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Old 11-14-16, 09:07 AM   #1
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Default What underground insulation for hdpe pipe???

OK you ravagers of window units, I'm about to bury 3 or 4 pairs of 3/4" hdpe in/out lines in 1 trench about 75' from my basement to the same # of vertical heat pump utube bores in the yard. Trench depth about 2 or 2.5 ft. Earth is clay/loam.
My first thought was to use the fat pool noodles that are on sale cheap at end of summer at the big box stores to insulate each line as their id seems about right but wondered if they would deteriorate or saturate underground?? Maybe food for earthworms?
Other idea was to get some 8ft sheets of 1" pink foam board, line the trench bottom with it and the sides maybe 6" up from the bottom. Then gang all the cold lines on one side, hot on the other, separate them with a foam piece dividing the hot gang from the cold, the top it with a sheet across both rectangular alleys - think a rectangular cold pipe alley beside a rectangular hot pipe alley extending along the bottom of the trench then and shovel in the dirt??
Not too cold here maybe lows of 5 - 10F and high of 95 in summer.
Then i wondered if these are commonly insulated or even separated in the trench since they are sort of married anyway in the bore holes?
Anyone with any experience on these?

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