Heatpump Repair

Design, Install, Repairs and Service of all types of Geothermal Heatpumps including bespoke controls. Our engineers normally can attend your property in less than 24hrs and carry out repairs, service or maintenance.
If you would like a repair, service or maintenance for your heat pump, call our heat pump team on 0800-1-ZEUNER or email using the below contact form.

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Heat Pump Repairs

What is a heat pump and how does it work?

The heat pump is a device that extracts heat from a source and transfers it to another area, much like your typical refrigerator, only instead of getting rid of heat, the heat pump makes use of it. The sun warms up our atmosphere and the outer layer of the earth’s crust each day, providing massive amounts of thermal energy that are stored in the air that we breathe and under the ground that we walk on.
A heat pump system consists of:
HEAT source (the air, ground or a nearby water body)
HEAT pump (which has an expansion valve, compressor and evaporator)
HEAT distribution system (under floor heating, radiators and domestic hot water)

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Air Source Heat Pumps

An air source heat pump (ASHP) is a system which transfers heat from outside to inside a building, or vice versa. Under the principles of vapor compression refrigeration, an ASHP uses a refrigerant system involving a compressor and a condenser to absorb heat at one place and release it at another.

Air source heat pumps eliminate the need for a fossil fuel heating system such as LPG, gas or oil, they are highly efficient with 1kW of electricity consumption generating 3kW to 5kW of renewable heat throughout the year.

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Thermal Regions in the Ground

The ground offers an excellent resource to incorporate ground source heat pumps into systems for heating and cooling of buildings. The ground temperature in the UK can generally be defined into three distinct regions. Firstly, there is a variable temperature region for the first 4m of ground, which will vary depending on the season.
The next 100m or so is constant throughout the year due to the large thermal mass of the ground and from around 100m and below the ground temperature warms due to radioactive decay effects. Ground source heat pumps are usually designed to use the thermal resource found in the first two regions.

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The Heat Cycle

EVAPORATOR: Low-grade energy is absorbed from the heat source and raises the temperature of the heat pump refrigerant to change from liquid to gas.
COMPRESSOR: The refrigerant is then compressed to significantly lower its volume but increase its temperature.
CONDENSER: A heat exchanger then extracts heat from the circulating refrigerant and transfers it to the heat distribution system.
EXPANSION VALVE: The refrigerant condenses back into a liquid and is passed through an expansion valve to absorb more energy and begin the cycle again. The cycle is reversible for cooling mode to achieve lower temperatures in your room during hot periods.

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Energy Management

Energy management systems require a link between the meter and the technologies that control electrical consuming equipment. The Java Application Control Engine (JACE) is the mechanism that provides connectivity between systems within or between buildings. Systems controlling HVAC equipment, lighting, and refrigeration can be integrated with metering technologies with the use of a JACE thereby providing the required link for Electrical Demand Limiting (EDL)…"if my demand exceeds 2,000 kW, reduce space temp in zone 1 by 2 degrees". The JACE connects it all. Scalability and reliability concerns are avoided with the unique distributed architecture that a network of JACE's creates.

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Alarm Service

Our Alarm Service provides you with an advanced and user-friendly alarm console to view, sort, and manage alarm conditions. Instead of being overcome with a multitude of alarms, you can sort and view alarms by operator, status, and level of severity. You can be notified via pager, email, or online, our systems ensures conditions are not overlooked. In energy management applications, our alarm service can be used to alert you of upcoming "energy alerts", real time pricing notifications, manual energy strategy interventions, or key equipment failures - each of which could cause significant energy cost overruns if undetected. Alarms and responses are archived in the history and can be audited by appropriate parties.

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Remote Monitoring

Our Remote Web Server (WS) software manages a network of JACE's around the UK. Data is collected in real-time at the JACE, then logged and stored locally. Periodically, data is archived from the JACE to our Web Server.

Once archived in the Web Server, data is available for applications such as Energy Profiler, which resides on our server and uses the archived data.

Third party applications that require archived data is also installed on the Web Server and integrated into the Energy system. Our web server also stores the cumulative database, manages alarms, and displays aggregated JACE information via a standard web browser.

