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by • November 27, 2012 • Water Heating & Plumbing & ToiletsComments (8)7060

Texas Tankless Water Heaters – 3 Reasons to Choose Them (or Not)

Upgrading to a tankless water heater is a relatively affordable and easy option for most people who are building a new home or doing a major remodel.  I installed a Rinnai exterior mounted tankless at my house when I remodeled my 70’s house 5 years ago and I’ve loved it.   

Photo: Rinnai RL94e exterior mounted at a remodeled 70’s house

If you’re in the Southern US and reading this there are three huge reasons to go tankless and it might surprise you that energy savings doesn’t make the list.
3 Reasons to Choose a Tankless Water Heater

1.  Square Footage Saved.  When I remodeled my house the 50 gallon gas water heater was located next to the pantry (odd, but we see this alot in TX).  By moving my water heater outside and hanging it on the house I gained 5 sq feet of floor space to my house.  In my 2100 sq ft house that’s a 2.3% bump in house size!  My pantry isn’t huge now, but it’s alot bigger without that 50 gallon water heater sucking up space.  In our mild Austin, TX climate mounting the tankless to the outside is a no-brainer.  The unit has an internal heater that keeps the copper boiler above freezing if it dips below 32 F, and the insulated pipes coming out of the wall are wrapped with an inexpensive tape heater for the odd 24-48 hour period every 2 years where the temperature outside dips into the teens.  For full disclosure, I have had my pipes leading up to the unit freeze once and two clients had this happen once too.  I simply took a heat gun on low (a hair dryer would work too), and unfroze the pipes.  My unit was thawed, had no damage, and worked again in 15 minutes.

2.  Luxury (Endless Hot Water).  My former 50 gallon unit was no match to my wife’s long nightly showers (20 minute shower X 2.5 gallons/min shower head = drained 50 gallon tank).  The new tankless unit allows her to take a 20 minute shower AND I can get a shower after she’s done!  This is indeed Luxury and could be construed as wasteful, but it’s sure nice to have “endless” hot water.

3.  Combustion Safety.  My first preference in the South is to mount these unit outdoors so there is ZERO chance of carbon monoxide gas leaking into your house’s air.  Tankless units are all internal sealed combustion and if you can’t mount yours outside an indoor unit is MUCH safer than a standard 50 gallon gas unit.  If you mount yours inside the house I would look at the condensing units that are a bit more efficient and use PVC concentric venting. 

Ok, so that’s the good news.
Here’s the three reasons to NOT go tankless:

1.  Maintenance.  Your old/cheap 50 gallon tank with it’s 25,000-40,000 btu burner would go non-stop for 8-10 years with zero maintenance.  Your new Tankless model with it’s 199,000 BTU engine needs a de-scaling flush every 12-24 months.  The copper boiler in these tankless units have a gas engine that’s about 8X bigger than the standard 50 gallon tank and they MUST be maintained to get their full 20+ year life span.  In Austin, TX our city water is pretty hard and tankless units WILL SCALE UP over time and the unit will see a 50% reduction in it’s life expectancy if not flushed (de-scaled).  If you are handy this is a super easy/cheap job to de-scale.  See my videos on how to flush a tankless.  Part 1 and Part 2.   If hire a plumber to do this work I would guess it would cost $125-200 each time.  Remember that this is something that needs done every 12-24 months depending on your usage and water hardness.  If you have a water softener this probably could stretch to every 2-4 years.  Keep this maintenance cost in mind as you tally up the total costs of ownership.   PS>You can make your own flush kit or buy one on Amazon. 

2.  Cost.  A good tankless unit is easily 3-4X the cost of a basic 50 gallon gas unit, but you also need to factor in a higher labor installation cost.  With the large gas requirements of a gas tankless unit you probably will need to upgrade the size of your gas piping inside the house, and they require a 110v electric supply so the electrician has to run a wire there.

3.  Increased Water Use.  I believe that a tankless water heater could increase the net water usage of a household.  If your teenage daughter is limited to a 20 minute shower because it gets cold after your 50 gallon tank is drained, then with tankless she can take a 40 minute shower without it getting cold (or an hour for that matter).   This isn’t a reason that will deter most households from going tankless but it can be a factor with some.

