In a geothermal heat pump system, it indicates use of high density polyethylene. But pipes should be able to conduct heat.. Isnt polyethylene a poor conductor of heat?? Then why are they used here?? If not, which would be the most adequate material??
Even though thermal conductivity of HDPE is low compared to metals, it would still be the material of choice for such an application. It is not low enough to have any effect on the desired heat transfer - it's not an insulator, just lower than metals. The option would be to use someting like copper, but there material cost and installation cost would both shoot way up, and you'd have to worry about long-term corrosion. A much cheaper solution is to use HDPE, and to use a slightly longer run to compensate for the loss in transfer. The systems that specify HDPE have this built into their design. The result is a system that costs less than a comparable one in metal that has a longer service life. The downside is an increased size.
nicely u see, its relatively user-friendly, blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah, and that's how warmth is extracted from the living house for the time of the cooling technique.
The guy just above is absolutely correct. But you might want to look into ABS piping instead of HDPE. It will cost a little more that HDPE (much less than metal) but it is stronger and thus you can have a thinner wall thickness. While it has approximately the same thermal conductivity there is less wall thickness to conduct through and will work more efficiently.
