7. Split Type Air to Water Heat Pump System - Layout Heating Only
8. Split Type Low Temperature Air to Water Heat Pump System - Layout Heating and Hot water
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15. Domestic Heating Compliance Guide - Part L. (ADL1A & ADL1B 2006 Section 8 : Heat Pumps (Section 9 in 2010) 30°C to 40°C 40°C to 55°C 35°C to 45°C Table 29 Minimum provisions for warm (and hot) water heat pumps (ground to water, water to water and air to water systems) Minimum provision Supplementary Information a. Supply water temperatures and/or efficiency Under floor heating Supply water temperatures to the under floor heating system should be in the range See section 7 of this guide on under floor heating Radiators High-efficiency radiators with high water volume should be utilised Supply water temperature to the radiators should be in the range Space Heating may be sized to meet all or part of the space heating load. Secondary heating will be required if the heat pump is sized to meet part of the space heating load Fan coil units Supply water temperature to the fan coil units should be in the range Fan coil units may be utilised for heating only or for winter heating and summer cooling
16. Standard Heating & Hot Water System (fossil-fuel) Conventional Gas or Oil boiler with flues Oil tank and ventilation Hot water cylinder by Heating Engineer or existing Conventional Heating & hot water system by Heating Engineer Convector or Fan Coil Unit Under Floor Heating Radiator Sanitary Hot & Cold Water
Introduction to the speaker and to Space Air Conditioning plc and its subsidiary domestic heat pump supplier Space Air Solutions Ltd.
Brief background of the company Established in 1980, Space Air has been very active with industry related issues.
Renewable elements of air source heat pumps The available free energy (heat) in the ambient air (Ambient temperature simply means "the temperature of the surroundings" ) is absorbed by the refrigerant, via the outdoor evaporator (heat pump unit). This is then transferred to and upgraded by the refrigerant DX cycle, (DX cycle explained in the next slide) where water circulating in the condenser heat exchanger absorbs the heat, which is then distributed through the heating water circuit via radiators, under floor, fan coils. In the case of air source, air to water heat pumps, extract heat (energy) from the ambient air. Ground source heat pumps extract heat (energy) from underground. Europe recognised Heat Pumps as renewable technology on 17th December 2008.
Basic explanation of how a heat pump functions. The DX (direct expansion) cycle is used in 98%of heat pumps. (See image of fridge for explanation) (The DX cycle is a sealed system which is the heart of the heat pump. This enables the heat transfer media (refrigerant) to change phase form gas to liquid & back to gas in the process of absorbing and rejecting heat. To handle & control this process & to achieve the required temperatures, the cycle involves the 4 components. 1)The evaporator 2)the compressor 3)the condenser 4)The expansion device). The reason for this is that refrigerant can carry far more energy (heat) than the alternative, air or water from point A to point B. Water carries 5.8w/kg air carries 2.8w/kg and refrigerant carries 57w/kg The pipe work is also smaller in comparison, saving space and is also easier on the eye.
Types of Air Source Heat Pumps There are basically 3 types of air source, air to water heat pump systems. Split Type - Outdoor heat pump unit + indoor heat exchange unit with interconnecting refrigerant pipe work. This system offers huge flexibilities as the outdoor unit can often be some distance away from the indoor unit. Normally one outdoor unit connects to one indoor unit, but there are split air to water heat pumps available where up to 10 indoor units connect to the outdoor unit, and this is used for apartments. The indoor unit has no burning fuels and therefore can be situated anywhere in a property, even under the stairs, as there is no need for flues or ventilation. The Packaged system - where everything is self contained need to be close to the property due to water connections. A major disadvantage of these types of systems is they need anti-freeze to be added. This needs replacing between every 3 - 4 years and can be costly. The Cascade heat pump system - this is where there is a DX cycle in the outdoor unit, raising the temperature, then it goes through a further DX cycle raising the temperature even more.
Types of Air Source Heat Pumps Basic components of a split heating only system. Outdoor unit (containing the DX cycle, absorbing the heat (energy) from the ambient air) + indoor unit (transferring the heat (energy) from the refrigerant cycle to the water circuit).
Typical Components. If domestic hot water is required a storage cylinder is added and a 3 way valve to divert the system to heating and hot water, as demand dictates.
