Boiler Pipe Insulation - Energy Efficiency - Richard, I have lots of my boiler pipe under the house in a crawl space and some in the basement and none of this pipe is insulated. I just bought the house last year and this past winter my gas bill was crazy high. Can I increase efficiency by insulating these pipes and what are some other ways to keep the gas bill lower by optimizing the boiler system?

Thanks and I look forward to your answer……….Bill – Pittsburgh, PA

Boiler Pipe Insulation

Boiler Pipe Insulation

Boiler Pipe Insulation


You can definitely save a lot of money by insulating those pipes. That is unless you have a good reason to heat under your house or your basement.  Some people can use a little heat in their basement but using the boiler pipe to heat the basement is not an efficient way to heat a space as the pipe is designed to transfer heat from the boiler to a radiator designed to release the heat into the space.

All the piping in the loop aside from near boiler piping where the pump and controls such as zone valves and water loop air management devices need to be insulated. The more pipe that is insulated the better your efficiency will be as this will lessen the heat loss experienced in the non-insulated boiler loop pipe. There are alternatives for insulating the boiler loop pipe and in certain cases, you need to proceed with caution. Read on for more Boiler Pipe Insulation information.

Boiler Pipe Insulation - Safety First and the Old Asbestos Insulation

There are lots of homes and businesses that have asbestos insulation on the pipe. Sometimes this asbestos insulation is falling off or in some kind of disrepair. Asbestos is very dangerous to your health. It is best to hire a professional asbestos removal company to mitigate or remove the old asbestos. In some cases, the old asbestos can be encased in something. That it is never a danger to anyone ever again unless it is disturbed and re-exposed. It can be covered up so that the old asbestos does not present a problem to anyone ever again.

Believe me, you will want to be careful around asbestos…………………. my uncle suffered and eventually died from asbestos-related illness. Take it very seriously and be careful around the old asbestos. Hire an asbestos removal company to get rid of it forever. Then you can insulate those pipes with something safer like the fiberglass insulation shown in the photos here.

Boiler Pipe Insulation Types

Fiberglass insulation is made especially for pipe and boiler applications and can be used on boiler piping insulation with temperature ranges from -20 degrees Fahrenheit up to +500 degrees Fahrenheit which covers the range of temperatures if you have either a steam boiler or a hot water boiler. Fiberglass insulation (as in the photo) will make the best type of insulation for either steam or hot water boiler piping and can be purchased in various sizes along with various fittings such as T’s, 90′s, and 45′s.

Wear some gloves when handling the fiberglass pipe insulation as this insulation will make you feel itchy if it comes into contact with your skin. Additionally, the best you can get is the fiberglass pipe insulation with a jacket on the outside and an adhesive strip to join it after you wrap the pipe. This makes it look professional and neat and it is also durable. Fiberglass does lose its R-value if exposed to water and the jacket will prevent limited contact with water if there is a leak or drip on the pipe insulation. The jacket will not be that effective if flooding occurs but probably nothing will be effective in a flood.

Boiler Pipe Insulation - Rubatex Insulation

Rubatex pipe insulation would not be a good pipe insulation for steam boiler piping insulation. There is a temperature limit (steam pipe temperatures exceed 200 degrees Fahrenheit). However, Rubatex would be suitable for hot water boiler pipe insulation. Rubatex is flexible and can easily be fitted for T’s, 90′s, and 45′s. It is available for purchase for very small pipe 5/8″ all the way up to over 6 inches. Another consideration for Rubatex is the UV rating if the insulation is going to be exposed to sunlight. Some Rubatex pipe insulation is not rated for direct sunlight use. Keep that in mind if the pipe you are insulating is in direct sunlight.

Properly Sealed

Rubatex is also purchased as a solid and split seamed with and without an adhesive strip. The adhesive strip seals the split in the Rubatex after it is applied to the pipe. There is a special adhesive you can purchase to join the Rubatex with the adhesive. It is painted on the seam with a brush and after it dries the Rubatex is permanently joined for a good seal. A good seal is normally not important for boiler applications as it is for chilled water or refrigeration lines. These lines operate below the dew point. In that case, it is very important the pipe is properly insulated. It must provide a vapor barrier to prevent air moisture from getting to the pipe.

Moisture Problems

If moisture gets to the pipe then it will leak water. Cold pipe without insulation operating below the dew point will condense the water from the air surrounding the uninsulated pipe. This can create problems especially with wood damage, mold, and mildew to the dwelling. Rubatex is commonly used for residential air conditioners and heat pumps to seal the suction line. This line commonly operates below the dew-point and will drip water creating problems. However, Rubatex insulation can also be used to insulate hot water boiler piping. Make sure you check the temperature ratings before purchasing. There are different types of Rubatex insulation with different temperature ratings.

Related Link: Boiler Water Loops - offers information on the basic types of boiler water loops.

Use our handy calculator to see how many BTU's your natural gas appliances are producing:

Boiler Pipe Insulation - Conclusion

There are several other types of foam insulation available for boiler pipe insulation applications. However, the two types of insulation above are the most common. Most are available for purchase either locally or online.  Rubatex can even be purchased at one of your local big box hardware stores. That will get you started on your boiler pipe insulation project. While you are at it, you can go ahead and insulate all the hot water pipes for your water heater. That will help the efficiency of your water heater and help the hot water get to the faucet faster. Good luck and I hope I have answered your question.

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Boiler Pipe Insulation

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