DESCRIPTION
There are 3 main types of geothermal drilling which can be utilized in ground source heat pumps. The first two are the most common and can be utilized anywhere you have the physical room for two or more wells.
CLOSED LOOP SYSTEM
A closed loop system utilizes a field of vertical loops filled with glycol. Each of these holes is generally between 200' and 400' feet deep. The number of holes and the depths depend on your heating needs and cooling capacity, and the local geothermal gradient. A small circulating pump circulates the glycol over a heat exchanger on your heat pump. In short, the heat pump pulls the chill out of your home, and places it in the ground. At the same time, it pulls the heat out of the ground and places it in your home, efficiently heating your home. The process can also be reversed to cool your home. This process uses no propane or natural gas and requires little power the electrical -since it only needs to circulate the gycol through your loop field and the heated air through your home. Depending on your heating requirements most homes use between 2 and 10 vertical loop wells. Closed loop systems are generally more efficient than the pump and dump system covered below.
PUMP AND DUMP SYSTEM
If you are in an area with an ample amount of shallow ground water, and your local geology can accommodate a pump and dump system, it may be the most reasonably priced. Pump and dump systems can be almost as efficient as a closed loop system with far less initial cost. The cost difference arises from the ability to only need to drill two shallow wells, instead of two deeper wells. A pump and dump system works identically to a closed loop system, except ground water is pumped over the heat exchanger instead of gycol. Groundwater is pumped from one well and dumped into the other. No water is wasted in the process as you put the water right back into the same aquifer you removed it from.
DEEP GEOTHERMAL DIRECT SYSTEM
The most efficient form of a geothermal heating is a deep geothermal direct system. Most places in Montana have a geothermal gradient of between 10 and 15 degrees per 1000' of depth. The geothermal gradient is generally higher in places that are close to igneous or volcanic rocks such as Central Montana. The shallow ground water in Montana is generally around 50 degrees F. This means if you pull water from a 3000' deep well, it is often 80 degrees or warmer. Another benefit is that many of Montana's deep aquifers actually artesian and don't require a pump, saving even more energy. This warm, or even hot, water can be circulated over a heat exchanger and used to heat your home, shop, and provide an unlimited supply of hot water. However, deep aquifers often have poor water quality; making it unlikely that it could be used as a fresh water supply. Occasionally, deep wells produce fresh, and potable water, but your changes are low.
There are 3 main types of geothermal drilling which can be utilized in ground source heat pumps. The first two are the most common and can be utilized anywhere you have the physical room for two or more wells.
CLOSED LOOP SYSTEM
A closed loop system utilizes a field of vertical loops filled with glycol. Each of these holes is generally between 200' and 400' feet deep. The number of holes and the depths depend on your heating needs and cooling capacity, and the local geothermal gradient. A small circulating pump circulates the glycol over a heat exchanger on your heat pump. In short, the heat pump pulls the chill out of your home, and places it in the ground. At the same time, it pulls the heat out of the ground and places it in your home, efficiently heating your home. The process can also be reversed to cool your home. This process uses no propane or natural gas and requires little power the electrical -since it only needs to circulate the gycol through your loop field and the heated air through your home. Depending on your heating requirements most homes use between 2 and 10 vertical loop wells. Closed loop systems are generally more efficient than the pump and dump system covered below.
PUMP AND DUMP SYSTEM
If you are in an area with an ample amount of shallow ground water, and your local geology can accommodate a pump and dump system, it may be the most reasonably priced. Pump and dump systems can be almost as efficient as a closed loop system with far less initial cost. The cost difference arises from the ability to only need to drill two shallow wells, instead of two deeper wells. A pump and dump system works identically to a closed loop system, except ground water is pumped over the heat exchanger instead of gycol. Groundwater is pumped from one well and dumped into the other. No water is wasted in the process as you put the water right back into the same aquifer you removed it from.
DEEP GEOTHERMAL DIRECT SYSTEM
The most efficient form of a geothermal heating is a deep geothermal direct system. Most places in Montana have a geothermal gradient of between 10 and 15 degrees per 1000' of depth. The geothermal gradient is generally higher in places that are close to igneous or volcanic rocks such as Central Montana. The shallow ground water in Montana is generally around 50 degrees F. This means if you pull water from a 3000' deep well, it is often 80 degrees or warmer. Another benefit is that many of Montana's deep aquifers actually artesian and don't require a pump, saving even more energy. This warm, or even hot, water can be circulated over a heat exchanger and used to heat your home, shop, and provide an unlimited supply of hot water. However, deep aquifers often have poor water quality; making it unlikely that it could be used as a fresh water supply. Occasionally, deep wells produce fresh, and potable water, but your changes are low.