Within the past 6 months or so I purchased a new 50 gal LP tank water heater to replace one that was leaking. I am in the process of designing a remodel of my master bath and my current heater is insufficiently sized to handle the load (bad planning on my part). I intend on having a shower with a 2.5 gal/min shower head and 4 body sprays (1.6gal/min each) for 8.9gal/min. Additionally, I will have a 87 gallon air tub. There are 2 1/2 other baths in the house and frequently two showers running at once. The house is a little over 4000 sqft.
What I am wondering is can I use a tankless water heater as a preheater for the tank heater? If so, that should ensure that I always have hot water and should take care of all my problems regarding insufficient quantity, unless I am missing something.
Thanks for your help.