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Model # SP57/11C

Internet # 100139225

Store SKU # 417920

Fiberglass Water Heater Insulation Blanket

This item has been discontinued.
The Home Depot no longer carries this specific product.

$21.57 /each




Model # SP57/11C

Internet # 100139225

Store SKU # 417920

Store SO SKU # 923710

The Thermwell Products Co. Inc. Fiberglass Water Heater Insulation Blanket fits up to a 60-gal. tank. It is compatible with both gas and electric water heaters. This blanket helps you save energy by reducing your water heater's recovery time.

  • For use with both gas and electric water heaters
  • Fits up to a 60-gal. tank
  • Insulates a water heater
  • Reduces water heater recovery time to save energy
  • Durable fiberglass body with R-10 insulation


Product Depth (in.) 
Product Height (in.) 
Product Width (in.) 
Finish Family 
Product Type 
Product Weight (lb.) 
4.95 lb 
Warranty / Certifications
Manufacturer Warranty 
180 days 


Rated 3.4 out of 5 by 70 reviewers.
Rated 3.0 out of 5.0 by "Up to" 60 Gallons...if you by the correct model number I couldn't help but notice how almost everyone commented on the fact that there wasn't enough material. Pay attention to the model number - SP57-11C. If you go to the Frost King website, you'll see there's another model SP60 which is 90 inches round vs. 75 inches. That's the model that fits up to 60 gallons. September 30, 2015
Rated 3.0 out of 5.0 by Barely Fits around 50 gal water heater Package says fits up to most 60 gal water heaters. It barely fit around my 50 gal. I have an electronic Whirlpool water heater and it kept messing up due to the cold so that is why I bought this. It does serve the purpose of covering up the digital display and keeping it warm. It actually did not completely fit around my water heater. There is probably a 2-3 inch gap where I had to tape it to the water heater all the way down for it to stay. If I would have stretched it probably would have fit, but if you compress insulation it decreases its R-value which defeats the purpose. I also must say that the tape that comes with it works extremely well. December 14, 2013
Rated 5.0 out of 5.0 by Easy install Easier to install with a little help from a 2nd person to hold it in place while cutting/taping in place. July 28, 2015
Rated 4.0 out of 5.0 by Product is ok but could be better. I installed the insulating blanket around a new 40 gal. electric GE water heater and just had enough to reach around the tank. I had no extra material to finish covering the top of the tank. For the price of the Kit they should include more material. Tip: For additional insulating value add an 1" block of high density foam under the tank, if an electric water heater. September 17, 2013
Rated 2.0 out of 5.0 by Skimpy This product, while useful in containing some heat loss, is not as advertised or pictured. 1. There were no tabs to affix top as indicated 2. 48" depth isn't enough- barely the length to thermo box, leaving a good 12-18" to the bottom of unit 3. 75" width is just enough for my 40 gallon heater. A 400 lb. gorilla may be required to wrap a 60 gallon heater. 4. As a previous reviewer suggested, a mask and gloves should be worn when handling fiberglass 5. It should be noted that the blanket must be wrapped UNDER the copper relief tube for best fit 6. The print on the directions is too small and difficult to read. 7. Directions are printed on the shrink wrap bag containing the blanket. Use care in cutting the bag to avoid obscuring the directions. 8. The tape included is cheap and difficult to manage. Suggest use of white duck tape. November 1, 2011
Rated 3.0 out of 5.0 by Does not fit stated sizes and messy Horrendous amount of fiberglass "dust". Much more so than any fiberglass insulation I've installed. After installing this my hands and clothing sparkled like they had been sprinkled with glitter. "Tools" needed should include a respirator. Had measured my water heater so I knew what size I was looking for but this certainly won't fit the advertised size...unless "fit" no longer means completely covers. Too soon to tell how much this will save on the heating bills but adding insulation is never a waste in the long run. Might be better off using left over home insulation (with backing) if you have any. December 11, 2013
Rated 1.0 out of 5.0 by Waste of money This doe not fit my 50gal tank. It's way too short in height and wrapping around. It's a mess to even bother removing it to return to the store. The outer side of this insulation has a very thin plastic covering which tears easily. The tape is useless. There is no backing on the inner side, it is just bare Fiberglas itchy mess. Don't waste your money. January 26, 2013
Rated 3.0 out of 5.0 by Water heater cover The outer material is very thin and hard to keep from sliding while you are taping to the unit. I think they should add another piece or two of tape since 3 doesn't hold it up without sagging. Considering it was the only one available and I needed it, I kept it. They really should use a heavier plastic over the insulation. It does the job though. September 8, 2015
  • 2015-11-26 T09:32:19.869-06:00
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