Eccotemp fvi12-NG FVI-12 Natural Gas, 3.5 GPM, High Capacity Tankless Water Heater, White

This water heater has great high end features of far more expensive versions. It is very well made and once the knobs are set for your particular needs, it works consistently.The 'water temperature' adjustment knob could use a better description. From tinkering with it, I concluded the 'water temperature' knob is really a flow rate adjuster. A higher 'water temperature' setting, makes the water heater turn on at lower flow rates (lower demand) but also limits the flow capacity. It seems to behave like a restricter, that increases the flow velocity which then triggers the heater to turn on, but like a restrictor, it also limits the maximum water flow rate.Turn the 'water temp' to a much lower setting and the heater flows a lot more hot water but also needs more water 'demand' (two small faucets together will do it) to trigger the heater to turn on.The gas knob simply adjusts the size of the flame. So with lower water flows (higher 'water temperature' knob setting) you will want a smaller flame to keep the heater from shutting off due to overheating from the lower water flow.So to clarify:A Higher 'water temperature' knob setting = more 'turn on' sensitivity but a lower maximum water flow rate.A Lower 'water temperature' knob setting = less 'turn on' sensitivity but a higher maximum water flow rate.Once you set the right 'sensitivity to flow' for your needs, then simply set the gas knob to a good water temp. I would err on the cooler side (lower gas knob setting) to keep the heater from over heating and shutting off. But if you have higher water flow setting (lower 'water temperature' knob position) the gas can be set a little higher. In order to warm the increased water flow.I hope this helps someone who was not considering this heater. It really works great, it simply needs a little patience to be set to your speciific water heat and flow needs.

Worked great! For a year, suddenly it started throwing an E3 error, I contacted tech support, they set up a time to call me to provide tech support at noon that day, I came home from work and waited... no call.... by 1:30 I gave up and went back to work. Later that day they send me an email stating they tried to call me and no one answered. My phone was next to me with a full signal the whole time, no calls came in. Based on my past experiences with tankless water heaters and the E3 error code I took it upon myself to order two sensors, hopefully, that will fix the problem.Build quality seems good, solid materials, easy to install. Just pray you don't have any issues. There are NO technicians to call to come to fix it. You're stuck with crappy tech support and ordering parts to replace and see if it fixes it.2019 Update to the previous review:Tech support finally called me back, we looked at the unit, I sent them pics and we discovered the E3 error was not the worst of my problem, something had short-circuited in the unit and fried the wiring throughout. At first, they thought it was a lightning strike to our house, but there's a washer plugged into the same outlet (GFCI) and it was unharmed. They had me send the unit in (That cost $50 for shipping) and after a day of review at their plant, they decided to send a brand new unit. Which I thought was the least they could do, since now my household has been without hot water for a month. (Thank god for the shower in our RV).I installed the new unit on 7/24/2018, the new unit worked flawlessly until the first week of January 2019. One of my daughters took a very hot shower (about 112F at the unit) for about 30 minutes. ever since then, it's developed E3 code ignition issues.So now I'm back to contacting tech support. Once we get this fixed, this Summer I'll be shopping for a different brand. I'm done...

Update after 1yr 6mo. Still working great. my gas and electric bill is averageing $104mo. Used every day with two people (one thing we had to do is run the hot water just before starting the cloths washer because these new effeciant washers pulse little amouts of water to fill and it does not give time for the heater to turn on).This water heater lived up to exactly the expectations I was hoping for. It was an extremely low cost replacement for my 1100 sqft 1 bath home. After reading all the reviews I knew it was going to be finicky but I thought with a few adjustments it would be worth it. And it was. It never made sense to me to add cold water to hot water in the shower cooling off the hot water you just paid money to heat up so when I read someone else's review about putting the shower all the way to hot and having someone adjust the temp on the unit while you're in the shower that sets the Baseline for the whole house perfectly. Now when I get in the shower I put it all the way to hot pull it on and it heats up to the right temp perfectly every time (the left knob). The other adjustment is the right knob for water flow and once I got it where I liked it for the shower I drilled bigger holes in the aerators on the sinks until each one would activate the heater properly. The other benefit is going from the old unit which was oversized for the house to this very small unit is saving me money on my gas bill.One thing that you have to understand with this unit is if you add more cold water to cool it then the water on the hot side run slower and sits under the flame longer and then heats up and get the temp right back where you were if that makes sense. So if you want a cooler shower you have to slowly turn the water valve till the showers a little colder than you want and then wait till that hot water gets hotter mixing with the cold water.