Types of Air Source Heat Pumps. Packaged system, all components are in the outdoor unit, the dx cycle and the heat exchanger. Water connections are direct from the outdoor unit to the indoor water circuit. However their will be heat looses as the unit need to be adjacent to the property and an anti freeze will need to be added reducing the efficiency of the system.
Typical Components. Again as with the split type, if dhw is required a storage cylinder needs to be added
High Temperature Heat Pumps. The cascade system is really for large old types of buildings, or where a high level of sanitary water is needed.
Quick overview of the general features and benefits of Air Source, Air to Water Heat Pumps as an energy and carbon efficient alternative to conventional central heating boilers. NB: Air Source heat pumps are now being recognised as environmentally friendly. Some manufacturers heat pumps have now been awarded the EU Eco-label. This award means that the heat pump systems are independently tested for Heating efficiency, Refrigerant Global Warming potential, Noise, Absence of RoHS, Training, Documentation, Spare Part availability, and detailed information at point of sale. In addition the EU recognises Heat pumps as renewable technology.
Statistical Data. We are always being told to turn off our computers, televisions and game stations instead of leaving them on stand by and to change our light bulbs in our homes to save energy. However 84% of our domestic energy use is actually for our central heating and heating of sanitary hot water. Power Stations are reducing their energy and this is how we can reduce ours.
Statistical Data This graph shows the UK mean temperature in winter. Air source heat pump systems should be designed to local weather conditions. Ie; there is no point designing a system at Aberdeen weather conditions for a home in London! This is so important otherwise systems could be undersized, and in the long term cost more to operate, as they will be relying on back up direct electric.
Part L Building Regulations (2006/2010) Compliance Guide data for domestic heating. Before a heat pump system is designed you need to consider the heat emitters, as they will effect the system efficiency and sizing of the unit due to the different temperatures. Guidelines are available on all types.
Typical domestic central heating system components. This is a standard layout of a conventional fossil fuel central heating system. The heat generator i.e. boiler is connected to heat emitters, dhw storage via water pipe work distribution. The standard of installation will effect any central heating system efficiency. Price of fossil fuels has been on the rise in the UK over the past few years, and is considered to continue to rise. Home owners are looking at alternative, cheaper and sustainable technology for heating in the UK, hence the increase in heat pump technology.
Domestic Central Heating using a “split type” air source air to water heat pump. This shows a split type air source, air to water type system and replaces fossil fuel boiler, but you will notice that the internal water pipe work distribution is the same. (The only difference is the additional outdoor unit) Air source heat pumps deliver Considerable energy savings over fossil fuel And Significant CO2 reductions compared to fossil fuel
Benefits of Heat Pumps that feature inverter control. Energy efficiencies of inverter technology. In standard systems the compressor will simply run on or off, for example a domestic refrigerator. With inverter control the speed of the compressor is controlled to meet the exact demand at any one time, increasing the efficiency of the system and the lifetime of the compressor. Description of inverter technology. The inverter technology is integrated in the outdoor unit and can be compared to the technology in a car: " The harder you push your accelerator, the faster you go, and the more fuel you consume). An inverter unit will gradually increase its capacity based on the capacity needed in the room heat up.
Advantages of inverter control explained further. Inverter control has 25 steps, thus saving energy and pro-longing the system life. You can see from the illustration that an inverter air source heat pump has spare capacity, which can be diverted to the hot water.
Heat transfer efficiency terminology. It is important when comparing systems that you ask for the SEASONAL performance factor. This will give a far more accurate estimate of the energy consumption as it is based on real conditions, rather than factory set conditions.
Optimising heat pump efficiency through temperature control. With any system the lower the leaving water temperature the more efficient the system. There are guidelines for both space heating and sanitary hot water temperatures. The water temperature should be raised above 60°C weekly to de sanitise the sanitary system for microbial growth - legionella.
Factors that effect the efficiency of any heating/hot water system. Already covered the heat generator. Heat emitters already covered. The controls will also effect the operation and efficiency of a heating system, depending if the control is electronic or electro mechanic. The flow rate balance - of the system isn ’t balanced and the water isn’t reaching all parts of the system, this will seriously reduce efficiencies. With regards to the installation, it is a surprise how often basic measures such as insulation of the pipe work are often ignored.
