Guest Blog


To Believe, or Not

February 17, 2011
/ Print / Reprints /
ShareMore
/ Text Size+

So, the other day a guy called me up and asked for help sizing a heat pump for an addition on a house. I asked him if he had done a load calculation to which he replied “Yes, but I’m not sure about it”. “You’re not sure about it? Why, did it tell you that you looked like a goat?” I asked, looking for clarification. “No, no, I mean that I’m not sure about the size that it came up with. It said that I should put in a 5-ton unit.” Passing right over my prepared defense of the goat resemblance, I asked what was wrong with the 5-ton prescription. “Well you see, the room is 19 feet by 19 feet, and it just seemed like a lot.”

OK, now you’ve got my attention there, Billy. “You have a room that is 361 square feet that is calling for five tons? Are you sure that you didn’t enter ‘19x91’?” “Nope, I checked that.” “Alright then, is it possible that you’re not giving me all of the details here? Are there a lot of windows in this room, is this a Laundromat, an iron smelter, what already? Come on, you know what I’m going to ask!” I was beginning to lose my patience with goat-boy. “Well, oh yeah, I forgot. It’s a three sided addition facing south, windows from floor to ceiling on all sides, with a 12-foot height. Oh, and the roof is all glass.” “Uh, huh; ……details.”

In contrast to the extreme case described above, picture a typical 1,600-square foot, three-bedroom ranch, in Anytown, USA. Load calculations are done on these cookie cutter homes every day resulting in a heating load of 20,000 to 50,000 Btus. Why then, do most of these dwellings have 100,000 Btu furnaces/boilers installed? Do we believe in load calculation technology, or not?

More and more we are required to present load calculations to inspectors, or just to take out a permit. So, doesn’t it make sense to learn how to do it properly and then, possibly, actually, even use the results we come up with to size the system? Believe it or not, it even works better than the “stand at the curb, and count the fingers” method.
You must login or register in order to post a comment.

Multimedia

Videos

Image Galleries

2014 Energy Efficiency Forum

Highlights from the 25th annual Energy Efficiency Forum in Washington, D.C.

Podcasts

NEWSMakers: Jeremy Begley

Jeremy Begley, home-performance specialist and Web and social media manager with National Heating and Air Conditioning Co. in Cincinnati discusses how and why you should add home-performance philosophies to your contracting repertoire. Posted on Sept. 12.

More Podcasts

ACHRNEWS

NEWS 09-15-14 cover

2014 September 15

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe

Venting R-22

The NEWS reported that a man received prison time for venting R-22. Should EPA step up enforcement?
View Results Poll Archive

HVACR INDUSTRY STORE

plumbing-hvac.gif
2014 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

Clear Seas Research

 

Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.

DON'T MISS A THING

Magazine image
 
Register today for complete access to ACHRNews.com. Get full access to the latest features, Extra Edition, and more.

STAY CONNECTED

facebook icontwitter iconyoutube iconLinkedIn i con