Re: [VAL] water heater - tankless

[root <geraldj@xxxxxxxxxxx>]

Tom, don't count on that new tankless water heater saving as much energy
as the vendor claims. Those claims are based on the poorest of
insulation on the tank type water heater and neglect the fact that the
heat from the heater that leaks goes to heat the house in the winter, so
that "wasted" heat will have to be replaced by the furnace to keep the
house at the same temperature. And neglect the fact that your A. O.
Smith held water hot for days without energy input.

A major flaw in the tankless heaters, whether electric or gas is that
they take their energy in a large lump, larger than the peak consumption
of the tank type heater. This peak consumption can increase the size
needed for the pole transformer and if many consumers used the tankless
heaters, the size of the power plant required to feed the electric
utility. And that raises the cost of that energy. Today most utilities
work to smooth out peaks and one classical function of the storage hot
water heater has been to heat at night with way off peak energy and then
disable the water heater by a time clock or remote control device during
times of peak power consumption. At times storage hot water heaters and
in some places were given a special rate when fulfilling that peak
reduction mode. The tankless water heater does just the opposite to the
utility.

And in the RV situation where the propane comes from just a pair of 30
or 40 pound tanks, its quite possible for the peak gas demand of the
tankless heater to be greater than the ambient heat will vaporize LP in
the tanks, so that the tankless heater may start out good, but soon fail
to keep up with the water flow leaving the shower getting cold. In some
applications (like vehicles running on propane and farm corn dryers)
liquid propane is run to a vaporizer to be able to get gas at a rapid
enough rate without having to carry several hundred pounds of propane
tanks. I know my standby generator running just 5 KW needs a minimum of
a pair of 100 pound tanks to get enough gas to run in the winter. It
doesn't have a vaporizer.

Gerald J.