Heating and cooling with heat pumps (geothermal systems)

The application of geothermal systems (heat pumps) for heating and air conditioning of space.

In recent years, there has been a rapid increase in consumption and production of energy. The existing reserves of energy resources of classical type (coal, oil, gas, nuclear materials) are limited, non-renewable, and therefore more expensive.

New energy sources have been intensively researched and used substantially. They would solve the problem of the source of heat and electricity. Scientists and economists around the world are especially interested in alternative i.e. renewable sources of energy, such as geothermal energy, i.e. the use of the heat of the Earth's interior.

The heat energy of the Earth’s inside, i.e. rock masses and liquid fluids in the earth's crust are geothermal resources.

However, high temperature reservoirs are benefits of a few areas only. Here, high temperature geothermal reservoirs are present in Semberija and Posavina in wider area and in several smaller localities. Glowing Earth's core has nearly a constant temperature of the rock crust, and cooling of the heat towards the Universe is slowed by the Sun which seasonally and unevenly heats the shallow layer of soil.

How does a geothermal system function ?

A geothermal system can function in 4 different modes:
- Horizontal loop
- Vertical loop
- Lake-loop
- Open-loop system

Horizontal loop

- Horizontal loop is used where space for loop is not significantly limited;
- There are various forms of horizontal loops. There is no type of horizontal loop that is the best for every application;
- The choice of the type of loop to be used depends on the size of the system, space availability, conditions of the soil and the type of equipment which is used for excavation;
- Regardless of the type of the loop we choose, the price of performing does not change significantly;
- When the loop is installed a few meters below the ground, the space is backfilled and used for other purposes.

Vertical loop

- Vertical loop is used when an available piece of land is limited or when the type of land is not usable for horizontal loop;
- Vertical loop installation requires the use of drilling equipment, and therefore multiple boreholes are drilled;
- Borehole is cemented in order to provide good contact around the pipe and seal the borehole;
- Vertical pipes are connected in a horizontal system a few meters below the surface.

Lake-loop

- Lake-loop is a series of spiral pipes connected together and set on the bottom of the lake;
- Geothermal system for a regular house is a convenient choice for the lake loop;
- Lake must be at least 20 acres of land and 2.4 meters deep;
- Ideally, the lake would have to be away from home, but not more than 60m.

Open-loop system

- The only alternative to a closed-loop system is an open-loop system, known as a well-system. If your system is an open loop, it uses water that comes from the well. The water from well always circulates when the unit heats or cools. When the unit is not in use, it does not use any water.
- One of the ways to use the water in the unit is taking the water from a pond, a drainage ditch, a reservoir, etc. It is not allowed to re-use the water in the unit in households.

The advantages of using geothermal system technology

Energy savings

- Geothermal system produces 3 to 4 kW for every kilowatt of consumed electricity;
- Many people have experience in energy savings of 30-60% more than other common systems for heating and cooling.

Effective price

- Because of the remarkable efficiency of the system, any costs related to installing of geothermal units are usually much lower than your energy savings

Comfort

- You will experience a precise temperature adjustment without drying and warm air circulation from a furnace or cold blowing inthe air source of a heat pump

Reliability

- If you buy quality components, this system has a high reliability and reputation;
- Installation of loops is done by IPIN, a company which has great experience in the field of applied geology, drilling and construction of wells
- As well as your air conditioning system, your geothermal unit will operate for many years without causing any worries to you and with minimal maintenance and human intervention

Low-noise

- Different usual air conditioners or heat pupms are quiet outdoor units. These units are designed to work as the so-called "whisper quiet", similar to your refrigerator.

Safety and cleanliness

- The system does not burn fossil fuels, so there is no flame, smoke, burn or concerns about toxic carbon monoxide.

Environmentally friendly

- Your geothermal system does not release harmful gases ("greenhouse gases") into the air, as is the case with burning fossil fuels;
- Reduced energy consumption in the geothermal system in the future will reduce the need to burn coal and it will create space for smaller requirements of current capacity for electricity production;
- Geothermal units use far less refrigerant than an ordinary heat pump or air conditioning, and
they have already been sealed preventively in the factory;
- Significant reserves of coal used in BiH have a high sulfur content (over 1%): Čelebić 5.3%, Ugljevik 5.0%, 3.2% Mostar.

