On 11/11/2010 5:47 AM snipped-for-privacy@optonline.net spake thus:
Hmm; interesting that in your replies to me above you were fairly pro-tankless in terms of energy savings, while you're much more cautious here.
I think what this really shows is that any energy savings due to tankless water heaters is pretty much on the margins. This isn't a bad thing from an energy-saving standpoint, of course: a therm saved is a therm saved (or a kilowatt). But it does indicate that calculating any kind of payback period for installing tankless heaters is problematic at best. This is where I think that some kind of curve showing usage patterns vs. fuel savings might be useful. I can accept the assertion that tankless heaters save energy overall; it's just not that apparent how much, exactly, they save or whether installing one is a good decision financially speaking.