown between 4-tons and 5-tons. So if your system called for 4.5-tons, everyone would put in a 5-ton system. That would, of course, make it slightly oversized. We do load calcs for every system we propose but we're in the northeast and are not familiar with your local design criteria. In that respect we'd probably not be the best ones to run that load for you. :)


Thanks for your input. We do have a copy of the load calculations; we just got them this morning. While the document we received has plenty of information on it, it really doesn't mean anything to us -- it's just a bunch of figures that may as well be Greek. :confused: :(

There's no final conclusion on the papers that we can see that says "install an x ton system" so we don't know if our sub has drawn the correct conclusion from the calculations. Plus, it's not actually our installing subcontractor who ran the calcs, but someone else we know nothing about. Our sub does not do load calculations; it sounds like he usually goes by some kind of rule of thumb when sizing systems, so he had to farm this out. This has us feeling a wee bit uncomfortable and that's why we're looking for someone to either run new calcs or simply review these and tell us if they look complete and accurate and the size of system proposed makes sense. Just a double-check if you will.

Our subcontractor is installing a 5-ton system, however, and based on what you said about there not being anything between 4 and 5 tons, that makes his comment about it being a bit oversized make more sense.

[MandJ]

I provide the full design process from the Manual J8 Load Calculations, Manual S equipment selection, Manual D duct design, flow balancing, testing, etc. Obviously the testing and balancing is out given that you are about 12 hours East of me, but the other items can be done remotely. Most of my work is done in the same climate zone as Knoxville. I am a licensed Professional Engineer and have a Class B HVAC license and would be happy to help you. I use the Wrightsoft RightSuite software and have done many residential and commercial designs.


Can you get in touch with me at the email address listed under additional information in my profile and let me know what you would need and charge?

Thanks

[jchunter]

I am curious how anyone could do load calcs without a careful measurment of a lot areas of the inside of the house and careful assessment of the type and thickness of insulation used, window and frame type measurements, etc. etc. Did the contractor's guy show up at your house?

Rules of thumb are not the way to do it.

[MandJ]

This is new construction with the framing just having been completed (there are no windows or insulation to look at yet). I believe the calculations were based on the floor plans and the window schedule.

[jchunter]

OK. House plans should be fine.

[classicrock4you]

It seems like it would be worth the time and money to buy your own load caculation program and take a 1 or 2 day load calc course. Then you will understand what the load is trying to accomplish. The class will also teach you what problem areas to look out for. Then if you question the HVAC guys equipment sizing you will have somethiung to back you uo.

[jaymay75]

DCM - I would also like to use your services. Could you email me at Jaymay75(at)hotmail.com. I need a load calc and some duct design.

Thanks

[dash]

This is new construction with the framing just having been completed (there are no windows or insulation to look at yet). I believe the calculations were based on the floor plans and the window schedule.

Good idea to double check,if your contractor didn't do it himself and is willing to stand behind it it.

That said Manual S for eqipment selection and Man. D for duct design are equally important to your indoor comfort,and room to romm comfort as well.

Hope you find someone to do all the calcs for you.