Convenient, easy to use. Would be nice to be able to change feet to meters because I'm fitting condos in Canada. Also allow changing cfh to mcfh or even btu just for convenience. Elevation plays a role too, you could tie into Google map meta and have the user type in a city to get elevation data.
Sizing rocks The app is great for sizing. Much easier than looking for the book or slide rule. I've always got my phone with me
Offer on iPad
Gas line sizing Easy to use
Improvements and bug fixes