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Technical Information
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Hydronic heating and cooling systems have long set the industry standard for comfort and flexibility. Whether the application includes radiant heating, forced air fan coil units, domestic hot water heating or process heating/cooling loads, the EW Series can fit every application from the simple to the complex. Sophisticated microprocessor controls and state-of-the-art components ensure many years of virtually maintenance-free operation. The EW also can supply hot water for pools, spas and ice melt under sidewalks.
Because it doesn´t burn fossil fuels, the EW Series emits no harmful greenhouse gases, which are associated with global warming. No flames. No fumes. No odors. No danger from carbon monoxide. Less dust and better indoor air quality. The WaterFurnace EW Series is the best in the business.
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DESIGN FEATURES:
Operating Efficiencies
- Environmentally responsible R-410A refrigerant.
- Optional desuperheater generates hot water at considerable savings while improving overall system efficiency.
- High-stability bi-directional expansion valve provides superior performance.
- Efficient scroll compressors operate quietly.
- Oversized coaxial tube water-to-refrigerant heat exchanger increases efficiency.
Flexibility
- Designed to operate with load temperatures of 30°F to 130°F (30-100 EST, 50-130 ELT).
- Source side flow rates as low as 1.5 GPM/ton for well water (50°F min. EWT).
- Dedicated heating, dedicated cooling and heat pump models available.
- Modularized unit design and master/slave controls for optimum capacity matching and staging.
- Stackable for space conservation.
- Compact size allows installation in confined spaces.
- Front or rear plumbing connections.
- Control Panel location is reversible.
Factory Quality
- Heavy-gauge steel cabinets are finished with durable poly paint for long lasting beauty and service.
- All refrigerant brazing is performed in a nitrogen atmosphere.
- All units are deep evacuated to less than 150 microns prior to refrigerant charging.
- All joints are helium leak-tested to ensure annual leak rate of less than 1/4 ounce.
- Evaporator heat exchanger, refrigerant suction lines, desuperheater coil and all water pipes are fully insulated to reduce condensation problems in low temperature operation.
- Sound attenuation features: isolation mounted compressor and high-density, weighted sound blanket.
- Safety features include high and low-pressure refrigerant controls to protect the compressor; hot water high-limit desuperheater pump shutdown.
Options & Accessories
- Optional desuperheater with externally mounted pump and water heater plumbing connector.
- Closed loop, source-side, circulating pump kit.
- Closed loop, load-side, circulating pump kit.
Anyone who has a refrigerator or an air conditioner has witnessed the operation of a heat pump, even though the term heat pump may be unfamiliar. All of these machines, rather than making heat, take existing heat and move it from a lower temperature location to a higher temperature location. Refrigerators and air conditioners are heat pumps which remove heat from colder interior spaces to warmer exterior spaces for cooling purposes. Heat pumps also move heat from a low-temperature source to a high-temperature space for heating.
An air-source heat pump, for example, extracts heat from outdoor air and pumps it indoors. A geothermal heat pump works the same way, except that its heat source is the warmth of the earth.
The process of elevating low-temperature heat to over 12c and transferring it indoors involves a cycle of evaporation, compression, condensation and expansion. A refrigerant, like R410A, is used as the heat-transfer medium which circulates within the heat pump.
- The cycle starts as the cold, liquid refrigerant passes through a heat exchanger (evaporator) and absorbs heat from the low-temperature source (liquid from the ground loop). The refrigerant evaporates into a gas as heat is absorbed.
- The gaseous refrigerant then passes through a compressor where the refrigerant is pressurised, raising its temperature to over 65c.
- The hot gas then circulates through a second refrigerant-to-water heat exchanger where heat is removed and pumped into the building at up to 60c.
- When it loses the heat, the refrigerant changes back to a liquid. The liquid is cooled as it passes through an expansion valve and begins the process again.
To become an air conditioner, the flow is reversed.
