insulating underground hot water pipes?
Hi:
I am planning on putting plumbing (hot and cold water) into an outbuilding which does not have its own water heater. I was thinking of using the home’s water heater and running copper pipe underground (about 20 feet) to the new structure but don’t want to waste the water and energy through the underground pipe. I was thinking of running the pipe inside of French drain pipe (with the holes facing up), with spacers to keep the copper centered and then filling the drain pipe with spray foam insulation. Will this work? (the run to the outbuilding is straight) Also, if it does work, would it work well enough for me not to have to worry about a return hot water loop to the heater? The climate here is temperate–the ground never freezes.
Thanks,
Pasta
Replies
I don't know where to get it, but I saw Bob Vila show on "shared housing" community and they had a cenral heat source and had a large flex pipe (looked about 3-5") filled with foam and a hot water and return tubing in the middle.
I don't see why what you want to do won't work.
But you want to make sure that it stays dry. I would not use the pref pipe, I think that there are way too many holes.
But rather I would drill fewer holes and put them 180 apart so that you have a fill hole and one to see when they are full.
What you need is here:
http://www.rovanco.com/index.html
They used it on TOH in Mass. The pipe is PEX. A return loop ? You need to decide how often you are going to use the hot water in the outbuilding to determine whether or not you need this.
carpenter in transition
I don't know what the outbuilding is, or how much or how often hot water is needed, but if it's only occasionally and in small amounts there are alternatives.
I have run hot lines and heating lines underground on many projects, I think the easiest way for you would be to lay 6" solid pvc sewer pipe from building to building with all joints glued then insulate your pipe with pipe insulation and slide them into your 6" sleeve this way you can always pull them out or add a recirc line or what ever at a later date.
Tks kevin
I've used the urethane pre-insulated copper pipe (as available from the vendor in Tim Kline's URL, above) for running 10 to 20 feet between house and garage a few dozen times in Massachussets. Comes in twenty foot lengths and often the trench could be done with no joints in it (just at the end, under the building footprint). That was however, solar hot water systems and running a gycol mix.
Insulation does NOT prevent freezing. Insulation increase the time it takes to freeze, but if the pipe is shallower than your frost depth, it can freeze when you leave for the month of January to Hawaii. Insulation WILL save you money for lost BTUs, but that is a separate issue. A high traffic area or just a low-snowfall, low-temp winter can create deep frost depths. Ask your buliding department for local worst case. In my town, water main have frozen at 14 feet. Of course it is worse in Fairbanks - it gets cold up there.David Thomas Overlooking Cook Inlet in Kenai, Alaska