Fred derf fred: I too was set on going tankless - till i saw the upcharge. It is coming to about $5,750 more to go with (4) gas tankless (Rinnai 94LS 9.4gpm top of the line) compared to State gas water heaters - as spec'd in the drawings of our house. I did research and found out that gas tankless do have an EF (efficiency rating) of .82, however GAS (i believe you compared electric tank) tank heaters commonly have .62, and a few have .68 efficiency. This results in savings of tankless is about $250 per year, for all 4 units combined. So it would take me more than 20 years to recoup the cost difference. This was based on a formula as provided by the dept. of energy. Additionally, State, who sells both, has a 'calculator' on their website that corraborated the results. Also, please note that your existing ELECTRIC tank heater was very OLD. New, gas models are much more efficient so I do not think it is a fair comparison. I am no expert, but these are my findings. I would greatly appreciate any other comments ASAP as we are about to make the decision on going tank or tankless

If you go with any sort of solar system, make sure it has a gas backup and not electric. My energy costs went up $100/month when I added our solar system down here in San Diego. I am now getting it corrected with the installation of a small gas tankless unit, using the solar storage system as a pre-heater. If you're building the home then many of the traditional drawbacks of tankless don't apply to you. You can build in the correct gas line and venting from the start. If I were in your shoes I'd probably go tankless (30 percent tax credit this year -- see the stimulus law or visit www.energystar.gov). If a single unit won't handle your demand then get two. And plumb it with the small tank system (10 gallon) for recirculation and to overcome any sandwich problems. This approach has been detailed in this forum somewhere.

We don't have much info to go on. We don't know what your needs are, what your wants are or what your budget is. All we really know is that you want gas in the event that the electricity is out. A tankless requires a small amount of electricity to operate - it would not operate if the power was out. A generator would solve that problem and provide power for other things as well. I don't completely agree with Dan, you can size a tankless to run more than one thing at a time. I sized mine so that in the coldest part of the year I could run the shower and the bathroom faucet - in the summer I can run about twice that amount. It works fine in my house, but if I had a larger family I'd go with a larger unit. There are also 50 gal Hybrid units - They store the water but have high BTU input and very high efficiency. They can produce a certain amount of continuous hot water as well. These meet the 30% tax credit requirements and vent with PVC pipe - making them cheap to install where long vent runs are needed. I have included an example - I'm not endorsing a particular brand. Note that these would not run without a small amount of electrical power. Here is a link that might be useful: State Hybrid

No, it isn't the thermocouple. The pilot light stays lit. It is still doing the same thing. If I turn it on it fires right up and works normally until it reaches temp but the next time it tries to fire up it hangs up. The power vent starts to go but instead of the burner lighting up it shuts down then tries again. Over and over. I disconnected the plastic tube that runs into the power vent and cleaned it out with a pipe cleaner. No change.