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Natural gas On demand brands

I'm replacing a side arm domestic hot water storage tank with a natural gas fired on demand heater. I'm just starting my research on what to buy. My plumber recommended a Navien brand heater. What brands are best? And how to do determine the BTUs that we need? We have a small home in Colorado with just the 2 of us. No dishwasher, and hot tub that we use a lot, so we take fewer showers.
With appreciation


  • Larry Weingarten
    Larry Weingarten Member Posts: 3,288
    Hello, Navien is a good brand, but I’d look to see if it is well supported in your area with trained technicians and parts readily available. Other things to consider are water quality, gas supply and venting. If your water is hard, the heater will need to be descaled more frequently. If you hire it done, any money saved on energy will be spent on service. About gas supply, do you have a 3/4” gas line to or close to where the heater will be going? If not, consider the cost of doing that. Lastly, venting will need to be changed. That’s another cost to consider. A question: what is making you consider tankless?

    Yours, Larry
  • Zman
    Zman Member Posts: 7,569
    What altitude are you at?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    Navies has pretty good call-in support. Plumbers often don’t do a lot of “appliances” so that’s helpful. Could also see if a HVAC company installs them. It’s more like a modern boiler or condensing furnace. The combustion system on a tank type water heaters has 3 parts. A tankless has like 20 and has electrical going to it, dip switches, etc.
  • Jolly Bodger
    Jolly Bodger Member Posts: 209
    Tankless success is all about installation and sizing.

    I like the Rinnai tankless units. A bit of a premium but I have not had to fix one yet.
  • crosicky
    crosicky Member Posts: 2
    Thanks so much for everyone who has responded and sorry for my delay in thanking you. Yes, I have 3/4" gas line. Will install the tankless mostly myself. Elevation is "Mile High Baby!" Go Broncos! Around 5 and half thousand feet. We have plenty of good HVAC service people around. I appreciate the recommendation of the Rinnai. My friends has been going for 16 years. I just helped her flush vinegar through it to learn a little about these systems and it was pretty easy. I will be doing that myself, so no worries for that expense. The reason I want to switch us from Tank to tankless is because there's just my wife and I in a small house and we use our hot tub a lot so take fewer showers. I think the savings will be significant to just not keep that tank hot 24/7. The old 40 gallon tank has started to leak but I have time to research and learn to install myself before the switch. Hopefully I answered all the questions. My question remains what brand and size to shop for - leaning Rinnai at this point. Also, my friends is outside her home so I'm also considering inside or outside installation at this point. Leaning inside due to that will make it closer to our bathroom and kitchen both. Also, should I just get one off of Amazon or better to go through a local plumbing supply company?
  • crosicky
    crosicky Member Posts: 2
    Also, how is altitude a factor?
    Many thanks
  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    The thing about working with your local supply house is that you might be able to find a real life dealer of whatever equipment you buy. Then, if you need parts or assistance, you have a fighting chance of getting some willing help.

    Amazon? Ah... maybe not. I like Amazon, but not for something like that.

    Altitude derates the equipment -- that is, a unit rated at x at sea level, will produce less than x at your altitude. The manufacturer will have that information.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • rick in Alaska
    rick in Alaska Member Posts: 1,457
    I have also found, after my customer tried to save money by buying it himself, is that not everyone supplies the valve kit for it. That is a big expense if it is not included. So, make sure you know what you are buying if you do. Also, by not buying through a dealer, you might not have a warranty.
  • Charley
    Charley Member Posts: 9
    Thank you Jamie and Rick!
  • pecmsg
    pecmsg Member Posts: 4,842
    Be very careful purchasing equipment off the Web. Unless installed by a certified contractor the warranty's are questionable and often void or limited. Most certified contractors wont touch customer supplied equipment.
  • mattmia2
    mattmia2 Member Posts: 9,625
    I have noticed most warranties are written "or qualified personnel" , which I think is to give them the choice of walking away from it if the problem is an installation issue or to honor the warranty if the owner installed it properly and there was a legitimate failure of the product (of course lots of licensed professionals screw up the installation and damage the product as well).

    There is a lot more to sizing the gas supply than looking at the size of the pipe. You either need to read up and understand the process or get someone who knows how to do it. I can't emphasize this enough. Tankless water heaters use several times the volume of gas as a conventional water heater and frequently use a larger volume than central heating appliances.
  • Charley
    Charley Member Posts: 9
    Thanks everyone. Really helpful!
  • Charley
    Charley Member Posts: 9
    Help me understand how getting a permit and doing an installation to the specs of the manufacturer’s installation manual and having it inspected when finished is a risky endeavor for a home owner
  • hot_rod
    hot_rod Member Posts: 22,118
    Charley said:

    Help me understand how getting a permit and doing an installation to the specs of the manufacturer’s installation manual and having it inspected when finished is a risky endeavor for a home owner

    As long as you know the codes regulating electricity, heating (venting etc) and plumbing gas line, fill water, & back flow requirements.

    And also the combustion analyzer and training on how to use it and read results.

    You could hire a local pro to do a start up at least to assure it is set up correctly and combustion dialed in.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream