Heat loss program comparison

ChasMan

Ok, well 17893 it is.

Dave Stroman

Would anyone like to participate in a heat loss program comparison? I have come up with a test room with the following parameters and have run it on the Slant/Fin heat loss program.

The room is 25' x 25". 2 exposed walls. 4 windows 3' x 5' each and a door 3' x 7' with a total sq. ft. of 81 sq. Ft. Attic space with R30. Unheated crawl space with no insulation. Design temp. of 0. Indoor temp. at 70.

I have attached a copy of the print out of the Slant/Fin program. The reason I am doing this is I have a feeling that the Slant/Fin program is a bit too conservative and would like to see how it compares with other programs.

Dave in Denver

ChasMan

Need to know the ceiling Height

ChasMan

Wall insulation would be good too.

Boilerpro_3

Check out the attachment...NM

ChasMan

I get 20893 but thats with all outside walls 8' high R13.5.

I dunno how to do 2 inside and 2 outside walls in this software. Theres no option for it it seems.

ChasMan

Duhh me :-)

ChasMan

Duhh I see now! You dont include those walls at all! Neat.. Anyhow, I get 17893. :-) With a big chunk from that crawl space. And as I learnt earlier.. If your on Ledge with a high water table look the heck out!

Dave Stroman

Yes, I had 8' walls with 3 1/2' insulated walls.

Dave in Denver

Kniggit

I have used the Kitech/Ipex freebie and the slant-fin for two complete jobs on both. The Ipex version shoots the usage a little lower however it allows me to select more info, the slant fin is based on all 2x4 walls have the same r-value, but we all know they don't. I prefer the way the ipex program allows me to select actual r-value. It is verry good as compared to the slan-fin, especially for a freebie. But both programs are good, and I could use one or the other, the most important thing is that we remember that a program will only figure the load for what we tell it. If you forget to measure something or miss a variable it monkeys everything up.

Brad White_9

When you get down to it

all heat loss progams have the same elements of area, u-factors and delta-T across the surfaces. Infiltration is the wild-card and that is designer judgement. CFM per SF of wall area, same of floor area, air changes per hour, the crack method (with associated cfm) all have their place and all are really SWAG's when you get down to it.

In other words, if you gave identical floor, wall, roof, glass and door areas with appropriate factors, those portions (transmission only) should be identical.

Any differences should be with user-input and infiltration method used, all other factors being equal.

But every program has an "ease of use" factor, the ease with which data can be entered, changed, and effect of changes made readily presented.

Brad White_9

Double-Post- sorry!

KBP&H

Slant Fin / Quick Load

I've used both Slant Fin and Quik Load comp versions, QL seems to be more detailed,Slant Fin seems almost too generalizing and always ends up 10-15% higher, even when compared to supply house or engineers( big deal) doing it, For estimates I do slant Fin and go 10% less.