Frequently asked questions about heating from the ground

The main principles

Questions that should be asked in relation to a new heating system

Heat pumps: What are they and how do they function?

Closed loop system?

Open loop systems

Parts of the system

How does a geothermal system function?

During a year temperatures vary as the seasons change. However, when it comes to temperatures of the underground, this is not the case. Temperatures are relatively constant in the range 1.2 to 1.8 m under the ground throughout the year. Geothermal system is a system that consists of an inner heat unit and a dug underground loop that uses energy on the basis of these constant temperatures. During winter, fluid circulation through the underground loop system absorbs preserved heat and transports it inside. The inner unit compresses the heat to a higher temperature and distributes it all over the facility. During summer, the system functions vice verse - it takes the heat from the facility, transforms it through the underground loop and deposits it into the cold ground.

What are the differences between a geothermal system and a conventional system?

A geothermal system uses sun energy which is kept in the ground in order to heat houses and buildings. Electric power is used just to run the fan, compressor and pump. So, unlike conventional systems, geothermal systems do not combust fossil fuels in order to produce heat - they simply transform heat from the ground towards the object.

How efficient is a geothermal system?

A geothermal system is three times more effective than most efficient conventional systems because it does not combust flamable fuels in order to create heat. It provides 3 to 4 units of energy for every unit that supplies the system.

What does a geothermal system mean to the environment?

Since geothermal systems work with nature and not against it, they minimise the occurrence of acid rains, air pollution and greenhouse effects. In a closed, continuous loop, fluid is used and it does not harm the environment.

Do geothermal systems demand special maintenance?

No, they do not. Actually, geothermal systems are practically not maintained. When installed properly, closed loops will last for generations. The other half of equipment - the fan, compressor and pump are placed in a house and protected from weather conditions. Usually the only change which needs to be done is the check and change of filter.

How strong is a unit that is recommended, expressed in kW?

Geothermal units of heat pumps are equipped to provide a certain amount of energy per hour. The term kWh refers to how much heat a unit can produce for an hour. Before you decide what size of unit you need, you have to calculate how big the costs would be and what gain you would acquire if you choose this option. By doing so, you will be able to determine the size of the heat pump you need. Most fossil-run furnaces are too big for the needs of heating and that results in the increase of costs.

Is the efficiency rate real or is it just a manufacturer's average?

All types of heating and cooling systems have a nominal efficiency. Fossil-run furnaces have a percentage determination of efficiency. In order to determine efficiency correctly, one has to bear in mind the following factors: the losses of gas heating, the losses of circulation caused by a bigger size, electric use of fans, etc. Geothermal heat pumps, as well as other types of pumps, calculate efficiency by their coefficient of performance (COP). This is a scientific way of determining - how much energy a system produces in relation to how much energy it spends. Most systems of geothermal heat pumps have a COP in the amount of 2.5 - 6. This means that for every unit of energy which is used to start the system, 2.5 - 6 units are gained as heat. In those places where fossil-run furnaces can be effective 50 - 90%, geothermal heat pumps have more than 400% efficiency. Certain manufacturers of geothermal heat pumps and power distribution units use computers to determine the efficiency of system operation for your house or building.

Will the minimal water temperature influence on what heat pump to buy?

Yes, it will. If you have an open loop system, the temperature of entering water (EWT°) can range from 7°C in hilly areas to 14° in the coastline. All heat pumps can maintain temperature from moderate to warm. A closed loop system will come across EWT beneath the point of freezing. Not all heat pumps can work at those temperatures. What is important for you is to know what EWT your pump can support.

Are the salesperson and those who install the pump qualified for that task?

Do not hesitate to ask recommendations from a dealer. A respectable salesperson will not hesitate to give you the names and phone numbers of those who can confirm his abilities. The same goes for a loop installer.

Will an open or a closed loop be best for you?

It depends on several factors which were stated earlier. A dealer should install what is best for you, and not what is best for him.

