Undeground Pipes

Something interesting has occurred that I thought I should mention to help others in the future. Reason for post: Concern that underground insulation gets wet and nullifies R value.

I buried four one inch Pex pipes five feet under ground. Each Pex has a layer of that black 1/2" thick foam pipe insulation. Then all four are wrapped in that foil faced bubble wrap. Then all four went inside 6" PVC pipe. Fact: wet insulation loses all it's R-value. After knowing that an electrician buddy told me he has never, ever, seen an underground pipe that was not full of water. With his comment in my head, when I buried my pipes I added something... a clear flexible plastic tube that goes down into the pipe and is secure at the bottom. The 6" PVC happens to go slightly downhill to the point under my outbuilding. The clear tube goes down inside the PVC and terminates at the bottom of the PVC at the low spot. I figured if I had a leak I could tell by sucking on the tube. If it became a problem I'd get some sort of pump. I knew darn well my PVC wasn't going to leak, but just in case... Fast forward to the underground pipe complete, the slab is in. I had taped a plastic cover over the end of the PVC so rain wouldn't get in. At some point I noticed a hole in that cover and it had rained. I sucked on the tube & got water. I figured it was rain water as it was clear & clean. A leak would give mud water. I fixed the leak in the cover and built the outbuilding. At some point, opened the bag.... More clear water! I thought the cover must have somehow leaked. Now it is inside under a roof. I sucked out a half gallon of water & thought that would be the end of it. NOT. Each day I was getting 2 or 3 cups of water. A light finally came on in my head.... It's condensation! The PVC is buried in earth that stays 48* year round. The cool walls were condensing water vapor and that is where the water is coming from. If I had no "test tube," I'd never have known and eventually the insulation would be soaked. A few days back I got an idea.... Foam in a can insulation. Plug both ends, stop all new air from entering and condensation would go to zero. It worked.... to a certain extent. I went from 3 cups a day to less than one cup a day, but still, it would eventually add up. I bought a little siphon pump & each day or two give it a couple of strokes. Today I only got 1/4 cup. I think between not much new air getting in and the pipes being warm have slowed it up.

I seen people write "I lose 2 degrees from the boiler to the house" (or three) . My pipes run about 75 feet from the coal boiler to the boiler room in the house. I do not get one full degree of difference.

So, if you're going to bury pipes underground, give thought to devising a way to have a low spot and a way to get water out of the pipe!

Vey interesting! And ingenious.

You da man, Freddy!! :nice:

Freddy,
Your wicked smaat!

I'm hoping that with this: I won't have an issue with water, except what is INSIDE the pex. For the price, I'd BETTER not have an issue with water.... or I'll be , really

But, I wanted to dig up the yard once and be done with it and not have to worry about a failure down the road. Since we ended up having to deal with a buried phone line that "wasn't there" 3 years ago when I had the lot located when we moved in, even though utilities haven't done any work in the area as well as finding a buried rock the size of a small planetary moon in our trench path, it went pretty well. 152 feet of pipe went in, and I can't even imagine trying to DIY that much. It makes a mess, too: Now I've got all winter and next summer to come up with a boiler setup for the garage - hopefully something I can run on our local Illinois coals.

Chris

Europachris, Nice looking pipe! It would be interesting for you to put thermometers on both ends of the pipe and see if the temp differences change over time. For $20 they sell a nice thermometer that goes in a well that's soldered into a copper tee. You can remove & replace the gauge without touching the plumbing.

Do something about those giant gophers!

Freddy wrote:Reason for post: Concern that underground insulation gets wet and nullifies R value.

You want to use "closed cell" insulation on your pipes. Properly installed it does not absorb water. It's commonly used to insulate A/C refrigerant lines. You want the tube style not the ones that are slit lengthwise. One brand is Armacell. The installation guides will give you all the details.

If you seal each end of your conduit you will not have a condensation problem. There will be some heat loss through the insulation no matter how good it is. This will dry the stagnant air and eventually the relative humidity will be below the dew point and there will be no condensation. All this assumes there are no conduit leaks allowing ground water in. The tube drain is a good idea. Or if possible pitch the conduit to one end.