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Cautionary notes

If you observe the following simple points when commissioning your geothermal borehole project, you may save significant amounts of money and aggravation.

The investment in a GSHP with a borehole, or borehole array is a significant one and should not be put at risk by making the wrong choice at the outset...


Beware, of anybody that recommends multiple boreholes of less than 70 metres depth (unless there is a good, documented, geological reason). 

Go For, a company that can demonstrate the ability to provide borehole array design, utilising boreholes of up to 150m depth or more.


Beware, of anybody who says that putting geothermal boreholes closer together than 6m is a good idea, it is usually not. 

Go For, a company that will recommend spacing of more than 7m within your cost and space constraints.


Beware, of anyone that simply tells you that less than 20m of borehole per kW of rated heat pump capacity is sufficient; unless they can produce geological survey data or professional calculations to back this up.

Go For, a company that uses the latest MCS guidelines and/or certified hydrogeologist borehole array design. 


Beware, of anybody that tells you that each borehole will produce 5 kW of heat (It depends on depth and geology, this simplistic figure can be out by 60% or more). 

Go For, a company that takes a conservative approach, based on real survey data, or the MCS look-up tables.


Beware, of anybody that does not recommend a geological survey for your borehole installation.

Go For, an independent geological survey costing £200-300 minimum, depending upon kW required, money well spent.


Beware, of anybody that cannot, or will not, give you a fixed price and fixed description for the borehole drilling. 

Go For, a company with a well defined scope of works with a fixed price. 


Beware, of any company that does not use electro-fusion welded pipe couplings i.e. uses compression or screw fittings, for all underground joints. 

Go For, electro-fusion welded joints for all underground connections. They are buried and must perform, for decades!


Beware, of anyone that claims to have a professional borehole drilling company to do the work for you and then does any of the above. 

Go For, a direct contact with a company with modern, environmentally friendly, quiet, clean, equipment. 


Make sure, that you get documented proof of both the quality of the geothermal probes and the geothermal grout used. 

Go For, a company that uses certificated, pre-tested geothermal probes and high thermal conductivity grout, applied using the most modern mechanised grouting equipment.


  • Make sure, that you check the actual drilled depth of the boreholes, and that you get a pressure test certificate for each borehole and associated pipe work (Headerworks). 
  • Go For, a company that can demonstrate by certification and physical dipping if necessary, that total specified borehole depths have been achieved.
  • Make sure, that the borehole array is filled with a good proprietary, (documented), brand of thermal fluid and biocide. 
  • Check, that concentrations (and therefore temperature protection levels) are guaranteed, i.e. documented.
  • Check, the track record and equipment standards of any contractor before committing. 
  • Make sure, that the equipment used is modern and conforms to the latest safety standards. Ask around