About 5 years ago I worked in a lab that had a gas tankless water heater and we had nothing but problems maintaining 70 degrees for B&W processing. When I built my darkroom I put in a 19 gal electric hot water heater in and has worked well. The only thing I would do different is a bigger one (40 gal).
Hi Michael. This is good information.
Can I ask why you feel you need a larger tank? Do you routinely run out of hot/warm water during your normal processing situations?