I would say that "not perfected" is a bit strong since folks in Europe have been using tankless water heaters for a couple of decades now.
Taking a quick look on www.rinnai.com and www.bosch.com looking at their residential models shows a minimum flow rate for activation of 0.5 or 0.6 GPM on most models. Some models went as high as 0.9 GPM, but those looked like much larger models. -- Blue skies. Dan Rossi Carnegie Mellon University. E-Mail: [EMAIL PROTECTED] Tel: (412) 268-9081