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Integration

Open Connectivity: Regardless of protocol or platform, the Niagara Framework connects to anything. NiagaraAX reduces development time by merging automation, IT and Internet technologies in a single solution. The Framework builds in the resources we need to implement advanced Web-services applications – TCP/IP, HTTP, XML, SOAP, oBIX – so our applications can read data, send commands, respond to alarms, etc., in real time… anytime, anywhere from a standard Web browser.

By wiring Niagara components together, we build control strategies, alarming, and scheduling applications as well as browser-based displays and reports. And because Niagara provides extensive open APIs, this allows Heat Pump Repairs to extend the behavior of the platform and create our own unique Heat Pump Repair products, applications, plug-ins, data views and business application logic.

Potential benefits

To maximise the efficiency of a heat pump when providing heating, it is important to not only have a low heating distribution temperature, but also as high a source temperature as possible. Overall efficiencies for GSHPs are inherently higher than for air source heat pumps, because ground temperatures are higher than the mean air temperature in winter and lower in summer. The ground temperature also remains relatively stable, allowing the heat pump to operate close to its optimal design point. Air temperatures, however, vary both throughout the day and seasonally, and are lowest at times of peak heating demand. Air has a lower specific heat capacity than water, so to supply the same energy more air must be supplied to the heat pump, which in turn requires more energy. For heat pumps using ambient air as the source, the evaporator coil is also likely to need defrosting at low temperatures.

For well-designed GSHP systems, used to supply low temperature, water-based heating systems (e.g. underfloor heating), seasonal efficiencies of between 300 and 400 per cent are common for indirect systems, and can be higher (350 to 500 per cent) for direct expansion systems. By comparison the seasonal efficiency of an air source heat pump system is about 250 per cent, although there is technical potential to increase this. The seasonal efficiency is the ratio of the energy delivered from the heat pump to the total energy supplied to it, measured over a year or heating season (including energy demands for circulation, e.g. to circulate fluid round the ground heat exchanger).

The high seasonal efficiency of GSHP systems reduces the demand for purchased electricity, and the associated emissions of CO2 and other pollutants. Figure 2 shows the relationship between utilisation efficiency and CO2 emissions for different domestic fuels.

For example it can be seen that (assuming an average CO2 emission factor for electricity of 0.422kg/kWh) using a GSHP with a seasonal efficiency of 350 per cent would result in the emission of 0.12kg of CO2 for every kWh of useful heat provided. By comparison a condensing gas boiler (assuming a CO2 emission factor for gas of 0.194kg/kWh), operating at a seasonal efficiency of 85 per cent, would result in 0.23kg CO2 for every) kWh of useful heat supplied – almost double the CO2 emissions from the GSHP. The emission figure for electricity is an average for the UK generation mix. If the heat pump was supplied with energy from a renewable source, CO2 emissions could be substantially reduced or eliminated.

As well as reducing purchased energy consumption and CO2 emissions, GSHPs have a number of other environmental and operational advantages:

  • High reliability (few moving parts, no exposure to weather).
  • High security (no visible external components to be damaged or vandalised).
  • Long life expectancy (typically 20 – 25 years for the heat pump and over 50 years for the ground coil).
  • Low noise.
  • Low maintenance costs (no regular servicing requirements).
  • No boiler or fuel tank.
  • No combustion or explosive gases within the building.
  • No flue or ventilation requirements.
  • No local pollution.
  • The heat pump

    GSHPs are special versions of conventional water source heat pumps designed to operate over an extended range of entering water temperatures. Typical temperatures for the source water entering the heat pump range from -5°C to +12°C for heat pumps delivering heat with maximum output temperatures that are sometimes as high as 65°C.
    Heat Pump Repairs
    The performance of heat pumps can vary widely so it is important to select an efficient unit. Theheat pump output is a function of the rated efficiency of the unit and this should be quotedbin the manufacturer’s data. This is determined by performance testing under standard test conditionsbsuch as those specified in BS EN 14511-2 ‘Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling. Part 2 Test conditions’.

    The performance data should provide the coefficient of performance (COP). This is measured as the heat output (kWth) divided by the electrical input (kWel), at standard test conditions for brine/water heat pumps of B0W50, B0W35 and B5W35 (i.e. brine input temperature of 0°C and water output temperature of 50°C, etc). ‘Brine’ is used in the standard to denote any water/antifreeze solution. The higher the COP the more efficient the heat pump is.

