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Community and Q&A

Insulating cold water pipes

calum_wilde | Posted in Mechanicals on

I’m getting a lot of condensation on my cold water pipes. The house is plumbed with pex, and most of the condensation is collecting on the copper and/or brass fittings.

I’ve been hesitant to insulate the cold water pipes because I don’t want the problem to move to an area where I can’t see it, namely, inside the walls. It seems the water is picking up enough heat in the house to prevent condensation in the walls now. So, should I just leave it alone, and worry about collecting the water and allowing it a path to a drain in an area where it wont be an issue? Or should I insulate the pipes?

As always, thanks!!

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  1. GBA Editor
    Martin Holladay | | #1

    As far as I know, the current versions of the International Residential Code require cold water lines to be insulated.

    For most builders, the question isn't "Should I insulate these pipes?" -- because most builders are required by code to insulate cold water lines.

  2. calum_wilde | | #2

    Thanks Martin,

    The house is 11 years old. Every part of the basement is finished, and I'm not excited about the idea of opening that back up just to insulate water pipes. (I say just, but if this is actually a very large heat loss area I might reconsider. To my understanding it's not though??) The one exception is the utility room, the ceiling is open there.

    After looking at things I've gone ahead and insulated the pipes up to the hot water. I figured there should be enough heat leaking up the pipe to prevent condensation after that point. But, that also leaves me about 8 feet of pipe to monitor before it disappears into the wall.

  3. charlie_sullivan | | #3

    Another thing to consider would be a drainwater heat exchanger such as The recommended installation connects its output to most of the cold water piping in the house. There's not guarantee of consistently avoiding cold water pipes but on average they will be warmer so you'll gain some margin against serious problems.

  4. calum_wilde | | #4

    Thanks Charlie,

    I've been looking at those, but I never thought to connect it to the cold being distributed to the house, instead of using it to preheat the hot water.

    I'll certainly consider it, it's seems like a valid idea, especially to prevent sweating toilets.
    As it is though, I only have 35 inches of vertical stack to put one, and house is plumbed with a single line, not a separate line for each user. IF my idea that heat leaking out of the water heater, up its supply line, will be enough to prevent condensation, I'll stick with my idea of using a drain water heater recovery unit to preheat the hot water. Otherwise, I think preheating the cold is going to be a must.

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