On Sun, 19 Oct 2014 15:14:05 -0700, josephkk
wrote:

On Sat, 18 Oct 2014 13:56:45 -0700, Jeff Liebermann
wrote:


An easy way to tell if your water heater is a piece of junk is to
measure the case temperature of the water heater. Use a contact
thermometer (Thermocouple or thermistor, not optical IR). It's
probably the worst at the top of the heater. If the outer case is
warmer than the ambient air, you're wasting energy heating that
atmosphere instead of the water. Same with a refrigerator. If the
case of the fridge is colder than ambient, you're cooling the kitchen.

No. Refrigerators always heat the kitchen, they have condensers as well
and ALL the heat removed from the interior and the operating losses are
added to the room heat.

?-)

I wasn't suggesting that you measure the temperature of the back of
the refrigerator. Just the case temperatures, which means the sides,
front, and possibly the top. The coils in back will certainly heat up
the wall and the back of the case, but I don't think it's huge because
the room and room air make a rather large heat sink.

It's easy enough to estimate how much heat the fridge delivers to the
room. A fancy new energy efficient 18 cubic foot fridge uses about
500 kw-hr/year or an average of:
500 kw-hr/year * 1yr/365days = 1.4 kw-hr/day
Over 24 hrs, that's the equivalent of:
1400 watt-hrs/day / 24 hrs/day = 57 watts
That's about the same heat that would be delivered by a 60 watt light
bulb running all day in the same room. Like I mumbled... not much
heat. Older fridges are not that efficient, but even 3 to 5 times as
much heat would not make much of a difference in room temperature.

I just checked my bar size fridge with a thermocouple thermometer. The
front door is the same as ambient at 17C while the top and sides are
about 20C. So, for a decent fridge, you're correct and the sides are
warmer. However, I've seen refrigerators that were sweating condensed
water and felt seriously cold on the sides and door. Sears took it
back and replaced it with one that had more insulation, which worked
as expected. Since then, I've seen a few others that were cold to the
touch.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558