    The efficiency for a specific installation will also be dependent on the power required by the ground loop circulating pump, which should be kept as low as possible.

    A standard is being developed for calculating heat pump system efficiencies (EN 15316-4-2 ‘Heating systems in buildings. Method for calculation of system energy requirements and system efficiencies. Part 4-2 Space heating generation system, heat pump systems’). This is currently available as a draft.

    Most heat pumps are designed to limit noise nuisance and vibration, for example by using antivibration mountings for the compressor and lining the heat pump casing with acoustic insulation. Inbbaddition flexible connections may be needed for the hydraulic connections from the heat pump. The heat pump should not be mounted close to sensitive areas such bedrooms.

    Types of ground heat exchanger

    Indirect - In an indirect circulation system the ground heat exchanger consists of a sealed loop of highdensity polyethylene pipe containing a circulating fluid (usually a water/antifreeze mixture), whichis pumped round the loop. Energy is transferred indirectly via a heat exchanger to the heat pump refrigerant. The majority of systems are indirect.

    Direct - Alternatively, the refrigerant can be circulated directly through a copper ground heat exchanger. This is called a direct expansion (DX) system. Direct circulation systems are more efficient than indirect systems because there is good thermal contact with the ground, the heat exchanger between the ground coil circulating fluid and the refrigerant is eliminated, and no circulation pump is required. This means that, for a given output, a shorter ground coil is required than for an indirect system, giving an installation cost saving that helps offset the higher material cost, but these systems require more refrigerant and there is a greater potential risk of refrigerant leaks. DX systems are most suitable for smaller domestic applications. They are uncommon in the UK.

    Heat exchanger - The ground heat exchanger is buried either horizontally in a shallow trench (at a depth of 1.0m – 2.0m) or vertically in a borehole. The choice of horizontal or vertical system depends on the land area available, local ground conditions and excavation costs. As costs for trenching and drilling are generally higher than piping costs, it is important to maximise the heat extraction per unit length of trench/borehole.

    Horizontal collectors require relatively large areas, free from hard rock or large boulders, and a minimum soil depth of 1.5m. They are particularly suitable in rural areas, where properties are larger, and for new construction. In urban areas the installation size may be limited by the land area available. Multiple pipes (up to six, placed either side-by-side or in an over/under configuration) can be laid in a single trench, but they should be at least 0.3m apart. The amount of trench required can also be reduced if the pipe is laid as a series of overlapping coils (sometimes referred to as a SLINKY™), placed vertically in a narrow trench or horizontally at the bottom of a wider trench. The trench lengths are likely to be 20 to 30 per cent of those for a single pipe configuration, but pipe lengths may be double for the same thermal performance.

    Vertical collectors are used where land area is limited and for larger installations. They are inserted as U-tubes into pre-drilled boreholes generally 100mm to 150mm in diameter and between 15m and 120m deep. DX systems are only suitable for shallow vertical collectors (maximum depth 30m). Vertical collectors are more expensive than horizontal ones but have high thermal efficiency and require less pipe and pumping energy. They are also less likely to suffer damage after installation. Multiple boreholes may be needed for larger residential applications.

    The collector coil can also be laid under water, for instance in a pond. Seasonal variations in the water temperature are likely to be greater than in the ground, but heat transfer rates can be high so overall efficiencies can be higher than for collectors buried in the ground.

    Heat pump sizing

    The actual performance of the heat pump system is a function of the water temperature produced by the ground coil (which will depend on the ground temperature, pumping speed and the design of the ground coil) and the output temperature. It is essential that the heat pump and ground heat exchanger are designed together.

    To size the system the design heat load must be known. An accurate assessment of the air infiltration rate is important, especially for highly insulated houses, and it is recommended that an air leakage pressure test is carried out to confirm that the design levels are met. It is also important to look at the load profile as the energy required to operate the system will depend on the operating conditions.

    The heat pump system can be sized to meet the whole design load, but because of the relatively high capital cost it may be economic to size the system to meet only a proportion of the design load, in which case auxiliary heating (usually an in-line direct acting electric heater) is needed. As the efficiency of the auxiliary heating system will be lower than that of the heat pump, its use is likely to increase annual energy consumption. Detailed analysis of the building loads, energy consumption and cost effectiveness is required. In general, a heat pump sized to meet 60 per cent of the design heating load is likely to meet 85 per cent to 95 per cent of the annual heating energy requirement.

