An increasing number of drilling contractors are successfully exploiting the technical benefits now available from offering PE100-RC probes and pipework rather than traditional PE100 in their ground source installations.

Sean Sowden of Go Geothermal, the UK's leading independent geothermal pipe and material supplier, says that it has seen demand for the new generation of ground source probes and pipework increase considerably since it was included as an acceptable pipe material in the GSHPA’s Vertical Borehole Standards, published in September 2011.

He says: "PE100-RC gives contractors an important differentiator in a competitive market and offers real technical and commercial advantages for both probes and collector pipes."

PE100-RC stands for Polyethylene Resistant to Crack and it is defined as an advanced non-cross linked polyethylene, characterised by longer lateral chains than those found in standard PE100.

What this means is that PE100-RC has the same properties as PE100 in terms of temperature resistance and the requirement for welded connections but crucially it offers better mechanical properties with increased resistance to both stress cracking and point loads.

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The PE100-RC pipework supplied by Go Geothermal is RAUGEO PE100-RC, developed by the polymer specialists REHAU and already used extensively in many parts of mainland Europe where PE100-RC is the ground source probe and pipework of choice.

With many European heat pump manufacturers now specifying only PE100-RC for use with their heat pumps, Go Geothermal predicts that the market for the pipework is set to expand even further.

The major benefit of PE100-RC for probes is the increased point load resistance over PE100. When a probe is inserted into a borehole, it does not always sit straight but instead rests against the borehole wall. If there are any “sharps” the pipe will expand and contract against this sharp and, over time, this ‘point load’ could eventually cause pipe failure in PE100 probes.

In both Notch Tests and Full Notch Creep Tests (FNC) measuring stress cracking and point loads for both types of pipework, PE-RC has been shown to outperform PE100. For example, PE100 achieves >1,000 hours in the Notch test and >2,000 in the FNC test, whereas PE-RC achieves >5,000 hours in both.

Both REHAU and Go Geothermal have also proved that the increased mechanical properties of PE100-RC pipe mean that it can be used in horizontal installations without the requirement of a sand bed. This saves a significant amount in installation time and material costs (sand).

In many instances, it actually works out more competitive to use PE100-RC pipe for horizontal collectors as the additional cost of the pipe is more than offset by the savings on the overall installed cost.

PE100-RC pipework is also used on the REHAU RAUGEO coaxial probe used for Geothermal Radial Drilling (GRD), providing optimum probe strength when the coaxial probe is inserted into the borehole and can easily be connected into the REHAU manifold chamber range via Electrofusion fittings.

Further details are available via the website at www.gogeothermal.co.uk, or by calling 01388 720228.