Pete C. wrote:
m Ransley wrote:

But is there realy enough insulation on any tank, maybe 2" of foam for
say R 12, but code for attics in my area is R35 and optimal is R60. Loss
also continualy occurs through the water pipes, you are keeping water
hot, there is alot of loss.


Based on the comparison for tank type electric and tankless electric
where there was clearly little standby loss from the heated tank I'd say
yes.

Newer heaters have little valves that are designed to limit heat loss to
the pipes in standby. Certainly insulating the hot water pipes is still
a good idea.

Pete C.

Losses in pipes are NOT a part of the Bosch comparison. Yes, we must
recognize them as they will extend our use of hot water while we wait
for the pipe to heat back up (or we use a recirculation pump).

The Bosch comparision said that electric tankless was a infinite payback
at 50 gallons and a near infinite payback at 80 gallons.

Yes, stack losses and insulation losses are the dominant factors in
energy use difference between tank and tankless gas heaters. In this
case, gas tankless makes a large enough difference to perhaps get a
positive payback in 5-7 years.