    Electrical requirements

    The heat pump is driven by an electric motor. This is an inductive load that can cause disturbances to the electricity distribution network because of high starting currents. It is a particular problem when using a single phase and can lead to flickering lights, voltage surges or ‘spikes’ (which can affect electronic equipment) and premature main fuse failure.

    The Electricity Supply Regulations 1988, require that any particular consumer’s installations do not interfere with the supplier’s system, or the supply to other consumers. In particular, the variation in voltage caused by switching a load on and off must be within recognised limits. The actual voltage variation caused by a particular piece of equipment at a particular point on the network, will depend on the electrical impedance of the network at that point, as well as the actual size of the load connected. It is therefore essential to contact the distribution network operator (DNO) – formerly known as the Regional Electricity Company – at an early design stage to determine the maximum load that can be connected to the network at that location, because this may limit the size of heat pump that can be installed. Heat pumps with a heating output greater than 12kW are unlikely to be suitable for use with a single phase electrical supply.

    Ways to overcome this problem include:

  • Using heat pumps that incorporate soft start controls to limit starting currents.
  • Reducing the required heat pump capacity by using an alternative heating system – for example a direct acting electric flow boiler to supplement the heat pump at times of maximum heating demand.
  • Using multiple heat pumps, for example one for the ground floor and one for the first floor.
  • btaining a three phase supply and using a three phase motor in the heat pump compressor where there is a choice, a three phase supply is preferable to a single phase supply).

  • In most other European countries this is not a problem as a three phase electricity supply is generally available in houses.

    Ground characteristics

    It is important to determine the depth of soil cover, the type of soil or rock and the ground temperature.

    The depth of soil cover may determine the possible configuration of the ground coil. If bedrock is within 1.5m of the surface, or there are large boulders, it may not be possible to install a horizontal ground loop. For a vertical borehole the depth of soil will influence the cost. It is generally more expensive and time consuming to drill through overburden than rock because the borehole has to be cased.

    The ground temperature should be determined because the temperature difference between the ground and the fluid in the ground heat exchanger drives the heat transfer. At depths of less than 2m the ground temperature will follow the air temperature and will show marked seasonal variation. As the depth increases the seasonal swing in temperature is reduced, and the maximum and minimum soil temperatures begin to lag the temperature at the surface. At a depth of about 1.5m the timelag is approximately one month. Below 10m the ground temperature remains effectively constant at approximately the annual average air temperature (i.e. between 10°C and 14°C in the UK depending on local geology and soil conditions).

    Information on the thermal properties of the ground is needed for determining the length of heat exchanger required to meet a given energy load.. Most important is the difference between soil and rock, as rocks have significantly higher values formthermal conductivity. The moisture content of the soil also has a significant effect as dry, loose soil traps air and has a lower thermal conductivity than moist, packed soil. Low-conductivity soil may require as much as 50 per cent more collector loop than highly conductive soil. Water movement across a particular site will also have a significant impact on heat transfer through the ground, and can result in a smaller ground heat exchanger.

    A geotechnical survey can be used to reduce the uncertainty associated with the ground thermal properties. More accurate information can result in a reduction in design loop length and easier loop installation. The British Geological Survey has an on-line service offering simple, or more detailed, GeoReports giving information on local ground conditions relevant for ground source heat pumps. (A basic GSHP report suitable for a domestic application currently costs £50 – and is available online.) For large schemes where multiple boreholes are required, a trial borehole and/or a thermal properties field test may be appropriate.

    Ground Loop Sizing

    The length of pipe required depends on the building heating load, soil conditions, loop configuration, local climate and landscaping. Sizing of the ground loop is critical. The more pipe used in the ground collector loop, the greater the output of the system. But asnthe costs associated with the ground coil typically form 30 to 50 per cent of the total system costs, oversizing is uneconomical.

    Undersizing leads to the ground loop running colder and could, at worst, result in ground temperatures being unable to recover so that the annual energy that could be extracted from the ground would reduce over time. The ground loop must be sized to meet the peak thermal power load, but also to deliver energy at no greater rate than the surrounding earth can collect it over a twelve month period. If a system provides cooling as well as heating, energy transferred to the ground in summer will be stored and will be available to be extracted in winter.