Importance of compliance with industry standards. This slide shows that while heat pumps are considered to be a new technology to the UK market, there are in fact European and British regulations already in place, which should aid with consumer confidence. Heat Pumps are already widely used in the rest of Europe.
Important Accreditation for Consumer protection Serious players / manufacturers in the market should aspire to these over and above the previous regulations. These additional accreditations may be required in order for the consumer to gain access to grant support.
Applicable Industry Standards. There is no excuse for a contractor providing poor standard of installation when all of these are in place, designed to help and assist them.
Types of Air Source Heat Pumps All in one packaged units, that only have water connections, will still need a refrigerant handling certified engineer for service, maintenance and repair in accordance with the f-gas regulation. Refrigerant checks should be done annually.
Importance of Controls. As mentioned previously electronic controls, will give you greater efficiencies and the ability to set separate temperatures for the space heating and sanitary heating circuits.
Accessories that optimise performance and quality of installation It is not only good practice but also a great contributor to efficiency if pipe work is insulated as show in the picture. As well as the use of heat pump accessories, such as the cage around the outdoor unit for protection and damage.
Accessories to optimise performance and quality of installation. Components shown will ensure that the overall operation and performance of a heat pump system is balanced currently, and is fully optimised.
Accessories to optimise performance and quality of installation. The components shown will contribute to the overall effectiveness of the system and safety of to the householder.
Accessories to optimise efficiency and quality of installation. Systems should have a filter as any impurities in the water will reduce its energy transferring capabilities.
Examples of air source heat pump installations. As the pictures illustrate it is essential that the outdoor units are not enclosed as this will reduced air circulation and limit the performance of the system.
Explanation of Bivalent systems. If required it is possible to link a heat pump with traditional heating systems for householder peace of mind. Bivalent systems run in parell with the heat pump and the fossil fuel based system or the boiler can be used as the back up heater. The boiler can be used to raise the temperature form 55°C to a higher temperature set.
Specialist applications. Heat Pumps can also be used for more specialist applications, including the more common use for heating swimming pools. When a heat pump is used for swimming pool applications a separate heat exchanger needs to be used. This is to stop the chlorinated water contaminating the heat pump system. A buffer vessel also needs to be connected to ensure sufficient flow of water. Once the pool reaches temperature the heat pump will only run when required to maintain the set temperature.
Case Study The Wiltshire Rural Housing Association is committed to developing sustainable, new and refurbished, affordable rental properties in Wiltshire. The energy efficient air-to-water heat pump was specified to supply central heating and hot water services in a new WRHA development of 10 two bedroom homes in Codford, Wiltshire. The installation, completed in December 2007, satisfies local planning authority requirements regarding the incorporation of low to zero carbon renewable technologies. With no mains gas available and other options considered environmentally undesirable by WRHA and the local planning authorities, an air to water heat pump system has been successfully applied in other Wiltshire developments. The WRHA were satisfied that the heat pump met their sustainable housing objectives, reduced construction costs associated with conventional fossil fuel systems, and offered considerably lower user operating costs and carbon footprint than the available alternatives.
Case Study 8 air to water Split Heat Pump Systems were used for space heating and domestic hot water to top floor luxury apartments of Montague Place. The indoor units and storage cylinders have been placed in the apartments ’ airing cupboards. There was enough space around the indoor units and cylinders to install washing machines and shelving. The outdoor units have been positioned on the roof, with easy access for the annual maintenance check. The developers had hoped to meet the at least 10% renewable technology by adding solar panels to the roof of Montague Place. Due to the number of apartments, 55 in total, the foot-print area on the roof was far too small for the quantity of solar panels that would be needed to satisfy the Merton Rule/CSH. The Local Authority and their Energy Assessor advised that they would need to equip some of the apartments with air to water heat pumps, (due to efficiencies, flexibility and space limitations). The developers specified an air to water heat pump system for 8 of the apartments in order to exceed the 10% renewable technology requirement.
Useful links Mark Houghton first joined the industry in 1998. He set up Space Air Solutions, a subsidiary to Space Airconditioning in the early 90’s dedicated to supporting the residential market. Mark has spearhead the Daikin Altherma air t water heat pump system into the UK residential market and was promoted to Commercial Director in August 2009.
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