Tank less water heaters

IDK, I’m watching the plumbing video, and rinnai is pushing the tank-less water heaters. The issues I’ve always had with these water heaters is (1) NO outdoor application where it freezes period.(especially a hard freeze) (B) If the ground water is above about 60* you may be o k with a tank-less, much colder and they struggle to reach temps or you have to restrict the flow rates down so low, so the water heater has time to heat! (3) Failing to de-scale or flush the water heaters annually causes the calcium (and other minerals in water) to build up on the heat ex-changer (D) not only does it trick the computer board about the flow rate, It becomes extremely inefficient at heating the water. (5) they Use tons of energy to heat water that quickly (hence the large gas line required). I would be doing a huge disservice to my customer to not warn them against it. Especially in cold climates. In warm climates where the ground water is warmer they work great. The higher the delta-T is the harder the unit has to work, the slower the water flow rate is. Unless technology has advanced by leaps and bounds since my experiences. It would be great to know!

They make interior mounted models and models with recirc pumps too. Yes, annual maintenance is recommended by all manufacturers I have encountered.

Hey Dave Fetty,
Do you guy’s like them in Florida?
They seem to work well for homes in California.
I lived in Colorado for 20 years and I just didn’t hear a lot of positive feedback because the ground water temps are so cold. I mean the minimum water service bury depth in Colorado is 48" Ha, that’s the frost/freeze line.

I’m seeing them used a lot in new construction in the Dallas-Fort Worth area. People love them, and say that they provide plenty of hot water even with multiple simultaneous users.

Per the manufacturer, they are supposed to be flushed annually, and it requires a pump, so it’s not for the casual DIY-er.

I can see that it would have trouble with cold supply water and freezing environments.

Retro-fitting can be tricky because of expensive venting duct material, which is why I see so many in-the-exterior-wall applications I suppose, and they need a larger supply pipe than most other gas appliances.

See a lot of them here… a couple years ago they were installing them all wrong. They finally started to read the installation instructions.

I heat my house, and hot water (indirect system supported by solar) with an electric slant fin tankless boiler. I’m in upstate NY, yeah cold up here, we went electric because we are 100% solar. Not had it long, but it’s faster and more responsive than my older Weils oil boiler. 2450 sq/ft farm house, 200+ years old.

I personally installed my tankless in 2009. I run hard well water through it. Though I put a service kit on it, I have yet to descale it. There is no noticeable difference in performance and I have no problem achieving a 70°F rise in temp at full flow. They last longer than tank-type units and are much less likely to flood your house.

Like all things, you need to match the tool to the application. If you don’t have adequate fuel to feed a 200,00 BTUH burner, you’re never going to get the designed performance.

Your post is kind of like someone in NYC that commutes five miles making a blanket statement that pick-up trucks are useless because they don’t fit available parking spaces and use too much fuel. That person would be better off using a bicycle. For someone hauling a trailer long distance or off-road, the equation is entirely different.

I would stay away from blanket recommendations on such things, as there are a whole lot of variables that go into providing informed advice.

Well said Chuck, as usual.