Hmm...4% difference in efficiency eh?
Originally Posted by nhmaster
You claim that tankless water heaters are only 4% more efficient compared with tank type water heaters. Could you provide us your source? From what I understand, even the best insulated tank water heaters have efficiency ratings in the 67% energy factor range. Now add condensing to the tank and you are still below 80%. If you believe this to be wrong information, perhaps you should visit any tank water heater manufacturer's website and look at their efficinecy ratings.
By the way, a condensing direct vent tank water heater costs more than a condensing direct vent tankless water heater. You said you are in the business, so you should know this. You should also know that nearly every tank manufacture today has gone out and secured a tankless OEM line for themselves. If the technology was not proven, they would not waste their time, energy, or efforts with tankless technology.