APPENDIX 2: Heating System The heating system in any building is likely to be the biggest user of energy, and the system in which the greatest savings can be made. There are many different ways that a heating system can work. Traditional gas boilers heat water which heats the air in the building. Air conditioning systems heat the air directly and then distribute it around the building. Many other fuels can be used other than gas, and air conditioning can come in many different shapes and sizes. Despite their differences, all heating systems have the same basic principles, and these are where we can locate possible energy savings. 1. 2. 3. 4. Energy is fed into the system Heat is generated Heat is transferred to where it will be used Heat is lost Where the energy is put into the system, this may be from a renewable energy source, or a very high carbon energy source. Similarly, it may be a cheap fuel or an expensive one. When the heat is generated, this process will never be 100% efficient, so there may be improvements that can be made, often by good maintenance of the boiler or other heating unit. While the heat is transferred, there can be losses in pipe work, or in the unit used to transfer the heat to the room. Pipes should be well insulated to keep as much heat in as possible, and radiators or fan coils should be well maintained, efficient models. Finally, once the building has been heated, this heat will escape. To save energy, ensure that the heat takes as long as possible to escape the building. Do this by improving insulation and draught proofing, and by keeping doors and windows closed while the building is being heated. More details on how to maintain an efficient heating system are given below. • At the end of the life of an air conditioning system, consider installing either a high efficiency boiler or heat-pump and remote condenser, selected from the ECA list. The ECA list provides 100% first year Enhanced Capital Allowances (ECA). This allows the full cost of an investment in designated energy-saving plant and machinery to be written off against the taxable profits of the period in which the investment is made. See www.eca.gov.uk/etl/ • Consider installing a high efficiency boiler or high COP heat pump selected from the ECA list to qualify for a 28% capital allowance. The heat pump could be part powered by any photovoltaics installed. • It is recommended that any heating system be investigated in order to identify areas for improvement, such as independent control of the different building parts. It is likely that not every room needs to be the same temperature all of the time, or run on the same schedule, so zoning is an important tool. • Consider commissioning an in-depth review of your Building Energy Management System to identify areas of savings and investment costs. • Consider installing destratification fans to provide mixing of the air within any rooms with high ceilings. This avoids heat collecting in the rafters and moves the heat to floor level where it will be used. • Consider installing sensors to windows to ensure that the heating is switched off should any windows be opened to reduce heat loss to the exterior environment. • The Efergy energy monitor1 also helped to identify good practice housekeeping measures such as the optimisation of hot water night storage heating at one club. At another club it helped to demon strate an annual cost saving of £839 achieved by installing LED lighting. MAINTENANCE Regular maintenance is essential for maximum efficiency. Ensuring the boilers are regularly serviced by qualified heating personnel is vital. Any leaks in the pipe work require urgent attention. Heat exchangers and fans should be checked and air intake filters cleaned or replaced regularly. Air distribution should be balanced so that all rooms are at an appropriate temperature. Poorly maintained or disconnected thermostats and central control systems are one of the most common sources of poor temperature regulation and high energy use in buildings with central heating systems. Ensure your maintenance contractor checks and reports on the heating control system and seeks specialised advice where necessary. THERMOSTATIC RADIATOR VALVES Thermostatic radiator valves (TRV) are very useful to improve the overall energy efficiency of any building. Heating and energy use account for a large portion of the UK’s annual CO2 output. By optimising our building’s energy efficiency you can reduce not only our heating bills, but also the amount of CO2 emissions released. TRV can cut heating energy costs up to 20% while improving comfort. They automatically control the flow through your radiator to heat each room based upon their “need” (in terms of the temperature setting for that radiator) rather than a manual or default flow. 1 See appendix ‘3 Cooling System’ for more information Whilst a standard “flow to all radiators” manual system does provide heat, it also wastes heat in overheating areas which are already