Lastly, lets talk about energy usage.  In general, gas is a pretty efficient and cost effective way to heat water.  Check out this chart I found from the American Council for an Energy Efficient Economy.

The tankless units are called “Gas Demand” on this chart.  It’s interesting that the don’t show any maintenance costs on this chart which add to the cost over 13 years, and they don’t include install costs, and the Gas Demand Avg Cost is way too low at $650.  I would budget $1200+ for a good unit from a well reputed manufacturer, and I’m biased but I wouldn’t get one that wasn’t made in Japan.  Rinnai, Noritz, Takagi are all good brands.  I hear that Rheem is made in Japan too by a third party and branded for Rheem.  Check out that last column which is the total cost for equipment and fuel over a 13 year period.  It’s very, very close between a conventional tank and a tankless unit over that period of time.  As I stated above, Tankless is a great option but not for the ways you might initially think. 
  In summary, I really like tankless water heaters and recommend them to most (but not every) client.  Just know ahead that they need maintained, and that their annual energy costs will be lower but not substantially.
-Matt Risinger
Principle of Risinger Homes in Austin, TX

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  • Matt,

    I live in the Dallas area and switched from 2 gas hot water heaters to a gas tankless for very similar reasons. In the case of two gas to one tankless, the payback is a bit faster, but, as you state, I had to run an additional 1″ gas line from the meter to support the large burner. At the end of the day, the reason for the change was to reclaim the floor space during a remodel. The extra efficiency and unlimited hot water are great bonuses. Since I did the work myself (with permits), the cost was reasonable.

    I went with one of those Rheem units (high efficiency condensing), and so far it’s been great. We’ve had it installed a little over one year in fairly large house with six people.

    Thanks for your blog. It’s both an inspiration and an excellent resource to myself and many other homeowners. Keep up the great work.

    • Steve, Thanks for commenting and your kind words about my blog! Going from two tanks to one isn’t a scenario I thought about but that definitely brings the differential closer. Glad to hear your Rheem is working well. Did you mount it inside the house and run PVC for venting? That’s a big bonus for the condensing units to run plastic pipe for air supply and exhaust. Best, Matt
      PS> How did you find my blog?

    • Yes, I placed the water heater in the attic which allowed me to re-use the space previously occupied by both tank units (2 separate closets). I’m using a concentric PVC vent (intake and exhaust) through the roof. This is in anticipation of a future move to a conditioned attic space.

      I’ve been an avid reader of your blog for at least 2 years. I think I first found you by doing a search for spray foam and conditioned attic space.

      Best, Steve

    • Thanks Steve. Great call on capturing that closet space. I think in our climate that’s a huge reason to go tankless. How much does 5 sq foot of house space cost? Multiply that by two closets saved and you’ve gained alot of house back by going with a tankless unit in the attic.
      Keep reading and commenting on my blog. Matt

  • I am redoing an apartment built in 1980. It is a one bedroom just under 1000 square feet. I am considering replacing the electric hot water tank for a tankless system. I have a disability and get cold very easily so waiting for the water to warm up or running out of hot water in the shower is not a fun experience. I figure out I need hot water for my half bathroom sink, main bathroom sink, main bathroom shower, kitchen sink, and dishwasher. What do you recommend? Any thoughts on the Titan Heaters?

    • Zachary, The tankless will certainly make a big difference for lasting hot water. Be sure you have a gas line, not all apartments have gas. In regards to waiting for the hot water, you might look into the Metlund DMand system. Here’s a post on that system that gets hot water to your faucet faster without wasting cold. http://risinger.blogspot.com/2012/10/instant-hot-water-without-dumping-cold.html
      I’m not familiar with the Titan brand of water heaters. Best, Matt

  • Matt,

    Love your blog and have been reading it for years!

    How would you compare the AO Smith Vertex to a tankless system? Seems that a 100k BTU Vertex would give you the best of both worlds – endless hot water at about the same cost at tankless units. Have you seen the same scaling issue in the Vertex?

    I’m thinking of a new build with the Vertex and recycling pumps you have reviewed – interested in what you thin is the latest best option – if cost is not a factor.

  • Thank you for sharing this! I have been thinking of which type of water heater to use, and this has been really helpful in seeing the pros and cons of a tankless water heater. I think that a tankless would be would be preferable for our family because of our water consumption.

    Elia Lester