When will the investment of geothermal heat system pay off?

If you want to have precise information, you have to know how much you are going to save in the costs of energy during the year when using a geothermal system. You should also know the difference in costs between this heat system and alternative heat system on one side and the central air-conditioning system on the other side. In order to calculate how effective this investment is, you should divide the additional costs with the yearly savings. Once you have installed a geothermal system in a new house, monthly savings will equal with additional monthly mortgage costs, resulting in a positive source of money during a month. Bear in mind that energy saving is only one of many benefits that you get by a geothermal system.

Provided that a household has a ceiling or underfloor heating, should the air channels be installed?

Not always. It is advisable to install room units of geothermal heat pumps (room units). For smaller houses, one room unit would provide the biggest part for heating and cooling. Underfloor and ceiling pipe units could be used as additional heating.

If you want to know more about a geothermal heat system, who should you contact?

You should contact "IPIN" Ltd. Bijeljina

What is a geothermal heat pump?

A geothermal pump is a device that is run by electricity and which uses natural properties of the ground and ground waters to cool and heat your household or a working space.

How does it function?

As any other type of heat pumps, it simply transports energy from one place to another. Your fridge also functions following the same scientific procedure. Using the process of cooling, geothermal heat pumps remove the heat energy which is kept in the ground and / or underground waters and they transform it into space.

How is the heat transported from a pump to a house or a facility?

The ground has the ability to keep and absorb the heat energy. In order for us to use that saved energy, the heat is extracted from the ground by a fluid mediator (underground water or a antifreeze solution) and pumped into a heat pump or a hear exchanger. There, the heat is used to heat the air. During summer, the process functions vice verse and the heat is extracted from the house and transported into the ground by fluids.

Does it heat and cool?

One of the things that make the heat pump so functional is that it can be both the heating and cooling system. You can switch from one mode to the other by simple clicking at your inner thermostat. When cooling takes place, geothermal heat pump uses heat from the inside and transports it to ground cooler through underground water or underground loop system.

Do I need separate underground loops for heating and cooling?

No, you do not. The sam loop performs both. Once we change the mode from heating to cooling or vice verse is that the heat flow switches.

What loop types are there?

There are two main types: open and closed. The next two paragraphs will tell you more about it.

Does an underground heat system really function?

A dug pipe or an "underground loop" is the newest technical breakthrough in heat pumps technology. The idea to set a pipe into the ground in order to collect heat energy occurred in the 1940s. Recently, a new project of a heat pump and improved pipe materials have been combined to make the heat pumps the most effective heating and cooling system.

What is a closed loop system?

The term 'closed loop' is used to describe a geothermal system of the heat pipe that uses a continuous loop of a special polyethylene pipe buried in the ground, which is a heat exchanger. The pipe is connected to the internal heat pump in order to form a sealed underground loop which antifreeze circulates through. Unlike the open-loop system which uses water from the well, the closed-loop system makes the heat circulate constantly through the pipe under pressure.

Where can the loop be located?

It depends on the availability of land and terrain. Most of closed loops are placed in horizontal trenches, in yards near houses. However, any piece of land close to a house or a company with appropriate conditions and adequate surface can be used.

How long and how deep should the trenches be?

Trenches are usually 1.2 to 1.8 m deep and 120 m long, depending on how many pipes there are in a trench. One of the advantages of a horizontal loop system is that trenches can be set according to the shape of the ground. By measuring roughly, the capacity of 150-180 m of pipes is required. A well-insulated house of 186 m2 will need a geothermal system of 10.5 kW of thermal energy, with 460-550 m of pipes.

How many pipes should there be in one trench?

Usually a drain pipe is placed at a depth of 1.5 m, then it is wrapped once around itself to a depth of 0.9 m, until the bottom is covered with ground. This allows the longer pipe to be placed in a ditch and this has no contrary effect on the system efficiency. Other projects of loops use 4 or 6 pipes and are more suitable for shorter trenches, if the surface of the land is limited.

What if there is not enough space for a horizontal loop?

