Does anyone know of a program for sizing brazed plate heat exchangers, for use in radiant heat and snow melt systems? Actually... any info, program or not, would be helpful.

Flat Plate publishes a chart, and so does Bell & Gossett. The software is usually reserved for the Mfg's Rep. You don't really need it anyway, as the charts are usually adequate.

First off a question. Why use a flat plate exchanger? The spiral ones are quite inexpensive now and have less issues with clogging.

I bought mine out of a place in Canada and one of the nice things is they helped size it for me. Not a complicated task but since I'm running low inlet temperatures due to the heat pump as a source I wanted to make sure I didn't mess up. They guy whipped out the numbers while I was on the phone.

I guess if you do it every day it becomes second nature.