Answering your questions.

Questions about GSHP (Ground Source Heat Pump) Boreholes

For questions about Waterwell Boreholes please scroll down.

Can anyone have a GSHP borehole system?

Almost anyone with a garden or free external area can have a GSHP borehole system.

Can you have them in town properties?

Yes, provided the geological conditions permit boring – that’s something we explore as part of our initial survey.

What about older or period properties?

It is perfectly possible to have a GSHP borehole system at an older property and the system can be linked to conventional gas or electric central heating, not just underfloor heating.

How much will I save?

You could save up to 70% on your fuel bill, added to which a GSHP system has low maintenance costs and can add value to your property.

What does the borehole look like at the surface?

At the surface you normally see only a manhole cover.

How many boreholes will I need?

This depends on how much  heat loss there is from your building and what kilowatt your system is. The bigger the property, the more boreholes you are likely to need.

How far apart can boreholes be?

Ideally boreholes to be over 10 metres apart (further if possible) in order to maximise the efficiency of the heat pump system.

How much room do you need to drill?

Our purpose-built geothermal rig can fit through 5ft gaps and work in an area of approximately 4 parking spaces per borehole.

What type of drilling methods do you use?

We use a rotary drilling rig and drill using compressed air or drilling fluids.

Do I need permission for ground source heat pump boreholes?

Not usually. However, each site should be assessed individually. There are sometimes drilling restrictions from the Environment Agency, local planning departments and London Underground. We will check this for you and complete any necessary paperwork.

What type of ground probes are used?

We use Probes manufactured from PE100 virgin grade High Performance Polyethylene Pipes (HPPE) with a Probe tip factory fitted and welded in accordance with SKZ HR3.26 test regulations. Each Probe is supplied with an individual Batch Test Certificate and is metre marked to ensure the correct depths are achieved.

How deep do the borehole probes go?

The average depth of borehole probes is 100 metres but depending on the nature of the site they can go as deep as 200 metres. It is essential that the correct amount of probe/probes are installed.

Why use thermally enhanced grout?

This ensures that maximum efficiency is achieved from your borehole. Thermally enhanced grout can be up to 3 times more conductive than cheaper grouts.

Geothermal Grouts – The Basics
1. Thermal Conductivity of most ground is  0.8 -1.8 Btu/ft degree Fahrenheit or 1.4 – 3.1 watts/m degree Celsius
2. It is logical then that the Geothermal grout should match the conductivity of the ground or be close to it.
3. Less than this level the grout is acting as more of an insulator than a conductor and impairs heat pump efficiency considerably, necessitating much longer pipe lengths and deeper holes.
4. Regular CE bentonite which is still widely used in Geothermal grouting can only be mixed to a maximum of 10 -15% solids and then only achieves a thermal conductivity of around 0.2 Btu/ft degree Fahrenheit or .35 watts/m degree Celsius so they behave as insulators and should NOT be used for Geothermal work.
5. Furthermore at low solids i.e (20%, Bentonite may loose water to formation and so dry out and crack so 30% solids should be considered the minimum for a Geothermal grout
6. Proprietary grouting bentonites such as Geoseal, can be mixed and pumped at ) 30% solids with relative ease and permit long placement times to achieve thermal conductivities around 0.38 Btu/ft degree Fahrenheit or 0.65 watts/m degree Celsius. If these special bentonites are then enhanced with thermal conductivity improvers (eg sand ) up to 70% solids they achieve thermal conductivities up to 1.4 Btu/ft degree Fahrenheit or 2.4 watts/m degree Celsius and still deform and seal better than cement based grouts.
7. One study in the magazine ‘Outside the Loop’ indicated a saving of 23% in pipe design length per ton was achieved by moving from a conductivity of .4 up to 0.85 Btu/ft degree Fahrenheit (0.65 up to 1.5 watts/m degree Celsius) and a further 19% saving in length was achieved when increasing conductivity from 0.85 – 1.4 Btu/ft degree Fahrenheit (1.5 -2.5 watts/m degree Celsius) giving a total saving of 47%. However for practical purposes most companies find little benefit in raising conductivity over .85 Btu/ft degree Fahrenheit or 1.5 watts/m degree Celsius
8.In nature, clay deposits are typically 65-85% solids and contain or seal off strata containing water or oil and even radioactive material, preventing migration or contamination of the ground above. In the same way, clay grouts deform and maintain a seal irrespective of most ground movement and the sand enhanced bentonite grouts are typically 60-70% solids. Furthermore bentonite/ sand grout will not shear the pipes if the ground moves as it simply deforms.
9. By contrast rigid cement based grouts do not deform with ground movement but fracture damaging any pipes buried within the grout and allowing leakage of gas or liquids around the grout mass.
10. Cement on its own has relatively poor thermal conductivity ( 0.46 Btu/ft° ) due to micro pores and shrinkage so must be mixed with bentonite and thermal conductivity improvers to achieve higher values. However while cement mixtures form harder grouts which are needed for certain applications, it is felt that for Geothermal work, these are not ideal.
11. To sum up, proprietary bentonite based grouts such as Geoseal mixed with sand, or pre-mixed bentonite/sand grouts like Thermoseal, are the best grouting solution available today. They can be tailored to produce efficient heat conducting mediums that protect and seal effectively and are stable long term.’

