Ionized: FYI: I put those formulas into an Excel spreadsheet so that they were more plug-n-chug. The original estimate for payback on my gas tankless was 5 years vs a standard 40 gal tank heater.(~a $500 difference in installed price - DIY) The revised payback with lower gas prices is 8 years. That's okay, but not great - but that's compared to a standard gas tank. I couldn't use a standard gas tank without re-lining my chimney or using a powervent. The powervent was the same cost as the tankless - so it's all savings for me. All that said, I live in central Indiana where it can get downright cold. Everything in my 100 year old house is gas incl. furnace, water heater, range and dryer. My average gas bill (budget) is $46 - and that's before the mild winter this year and the foam insulation I added on the basement walls and joist pockets. My winter electric bill is $35. I keep things at 68-70 degrees inside. The continuous hot water is very nice, not having a big tank is great, but not having anxiety attacks over utility bills is wonderful. Of course it's not just the water heater, it's the 92% furnace and insulation and such... I still have the original windows though. Even with the reduced cost of natural gas, if someone can install a tankless at a reasonable cost (no re-doing the gas service) I would advise that people consider it. In hot climates, the heat pump water heater sounds like a great option - esp in electric only situations.

RayPak, et al is a great heater. Whatever name you call it it is the same heater. The names are just separated for distribution purposes. One company gets the Ruud name, one gets the Rheem name and all others get the Raypak name. This will clear the obvious confusion that will come in later posts. The weakest part of the Raypak product is the thermostat board. It's insanely expensive as it integrates the ignition control now. But, every heater that loses a digital board is looking at a repair of at least $400+ these days so it's universally unavoidable. Aside from the board, this heater is the best but it gets little attention these days due to the cheaper products.

We have been using Jandy heaters for 30 + years now even when they were known as Teledyne-Laars heaters years ago. They all have there share of problems as do the other brands, but the new models, such as the Jxi have been great for us. No matter what brand you choose, first you must make certain your gas line on natural units, will provide the adequate supply to operate it correctly. Gas line size is paramount when choosing a heater. A 400K BTU is best for say a 20x40 pool, but if the gas pipe is too small, it won't function properly and it will fail early. Propane models too must meet gas/fuel parameters. I have many times replaced large natural gas heaters with smaller models based on the gas pipe size. Yes, it will take longer to heat, but it will work properly. Also equally important is managing water flow through a heater. Too much or too little water does not allow the heater to work properly and can cause premature failure. Flow must be balanced. All the manufacturers have a max and minimum flow rate. Of course properly balanced water chemistry is important in preserving heater parts. Most heaters will last about 10 years.

Hi Charles Ross Homes, Thank you for your thoughtful response. My home is a 1960 single story ranch situated in a Southeast Texas. All of the homes I have owned here have had the water heater (tank or tankless) in the attic. City code permits for this install location. Not all, but many, homes in the area have water heaters in the attic. I understand about the potential leak issues - we have water leak monitoring and emergency shutoff and water collection pan/drainage in place. My garage is detached and on the Northeast side of my property. It would take quite a bit of work and cost to move the water heater (and associated gas/power) to the garage. I could consider putting the Navien on an outside wall, but that would require it to be installed on my master bedroom wall or in an unprotected area. I don't feel it would help with the sound issue anyway and there is the cost issue as well. I think the Navien NPE-240A is just not a good fit for my needs and constraints -- given its operations and operating requirements. My last instant water heater was a Noritz - put in by the previous homeowners. I never heard it operating. I'm sure it made some sound but that sound wasn't loud enough to permeate to any of the living areas. They don't make that Noritz any longer. Do you have recommendations or suggestions for a "quiet(er)" tankless system? Thanks.