    Assuming that other conditions remain constant, the specific thermal power that a loop can extract (usually measured in: Watts/metre (W/m) pipe length for horizontal loops, W/m trench length for SLINKYs and W/m of borehole for vertical loops) will depend on the temperature difference between the circulating fluid and the ‘far field’ ground temperature (i.e. away from the influence of heat exchange with the collector coil).

    The amount of energy that the ground loop can deliver is derived from the hours of use at particular temperature differences (and hence energy fluxes) over a given period. Sizing is complex and usually performed with specialised software programs, the accuracy of which have been verified using monitored data. Software is available in the public domain, and has been developed by manufacturers. An up-to-date list of design tools and suppliers is available from the IEA Heat Pump Centre’s website. Details of a variety of design tools are also given, ‘Designing heat pump systems: Users’ experience with software, guides and handbooks’. Design of the ground heat exchanger will normally be the responsibility of the installer or the heat pump manufacturer.

    Loop depth, spacing and layout

    The deeper the loop the more stable the ground temperatures and the higher the collection efficiency, but the installation costs will go up. Horizontal loops are usually installed at a depth of between 1.0m and 2.0m.

    Health and safety regulations do not allow personnel to enter unsupported trenches if they are more than 1.2m deep. To reduce thermal interference, multiple pipes laid in a single trench should be at least 0.3m apart.

    To avoid interference between adjacent trenches there should be a minimum of 3m between them. Vertical boreholes should be at least 7m apart. Pipe layout should be carefully considered to keep the dynamic hydraulic pressure drop across the ground heat exchanger as small as possible, and so minimise the pumping power needed. For example, the maximum trench length for a single SLINKY loop is usually 50m. Multiple loops or boreholes should be connected to a manifold with individual isolating valves for each loop. This will allow individual loops to isolated when filling the ground collector or if a leak occurs.

    Piping material

    piping material used affects service life, maintenance costs, pumping energy, capital cost and heat pump performance. It is important to use high quality materials for buried ground collectors. In indirect systems, high-density polyethylene is most commonly used. It is flexible and can be joined by heat fusion. The pipe diameter must be large enough to keep the pumping power small, but small enough to cause turbulent flow to ensure good heat transfer between the circulating fluid and the inside of the pipe wall. Pipe diameters between 20mm and 40mm are usual. For direct expansion systems, copper pipe (12mm – 15mm in diameter) is usually used. Depending on soil conditions, a plastic coating may be necessary to prevent corrosion.

    Circulating fluid

    The freezing point of the circulating fluid should be at least 5°C below the mean temperature of the heat pump (i.e. the average of the inlet and outlet temperatures on the source side). As the mean operating temperature of the heat pump may be as low as -4°C, it is usual to add an antifreeze solution to prevent freezing to below -10°C.

    The specific antifreeze protection needed will depend on the design of the heat pump’s heat exchanger, so it is important to comply with the manufacturer’s specific recommendations for antifreeze concentration. The antifreeze should have good thermal performance. It is also important to make proper allowance for any change in properties of water/antifreeze mixtures as the loop temperature falls. For instance, below -10°C glycols (especially propylene glycol) become markedly more viscous and need greater pumping power, reducing overall system efficiency. If the flow ceases to be turbulent energy transfer will be significantly reduced.

    The ground loop circulating pump

    The circulating pump should have a low electrical load requirement, while still being adequate to ensure turbulent flow is maintained in the ground loop. In general the pumping power should not exceed 50W per kW (thermal) installed heat pump capacity. The pump must be suitable for the minimum design water temperature. Temperatures down to -10°C are possible so a pump that is suitable for use in chilled water circuits, and has its motor protected against the possibility of internal condensation, will be needed.

    Installation and testing

    Installation of the heat pump system, and especially the ground heat exchanger, needs to be carefully programmed so that it does not interfere with – or delay – any other construction activities. The time taken for installation depends on the soil conditions, length of pipe, equipment required and weather conditions. Typically, installation of a vertical or horizontal ground coil for domestic applications can be completed in one to two days. Prior to any excavation it is important to locate and protect any buried utilities, drainage pipes etc.

