coil heat exchanger calculator link

Try this for sizing coil heat exchangers....

http://www.mbamanufacturing.com/Quotes/CalcHeat.htm

That's really interesting, Chris. I wish they told you the length of the coil, instead of the square footage. The other sizing schemes I've seen size the hx from the boiler output, not the size of the tank.

with the square footage, you can calculate lengths based on different diameters....If they told you a length, they would be assuming a diameter...

True enough.

When I had SSTS size an hx for my system, all they wanted to know was the boiler's output. Not like I could afford it, in any event.