The key to any ground source system unsurprisingly lies under your feet. Our team of geological and hydro geological experts will use the excellent information available from the British Geological Survey (BGS) to assess a project for suitability. This geological information, along with site layouts and building loads allows us to provide a set of solutions for any given project. The key decision, dictated by the geology, is which type of ground interaction is to be used. There are three principal types of system, Closed Loop, Open Loop and Hybrid Systems.
The following information is key to integrating successfully the ground source system with your building design to optimum effectiveness.
Traditionally ground source heat pumps have been used for low temperature heating systems only. With modern heat pumps, using the latest compressors and R-410A refrigerant, heating, cooling and hot water systems can be 100% covered, with only minor changes to accepted engineering practice.
Most large ground source systems use water-to-water heat pumps centrally located in dedicated plant room areas. A modular approach provides system redundancy and accurate matching of building loads. As all WaterFurnace units are both compact and reversible, plant space requirements are significantly less than conventional equipment. Overall plant space savings of 50% are typical.
As a basic principal, the closer the distribution water temperature is to the local undisturbed ground temperature, the more efficient the overall system will be. For cooling circuits the traditional 6/12oC is common but circuits as high as 17/19oC are common with more innovate distribution systems such as chilled beams and under floor cooling. In heating mode low temperature systems, such as under floor at 35/30oC offer excellent efficiencies but temperatures up to 68oC are possible, all be it at lower efficiencies. Please note that extended running over 61oC is not recommended as this has an adverse effect on compressor life over the long term.
An alternative approach is to distribute either water-to-water or water-to-air units around the building; providing heating and cooling directly where required. The ground loop itself is used to provide the source and offers an extremely efficient method of heat recovery.
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Closed loop systems
As the name suggests, these are simply closed loops of polyethylene pipe buried in the ground and containing a solution of environmentally friendly anti-freeze and water.
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Vertical Closed Loop
Most commonly used for medium sized systems in the 100 to 1,000kW range, although we have installed both smaller and larger systems in the UK. 125mm bore holes are drilled and a pair of 32mm pipes are grouted into place. A typical grid of 3 to 6m is used between the holes and depths are typically between 50 and 150m below ground level. All headers are completed at least 1m below finished level and are simply buried under the finished surface.
Most suited to: medium to large projects in all areas.
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Loops in Building Piles (Energy-Piles©)
These can be used in any piled building and with any common piling method. They can typically cover about 50% of the building load and offer a very economic installation proposition. An important consideration is to minimise the impact of the inclusion of the pipes on both the pile design and installation program. This gives a very low additional cost over conventional equipment and the lowest possible extra over cost for the piling contractor. Our association with Cementation Foundations Skanska has given us a lead in this market in the UK.
Most suited to: new buildings with piles and little external space.
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Horizontal Closed Loop
If land is available 1.5m deep trenches can be used to install the closed loop. Various trenching methods and pipe geometries are used. At Geothermal International we prefer straight pipes rather than the slinky variety you may have seen used by other installers. This offers a more efficient collection of energy from the ground and makes the most of every meter of pipe installed. Horizontal systems do require a significant amount of land and for this reason systems up to 150kW are most common although where land is plentiful, larger systems can be considered and have been installed.
Most suited to: small to medium projects with access to land.
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Pond Loops
These are a particularly efficient method of ground sourcing and can cover practically any size of load, systems of many MW are common. They offer excellent installation costs. A constant water depth of 2 to 3m is required and as a guide 9m2 of surface area is required per kW of system capacity. Either stainless steel plates or polyethylene pipes are simply submerged below the surface and again water / anti-freeze solution is circulated through them.
Most suited to: any sized project with access to surface water.
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Open loop systems
Any body of water can be used as a direct source for ground coupling. Water is taken into the system and passes through heat exchangers before being discharged back into the source a short distance away.
An important point to note is that no water is actually used up by the system; we say there is “no net abstraction”. This fact ensures that the Environment Agency (EA) who license water abstraction in England & Wales, the equivalent is SEPA in Scotland, are keen to see these systems installed. Permission and licensing is still required and our team of hydrogeologists are key to this process.
