Nice job with thinking before building Renoman, you hit the nail right on the head, let me ask you a question, starting from the idea on a napkin to where you are now, labor included how much do you think you have invested
Well I guess if I would include labour I would probably have as much invested as a new unit. But that being said
I am the type of person who enjoys the challenge and really enjoy building stuff. Most of my days are spent either at work or at work in the shop working on different projects so I didn't track hours persay for expensing them but just as rough project time.
All said and done I have $9600 into all the materials to build the boiler, the slab (9' x 13" x 8"), the underground lines, the trench, the water hx, the furnace hx, sidearm in shop and the circ pumps. Also enclosed the boiler in a small enclosure plus some wood storage.
My payback should be fairly quick as my propane average use before was $4000 a yr. May have been $5000 or better this year with as cold as it has been!