    The GSHP manufacturer’s procedures must be followed. The installation of horizontal heat exchangers is relatively straightforward, but heat exchangers require highly specialist knowledge – not just by the drilling contractor, but also regarding pipe specification, joints, grouting etc. The ground heat exchanger should be installed by professionals who have preferably undergone training by manufacturers, or other recognised authorities such as the International GSHP Association or Zeuner Limited.

    When installing the ground heat exchanger it is important to ensure good long-term thermal contact with the ground. Horizontal loops are usually laid on a bed of sand and then covered with a further 150mm layer of sand for protection. Care must be taken to avoid damage when backfilling, and the backfill material should be screened for rocks, stones etc.

    For vertical heat exchangers, the space between the borehole wall and the inserted pipes is backfilled with a suitable grout material that is pumped from the bottom of the borehole. Low hydraulic permeability, high thermal conductivity grout (e.g. ‘high solids’ Bentonite), or a thermally enhanced, low permeability grout is used. Grouting over the full borehole length is required unless dispensation has been obtained from the Environment Agency. This not only provides good thermal contact but also prevents any vertical migration of groundwater.

    It is recommended that the ground heat exchanger is made from a continuous loop of pipe. Any subsurface connections in high density polyethylene pipe should be made using heat fusion techniques in accordance with relevant standards. For DX systems, work involving the refrigerant can only be carried out by personnel and companies certified to do this, for example Zeuner Limited.

    External pipework must be insulated within 1.5m of any wall, structure or water pipes, and sleeved where it enters the house. When the heat pump is delivering heat, the ground loop circuit will normally be operating below the building interior’s dew point temperature.

    Good quality insulation and vapour sealing of internal pipework and fittings in this circuit is therefore essential to minimise the risks, and the pipework should be configured so as to avoid potential damage if any condensation still occurs. A strainer, preferably a removable one, should be fitted. Also, it is good practice to fit a pressure gauge and pressure relief valve. Any arrangement for topping up the ground loop must not be permanently connected to the mains cold water supply. Warning tape should be installed over all buried pipes.

    The ground loop should be pressure tested before installation in the ground (this may be done prior to delivery) and again after installation. The loop should be flushed and purged of all air before being charged with antifreeze, and pressurised ready for connection to the heat pump. The antifreeze must be pre-mixed with water before it is added – unless there is a single loop, or the configuration of multiple loops allows individual loops or boreholes to be valved off and filled separately.

    Geothermal

    Our society has become increasingly dependent on fossil fuels such as oil, coal and natural gas. These are finite resources, having been created by natural processes over millions of years. Burning them to produce energy results in emissions of ‘greenhouse gases’, including carbon dioxide (CO2). These gases trap solar radiation in the earth’s atmosphere and cause undesirable changes in the climate.

    Despite their increasing use elsewhere, GSHPs are a relatively unfamiliar technology in the UK. But their performance is now such that, if properly designed and installed, they represent a very carbon-efficient form of space heating.

    Design

    The most important first step in the design of a GSHP installation is the accurate calculation of the building’s heat loss, its related energy consumption profile and the domestic hot water requirements. This will allow accurate sizing of the heat pump system, which is particularly important because the capital cost of a GSHP system is generally higher than for conventional systems, and economies of scale are more limited.

    Install

    Installation of the heat pump system, and especially the ground heat exchanger, needs to be carefully programmed so that it does not interfere with – or delay – any other construction activities. The time taken for installation depends on the soil conditions, length of pipe, equipment required and weather conditions. Typically, installation of a vertical or horizontal ground coil for domestic applications can be completed in one to two days. Prior to any excavation it is important to locate and protect any buried utilities, drainage pipes etc.

    Service

    Whilst it is rare to experience any problems with heat pumps, we recognise that everyone likes peace of mind and no one wants to be without hot water or heating. An annual health check is included in all of our service contracts help ensuring your heat pump continues to run at its maximum efficiency and can be an important requirement for validity of manufacturers warranties. We always aim to respond to any call outs as quickly as possible (depending on engineer availability) and will strive to be with you within a 48 hour period. The annual maintenance visit is planned with you in advance, normally just before the peak heating season. All heat pump maintenance clients benefit from reduced call out fees as well as an annual health check.
    Other charges may apply depending on geographic location. heat Pump Repair are avialable to support third party installations.
    Please call us on 0800-1-ZEUNER to discuss your requirements in more detail.