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Water Well Systems
An abstraction and rejection pair (or pairs) of water wells are installed as the source. The water is piped into the plant room and through a heat exchanger where heat is either taken or added to the water. The water is then returned to the ground, chemically unaltered. Open loop water well systems are best suited for larger projects and, provided water is available, any size of project can be undertaken. There is a risk element to water well drilling, in that water yields cannot be guaranteed. In order to mitigate this risk, which is borne by the client, we produce detailed hydro-geological studies to quantify the risk involved.
Most suited to: large projects in built up areas.
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Surface Water Systems
Where surface water is available, but closed loop is impossible, we can use this as a source by taking water through a similar system of heat exchangers to that outlined above. Filtration is the main issue with these systems and can constitute a significant maintenance requirement.
Most suited to: medium to large projects with limited access to surface water.
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Hybrid systems
Where a source is available, but is unable to cover the full building loads, for practical or commercial reasons, a hybrid approach is possible.
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Closed Loop & Dry Coolers
When a cooling load dominates over heating, as is common in many commercial buildings today, the addition of dry coolers on the ground loop itself provides a cost effective alternative to increasing the ground loop size.
Most suited to: projects with large cooling loads.
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Loops in Piles & Open Loop
This is a very exciting and recent addition to the options available to us. As the typical piling layout is capable of less than 100% of the building heating and cooling loads, the addition of open loop wells to cover peak periods is a natural solution. Working together the two systems can provide much larger heating and cooling loads for the building than the two systems in isolation.
Most suited to: large new buildings with piles in built up areas.
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How long will the loop pipe last?
Closed-loop systems should only be installed using high density polyethylene or polybutylene pipe. Properly installed, these pipes will last for many decades. They are inert to chemicals normally found in soil and have good heat conducting properties. PVC pipe should not be used under any circumstances.
How are the pipe sections of the loop joined?
The only acceptable method for joining sections of the special pipe used for the closed-loop systems is electro fusion. Pipe connections are heated and fused together to form a joint stronger than the original pipe. Mechanical joining of pipe for an earth loop is in some restricted applications an accepted practice. The use of barbed fittings, clamps, and glue joints is certain to result in loop failure due to leaks.
Which system is best, open- or closed-loop?
The net results in operating cost and efficiency are virtually the same. Which system to choose depends mainly on whether you have an adequate groundwater supply and means of disposal. If you do, an open-loop can be used very effectively. If not, either a horizontal or vertical closed-loop system is your best choice. Over a period of years, a closed loop system will require less maintenance because it's sealed and pressurised, eliminating the possible build-up of minerals or iron deposits.
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Is the efficiency rating actual or just a manufacturer's average?
All types of heating and cooling systems have a rated efficiency. Fossil fuel boilers have a percentage efficiency rating. Natural gas, propane and fuel oil boilers have efficiency ratings based on laboratory conditions. To get an accurate installed efficiency rating, factors such as flue gas heat losses, cycling losses caused by over sizing, blower fan electrical usage, etc., must be included. Geothermal heat pumps, as well as all other types of heat pumps, have efficiencies rated according to their coefficient of performance or COP. It's a scientific way of determining how much energy the system produces versus how much it uses. Most geothermal heat pump systems have COPs of 3.5 - 4.5. WaterFurnace units have typical COPs of 4 to 8. That means for every one unit of energy used to power the system; four or more units are supplied as heat. Where a fossil fuel boiler may be 50-90 percent efficient, a WaterFurnace geothermal heat pump is about 600 percent efficient. We use computer programs to accurately determine the operating efficiency of a system for your home or building.
Are all geothermal heat pumps alike?
No. There are different kinds of geothermal heat pumps designed for specific applications. Many geothermal heat pumps, for example, are intended for use only with higher temperature ground water encountered in open-loop systems. Others will operate at entering water temperatures as low as -4°C which are possible in closed-loop systems. Most geothermal heat pumps provide summer air conditioning, but a few brands are designed only for winter heating. Sometimes these heating-only systems incorporate a groundwater cooled coil that can provide cooling in moderate climates. Geothermal heat pumps can also differ in the way they are designed. Different heat pumps also use different refrigerant gases.
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