Logic of using a 30 gallon electric vs 9 KW tankless hot water heater.
"BoyntonStu" wrote in message
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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.
One thing I did not see mentioned is that if the power goes out, the tank
can be heated by an average 5 kw generator. The tankless can not be heated.
NOt sure how the power outages are in your part of Florida. Where I am at
the power has been taken out for a week or more due to ice storms. I have
been lucky and only have it out for about 2 days sofar at any one time.
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