On Jun 8, 8:02*am, " wrote:
On Jun 8, 8:46*am, wrote:





On Jun 7, 5:36*pm, ransley wrote:

On Jun 7, 2:25*pm, wrote:

On Jun 6, 12:12*pm, harry wrote:

On Jun 6, 1:30 am, BoyntonStu wrote:

A 9 KW tankless HWH manufacturer claims that it is sufficient for a
whole house at up to 3 GPM.

A 30 gal short tank HWH is about 30" tall and many are mounted over a
clothes dryer on a shelf.

That got me to thinking:

Size - not too important if hung.

Power - both 9 KW.

Instant hot water: - Tank water is preheated. The tankless requires
0.5 GPM to begin heating.

Cost - Conventional HWH is cheaper.

Longevity - Tankless is supposed to last twice as long.

Replacement elements - Conventional elements about $15 at Home Depot,
etc.
Tankless elements are not standard
and cost more.

Recovery - With 9 KW of heating available in both units they may be
equal.
(You must use up all the 30 gallons before additional
HW is needed.)

Upgrading: Conventional elements are available in 5, 5.5, and 6 KW
sizes.
Therefore a 12 KW 30 gallon is doable and it would
heat faster.

Efficiency: Tankless is slightly more efficient.

Location - I am in Florida where the input temperature is 70*F.

The main benifit of "tankless" or instantaneous water heaters is that
if you are storing hot water, there is a heat loss and
this can be considerable if you have the heater on 24/7. So a
tankless
is lots more efficient, you heat the water when you need it and the
amount you want. It can easliy save half or threequarters the
energy. *

Total nonsense. * In the summer, my entire gas bill which includes
both heating water for household use and occasional gas grilling is
under $20. * *It's pretty clear that only a small amount of that is
due to standby losses from the wayter heater tank. *The vast majority
is from water that is actually used. *If you turn off a water heater
and don't use the water, it will stay hot for a couple of days. I'd
like to see any credible reference that says the typical electric
water heater loses 1/2 or 3/4 of it's energy usage as standby losses.

However 9kW is OK for basins and showers but you would be
forever trying to fill a bath.

The stated output is 3GPM, which clearly is a lot faster than
forever. * And that is likely for water at a higher temp than you
would want for a bath, meaning you could also mix in some cold water.