    Controls

    Let us reduce your costs and control your energy usage. All commercial buildings need energy efficient, affordable and easy-to-use heating, ventilation and climate controls. At Heat Pump Repair, we specialise in the integration of all building management systems (BMS) and can equip any building – whether new, renovated or converted - with BMS controls that guarantee you a comfortable environment and efficient operation.

    Remote Monitoring

    Our Remote Web Server (WS) software manages a network of JACE's around the UK. Data is collected in real-time at the JACE, then logged and stored locally. Periodically, data is archived from the JACE to our Web Server.

    Once archived in the Web Server, data is available for applications such as Energy Profiler, which resides on our server and uses the archived data.

    Repair

    Do you have a heat pump that's not performing properly or worse?
    If you have a heat pump, even if it's not been installed by us we can repair or service it.
    Our engineers have been trained on installation and repair by the following manufacturer’s:
    · Water Furnace· Clivet· Dimplex· Stiebel Eltron· IVT (Ice Energy and Worcester Bosch)· Mitsubishi· Daikin· Danfoss

    Our in house expertise, gained over decades encompasses refrigerant based systems such as:

  • Air and ground source heat pumps.
  • Commercial refrigeration.
  • Air conditioning.

  • If you would like to arrange a repair or service visit please Contact us.

    Applications

    GSHPs can be used to provide space and domestic water heating and, if required, space cooling to a wide range of building types and sizes. But the provision of cooling in addition to heating will result in increased energy consumption however efficiently it is supplied. GSHPs are particularly suitable for new build as the technology is most efficient when used to supply low temperature distribution systems, such as underfloor heating. They can also be used for retrofit, especially in conjunction with measures to reduce heat demand. GSHPs can be particularly cost effective in areas where mains gas is not available, or in developments where there is an advantage to simplifying the infrastructure provided.

    Space heating

    The first aim of the space heating control circuit is to operate the heat distribution system at the lowest temperature that will still meet the required comfort conditions. This will optimise the efficiency of the heat pump. The three main control options are:

    Weather compensation

    This is the most efficient form of control. The output temperature from the heat pump is adjusted according to the outside air temperature. As the outside temperature rises the output temperature is reduced, so the heat pump never works at a higher temperature than necessary. In general an outside temperature sensor sends signals to a controller. This automatically controls the output temperature according to a factory set curve defining the relationship between the outside air temperature and the heat pump output temperature. For water distribution systems the operation of the heat pump compressor is usually controlled in response to the return water temperature, so this is lowered as the outside air temperature rises.

    Room sensor control

    A room temperature sensor located centrally in the house can be used in conjunction with an outside air temperature sensor to influence the curve control function.

    Fixed temperature

    The heat pump is switched on and off by an in-built return temperature sensor and always operates up to its maximum working temperature. This method of control does not offer optimum savings from the heat pump. Usually a single room temperature sensor is used to control the operation of the heat pump compressor. In addition the operation of the heat pump can be controlled by a timeclock, however, for water-based distribution systems there will not be the same potential for intermittent heating as there can be with conventional gas or oil fired heating systems. With output temperatures between 35°C and 55°C the response time of the heating system is long. GSHP systems are therefore designed to maintain a stable temperature rather than be able to raise the temperature quickly immediately before occupation. Night setback can be applicable but with a setback of 2°C to 4°C. The main function of the timeclock is likely to be to try and maximise the use of any cheaper electricity tariffs.

    Domestic water heating

    The heat pump is likely to be operating less efficiently when providing domestic water heating because higher output temperatures are required. Where the domestic hot water system includes a storage cylinder, it will be cost effective to make maximum use of any cheaper tariff periods for electricity. The basic control device is therefore a timeclock and a tank thermostat.

    The auxiliary immersion heater should not be able to operate at the same time as the heat pump is supplying heat to the domestic hot water cylinder.

    A tank immersion thermostat or sensor, rather than a strap-on one, should be used to sense the stored water temperature as it is more accurate.

