DIYbanter - View Single Post - 40 gal just not enough: Replacing water heater for 2400 sq home. Family of 2 adults + 2 children

Paul M. Eldridge

On Tue, 8 Apr 2008 08:26:00 -0700 (PDT), wrote:

I don't think that's fair. Ransley says he's actually bought one for
$500 and installed it himself relatively easy. And he's happy with
the results. I think his opinion is worth more than most here most
of whom don't have one and just sling mud. Especially those that
continue to spout misleading information, like "The heat loss from a
tank unit helps heat your home in the winter." It's been pointed out
repeatidly that much of the waste heat in a gas tank unit goes up the
flue. And the heat that escapes the sides of the tank only helps heat
the house if it happens to be in the living space, which isn't where
most are located. And then, in summer, the heat is still added to
the house and if you have AC as most do, then you're paying to remove
that heat. Yet, this same sad misinformation continues.

The OP has an electric water heater and electric units do not have
stack related losses. The only loss is through the tank wall and these
losses are less than 1 kWh per day if the tank has an EF of 0.93 or
better (the new minimum standard is 0.91).

Secondly, if the tank is located inside a conditioned space any heat
loss through the wall *will* offset a portion of the home's space
heating demand. If the home is electrically heated the net loss is
effectively zero during the heating season and for those who heat with
oil, the losses could result in a net positive gain now that
residential fuel oil is more expensive than electricity in many parts
of the country.

With respect to air conditioning, a central air unit with a SEER of 10
would eliminate 2.94 kWh of heat for every 1.0 kWh consumed (the ratio
is 3.8 kWh to 1 for a 13 SEER unit). Thus, the additional a/c burden
for a 10 SEER model if tank losses are 0.91 kWh/day would be less than
10 kWh/month.

Cheers,
Paul