Gas Hot Water Systems

If you plan to use hot water to fill the spa, then you need the largest tank you have space for. Preferrably 120 gallons if electric, 75 gallons gas. Thsi is one instance where an instanteous would be preferable because you need a lot of hot water in a short time to fill it. Efficiency and running costs are a function of the amount of water used in this case and would be similar.: We are a family of two adults and two toddllers and are building a house with spa and dishwasher & of course washing machine. I would like advice on an appropriate hot water system, we are flexible ie either instant (Rinnai Infinity, Vulcan Express) or tank style (Vulcan, Dux, Rheem – what size tank ?) : Any advice re efficience and running costs will be appreciated. : many thanks: Paul

Looking for a tankless demand hot water system with enough flow (gpm) to serve home with three baths, one of which has a jaccuzi (small). When we lived in Japan we had Paloma or Rinnai brand units. They worked great and would be just right for house we are thining of buying. Present unit is only a 30 Gallon tank type in a very restricted area room (manufactured home) 24 x 24 by 72 (h) room with a chimney vent ID of 4 fitted to system of plastic plumbing, Hot side has 180 F degrees rating on pipe material.