Propane Hot Water Conversion?

[Bullwinkle]

I have been picking up 85,000 btu units ... incl 3day priority for $239.00 fleabay 3 year replacement warranty (good idea for off brand units) $20.00

I bought two of them one runs the (small) house, laundry dishes and shower 10 liters (2.6 gallons) per minute 45 degree rise, I think they claim 80 hrs on a 20 propane lb tank

the other is wall mounted outside shower on the lanai -

I use three 20 lb cylinders in rotation between the 2