When it comes to tankless hot water heaters, bigger is worser IMO. My advice is to research your own usage patterns before purchasing a specific model. By research I mean literally turning on the shower at the flow rate that you or others in the home will use and sitting a bucket or trash can underneath to capture all the water for a long enough time period that you can to accurately measure your minimal gallons/minute flow. Same for washing your hands at the sink (probably need a smaller container and more error in the calculation) I think tankless units are improving all the time, to turn on at a lower flow rate, but the minimal flow rate that is more important than maximum flow IMO.Looks like My water heater is starting to fail. Leaking from the top. I would like to go tankless on demand. Bigger is always better. Can you guys recommend any brand names. The one that I want to get I can't due to them only selling to plumbers direct.
Ours is a natural gas unit, but need electricity to run the fans and the electronics.So the tagaki is electric?
Am I missing something?
I think those are the main considerations. Also, it is my impression that a whole-house electric tankless unit (meaning one capable of feeding 2-3-4 taps simultaneously depending on what else is happening inside the home) is not really cost effective or energy efficient. That those will have a very high current draw in order to produce the higher flow rate. But of course, do your own research if leaning towards an electric unit as my knowledge of them is limited.Okay lots of go over with the plumber. Check for minimum flow rate, with a bigger electric I might need larger amperage service, with a propane one I need to look at venting, look at condensing versus non condensing. Am I missing something?
I forgot to mention that I was also using a 110F setting. Months after installing I dialed our tankless unit back to that temperature setting. In the winter time I only open the hot water tap and do not touch the cold. I reduced the setting as otherwise I would need to mix in a little cold when set at 120F and waste water to keep the flow high enough to keep the natural gas burner lit. Everything I read about my unit and crudely tested using a big bucket indicated that it was flow rate and not temperature that determined when the burner turned on and off.We have a Stiebel-Eltron Tempra Plus. If I recall it's a 24 kW unit, which is funny to me because the hydronic heat boiler for the whole house is only 18 kW.
Our water supply is a well. The water is "slightly" hard, a bit of carbonate (makes good homebrew ale!) and some iron. We use a poly filter, 50 to 5 micron density, to remove flocs of iron. That's our only treatment.
The caution I have about tankless water heaters relates to the water hardness. A tank heater will gradually accumulate scale as it forms from heating the water and falls out to the bottom of the tank. With a tankless heater, all that scale gets spit straight into your water lines when you run hot water.
If that's a concern for you, then I recommend opening up every single faucet you have and removing the little stainless steel scale screens from them. Otherwise you'll need to do that at an inconvenient moment when the hot water plugs up and you're standing there in your birthday suit with soap in your eyes. This includes hot water lines into washing machines and dishwashers. You'll clean faucet aerators about once a week.
Tankless heaters need a certain amount of flow before they turn on. If you're someone who frequently runs the hot water at a low rate, it may not be enough to turn on the heater. You'll find ways. Also, when you first turn on the hot water, it will take a moment for the heater to catch up. You'll get alternating zones of hot and less-hot water in your pipes, which will simply flush out and be all hot once you've run the water enough to have it hot all the way from where you installed the heater to your faucet.
Amusingly, that means if you're one of those old Army-trained guys who shuts off the shower to soap up, you're gonna get a nice dose of ice water before it picks up again. Ask me how I know that...
Might not be obvious from the above, but we like ours. They work best set to a temperature that you like for your shower, and then just use the hot water. That's 110F for us. The great thing is you'll never run out of hot water. The other advantage to only using the hot water is that when some well-meaning person flushes a toilet in the house you will never notice. One may choose, of course, to utter a hoarse agonized scream on general principle to remind them, but it's not de rigeur.
O.H.
You can get an uninterruptable power supply to solve that. Like the ones they make for computers.And no power = no hot water.
I did not realize that tankless were more of a leak risk. Makes me wonder if a "smart" water meter monitoring system is worth the time and expense. Since it seems to be only a matter of "when" and not "if" a leak will occur.Water heaters are a big deal in our house. The biggest issue with all conventional water heaters are leaks, and catching them before they become a burst. Once they start dripping, you sometimes can have only weeks before it floods out a room, or worse. We keep ours next to a higher end fully finished walk out basement with a huge custom bar area, so pay very close attention to ours.
I won't buy less than a ten year warranty unit, and we presently have a 12 year TOTL Rheem about to reach warranty end. But depending on your water and operating conditions, they can start going long before the warranty runs out. Still, we intend to keep this one quite a few years past warranty, just like we did the last one. It has been flawless and tight since the day it was installed.
The secret weapon to go safely to warranty, and many years beyond, is to keep up with the anodes on them. On say a 12 year unit, I'll change out the factory anode at 6 years, and then change it out again every 2-3 years. If you change the anode that often on them, before they are entirely consumed, they do not freeze up in the tank, and come out easily each time.
It's the anode that is sacrificial, and keeps the tanks from rusting, and bursting. Once the anode is fully consumed, the tank is exposed to the continuing electrochemical process. If there's some anode left when you change it, the tank has been protected. Depending on the water, you can go with magnesium or aluminum. We use the former with well water. A replacement anode is under $50.
And I'll add that most plumbers rarely consider replacing anodes. They only think about replacing water heaters, and won't tell you about the anodes, mainly because they don't ever think about them. You'll have to educate your typical plumber on anode changes, like we did with ours.
The other tips to get a good unit to reach 20+ years is to keep the pressure not too high, and don't run them too hot. Higher water temps speed up the corrosion process.
But the best way to prevent leak catastrophes is to plan for them. We put our heater in a leak pan that drains to the perimeter drain for the slab, and have a water shutoff sensor/alarm on the floor a couple feet away. Hopefully, any leaks or relief valve events go right into the perimeter drain. And if any water reaches that sensor, it shuts the well pump off instantly, limiting the spill to the 50 gallons in the tank.
I'm told, due to their construction, the tankless models are more of a leak risk than the conventional ones, and are also more prone to fail catastrophically when they do go. They are similar to the old Laars mini-therm boilers from the 1990s that way, according to one old timer. Very efficient, but they need to be thin-walled to do so.