If you do not interview the customer as to actual usage, the default product loads in software can cause you to way over rate the load, and put you out of the running in the price department. It has a 'quick selection chart', from you you selct by room dimesions, room temperature, and heavy or normal usage.A -10degF room, 12'x20'x8' is indicated as (13599btuh X 2) 27,198 average duty, (28524 x 2) 37,048 btuh heavy usage.Most of your load is usually latent infiltration which is dependant on the outside (of the room) ambient, and the construction (insulation) of the walls.Using load calc software in rooms as large as this can also lead you awry. Heatcraft has an 'Engineering Manual', Pub. Of course, now I am thinking that it more like 12,000 Btu's, but when I guess at stuff, I know I should pad it a bit.This is definitely not a proper way to do load calculations.:).
Rules of thumb imply you can imitate feel.I cannot wait to see how close I was on your example problem. If one is to commit bad practice, one must be good at it.I differentiate between 'rules of thumb' and 'feel.' Feel means you have an instinct born of experience. Bad practice is an important component of an imperfect world. Many will say it is bad practice to do so, but more buying decisions are made this way than by thorough methods. But.I have to think your question points to the need to make quick decisions in front of people. And I didn't consult anybody or anything.įor all I know I could be a mile off target. Cold room size 40 foot x 12 foot x 8 foot highI am guessing 16,000 Btu/hr.