Unplggd's Sonia Zjawinski recently moved to a new house in Northern Cali outfitted with a common feature in Europe and Asia, but still a rarity in the States: the tankless water heater. We've discussed the importance of the installed location of these energy saving appliances, and now Sonia goes into detail about whether the on-demand heaters are the right choice for your household for the NY Times' Gadgetwise blog…totally worth a read if you're considering switching to a tankless setup.
• Read the full post at "Home Tech: Tankless Water Heaters Explained"
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Another thing to think about when considering a tankless is your motivation for investigating other options. If you are trying to use less fuel or electricity to help the environment then tankless may end up being the way to go. But if you are considering tankless to save money then the lifetime cost of the tankless (initial investment + cost to run) is much higher than the traditional version.
There are a few instructables I've looked at about using a solar heater (outside radiator) or radiant heat (radiator in the attic) to help heat up the water before it goes into the tank so that the "non-free" energy source is used less.
Another reason for considering tankless is space.
We renovated our laundry room a couple years ago. Our 25 year old water heater was going to be replaced one way or the other. By installing a tankless we were able to be more environmentally friendly and gain a good chunk of floor space at the same time.
Our power bills are a bit lower but the biggest gain for us was in available footage in the laundry area.
I like the idea of tankless heaters, and have wanted to install one in each of the 3 properties I've owned. Never been able to do it.
1st place: A condo without gas service. The time came to replace my electric hot water heater and I was ready to go tankless, except: the power requirement was much higher than the existing electrical circuit could supply, and the electrical panel was clear on the other side of the unit. Not worth it. Killed me, too, because I'd have gotten a whole new kitchen pantry out of it.
2nd place: Never needed to replace the tank while I lived there, but it would have been the same issues as at #1.
3rd place: Finally a house with gas service, but the chimney flue isn't big enough to handle the higher rate of exhaust flow. I'm not rebuilding that brick chimey!
Boo! So, I'm thinking this is best done in new construction, where all the issues can be planned for in advance. I've personally seen a retrofit that actually happened. (Though I've heard of successes like Ms. Vickie's above.)