Pipe Insulation Adventures

Now that our boiler job is complete, I’m going through and insulating all of the near-boiler pipes, which put off quite a bit of heat. First priority is the primary loop (1-1/4″ copper), followed by the secondary loop for the indirect water heater (1″ copper), followed by the DHW piping near the indirect (3/4″ copper), and lastly the secondary loops for our 3 heating zones (mix of 1″ and 3/4″ copper). I’m using the pre-formed fiberglass pipe insulation that has a white scrim jacket, as that’s what was recommended to me. Home Depot carries this stuff. I found it in the aisle with the furnace/air handler filters, thermostats, and ductwork. Here’s the catch — the stuff is tagged as being for various sizes of copper pipe, but the tags have no bearing on reality. I initially bought the stuff labeled for 1-1/4″ copper, but it was way too big for my 1-1/4″ pipe. I had to return it and get the stuff labeled for 1″ copper, which was a snug fit on the 1-1/4″ pipe. And, the stuff for 1″ pipe is actually more expensive than the stuff for 1-1/4″ pipe (by about 50¢ per 3′ length), which makes absolutely no sense.

Fast forward to the actual installation. The insulation slips easily over the pipe, and seals shut with an adhesive strip on the scrim jacket. However, on the stuff I bought, the adhesive doesn’t hold up very well against the expansion and contraction of the pipes as they heat/cool… a lot of the seams were popping loose just a few hours after I wrapped the pipes. I’ve compensated by adding some strategically placed wire ties, but I may need to track down a better adhesive to apply to the problem areas.

For butt joint (and possibly seam) sealing, I found some white scrim tape at Grainger, but it’s mind-numbingly expensive: Around $35 for 50 yards. That’s almost 25¢ a foot. I can’t imagine what’s in the stuff to make it that expensive.

On a totally unrelated note, I see that Home Depot is now carrying trench drainage systems. This could come in handy for my driveway down the road….