Closed-loop systems can also be vertical. Boreholes are performed to a depth of 11.5 m -13 m per kilowatt capacity of a heat pump. U-shaped pipe loops are inserted into the boreholes. The boreholes are then sealed with special cement mass.

How long will the loop pipes last?

Closed-loop systems should be installed using polyethylene pipes and polybutylene pipes of high density. If they are placed in a proper way, these pipes will last for decades. They are resistant to chemicals that are commonly found in the ground and they are well tolerated to heat. PVC pipe should not be used in any case.

How are pipes in the loop connected?

The only acceptable method of connecting sections of pipe is heat (electric) connection. Places where the pipes are connected, are heated and fused together to form a compound stronger than the original pipe. Mechanical pipe joining to the underground loop is not acceptable. The use of a valve gear, screws and sticky compound will certainly result in failure of the loop, which would lead to leakage.

Will the underground loop influence the appearance of my lawn?

No, it will not. Research has shown that loops have no adverse effect on grass, trees or bushes. Most horizontal loop installations use trenches about 6" wide. Of course, this will leave a current footprint from the excavation which can be re-planted with grass. Vertical loops require little space and they damage the lawn minimally.

Can I bring the heat back from my sewage system?

No, you cannot. The underground loop will reach a temperatures below the freezing point during extreme conditions and it may freeze your septic system. Such usage is prohibited in many areas.

Can I install the underground loop myself?

This is not recommended. Apart from the thermal pipe connecting, a good contact of the ground and the spiral is very important for successful functioning of the loop. Unprofessional installation can lead to system's less efficiency.

There is a small lake near my house. Can I put the loop into it?

Yes, you can providing it is enough deep and spacious. The minimum depth of 1.8 m is the lowest level required during the year in order to consider the possibility of using the pond. The area that is required depends on the overall structure of heating and cooling.

What is an open loop system?

The term "open loop" is commonly used to describe a geothermal heat pump system that uses ground water from conventional sources / wells, as a source of heat. Ground water is pumped into the heat pump where the heat is separated and then water is discharged in a certain way. Since groundwater has a relatively constant temperature throughout the year, it is an excellent source of heat.

What do we do with the released water?

There are several ways to get rid of the water after it passes through the heat pump. The open method of release is the cheapest one, but it is not recommended due to legal restrictions and necessary permits and payment of fees and a mandatory procedure of concession to exploit groundwater. Open release simply means draining the water into a stream, river, lake, an artificial lake, ditch or drains. Any of these alternatives has to have the capacity to accept the amount of water that is used in the heat pump, before the open release takes place. The other, acceptable manner of water release is the returning well or absorbent well, i.e. injection well. The absorbent well is another well that returns water to the undergrouond water-bearing layer. The absorbent well has to have sufficient capacity for the water that flows through the heat pump. It should be performed, like the exploitation well, by the appropriate drilling equipment designed for performing wells. Also, a company which meets the requirements of the Law on geological research, should perform exploitation well and absorbent well, and it should also test the capacity of both wells before they are used (and the absorbent well, as well).

How much groundwater is needed for the closed loop system?

Geothermal heat pumps, which are used in open loop systems, require different amounts of water depending on the size of the device and the manufacturer's specifications. The needs of a specific model for water are usually expressed in liters per minute or liters per second (l/s), which can be found in specifications for that device. Your heating supplier should have this information. All in all, the average system will use 2 liters / min per kilowatt of capacity during work. Your combination of the well and pump should be large enough to provide the water needed for the heat pump, together with the needs of the household for water. You will probably need to increase your bottle under pressure or to modify your installation of water in order to provide adequate water for the heat pump.

Which problems can be caused by poor water quality?

Poor water quality can cause serious problems in open loop systems. Your water should be tested for hardness, acidity and iron content before installing the heat pump. Your contractor or equipment manufacturer can tell you which water level is acceptable. Minerals can sediment within the heat exchanger of the heat pump. Periodic cleaning by a mild acid solution is all that is needed to remove the plaque. Impurities, particularly iron, can eventually clog a returning well. If your water contains too much iron, you should make sure that the water which is discharged is not filled with air before it is inserted in the returning well. Finally, you should not use water from streams, rivers, lakes as a source for your heat pump system unless it is proven that there are no too many particles and organic matter. They can clog a heat pump system and make it unusable for a short time.