warm enough. It also cannot compensate for variable aspects such as the sun shining through a window, people being in the room, heat generated by appliances in the room etc. This results in half the building being too warm, and parts of it not being warm enough. Thermostatic valves need no external power; they maintain the room temperature by controlling the volume of hot water or steam flow. The valve body are usually made of noncorrosive nickel-plated bronze/ brass. TRVs cost normally between £5 and £20 depending on make, style, aesthetics, flow direction (one way or dual) and where you buy. WHAT ARE THE ADVANTAGES OF A THERMOSTATIC VALVE? • • • • • • Wide temperature control range. Automatic “freeze protection” and shut-off-protection. The specially designed valve head with its air circulation feature and long isolation stem prevents interference by flow medium temperature. The head is securely fastened to the valve body through its unique holding nut design which prevents any loosing problems. Wide range of thermostatic heads suitable for all applications Lockshield ring or protection cap prevents theft of or damage to the thermostatic head. TIMERS Running the central heating/hot water system continuously is prohibitively expensive for most users. One certain way of holding down a building’s heating bills is to switch the system off as often as possible. Of course, this can be done only when room and water heating system are not needed. Time controls on most heating/hot water systems are among the first essentials for improving home comfort and reducing running costs. All pumps, fans, boilers and furnaces should be switched by an automatic timer. These can often be set such that they will not operate over holidays and weekends. A 7-day timer can be programmed to eliminate weekend operation, and each day can be given a different schedule at the beginning of the week. Analogue timer Ensure as well that there is a different program for each season, since requirements for space heating will not be the same in summer, winter, autumn or spring. THERMOSTATS Digital timer Controlling room temperatures is an important way of saving energy. A 1°C reduction in room temperatures can lower heating costs by up to 10%. The calibration of room thermostats can be checked by reading room temperatures with a thermometer placed next to the thermostat. Control panels can be enclosed or protected so that only authorized personnel can change the settings. The most important rule with thermostats is to ensure that they are in the right place. If a thermostat is placed next to a source of heat or a draughty place, the thermostat will not work properly. The extra heat generated by a computer, a kettle, or even a light bulb that is too close to the thermostat will make the thermostat think that the room is hotter than it is, and will turn the heating off when it should still be on. Similarly, if the thermostat is in a cool place, in a draught or near a chilled object, it will think that the room is cooler than it is and turn the heating up. Use thermostat controls to prevent over or under heating. Over heating can be a problem during spells of mild weather. Under heating can also be an expensive problem if portable electric heaters are used to top up the main heating system. Set thermostats at the lowest comfortable temperature in winter (18°C–20°C). Temperatures in changing rooms need to be set slightly higher at about 21°C. Corridors and stairwells can also be at a lower temperature provided this does not result in cold draughts into the rooms. MOTORISED VALVES Motorised valves in ‘wet’ central heating systems control the flow of heated water from the boiler to primary circuits, i.e. to radiators and HWS cylinder coils. Operated by small (5W or 6W) synchronous electric motors and activated by time controls and thermostats, they help maintain desired comfort levels and save fuel by ensuring heated water goes only to where it is needed – and when. Motorised valves are the last step to complete the operating sequence for “wet” central heating systems, where each user-set, timed switching Motorised valve programme helps maintain desired comfort levels and prevents excessive fuel consumption by inhibiting unnecessary boiler firing. This is one of the best ways to keep your building with the maximum comfort and with a high efficiency. Please see below the operating sequence for central heating systems, with the different parts and their following explanations: TIME CONTROL Sends time ON/OFF signals to thermostat THERMOSTATS (ROOM OR CYLINDER) If heat demand exists, switches close and pass signals to valve(s) RELEVANT MOTORISED VALVES BOILER AND PUMP Motor opens valve(s), activates auxiliary switch to boiler/pump Boiler can only fire when a demand for heat exists INSTALLING RADIATOR REFLECTOR PANELS Radiator reflector panels (insulated sheet of aluminium foil) are an attractive low-cost option. Fixed behind your radiators, they reflect heat from