Does it make a mess?
As with all ground works there can be a mess, however Teckna Group try to minimise mess and disruption to your garden or premises by utilising specialised drilling and separation equipment.
All header pipework (pipe work that connects the boreholes) installed to MIS 3005 standards will be below the local frost line and is usually 1.0m deep with flow and return pipes seperated in a 500mm wide trench or individual trenches to suit. Working on thes guidelines insulation would only be required should the flow and return be run together in the same trench or where the pipework rises above the local frost line – this is usually at the manifold and should be Armaflex closed cell type insulation.
What size loops are required?
Below 110m deep – 32mm loops.
Over 110m deep – 40mm loops.
Depths between 100 to 120m may use both.
Loops should be sourced from a reputable manufacturer, be manufactured of PE100+ polymer with an SDR rating of 11 (not inferior PE80 SDR17) and be suitably pressure tested with water (not air) before installation into the borehole and after grouting.
How far apart should loops be spaced?
Loops should be at least 6m apart to avoid thermal linkage, but this again can vary depending on the ground strata.
Loops should be at least 5m away from buildings and walls, as well as siting well away from trees.
The following calculation can be employed using an average value of 35W/m.
Heat Pump capacity in KW 12KW (Heating an average family 3-4 bed house with reasonable insulation)
Assumed COP, ie, coefficient of performance of 4, i.e. for every 1KW input, 4Kw of heat are output. Or to look at it another way, 1kW of electricity put in (to drive the pump etc.) liberates 4 from the ground, a net gain of 3, hence the following calculation.
Energy to be provided by ground source = 12 / 4 * 3 = 9.0 KW (9000W)
Using an Energy yield per metre of active collector 35 W/m the required amount of borehole would be 9000/35 = 258metres.
This could be achieved by installing:
2no boreholes to 130m deep or
3no boreholes to 86m deep.
This assumption of 35 W/m depends upon geology and is a summarized extract from the latest MIS 3005 – Issue 3 publication.
How many boreholes and how deep?
As the boreholes are part of a bespoke system design your heat pump supplier/installer should be able to provide this critical information, however for an approximate calculation see below.
Vertical borehole heat collectors usually operate at a higher efficiency, i.e. produce a higher heat yield per metre, than horizontal collectors. They are however, usually more expensive to install than horizontal collectors.
Vertical borehole collectors can provide between 25 watts per metre (W/m) in dry loose gravel and 60-70 W/m in saturated stone of active collector. This figure varies upon the thermal conductivity of the strata in which the borehole is drilled and backfilled with high thermal conductivity geothermal grout that is installed from the bottom of the borehole to the top.
This is one of the reasons that a geological survey is usually required for the site which will give a, usually reliable, projection for this value where you are. Relying on assumptions for this figure, can turn out to be expensive if your new heat pump installation fails to deliver the performance that you expected.
For larger installations this value becomes more critical to the succeful installation of a properly designed heat pump system.
Do I need filtration equipment?
As a minimum we would recommend that all newly installed wells have a full water analysis report done before the well is put into use to determine if any filtration is required and the type, as a minimum a bacteria test should then be done yearly.
The report can be commissioned by us on your behalf for a nominal fee prior to the completion of the well and a sample sent to one of the UKAS registered laboratories that we use.
On completion of the water analysis a suitable filtration system, sized to the rquired water flow can be installed which should have as a minimum for any drinking water a UV Filter to kill bacteria.
Does it make a mess?
As with all ground works there can be a mess, however Teckna Group try to minimise mess and disruption to your garden or premises by utilising specialised drilling and seperation equipment.
How long does it take?
The Hydrology Report usually requires 14 days to obtain, with a quote provided to you usually within 48 hours of receiving your enquiry or the the report. The drilling and installation works depending on the depths and ground will normally be 3-10 days on site.
How much water can I use?
Anyone can abstract and use 20cubic metres (20,000litres, 4400gallons) per day with no licence required. If you require more than this then a licence will be required from the Environment Agency.
On completion of any well over 15m the BGS should be provided with the information on the borehole drilling, water levels, etc and we will provide this to them.
Can I put a well anywhere?
Wells can be sited practically anywhere a drilling rig can be placed, however there are some equally important places that they should not be placed to avoid contamination of the borehole water.
Preferably wells should be upslope of any potential sources of pollution – septic tanks, fuel tanks, soakaways, grazing areas or anywhere that low lying water may stand.
Is water always guaranteed?
Water quality or quantity cannot be guaranteed, no reputable drilling contractor will. Although optional we always recommend that a Water Hydrological Survey is undertaken before any drilling work starts on site to assess your chances of water and predict what depths this may be at (as this will affect the cost of the borehole) and enables us to offer a fixed cost for the works.
As part of our service we can commission a survey on your behalf with a Hydrology company such as the BGS for a nominal fee of £550.00 this will indicate likely availability of water and enable you to have a fully informed choice whether to invest into a borehole or not.
If you require us to commission a survey for you, or to discuss your project please contact Sue on 01257 421700 or email us here
How much does it cost?
Costs will vary depending on the specifications that you require, the geology of the area you live, depth of water aquifers in your area and ancillary equipment you may require – such as holding tanks.