Does an open loop system disrupt the environment?

No, it does not. If the water returns to the absorption well, it does not pollute the environment. The heat pump only removes heat or provides heat to the water. Moreover, there is no pollution at all. The only change in the water that returns to the nature is a small increase or decrease in temperature. Some people are concerned that the open loop systems contribute to pumping of our groundwater sources. If the water returns through the absorbent wells in the aquifer, there are no grounds for such fears.

Are there any laws regulating the installation of open loops?

In some localities, all installations or parts of installations may be the subject of a local cadastre, codes, covenants or licensing purposes. You should check with local authorities to see if there are any restrictions on your location.

What are the components of the geothermal heat pump system?

There are three main parts: a device of the heat pump, liquid agent for the exchange of heat (open or closed loop), and a system for getting air (system of ventilation channels).

Are all geothermal heat pumps the same?

No, they are not. There are different kinds of geothermal heat pumps, designed for specific purposes. For example, many geothermal heat pumps use underground water of high temperatures, which can be found in open loop systems. Others may work with the temperature of the incoming water which can be low up to -3.9 ° C, which is possible in closed loop systems. Most geothermal heat pumps provide air conditioning during summer, and several types are projected only for winter heating. Sometimes, these systems, which are used for heating only, contain a spiral for cooling groundwater, which can provide cooling in moderate climates. Geothermal heat pumps can also differ by the way they have been made. Some devices contain a combination of a fan, compressor, heat exchanger and spiral in a simple case. Split systems allow the spiral to be added to the air unit ejector later, and they use the existing fan.

Will I have to add insulation to my home if I install one of these systems?

Geothermal heat pumps will reduce your heating and cooling costs, regardless of how your house is insulated. However, insulation against weather conditions is a key factor in achieving the greatest savings at any type of heating and cooling systems.

Can a geothermal heat pump also heat water?

Yes, it can. Using something called a ''desuperheater'', some types of geothermal heat pumps can save up to 50% of the bill for heating the water, by heating the water tank. Desuperheaters are standard on some devices and an alternative on some other ones. Some geothermal models can provide all your needs for hot water by the same high efficiency, which takes place at the process of heating and cooling.

Is a geothermal heat pump difficult for installation?

Most of the units are easy to install, especially when they replace another system of expelling air. They can be installed in areas where there are no conditions for fossil-fuel run furnaces because there is no combustion, and therefore no chimneys. The system of heating pipse must be installed at homes that do not have the existing air distribution system. Difficulties in installing the system of channels will vary and it must be evaluated by the contractor.

Can a geothermal heat pump be added to my fossil-fuel run furnace?

Separate systems can be easily added to the existing furnaces for those wishing to have a dual fossil thermal system. Dual-fossil systems use the heat pump as the main heating source, and fossil-fuel run furnace use additional heating as an aid in extremely cold weather, if necessary.

I have a channel system, but will it function with this system?

Probably, it will. Your installation contractor should be able to determine the needs of the heating channels system and any minor modifications, if needed.

Do I need to increase the amount of spending my electric services?

Geothermal heat pumps do not use large values of thermal resistance, so your existing service may be adequate. In general, the service of 200-amp will have sufficient capacity, and smaller amp services can be large enough in some cases. Your power company or contractor can determine your needs for these services.

Should I buy a heat pump large enough to heat without any additional heating?

Your contractor should provide you with a calculation of costs of heating and cooling (heat gain and loss) to help you in the selection of equipment. Geothermal heat pumps are big enough to satisfy your need for cooling. Depending on the need for heating, a geothermal heat pump will supply 80-100% of your planned amount of heat. If you determine the size of the heat pump to perform entire heating, this can lead to a slightly lower heating costs, but the savings cannot compensate for the additional cost of a larger unit of the heat pump. A unit (device) which is too large can also cause problems with the lack of moisture in the cooling manner, which can lead to reduced summer comfort.