Insulating the hot waters pipes in your house is something of a no-brainer. Why let the heat escape willy-nilly? Pipe insulation is inexpensive, and the project is one that any homeowner could finish on a Saturday afternoon.
Whether to insulate the cold water pipes is less clear-cut. The project is still pretty inexpensive and easy — but does it have a point? Insulation retains heat, and these are cold water pipes. So why do it?
Protect pipes from freezing and limit condensation
There are a few good reasons. If the basement or crawl space has uninsulated walls (and really, you should insulate your basement walls), insulated cold water pipes would be less prone to freezing in cold climates.
If the basement is conditioned space, an insulated cold water pipe won’t absorb heat. If it is in a 1000% humidity climate like Georgia, cold pipes can be prone to condensation issues. A fully taped and insulated cold water pipe won’t condense moisture on its surface.
Should cold water pipes be insulated in cold climates?
My father grew up in houses where pipe freezing was a common occurrence. Since he slept in the basement bedroom of his childhood home, it’s not a surprise. That was one cold basement.
From USGS groundwater temperature data, we know that groundwater temperatures in Maine are generally below 50°F.
Many houses in Maine and similar heating climates have uninsulated copper and PEX pipes running through the basement ceiling joists. With winter temperatures routinely dipping below 0°F, it’s no surprise that cold water pipes can freeze.
Insulation is simply a material with above average resistance to thermal energy movement. The water comes out of the ground below 50°F into a winter environment that could be below 0°F. Wrapping those cold water pipes would keep what heat energy the water possessed in place, protecting against freezing.
Cold water pipes absorb heat
If the basement space is insulated, cold water pipes may absorb heat. The basement air temperature would be in the high 50s while the cold water pipes would be 10-12 degrees colder.
If the pipes were left uninsulated, this would be a continual, low-level draw of heat from the building. Normally this might be too small to bother, but the cost of insulating pipes is so minimal it becomes worth discussing.
Cold water pipes are a condensing surface for moisture in the air
Lastly, condensation concerns can be alleviated with pipe insulation. (Or rather, the possibility of condensation would be gone — you’re free to remain concerned.)
Basements and crawl spaces are embedded in damp soil, surrounding the permeable concrete with moisture. The spaces under houses often have elevated humidity levels and cold water pipes are a natural condensing surface. Stick any paper or valuables or valuable paper (perhaps your original run of Claremont X-Men issues) under a pipe elbow, and you’re in for a nasty surprise down the road.
The key for preventing condensation is to be sure that the pipe is insulated and that the insulation is sealed along the seams. Moisture-laden air must be kept from contacting the pipe surface. The pipe insulation should be a vapor-impermeable foam with all the seams and edges taped tight.
Insulating hot water pipes in a cold climate is a no-brainer. But there is a lot to be said for insulating cold water pipes as well.
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