I need to figure out which circ would best suits my needs. I have to pump 160 feet from my solo plus 60 and 740 feet of pressurized storage to my propane furnace with a water to air exchanger through 1.25 inch thermopex. My heat calc is 80,000 btu for the house and I want to include my 700 sq/ft attached garage with enough gpm for moderate heat. I currentlty have a 50gal propane water heater which I will convert to a sidearm or use a indirect water heater next year. I hope I can use variable speed,but dont understand how to figure it out for proper sizing.