Our Geothermic Method
Geothermal drilling and heat pump systems being two distinct technologies, you will need the services of both a heat pump supplier/installer as well as the expertise of a geothermal drilling specialist.
This is where Brewster Well Drilling comes into play. Our many years of experience ensures the success of your drilling project, and an installation guaranteed to meet the highest industry standards. As the initial financial investment of such a project is considerable, it is important to be surrounded by a solid team of geothermal drilling experts. This is what you will find at Brewster Well Drilling.
1. Needs Assessment
According to the size and cooling/heating needs of your building, your heat pump supplier will recommend a heat pump able to provide the proper tonnage. Prior to that, Brewster Well Drilling and your heat pump supplier will also have determined whether your geothermal system should be open or closed.
The open loop circuit consists in drilling two wells. The first one used to supply the heat pump and the second one to be used as absorption well. The water pumped from the ground is used as the medium for heat transfer.
The open loop system is suitable where there is access to a large amount of water, not too deep into the ground. The source must also be of high quality (low in iron, calcium and sulphur), in order to avoid a build up of deposits. Deposits could damage the pump in the long run. Note that open loop systems are mainly used for larger projects.
The closed loop system is the system is the most common system used in recent years . A closed loop system circulates a heat transfer fluid (usually 25% antifreeze / 75% water) through a system of pipes inserted in the boreholes connected by supply piping below grade.
The space between the piping and the borehole's wall is then filled with a thermally enhanced bentonite grout in order to allow efficient heat transfer from the ground to the heat transfer fluid. This system is very stable and highly reliable when installed by geothermal drilling experts.
Prior to installation, one of our specialists will meet with you, on site, to discuss the borehole locations and survey the area.
2. Borehole(s) Drilling
When drilling, our experts use 6 inch wide rotary drills. On average, we need to drill 150 feet for every ton of heat/cooling required. In other words, we need to drill 300 feet deep for a building requiring two tons of heat/cooling. Depending how many feet are needed, we will decide whether to drill more than one borehole. Rarely do we need to drill more than 600 feet deep.
For a location requiring 900 feet of drilling, we will usually choose to drill 2 boreholes of 450 feet each. When more than one borehole is needed, there must be a minimal distance of 15 feet between each one. In order to keep soil from collapsing into the borehole a steel liner is used from ground surface to bedrock.
3. Piping Installation (Closed Loop)
High Density Polyethylene (HDPE) pipes are used in order to circulate the anti-freeze solution inside the borehole. In our workshop, the pipes are heat fused, filled and then tested for 24 hours, in order to ensure there are no leaks. When we are satisfied there is no leak, the pipe is Installed in the borehole with pipe spacers to maximize efficiency of the borehole.
4. Borehole(s) Grouting (Closed Loop)
Once the pipe is inserted, the remaining space around the pipe is filled with a non-permeable grout with a high conductivity additive such as silica sand or graphite. This will guarantee a good heat exchange between the ground and the heat transfer fluid in the piping.
Depending on the project, we may also choose to use a grout mix consisting of silica sand, Therm-Ex bentonite and water. A high pressure injection pump will inject the mixture from the bottom to the top of each borehole (tremie type injection). This method meets CSA standards.
5. Horizontal Piping Installation
Afterwards, we install the horizontal piping, complete extensive pressure testing and finally purge the system while conducting flow verification tests. These pipes will be used to carry the heat transfer fluid from the boreholes to the building. This is where your heat pump installer takes over by connecting the piping to the heat pump.
Brewster Well Drilling : The Right Choice For Your Geothermal Project!
Over the years, Brewster Well Drilling has carried out as many large scale projects as it has residential ones. We have the knowledge, equipment and employees to successfully conduct any of these mandates. Whether your site requires 100 boreholes, or you just want to take advantage of this technology for your family residence, Brewster Well Drilling reliability and professionalism is what you need! We will complete your geothermal project successfully!