I have a gas water heater for which I can't find a water heater blanket that will fit. Can I just use faced fiberglass attic insulation as long as I avoid the vents and top of the heater? Is there a fire hazard? Seems not to me.
I have a gas water heater for which I can't find a water heater blanket that will fit. Can I just use faced fiberglass attic insulation as long as I avoid the vents and top of the heater? Is there a fire hazard? Seems not to me.
Well, I guess that's my question. I don't think the fiberglass is any different from the fiberglass in a water heater jacket. Is fiberglass a "combustible material"? Does the facing change things?Not if the insulation would be considered a combustible material. Your local area will have a min. distance your HWT needs to be from combustible materials.... usually 3'.
Mineral wool melts at 650C, FG at 1000 to 1400C.Is fiberglass a "combustible material"?
As a quick test, I wrapped part of the heater. Sticking my hand between the fiberglass and the outside of the tank results in a significant warmth. Much warmer than the un-wrapped surface of the tank.1. Many water heater manufacturers specifically say NOT to use a blanket.
2. Most heat loss in a gas heater is through the center flue which a blanket will not help.
3. Unless your heater's jacket feels hot, or warm, to the touch a blanket is not going to save enough money in a year to buy a cup of Dunkin' Donuts coffee.
I have a gas water heater for which I can't find a water heater blanket that will fit. Can I just use faced fiberglass attic insulation as long as I avoid the vents and top of the heater? Is there a fire hazard? Seems not to me.
This is untrue as was pointed out in a recent thread. Some manufacturers claim the blanket is unnecessary and for compliance with national standards they are correct. That in however, does not mean they are prohibited or actually cause any harm.hj said:1. Many water heater manufacturers specifically say NOT to use a blanket.
This is probably true or close enough to it. However, that does not in any way negate reducing other heat losses.2. Most heat loss in a gas heater is through the center flue which a blanket will not help.
3. Unless your heater's jacket feels hot, or warm, to the touch a blanket is not going to save enough money in a year to buy a cup of Dunkin' Donuts coffee.
Out of curiosity, what are the dimensions of the insulated sections of the tank (diameter and length?)
This is untrue as was pointed out in a recent thread. Some manufacturers claim the blanket is unnecessary and for compliance with national standards they are correct. That in however, does not mean they are prohibited or actually cause any harm.
This is probably true or close enough to it. However, that does not in any way negate reducing other heat losses.
As pointed out before your reasoning on the touch test is completely wrong as are your wild ass guess at benefits. Even for a water heater in a utility space within the home the savings exceed that.
Typical 1" foam insulation gives R8. With a blanket one can acheive up to about R18. By comparison some of the high efficiency water heaters (that you stated you've not sold?) tend to have 2" of insulation for R16. Looking at the State product line it appears that the average 1" insulated tank runs about 0.59 eff. and the 2" at 0.62. That 0.03 delta works out to about 12 therms a year. (Note that the efficiency factor change with increased insulation is inline with what I manually calculated for my tank.)
Average cost around here is around $1/therm (although the Great Recession has made it cheaper for the past year.) Cost of an insulation blanket? I've seen them from about $16 - 24. So worst case you are looking at about 50% annual return on investment.
Run the water heater at higher temps and/or put it in a garage in a northern climate and the actual benefits will be a multiple of the above.
As a quick test, I wrapped part of the heater. Sticking my hand between the fiberglass and the outside of the tank results in a significant warmth. Much warmer than the un-wrapped surface of the tank.
65" in diameter and 57" tall (50 gal). The local HD only carries 48" widths and carries *no* unfaced R13 attic insulation (thicker won't fit). So I'm back to looking (online) for a wider jacket. Any help there is appreciated.
You are absolutely right. The 48" x 75" should work OK. Time to think out of the box...The tank is actually about 20-21" in diameter; 65" is the circumference. And the 57" height includes the burner section and such which you don't insulate.
You will find that the standard 48"x75" blanket works. I have one on mine and the dimensions sound identical to your tank. I'm not sure why they list the "width" of the blanket as 48 and the "length" as 75". It actually goes the other way. I wrapped mine starting in line with the T&P with the overlap being trapped under the T&P discharge line. This provides a compression fit so that I don't even need tape along the overlap.
Follow the directions to cut out for the thermostat and T&P valve and don't cover any air intake grating (typically near the bottom.) You should be able to tape the uninsulated flap to the top of the tank. You don't want to put any insulation on the top of the tank as it could interfere with the flue.
Before you do all of this, record all of the information on the tank label and attach that info to your manual. (Serial #, model #, etc.) That way you won't have to remove the insulation to find it.
Seems to me that this will equate to savings. Heat loss decreases as the temperature difference between inside and outside the tank decreases (assuming everything else stays constant). The purpose of the insulation is to trap heat between the insulation and the tank, raising the temperature on the outside of the tank and decreasing the temperature difference. Seems to me that this is how all insulation works (e.g. attic insulation).It will always do that as you are trapping the heat and slowing it...this does not equate to savings, all insulation does is slow the rate of heat loss...there is a point where reguardless of the amount of insulation you have your rate of loss is the same...
Seems to me that this will equate to savings. Heat loss decreases as the temperature difference between inside and outside the tank decreases (assuming everything else stays constant). The purpose of the insulation is to trap heat between the insulation and the tank, raising the temperature on the outside of the tank and decreasing the temperature difference. Seems to me that this is how all insulation works (e.g. attic insulation).
Additional insulation will always reduce the heat loss in that direction with everything else being equal. However, there is a point where the additional cost of the insulation will not be recovered by energy savings.
In addition, there is a point where you will not see a benefit to the additional insulation as the losses in the other directions (bottom of tank, top of tank, conduction through the piping, etc.) will dominate the losses.
Most modern tanks benefit little from the blankets compared to the older tanks. I know that the manual for my GE/Rheem (electric) specifically states that a blanket is not needed.
Where is your tank located? Garage or in conditioned space? If inside, the dT is lower during the winter (compared to a garage/attic) and the heat loss does go into warming the house, so the heat that is "lost" isn't really lost.
As a quick test, I wrapped part of the heater. Sticking my hand between the fiberglass and the outside of the tank results in a significant warmth. Much warmer than the un-wrapped surface of the tank.
This is awkward, but...
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