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Posted by HeatPro on July 05, 2007 at 10:32:22:
In Reply to: Ergomax or equivalant posted by Dee on July 04, 2007 at 18:25:41:
The mixing valve is a passive machine that makes no difference in energy. Running a boiler at 180F all the time instead of having it vary to lower temperatures with the weather as needed for heat does lower efficiency; but not greatly enough to notice a difference in a total fuel bill when having no coil in the boiler and separate water heaters also being on at the same time and all the time.
Frequently, people install separate water heaters supposedly to save in the summer, but electricity costs three times that of the fuel, so there is actually more total yearly cost from having a separate electric water heater on just in the summer. A separate gas or electric water heater would run at the same fuel costs; but now there is no payoff for installing them.
The benefit of the mixing valve aside from the temperature safety is that you are mixing cold with the hot, so 2 gallons of 180 hot with 1 gallon of 70 cold makes 3 gallons per minute (180 gallons per hour capability vs 120 gph.) Thus the ability to take a shower AND fill something else.