Drilling the hole (well) for geothermal vertical collector

And then we started … I went into action and made a deal with one drilling and mining company from my country to drill holes. It is important to make a real contract for this service and to sign the contract from both parties (you and company). Important things about the contract:

• article with deadline and penalties for not meeting the deadline must be included


• article about possible damages made by company and their responsibilities (e.g. in case where the driller damages your house, because he was not careful enough when he was moving the drilling machine – see it on the picture)


• If you are not sure, see legal advisor

We first planned to drill two holes for 100meters. The first one was O.K. When drilling the second one some problems occurred, the hole (well) was not stable enough and we only reached about 60 meters. According to the calculations 160 was not enough, so we made the third well for another 60 meters. Together we have 220 meters.
Important things:

• wells or holes should not be to close together, it is recommended to keep 10m distance between two wells


• It is quite noisy when drilling,… your neighbors will complain if you will not inform them in advance


• It could be quite messy around drilling machine and underground water could erupt from the hole


• If you already have a house with nice colored façade and the machine in near the house, be sure to protect the house and window

We were drilling about 14 days.

Calculation of energy losses and energy needs for the building

Building insulation is the most important factor when calculating energy loses or on the other hand energy needs for heating. Heating system must be aligned according to building energy loses. Here are my final numbers and calculations:

Building parameters:

• Building square meters (room surface): 180 square meters to heat
• Type of heating: ground heating
• Building walls: 30 cm brick and 10 cm isolation (glass wool)
• Building roof: wood structure with, 21 cm of isolation (glass wool), standard knauf
• Building ground floor (to the ground): 5 cm concrete, 8 cm isolation, 5 cm concrete, 40 cm sand layer
• Windows: thermo glass

Coefficients:

• Windows thermal transmittance: U=1,1W/m2K
• Glass wool thermal conductivity: 0,035 W/mK

Final calculation for heat pump system installation. We need:

• Heat pump with output power: 14kW + 6kW Optional Extra Heater for Extreme Low temperatures
• Geothermal vertical collector according to ground structure: 2x100m
• Water Heater: 300 liters

There were also other numbers and quite complicated parameters and calculations. I think shown numbers are enough to get an impression. I will put some calculations in PDF to this blog for download in near future.

Choosing renewable resource (source)

When deciding which renewable resource to use (air, ground water, water from lake or river, ground source – geothermal - heat of rocks) it is necessary to consider many aspects, the most important are:

• what resources are available in the neighborhood and what are temperatures (e.g. temperature of underground water)
• what resources you are allowed to use according to the local regulation (e.g. in some countries it is prohibited to use underground water in others you should get special permission from the government)
• what is your climate (winter air temperature)
• how much money are you prepared to spend for the project (e.g. air sourced heat pump installation is probably the cheapest, ground sourced heat pump (geothermal) installation with vertical collectors is probably the most expensive)
• are you planning to use your heat pump also for water heater
• are you planning to use your heat pump also for cooling
• how much isolation coat are you planning to put on to your house and what would be the energy loss of your house
• what kind of heating are you planning to implement (low temperature floor heating, high temperature)
• what is or should be coefficient of heat pump performance (I will explain this term latter)

When considering described issues you should definitely involve someone who is familiar or even better professional in those calculations. At the end you should know all calculations, energy loss, primary source temperature, type of heating (e.g. floor heating) and other parameters.
For my project I have engaged one local professional who was very familiar with this numbers and calculations. I have paid to him 100 € and it was worth paying. Finally I have decided to use ground sourced heat pump with vertical underground collectors (geothermal).