You are trying to sell heaters in August. No wonder you are spamming.

Thanks for that RJ. You are right about most of the things you mentioned. Gas tankless will use less energy, they take up less space and they do last longer - especially if you don't have hard water. There are downsides: They take longer for hot water to get to the faucet (5-8 seconds longer), they are often stupid expensive to retrofit, and gas supply, in particular, can be a problem. I don't consider the "tank" issue to be that much of an issue - because if a water heater opens up (catastrophic failure) it's not the 40 gal in the tank, it's the 12 gpm from the supply line that's a problem. What I didn't hear you mention was that you needed continuous hot water - which is one of the big selling points for a tankless heater. You can't re-use your existing vent other than the actual hole in the roof. You can't use the metal flue with either a condensing or non-condensing unit. You live in S. California. Water is an issue - so I'm not sure that running water while you wait for a tankless to get hot is a good plan. I think you should at least consider a hybrid electric heater. They pull heat from the space around the heater and usually cost less to operate even than a tankless gas. They are typically cheaper to install and will not increase the wait time for water. They pair very nicely with Solar (PV). They do use a tank though - so there would be no space savings. They do output cool/dry air which would be a bonus for you. BTW: There are probably significant rebates ($500-800) for installing a hybrid electric heater in your area.

mike_home, Of course if a Hybrid Hot Water Heater is not operated in Heat Pump mode it will not be any different than a plain electric heater. However, that is something that the OP must research before hand while making the comparison of various options. There are two of us in my home and we have a GE 50 Gallon Hybrid - we only operate it in Heat Pump mode and it provides our needs just fine. That said, over the Christmas Holidays we have my sons and their families with us for a week - including four teenager granddaughters. For that week we switch the operation from Heat Pump to: High Demand/Boost Mode "The perfect mode for when homeowners have house guests or anticipate having higher-than-average hot water usage. In this mode, the unit will utilize the back-up electric elements sooner to recover the tank faster and for a longer duration of time to ensure they have plenty of hot water." When in this mode, back up hot water comes from two 4500 Watt electric elements - just like any conventional electric unit. Bottom line, if you buy a Heat Pump hot water heater that is undersized for your usage, it will obviously not give you the savings you want. Doh! PS I hope that I have not given the OP the impression that NG is not a likely good choice ALSO. Usually a comparison of NG vs Heat Pump is close - depending on local utility rates and how well you can predict the future. In my particular case, NG is not available and I will not have a propane tank. YMMV

Just wanted to chime in two years later and say the heaters are one of the best add ins we’ve done on the house. We are regularly out there enjoying and using our covered deck because of the heaters. We do propane campfires and s’mores with the kids, have our coffee snuggled up on the outdoor sectional and today I’ll sit and stare at the snow. 100% happy with this investment, notice no change in electrical costs.