There’s a lot of interest in demand water heaters these days and it’s about time. Up until a few years ago, they were mostly used around here as back up for solar water heating (hydronic) The rest of the world has been using demand or “flash” water heaters for a long time.
Here in North America, energy used to be cheap and space not an issue, so tank type heaters, keeping 30-50 gallons of water hot all the time, were standard. In the 70’s and 80’s one could find Northern European units, made in Finland and Germany, but then the Japanese engineers did their thing and now we have several Japanese brands that have sophisticated electronics, user friendly controls, and super reliability.
We originally got interested in tankless water heaters because they provided a solution to the whole house fan/ water heater conflict (see link to whole house fans), since many of them are “sealed” units and draw their combustion air from outside. Earlier models had two “flues”, one for exhaust and one for intake air. Newer models incorporate concentric pipes. The inner one for exhaust and the outer for fresh air. Now they are gaining popularity because they really save on energy, since water is only heated as needed.
For information and answers to some frequently asked questions check out our Demand Water Heaters FAQ's
We install Rinnai demand hot water heaters. Visit their site here: Rinnai.