the radiator back into the room, instead of letting the heat out through an external wall. This is cost-effective for all types of wall construction with the largest returns expected with solid, un-insulated walls through which the rate of heat loss is greatest. The price for these panels is around £3.50 per sheet, and is even cheaper if bought in bulk, so this solution is highly recommended given its cost to savings ratio. INSULATING PIPES Insulating hot water pipes means encasing the pipes that conduct hot water from the hot water heater to where the water is demanded. This includes hot water for space heating. Insulating these pipes saves water, energy, and money compared to leaving pipes un-insulated. BENEFITS It is advisable to have proper pipe insulation installed, especially in the cold season. Pipes without insulation are subject to increased heat loss, which can make heating your building and using hot water more expensive, simply because more heat has to be generated. Pipe insulation is useful, cheap and easy to install, therefore you should make sure that any pipes that require insulation are properly taken care of. Since pipe work can operate at temperatures very different to the ambient temperature, and the rate of heat flow from a pipe is related to the difference in temperature between the pipe and the surrounding ambient air, heat flow from pipe work can be considerable. In most situations, this heat flow is undesirable. For example, in a radiator heating system, the rooms will gain heat more efficiently from the radiators than the pipes, partly due to the location of the radiators, but also due to their design. The application of thermal pipe insulation introduces thermal resistance and reduces the heat loss rate. Make sure that it is not just the straight sections of pipe that you insulate. It is just as important to insulate the bends and joints in the pipes. There can be as much heat lost in one joint as in 1m of straight pipe. REASONS FOR PIPE INSULATION There are two main uses for pipe insulation: • To prevent heat loss: This will save energy and money and make using hot water more convenient, with proper pipe insulation hot water will be available as soon as you open the tap. • For safety reasons: hot pipes can be dangerous, especially in rooms where small children play or in places where you might touch them accidentally. Pipe insulation can reduce the risk of scalding yourself on an unconcealed hot pipe. COSTS AND SAVINGS Rubber foam tube insulation is quite inexpensive, two metres of foam tube pipe insulation costs around £3-£5 and most fibreglass products will cost around the same. Thicknesses of thermal pipe insulation used for saving energy vary, but as a general rule, pipes operating at more-extreme temperatures exhibit a greater heat flow and larger thicknesses are applied due to the greater potential savings. Poorly insulated pipes are responsible for annual non-recoverable heat losses of up to 40 of the net heat demand. By insulating the distribution pipes these losses can be reduced to 12. HOW TO INSULATE HOT WATER PIPES For efficient pipe insulation it is best to rely on the experience of a professional plumber or heating engineer who has the proper knowledge to identify hot pipes with potential for heat loss and to choose the best kind of insulation. HOW TO DIY PIPE LAGGING (Please note that we recommend using professional help to obtain the best results possible) Begin by cleaning the pipes and allowing them to dry completely before installing insulation to avoid mould or mildew. Select fibreglass, foil, or tubular sleeve insulation. Tubular sleeve insulation is the easiest to install, simply cut the desired length and snap it around the pipe. Use duct tape to join seams and joints where the pipes change direction. Be sure to install the sleeves so the seam faces downward. Install foil or fibreglass insulation with a ½ inch overlap, making sure to duct tape the ends. Fibreglass insulation should be wrapped with plastic to avoid condensation drips. All hot water pipes should be insulated, especially within 3 feet of the water heater. Fibreglass insulation is the safest to use with a gas water heater because tubular sleeve insulation is more flammable. Both fibreglass and foil are capable of insulating pipes at an R-4 efficiency level which is advisable for hot water pipe insulation, depending on their thickness. Foam often comes in pre-cut tubes of one metre length and is usually rubber foam, while there are also other synthetic foams on the market. Fibreglass comes in different shapes; there are shell coverings as well as sheets that would be wrapped around the pipe. It is important that the pipe insulation is properly fixed to the pipe; loose insulation will work less efficiently. Look for the Energy Saving Trust Recommended label if you’re buying pipe insulation – it will help you recognise the most energy efficient products.
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