Have One
We have a Rinnai. It is a natural gas model I put it in a little over two years ago. I did it when there was a 500.00 tax credit going on. Now the tax credit is 30% of the cost installed up to 1,500.00.
We sell the Rinnai brand where I work and it has proven to be a very reliable brand. Our plumbing department has sold quite a few with pretty much a 0 problem. I have had 0 problems so far. I like the fact that I can turn the faucet on and leave it on as long as I want and have hot water.
It is very important that it be installed properly! Gas line is important on these heaters. It was mentioned about a lot of BTU's...This is true. Top fire rate of the thing is 180,000 BTU's. This is much more than most residential furnaces. It requires a 3/4 inch gas line ran to it where tank water heaters have 1/2 inch. If the gas line is too small, they will cut out when the demand gets high. We have well water. Although the well water is very good, we have a water softner. There is no way that I would have a tankless heater without a softner. The tankless water jacket (heat exchanger) is not very big and they will lime up. This will greatly reduce or disable the heating of the water. You then have to flush them out with vineger. Mine has the service valves that allow me to do that if needed. It cost a little more but it will be well worth it if I have a problem. I have my temperature keypad located on the wall close to the heater. It is digital and I have the exact water temperature set. I currently have it set at 125 degrees. I think it will go to 140 or 145 degrees. The burners is "variable" and so is the draft inducer in the unit. Use a little water and the burner runs very low and increases as the demand for more water increases. I hardly ever demand 180,000 btus out of it! I have tested everything out. I have had the gas firelace on, the furnace in second stage and the water heater going at full capacity. I turned on the kitchen sink, both bathroom faucets, the tub faucet the shower faucet, the washer and the dishwasher. Nothing cut out and my water maintained the 140 degree temp I had for testing. The amount of water flow required to bring on the unit is 1/2 gallon per minute. Our dishwasher has enough flow to bring it on.
I have been to several Rinnai classes and know that they are built very well. Every component in it is built by Rinnai. We had a phillips head screwdriver and needle nose pliers and was able to disassemble the whole thing. I thought that was pretty impressive. Flow rate to bring the heater on is one of the lowest in the industry from what I understand. I was so sick that day of the class, I was lucky to make the drive home! I sure didn't feel like working on a heater!
Do I like it totally??
I did not see a huge savings. This may not be fair because it is only me, my wife and son. The bigger the family the better. I hate the "cold water sandwich" effect you get with a tankless. If you are running the hot water and shut off the faucet, the heater shuts off. If you turn the water on there is a very small delay to get the heater heating again. That small delay allows a small pocket of cold water to flow through the heater before the burner starts to heat again. If you turn the hot water off and then back on. You will get hot water, then a period of cold water before the water gets hot again.
The heater is supposed to last a very long time. With the life of the heater versus a tank heater and with the savings of them being so efficient, they are supposed to pay for themselves over an extended period of time. We will see.
Go to
Tankless Water Heater, Water Heater, Tankless Water Heaters Gas - Rinnai
They should have some info for you on savings and actually be able to tell you how much you can save with a Rinnai. I have had the oppourtunity to work on other brands of tankless especially from the box stores. I haven't worked on all of them, but the few that I have there has been a huge quality difference. Rinnai is not cheap. Even for me to buy from our supplier and install myself I was at about 1,400.00. I do know the great history we have with them, and my own personal service from the heater has been good.
Sorry for the long post, but I hope it helps.