When I was looking at tankless water heaters, these were a single heater in the basement to heat the water for the entire house. So, the pipe run to the fixture would be the same distance as with my regular hot water tank, and thus no instant hot water at the fixture and no water savings.
The energy savings comes in two places; first, you don't keep a big tank of water hot when you are not using it. This is somewhat offset by having to use greater energy to heat water faster, but apparently still a savings. Secondly, you don't need to heat water as hot. Since a hot water tank has a limited amount of hot water in it, you tend to mix hot and cold water to get a warm shower and more overall water at that warm temp. The tankless heaters can produce water at a specific temp, so you can just run hot water, which is now just warm, instead of hot and cold water. Again, somewhat balanced by the fact that you will be using more heated water, but heated to a lower temp. apparently, still a savings. I only looked at gas heaters. Some of them were sealed combustion chambers, side vented, running as high as 94% efficient. Others were open combustion chambers running more like 84% efficient. I ran into trouble since the tankless heater and furnace would have been too close together to place the air intake and exhausts for both systems in such close proximity. I ended up going with a hot water tank that is heated by the furnace. So, one burner for both potable hot water, and home heating water. One loop heats a water jacket around the hot water tank. The other loop heats the house. -- Blue skies. Dan Rossi Carnegie Mellon University. E-Mail: [EMAIL PROTECTED] Tel: (412) 268-9081
