On Fri, 09 Dec 2005 03:25:32 GMT, "John‰]*
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wrote:


I have an apartment building with five thirty gallon electric water
heaters located in closets in the bathrooms.

Some people tell me that every water heater needs a blanket; no
exceptions. Others tell me that water heaters manufactured in the last
five years are so well insulated to begin with that if they are
installed in heated space, a blanket is a waste of time and money and
will produce negligible energy savings.

What do you think?


Put your hand on it. Is it warmer than the cement it's
sitting on? Why?

wrote:
Some people tell me that every water heater needs a blanket; no
exceptions.

There are a lot of idiots in this world.


Others tell me that water heaters manufactured in the last
five years are so well insulated to begin with that if they are
installed in heated space, a blanket is a waste of time and money and
will produce negligible energy savings.

What do you think?

I think they are correct.

Edwin Pawlowski wrote:

wrote:

Others tell me that water heaters manufactured in the last
five years are so well insulated to begin with that if they are
installed in heated space, a blanket is a waste of time and money and
will produce negligible energy savings.

What do you think?

I think they are correct.

WRONG!!! If Grainger's $204 1PZ75 50 gallon 19" diam. x 56.5" tall electric
heater with 27.4 ft^2 of R11.5 surface loses 8765h(120-65)27.4/11.5 = 1.15
million Btu/year, ie 366.6 kWh worth $36.66 at 10 cents/kWh at 120 F in a
65 F room, adding $7 worth of R19 insulation would lower this to $12.69,
for a net $23.97 savings and a $7/23.97x365.25 = 107 day simple payback.

Nick

can they be installed on gas water heaters?

jeff wrote:

can they be installed on gas water heaters?

Sure. Looks like they have even less insulation, R5.6 vs R11.5 for
Grainger's Rheem versions. The blanket savings would be greater, with
a faster payback, but it's likely to be a smaller proportion of the total
heat loss, given the large open flue up the middle, unless there's
a gadget that closes the fluepipe when the heater stops running.

Nick

wrote in message
I think they are correct.

WRONG!!! If Grainger's $204 1PZ75 50 gallon 19" diam. x 56.5" tall
electric
heater with 27.4 ft^2 of R11.5 surface loses 8765h(120-65)27.4/11.5 = 1.15
million Btu/year, ie 366.6 kWh worth $36.66 at 10 cents/kWh at 120 F in a
65 F room, adding $7 worth of R19 insulation would lower this to $12.69,
for a net $23.97 savings and a $7/23.97x365.25 = 107 day simple payback.

Nick

Sorry Nick, but your fancy figures don't tell the whole story.

First, where did the loss figures come from? Where does the alleged lost
heat go to? It goes into the space that you are paying to heat, thus not
saving anything more than the difference if fuel costs if the central heat
is a different fuel.

You are also basing your assumptions on a 65 degree ambient. In reality, it
may be much different especially in summer. As a side benefit, some people
like a warmer bathroom on a chilly morning. Any added heat would be
welcomed.