I have read numerous discussions here regarding the merits and problems with tankless systems. I am thinking about installing an electric point of use unit in the master bathroom I am building.
I live with my wife and we enjoy plenty of hot water from the 40 gallon tank we currently use. We are not big hot water users and would not need to enhance our current heater were it not for the 85 gallon bathtub I am putting in. (I believe this is total capacity, not how much water will be needed to fill it.)
I predict that this tub will get used at most twice a week during the coldest months of the year and sometimes it will go weeks without being used. Because of this I am hesitant to get rid of our relatively new 40 gallon tank and put in a larger model just for the few dozen times a year the tub will be used.
Understanding that tankless units have their own inherent issues, might this be a reasonable case for installing one? I'm in the Bay area and I believe the water is a relatively consistent 65-70 F temperature. Could a tankless unit be used to enhance or "warm up" warm water from my tank? My thinking is that 40 gallons of hot water could be mixed with cold on the way into an electric heater to stretch the volume further. Or perhaps there are units that can handle 3-4 gallons of cold water per minute to produce hot bath water?
I have over 60 amps of 220 and enough space. I'm hoping to use electric instead of gas for ease of installation and I don't think the energy savings of a gas versus electric in my situation would be a significant factor.
Thanks for any advice on this or other ideas to solve this problem.