I have 2 -50 gallon water heaters installed in my attic (2 story home, 3 full baths) that use natural gas that i want get replaced with a tankless water heater that also uses natural gas.

Thinking about a Rinnai 11GPM 199,000 BTU/h as the unit to install.

scope would be to remove the existing tanks and dispose of them and to install the new tankless unit. Plumber will provide all parts/ labor.

Anybody have a ballpark estimate for hours and overall price?


Home is in DFW.

DOD said:

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I have 2 -50 gallon water heaters installed in my attic (2 story home, 3 full baths) that use natural gas that i want get replaced with a tankless water heater that also uses natural gas.

Thinking about a Rinnai 11GPM 199,000 BTU/h as the unit to install.

scope would be to remove the existing tanks and dispose of them and to install the new tankless unit. Plumber will provide all parts/ labor.

Anybody have a ballpark estimate for hours and overall price?


Home is in DFW.

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I'm in B/CS and had one tankless replaced with another (bought what is likely the same Rinnai unit you're looking at) so all lines, power, etc already in place. Cost me $3295 installed for that one unit and it was done in about 4 hours.

I have three Rinnai units in my home and they working just fine. Two are in series and supply a hot water loop. Just make sure you have an installer/plumber that has experience with the units. The knuckleheads that did the initial new home installation didn't have a clue on how to set them up. I finally found a person who knew what he was doing and they have worked perfectly since.

I believe the Rinnai website has a list of authorized installers, but if I were to do it again I would really check them out before selecting one for the job.

Replaced 2 water heaters with one tankless in Houston, for the haul off, plumbing and installation total cost was $5k. Make sure you have the proper size gas line otherwise your cost could be higher. Believe you need a minimum of 3/4" gas supply line but double check with installer. Probably could have found someone to do it for less but knew this company from previous work and knew it would be done right.

thanks for the information, all very helpful

I had a Navian installed about a year and a half ago. That's the brand I would recommend. Only plumbers can get it, and most recommend it over the others. My out of pocket was similar to above, but the price is probably higher now.

Go to the Navian site and they can get you a plumber for your area.

Have a Navien as well. Both heat exchangers being stainless steel plus options for recirculating were big selling features for me.

Plumber and 2 helpers took about 6 hours to drain and remove the existing tanks, install the new tankless, added some back plates between existing 2x4 structure, reroute a bit of plumbing, replaced the existing roof vents....$4400. Submitted for $250 rebate from Atmos and will take $600 tax credit on 2024 tax return next April.