I wouldn't install one of these, new things scare me. :-) But my boyfriend explained it in a way that made it make more sense efficiency-wise to me. With these units You're not paying to constantly heat 40 or 50 gallons of water to a certain temperature, you're only paying to heat the water you USE. This put it into perspective for me, thought I'd share.

$10 a month saving is just about exactly right. There are also increased maintainence costs as well associated with these units. If space is an issue, than that's another story.

One other real advantage is, if you are on a well, the tankless heater does not provide a 'breeding ground' for organisms in the untreated well water as does a typical tank water heater.

Anyone setting their home water heater at 160 degrees F is asking for very high energy bills and subject to scalding the users. Of course, that mixing valve you mentioned would help that potential problem.

[This message has been edited by LDoyle (edited May 07, 2003).]

I figured out what my gas consumption is with my tankless unit.

40 gallon 40,000 btu heater runs about 4 hours a day to keep the water hot, about 160,000 BTU's a day.

Tankless 100,000 BTU heater runs about 20 minutes a day, 33,000 BTU's used.

Thats around 127,000 BTU's a day not being used.

I have a propane powervent heater that I metered the vent motor to get the amount of time the heater runs per day.

I base the other one on taking 2 10 minute showers a day. There is a little more for when washing hands, but can't amount to more than a few minutes of use. The trick is to have the heater as close as possible to the faucets with these units. For my kitchen I am going with a small electric tankless unit since it is in the middle of the house and at least 30 feet or more from each heater. WE will be replacing the tank heater soon with another tankless unit for that section of the house.

If we were using natural gas, it wouldnt matter what we used, but since we are using propane, and its a limited supply, we want to conserve as much as possible, over $1000 to fill is pretty damn expensive.

Your hot water heater runs 4 hours a day!!!! That really seems excessive to me. Especially with 2 10 minute showers. Have you put a timer on this to verify it? I do like tankless, but that seems a little long for a hot water heater to run.

Yep as I stated, it has a powervent, so I metered the time it ran each day. Our basement is a constant 55 degrees, about the same as the water coming from the well. It runs about 10 minutes an hour. 24 hours in a day = 240 minutes / 60 = 4 hours.

I recently installed a tankless in my house and so far so good. They are certainly not recent technology as some people seem to think. They have been used in other more progressive countries for decades. Typically it is the tank that rusts and fails on WH with tanks. Tankless models, with copper heat exchangers will have a longer "tank" life, but since they are more complex could break in other ways, i.e. circuit board problems, motor failure, etc. None the less, my VCR has been working well for 7 years now and is more complex than my tankless water heater. Good luck.