Wet Fiberglass Insulation at Chilled Water Lines

I'd go closed foam with duct tape to secure. Available at HVAC supply houses.

John Manville has a good glass with acrylic wrap. We have used it in the past and it is very good and clean looking. We usually hire a company that specializes in insulation to complete the job so it looks professional. Good for hot or cold pipes. Not sure what length or size you are looking for but it is worth doing and a final solution.

The humidity in the tunnel may require some sort of dehumidifying process. It is the humidity in the air condensing on the cold pipe and dripping.

First make sure what you are removing really is fiberglass, many older plumbing installations were insulated with asbestos. Either way I would rather remove it wet as less fibers becomes airborne. Also, if the water line must stay active, it may also need to stay chilled, consider removing and replacing sections.

What you can replace it with will likely be determined by the size of the pipe. You are looking for something that will provide insulation and a vapor barrier. The closed cell foam shown by kramarat provides both when taped. It goes on fast, is durable, and unaffected by moisture. It's a good choice if you can find the size that fits your pipe. The pipes are probably large if you're looking at cellular glass. The manufacturer or distributor is going to be your best source for installation procedures for their product.

For larger pipes (say 2" or greater), one choice is expanded styrene or polyurethane foam, made in trough-shaped sections. An external vapor barrier such as Mylar, or bitumen-based "Insulrap", is essential; sheet PVC outer coating is too permeable to water vapor.

Joints in the insulation should be staggered/overlapped, and caulked. For longer pipe runs, where thermal expansion may be a factor, there are ways to make expansion joints in the insulation. Right now I am forgetting manufacturers' names, but they have installation guidelines. If you are good at cutting intersecting contours, you can do this yourself.

You've got my vote... GA

Heres a link to a site with different insulators and their operating ranges. http://www.crossroadsci.com/PRODUCTS/ThermalComparison/tabid/65/Default.aspx

I can't believe anyone would use glass where they knew moisture was a factor!

Anyways my vote would be to use "elastomeric". I've used this type of insulation about a million times. You can get more than 1 choice on wall thickness. I suggest you use the thickest wall that will fit in your application. The thicker the wall the less amount of heat that will be attacking your pipes. You can get this type of insulation that has been "split" from the factory. It's made to be slipped over existing pipes, almost all of them have 2 tacky surfaces that can form a tight seam once the insulation has been fitted and applied. Also be sure and seal all the joints and inspect them from time to time. So it's a good installation practice to have the gaps facing to where they can be inspected easily. Just a slight gap will allow warm air to enter and condense.

Follow my advice and you'll never replace the insulation again. Good luck

Let me see if this is close.

We have applied a radiant barrier coating to interior AC ducts that were sweating heavily. It stopped the problem completely.

Think about it. Heat energy travels towards cold. In that process, it carries any humidity in the air with it until it runs into something solid, whether it's a wall, a pipe or an AC duct. That is why your pipes sweat, why your interior walls sweat in the winter, and why interior AC ducts can sweat.

Our URL is on my profile page.

Why did you put it on the inside?

Hi Fredski,

Our coating works as an insulating material on the inside or outside of a building or structure. It also works on the inside by not allowing any heat generated inside the building or structure to enter the walls or ceiling. On the other end of that, when applied to interior walls and ceilings, it also stops the radiant heat that has entered the walls and attic from radiating down /in to the living space.

It is a thermal energy barrier. Many people feel that because it is an Energy Star 'Cool Roof' coating, that is the only application where it is an effective insulation material.

It does alot more than roofs.

My question was about insulating the inside of ducts but thanks for taking the opportunity to make your sales pitch on all it's other uses.

"Why did you put it on the inside?"

Thank you for making the question specific to ducts. I assumed you meant the "inside" of a building.

Guess I should of asked "Inside of what?".

Pipe surface should be completely dry, hence stop chilled water flow for 24-48hours before applying adhesive or factory applied premoulded sections. Recommended insulations are nitrile rubber, poly urethane foam, expanded polyestyrene etc. Further ventilate tunnel to ensure fresh conditions & minimum humidity within. Fibre glass & rockwool are meant to insulate hot dry surfaces only