Water Heater Blankets

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?
John
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Since the tank is inside, in the winter, the heat loss from the water heater is helping heat the apartment, so it really isn't a loss. In the summer, it's working against you by adding some heat against the air conditioning. Overall, IMO the added insulation isn't going to make a big difference, especially since the unit is in a closet and it's probably not worth the cost or trouble.
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John‰] wrote:

Are you paying the utility bill?
hvacrmedic
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"John‰] "

I say they're so cheap, why not?
And one of the major things is that people keep their water too hot, spending a lot of money to have hot water the 23 1/2 hours a day they don't use it. Keep it at a low setting, put a blanket on it, and fergeddabout it. That's about as good as you can do.
Steve
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open the closet door and heat the bathroom with any leftover heat.
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What's the fuel source of the apartments ambient heat ?
If its gas fired apartment heat that would seem to me to be both cheaper per BTU and more efficient than electric heat.
It seems to me silly to use electric heat from the waterheater to add a few tenths of a degrre to the apartment ambient temperature. Those few tenths of a degree of "waste" or "free" heat from the water heater are the most expensive heat you'll get.
If the apartment heat is anything other than / cheaper than electric, I think it pays to insulate the water heaters and turn down the ater heater temperatures to no more than 120 F
--
Jim McLaughlin

Reply address is deliberately munged.
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They're boob bait.
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On Fri, 09 Dec 2005 03:25:32 GMT, "John‰]                                                                 "

Put your hand on it. Is it warmer than the cement it's sitting on? Why?
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There are a lot of idiots in this world.

I think they are correct.
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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
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can they be installed on gas water heaters?
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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
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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.
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"John?] "

The WHs are in closets, they are already insulated by the small volume of air in the closet and close adjascent walls. Insulate only if the WH is in a cool garage or outside closet.
Blankets also cover any warnings, instruction labels and often unintentionally cover vents that let out water vapor causing it to be trapped inside to cause rust.
If you want to insulate something, insulate the hot water pipe coming out of the WH as much as access allows. If you want to spend money to save money, replace the Anodes after 1/2 of the tanks rated lifetime and you'll add years of service to them.
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best savings is to turn down the water temp...
the heater will last longer too for a real savings...
Mark
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This is Turtle.
years ago i thought Bullshit but i had a friend that had a camp on the lake where i have one and he only run his hot water tank while he was gone. if he never went to the camp it cost him $10.50 to run the hot water tank on very low while gone. He and I went up there and put a blanket on his electric hot water tank and then the next bill was $7.50 with no body using it. That is a 28% cut in useage of the water while at stand still job with no useage !
Now it could have used less electricity for a space man come down and stopped taking showers at the camp after we put the blanket on it.
TURTLE
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Years ago the tanks were not insulated as well as they are today.
Another factor is the temperature of the building while not occupied. If it was kept very low, there would be more heat transfer at 50 degrees than at 70 degrees.
Still another factor for part of the year is total heating cost. If the water heater gives up some heat to the room, the central heating system will have to put out that much less.
While some added insulation may help, I doubt anyone will realize anywhere near the 28% the fellow in your example was able to get.
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wrote in message : > : > years ago i thought Bullshit but i had a friend that had a camp on the : > lake where i have one and he only run his hot water tank while he was : > gone. if he never went to the camp it cost him $10.50 to run the hot : > water tank on very low while gone. He and I went up there and put a : > blanket on his electric hot water tank and then the next bill was $7.50 : > with no body using it. That is a 28% cut in useage of the water while : > at stand still job with no useage ! : : Years ago the tanks were not insulated as well as they are today. : : Another factor is the temperature of the building while not occupied. If it : was kept very low, there would be more heat transfer at 50 degrees than at : 70 degrees. : : Still another factor for part of the year is total heating cost. If the : water heater gives up some heat to the room, the central heating system will : have to put out that much less. : : While some added insulation may help, I doubt anyone will realize anywhere : near the 28% the fellow in your example was able to get. : :
Easy enough to empiracally figure out how good the insulation is; put a partial wrap around the heater, give it a day or so, then slip your hand in under the insulation: you might be pretty surprised at how hot it is in there. Both heater and pipes should be wrapped; one without the other is much less efficient.
Water heater insulations just are NOT very good in my experience; new or not, there isn't much difference. And there's a lot of loss in the first few feet of pipe on the output side too, less on the input side, much less if plastic pipe.
Pop
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