On Apr 9, 2:19*pm, Paul M. Eldridge
wrote:
"ransley" wrote

1 - At least one regular poster here continually mentions the
winter benefit of heat loss without regard to where the water
heater is located and totally ignores the AC impact in the summer.

Hi Mark,

The impact of standby loss with respect to added a/c demand is
generally very modest for three reasons:

*1) with the exception of some of the southern most states, heating
degree days exceed those of cooling throughout most of North America,
in some cases by a factor of ten or more (e.g., Minneapolis MN).
Pittsburgh PA, a mid-eastern seaboard city, has 5,968 HDD and 654 CDD.
Even in San Diego CA, heating demands exceed those of cooling, i.e.,
1,256 HDD versus 984 CDD;

*2) *generally speaking, water heaters are located inside conditioned
spaces in colder regions due to the risk of freeze damage whereas they
are typically placed in non-conditioned spaces (e.g., attached
garages) in warmer climates -- located outside the home's thermal
envelope, there would be no impact on cooling demand;

*3) for every kWh used, an air conditioner will remove three or more
kWh of heat. *A 10 SEER air conditioner will purge 2.93 kWh of heat
for every one kWh consumed and a 13 SEER air conditioner (the current
minimum standard) will eliminate 3.8 kWh of heat. *Thus, each kWh of
standby tank loss translates to 0.34 kWh of cooling demand at 10 SEER
and 0.26 kWh at 13 SEER.

Taken together, it's pretty clear the benefits in terms of heat gain
far outweigh any potential loss with respect to added cooling demand.

Cheers,
Paul

No, it's not clear at all to me that is the case. Because contrary
to your claim, in my experience most water heaters I've seen, from NJ
through New England are NOT in conditioned spaces. Most are in an
unfinished basement. That's where mine is. Some others are in
garages. I would say only a minority are in conditioned living
spaces. In all the condos and homes I've lived in, I have never had
a water heater in the living space. I know they exist, but the point
is, they are not the majority of cases. Even where you have one in a
utility closet, it's not clear to me how much of that waste heat gets
into the living space itself, as opposed to just raising the temp of
the closet that it's in.

Now, even hallerb apparently conceeds that most of the standby loss is
up the flue. And the rest of the loss, that escapes the tank sides,
doesn't by some miracle all go into the living space above. In fact,
I would bet that in a water heater in the basement, which is a typical
case, only a small amount, probably unmeasureable makes it up there.