    Space heating

    Typical delivery temperatures for various heating distribution systems:
    Distribution system Delivery                temperature (°C)
    Underfloor heating                                30 - 45
    Low temperature radiators                   45 - 55
    Conventional radiators                         60 – 90
    Air                                                        30 – 50

    GSHP systems are not suitable for directly replacing conventional water-based central heating systems which have been designed to operate at 60°C to 90°C however if measures are taken to improve the thermal insulation of the building the reduced heating requirement may then be met using a reduced distribution temperature. Alternatively the radiator area can be increased. A drop in circulating temperature of 20°C would require an increase in emitter surface of 30 to 40 per cent to provide the same heat output.

    For new housing where high insulation levels result in low heating demand, low temperature air distribution systems, low temperature waterbased systems or underfloor heating are all possible options.

    The seasonal performance of a low temperature radiator system will not be as high as that for an underfloor design because of the higher output temperature. Fan convectors can be used but flow temperatures of around 50°C may be necessary to ensure high enough air supply temperatures, which will also reduce the system’s efficiency.

    The thermal capacity of the distribution system is important. If it is too low the heat pump may suffer from artificially long off periods at times of light load. This effect is partly due to the presence of a restart delay (designed to reduce wear on the compressor by preventing rapid on/off cycling) in the heat pump.

    To avoid this, sufficient non-disconnectable thermal capacity needs to be provided to compensate for the loss of output during the delay restart period. The heat pump manufacturer’s guidance should be followed, but it may be necessary to install a ‘buffer’ tank in order to optimise the running time of the heat pump. The required capacity will depend on the system but is likely to be between 60 and 200 litres. Use of a buffer tank will allow more flexible individual room temperature control.

    Domestic water heating

    Water heating provides a year-round load and can improve the load factor for the heat pump. Hot water usually needs to be delivered from the tap at temperatures ranging from 35°C to 45°C. For domestic installations the thermal power output of the heat pump will be inadequate to deliver direct heating of incoming mains water to this level, so a storage system is required.

    Heating is usually carried out via a primary coil or jacket to a storage cylinder. For most domestic heat pumps the maximum output temperature is 55°C, and the maximum water storage temperature achievable is 50°C. An auxiliary electric immersion heater is needed to provide a ‘boost’ facility, and also to raise the water temperature periodically to over 60°C to reduce the risk of Legionella. For full water heating the heat pump should be capable of supplying water in the range 60°C to 65°C.

    The stored water volume should be sized so that virtually all the energy input can be supplied during a reduced rate electricity tariff period (such as Economy 7). Where auxiliary heating is provided by an efficient fossil-fuelled boiler it may be more economic to use the boiler to heat the stored water at temperatures above 45°C, because the efficiency of the heat pump falls as the output temperature rises.

    Another option is to preheat the incoming cold water in a separate preheat tank, via an indirect coil, at whatever temperatures are being used to perform space heating.

    Heat pumps, especially those for the US market, can be supplied with a desuperheater designed to provide partial domestic water heating. A desuperheater is a refrigerant hot gas-to-water heat exchanger that is installed between the compressor and the reversing valve of a space conditioning heat pump. It has a small thermal power output (about 10 per cent of the total heat pump power), but output temperatures up to about 70°C can be achieved. It is designed for use in situations where cooling loads dominate, as it then acts as a heat recovery system – whereas in heating mode the desuperheater leads to a small reduction in thermal power output.

    The desuperheater only works when the heat pump is working. If the space heating need is satisfied (house up to temperature) the heat pump will be turned off and there will be no energy available at the desuperheater for hot water production, so an auxiliary immersion heater will still be required. The cost benefits of using a desuperheater need to be carefully assessed.

    Where an unvented hot water cylinder is used it must meet all relevant UK regulations and be installed by a competent person.

    Cooling

    Most water-to-air heat pumps are reversible so a forced air distribution system can readily be adapted to provide cooling as well as heating.

    A reversible water-to-water heat pump coupled to an underfloor distribution system can also be designed to supply space cooling in summer. Even with water-to-water heat pumps designed for heating only, a limited amount of ‘passive’ summer cooling can be provided by direct use of the ground loop, for example by by-passing the heat pump (using a 3 port actuator) and circulating fluid from the ground coil through a fan convector or plate heat exchanger. Protection against condensation should be provided especially for underfloor systems so we advice no less than 16 degrees cooling.

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    We will undertake any heatpump design, repair, maintenance and installation of any type of heatpump and associated controls.