Can I use a water borehole for water and also a closed loop ground source heat pump system?

No, because these systems need to be kept separate. However, they can be installed on the same site. In larger projects an open loop system may be used which uses the ground water and re introduces it to the ground. An abstraction licence would be required from the Environment Agency if over 20,000 litres is used per 24 hour period.

What about maintenance?

Nicholls Boreholes offer an ongoing maintenance contract for your GSHP, for your complete peace of mind.

Is there any funding to help with costs?

Yes, the Renewable Heat Incentive (RHI) scheme reduces the time it takes to recover your initial capital investment. Email or call us now on 01403 820750 for more information.

Questions about Waterwell Boreholes

Can anyone have a water borehole?

Almost anyone with a garden or free external area can have a water borehole.

Can you have them in town properties?

Yes, we have installed waterwell boreholes in areas as central as Chelsea!  If the garden space is restricted, we can use especially compact drilling equipment to carry out the work.

How much will I save?

Once installed, your water could be virtually free.  For more information please email or call us on 01403 820750.

What does the borehole look like at the surface?

In most cases at the surface there is just an ordinary manhole cover.

How do you know if there is water down there?

We use the help of the British Geological Survey, who provide an accurate prognosis of groundwater depth, so we know how far down we need to drill. On some occasions we contact a dowser because on some that helps us to find out the best place to drill.

Is groundwater always safe to drink?

Usually, but not always. It may have minerals in it that can give the water an unpleasant taste or in rare cases be contaminated. We recommend that the groundwater is tested and correct filter systems are fitted as required.

Do I need a licence or permission?

Not usually. Anyone is allowed to extract up to 20,000 litres per day without a licence or a charge. If you do want to extract more than this, you will have to get an abstraction licence from the Environment Agency.

How deep do you need to drill?

This depends on the geology of the ground and how far you need to drill to get to the water level.

What about maintenance?

When the job is completed we offer you an ongoing maintenance contract for your complete peace of mind.

Is there any funding to help with costs?

Yes, as well as saving up to 40% on your water bills you could benefit from FREE borehole installation – simply contact us now or call us on 01403 820750 to arrange a site survey and no-obligation quotation.

Questions about drilling

Can you drill in my garden?

Yes we can drill in your garden, so long as we can get our equipment in there – our smallest rig can access with a clear space of just 1.5m.

Does it make a mess?

Nicholls Boreholes always prepare the site prior to work commencing ensuring that the surrounding ground is disturbed as little as possible with as little disruption as possible. They use their track mounted rigs that spread weight evenly preventing gouging of the ground.

How deep do you need to drill?

This depends on the geology of the ground and how far you need to drill to get to the water level.

How much room do you need to drill?

Our purpose-built geothermal rig can fit through 5ft gaps and work in an area of approximately 4 parking spaces per borehole. It is essential that the boreholes are drilled to the correct depth so don’t be fooled by a cheaper quote that may not have enough metreage.

Do you have a question that’s not answered here? If so, please email us or call us on 01403 820750 with your questions and we will be happy to answer them.