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Online advertisers know me way too well. They caught on quickly to my fondness for pocketknives and nylon tool pouches. And when I started researching backup power for my rural cabin, my feed filled with ads for PV modules, batteries, and inverters. Recently, the algorithms showed me a tool I never knew existed: a pipe insulation cutting guide. The ad took me back to my years as a home performance contractor and the thousands of linear feet of insulation I installed on domestic hot water, hydronic, and steam piping.
Pipe insulation is one of those humdrum efficiency measures that gets little attention beyond its perpetual appearance in lists of “simple things you can do to cut your utility bills.” But it delivers a surprising list of benefits. The first, of course, is saving energy. According to the Building America Solution Center, insulating pipes can reduce water heating energy use by 4% to 5%. For a typical household, this can translate into savings of $15 to $30 per year.
Pipe insulation saves energy
One way pipe insulation saves energy is by reducing standby losses from hot water storage tanks. While the jackets of modern water heaters are insulated with a thick layer of polyurethane foam, the metal or PEX inlet and outlet pipes can still conduct heat, as can other fittings like the drain valve and temperature/pressure-relief valve. Thermosiphoning can also contribute to standby losses; hot water rises into the pipes, cools, and flows back into the tank. Pipe insulation slows both these processes. (Many modern water heaters have “heat traps,” small flaps or balls on the inlet and outlet ports, which also reduce convective losses.)
Pipe insulation also reduces the temperature drop between the water heater and the point of use. According to…
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One Comment
Dear Jon: Great article! This is a simple upgrade for many homeowners, with clear savings and benefits. Here are a few more tips:
(1) Tape the entire joint: Foam pipe sleeves have a self-adhesive face; simply peel off the cover and stick 'em together. The problem is that (a) you get what you pay for, and foam pipe sleeves are cheap, and (b) this cheap adhesive gives out over time, opening the foam sleeve to the cool air in your basement - and the foam sleeve doesn't fit tight, so air circulates, robbing you of much of the benefits. Believe me, I've seen this failure. So... run HVAC foil tape down the length of the joint. Note: HVAC foil tape is NOT silver duct tape - which should NEVER be used for any HVAC project! For example: Nashua https://www.homedepot.com/p/Nashua-Tape-1-89-in-x-50-yd-322-Multi-Purpose-HVAC-Foil-Sealer-Duct-Tape-1906075/100030120 This tape sticks forever.
(2) R3 - really? As you noted, basic foam sleeves deliver only R3. No one would insulate a wall to R3, so why would you do this with pipes you've paid to heat? Unlike an entire house, which is difficult to insulate and air seal, here you have a 'point source' problem you can solve! You can simply wrap the foam sleeve with a fiberglass sleeve. For example: add a fiberglass wrap OVER the foam sleeve, to add another ~R3. Again, tape the joint. https://www.homedepot.com/p/1-1-2-in-x-3-ft-Fiberglass-Self-Sealing-Pre-Slit-Pipe-Cover-F14XAD/100134569
(3) This also applies BIG TIME to 'air conditioner / heat pump' lines, which often run for 10s of feet, with R3 insulation - if any! When we added AC to our home in Massachusetts, I built a 'chase' for the 1/2" lines, which ran from the condenser at ground level to the air handler in the attic of our 2 story house. The sides of this chase were insulated with 2" of iso foam board, air sealed at top and bottom - and there were two sides for the 'cold' supply and the 'warm' return. Everyone with an external heat pump or AC condenser should separate and insulate their lines. (Often the supply / return lines are bound together with a zip tie! What ignorance - and costly waste!)
(4) This also applies to HVAC plenums and ducts - which are often poorly insulated, despite all of the money that goes into cooling and heating the air! And air leaks are much harder to find than water leaks. Plenums are often wrapped in 'shiny bubble wrap' which provides R1 - despite the claims on the package. Joints are often un-insulated and un-tapped. Ducts are often poorly sealed and insulated. Fiberglass sleeves and foil HVAC tape are the answer!
I hope this is helpful.
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