Finally swapped the 9 gallon water tank out for a 15 gallon last weekend. A bit more of a job than I anticipated. I purchased tank model# B264 from Plastic-Mart (
www.plastic-mart.com) and had the fittings located per my drawing to them. I also put 3/4" foam insulation under the tank to allow it to sit on top of some of the existing PEX tubing and to provide some thermal insulation.
The tank just fits front to rear without major modifications to anything. It just fits up against the cabinetry that houses the furnace and hot water heater to the rear and I had to move the pump assembly forward maybe a half inch or so.
I still need to clean up some of the PEX tubing even though it is all functional the way it is now (which probably means that how it will be in another year or two or three ....).
15 gallons will be much better sized for my needs than the 9 gallon.
Check another project off my list!
Phil