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Originally Posted by DavidF
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I suspect the biggest reasons are that they are relatively new (RVs atend to be quite traditional) and relatively expensive (a huge factor in RVs). There are also operational factors.
Quote:
Originally Posted by DavidF
It seems that every trailer has a replica of a domestic house water heating system. Are "on demand systems" not used in North America?
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Domestic water heaters can be "on demand", too. No, they're not common (for houses or RVs) in North America.
Quote:
Originally Posted by gbaglo
I believe the issue is that they waste water. Gotta run water until the unit gets it up to temp, so you are emptying your fresh water and filling your grey tank.
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The volume in the heater should be quite small, minimizing this, but I do see the point.
Quote:
Originally Posted by cpaharley2008
Correct, you adjust the temperature via flow control, more slower, the hotter the water, more faster, the cooler the water becomes. They are also more $$ and prone to electrical issues in moderating the variable speed burner.
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If it has a variable-rate burner, it shouldn't have this flow-dependent temperature effect. The cheap units have a fixed heating rate, so the temperature can't be controlled independently from flow. The Atwood is variable so it should maintain a constant temperature; however, with a 16,000 BTU/hr minimum, it will have the effect Jim describes at low flow rates. Perhaps a smaller version would be more appropriate for the low flow rates typically used in small trailers with small tanks.
Aside from the control system, the cost is typically high simply because a large burner is needed... in the case of the Atwood, 50,000 BTU/hr is about six times the rate of a typical "6 gallon" water heater.