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ABBE Level 3 Diploma in Domestic Green Deal Advice 7. Heating Systems. Presented by . Comparing Heating Types Fuel Storage, Heat Recovery and Ventilation Storage Heaters Heating Controls Changing Heating Systems Hot Water Cylinders & Insulation. Comparing Heating Types. The Measures.
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ABBE Level 3 Diploma in Domestic Green Deal Advice7. Heating Systems Presented by Comparing Heating Types Fuel Storage, Heat Recovery and Ventilation Storage Heaters Heating Controls Changing Heating Systems Hot Water Cylinders & Insulation
Regular Boiler A regular boiler is one which provides space heating directly, but stores hot water in a separate storage system.Along with the boiler unit, it requires a feed and expansion cistern, controls and a hot water cylinder. Advantages Can provide a high hot water flow rate. Straight-forward design ensures easy maintenance. Can be used with low mains pressure. Disadvantages Space requirement for feed tanks, hot water cylinder and pipework. Heat loss associated with hot water storage and pipework. Low pressure hot water. Poor flow rate for showers.
Combination or ‘Combi’ Boiler A combination boiler is one which provides space heating and hot water directly. In its simplest form (an ‘instantaneous combi’) water is provided ‘on-demand’ rather than via storage. The boiler is fed directly from the mains supply, negating the need for a cold water tank and associated piping. Combination boilers are available which incorporate hot water storage within the appliance. Showers must be of a thermostatically controlled ‘mains pressure’ type.
Combination or ‘Combi’ Boiler Advantages Instantaneous hot water. High pressure hot water. Space efficiency (no cylinder, feed tanks). Good flow rate for showers. Cheap to run. Drinking water available at all taps. Disadvantages Suitable for small homes only. Unsuitable for low pressure supplies. Ancillary water heating (e.g. solar) requires extra storage and compatibility. Poor flow rate for baths. No back-up supply if mains supply fails.
Gas Heating Systems Annual fuel cost for heating and hot water (not including installation costs): Gas is the most widely used heating fuel in the UK. Most households in the UK have mains gas central heating. This is a so-called ‘wet system’, which means a gas-fired boiler heats water to provides central heating through radiators and hot water through the taps in the home.
Gas Heating Systems These are estimated figure based on installing a new A rated condensing boiler and full heating controls, to a semi-detached property with three bedrooms assume a boiler swap at a cost of £2300
Gas Heating Systems Advantages Gas is a highly-efficient fuel, so you get a good return on every unit of energy. Modern condensing boilers, which use hot flue gases that are wasted in a standard boiler, have very high efficiency - 90% or more. Gas is piped direct to your home so you don’t need to store any fuel. Replacing a standard gas boiler with a modern condensing boiler is relatively straightforward. Gas is the most widely used heating fuel in the UK. Finding a plumber on the Gas Safe Register scheme should be fairly easy. Anyone proposing to carry out work on your boiler is required by law to be on the Gas Safe Register. Gas boilers can be serviced annually to ensure they run efficiently and last as long as possible. Disadvantages Gas prices are on the rise and are likely to remain high. Installing a gas central heating system from scratch can be expensive and disruptive. If you’re not on the gas network, connecting your property can also be costly. As a fossil fuel, gas produces carbon dioxide when it’s burnt and can’t be considered a clean source of energy.
Electric Heating Night Storage Heaters The most cost-effective form of electric central heating uses night storage heaters. These heaters use electricity supplied at a cheaper ‘night-time’ rate to heat up special heat-retaining bricks. These bricks then heat the home around the clock using the heat stored in the bricks. Night storage heaters give out heat slowly and are designed to keep warm for the whole of the following day. Cheap-rate electricity can also be used to provide hot water via an immersion heater in the hot water tank.
Electric Heating Economy 7 and Economy 10 Many households use an electricity tariff that offers cheaper rates of electricity at night. Electricity tariffs that provide cheap-rate electricity are usually known as Economy 7, as they give seven hours of cheaper electricity overnight. Economy 10 works in a similar way and gives an extra three hours of cheap electricity – usually in the middle of the afternoon. Electric radiators that run off a normal single-rate electricity tariff are also available. However, due to the relatively high price of electricity during the day, these can be expensive to run and should only be considered in very well-insulated properties where they won’t be used regularly.
Electric Heating Advantages Electric night storage heaters are much cheaper to install than gas central heating systems as they require no pipe-work or flue. With very few moving parts, storage heaters need very little maintenance and don’t need to be serviced annually. Unlike gas, mains electricity is available almost everywhere in the UK.
Electric Heating Disadvantages Heating your house with electricity can be expensive Electricity prices are about three to four times higher than gas prices per unit of energy. And like gas, electricity prices are also rising and are likely to stay high. As most electricity in the UK is generated in gas-fired power stations, any increase in the price of gas will also be reflected in the cost of electricity. The daytime rate on Economy 7 or Economy 10 tariffs is higher than on standard single-rate electricity tariffs, so while you’ll get a cheaper rate for your heating, running appliances during the day – particularly if you need to use an electric heater to provide extra heat – could be expensive. You don’t have instant control over storage heaters: older models give out heat as long as the bricks remain warm - day and night. If you haven't had the heating on lately and switch on your night storage heater, you won't get heat until the following morning. Some heaters do have a convection heating option for instant heat, but this runs on peak rate electricity. If your storage heaters don’t have an automatic charge control which measures the temperature in the room and adjusts the amount of heat stored overnight, you’ll have to set this yourself – so keep an eye on the weather forecast for the following day.
Electric Heating Fuel cost for heating and hot water: £2500 less with Economy 7/10 Modern storage heaters vary considerably in price. Once you have replaced all your old heaters with fan assisted models with CELECT controls ( a centralised control point ) you could expect to save on up to £180 your electricity bills
Modern Fan-Assisted Storage Heater Some more modern storage heaters are fan assisted to improve the distribution of heat from the device. These heaters have additional vents at the bottom and two separate wires coming from the device, one for the peak rate meter, for the fan, and the other to the off peak meter, for the overnight charging. These storage can have a direct acting panel heaters integrated into the device. This means the device is capable of providing on-demand heat as well as the release of stored heat.
Storage Heaters Reasons to upgrade Older storage heaters are much less efficient Improved heat distribution Fuel cost Controllability Aesthetics Reduced space requirement (2 appliances in one)
LPG Central Heating Although most households in the UK have mains gas central heating, around 4.2m households are not connected to the mains gas network. In parts of the UK with no mains gas, some homes use liquid petroleum gas (LPG) instead. This is normally used in a ‘wet’ heating system where an LPG-fired boiler heats water, which provides central heating through radiators and hot water through the taps in the home. The main difference between mains gas and LPG is that the latter is delivered by road and stored in a tank, which the householder may have to buy or rent from their supplier. Some boilers designed for mains gas can be converted to use LPG.
LPG Central Heating Advantages LPG is a highly-efficient fuel, so you get a good return on every unit of energy. Modern condensing boilers, which use hot flue gases that are wasted in a standard boiler, now achieve efficiencies of 90% and more. Replacing a standard LPG boiler with a highly-efficient modern condensing boiler is a relatively straightforward job. As gas is the most widely used heating fuel in the UK, finding a plumber should be fairly easy. Disadvantages Like mains gas and oil, LPG prices are on the rise and are likely to remain high as the UK As LPG is delivered by road there is a possibility that you could run out of gas LPG boilers need annual servicing to ensure they run efficiently LPG isn't considered a clean source of energy.
Oil Heating Systems Although most households in the UK have mains gas central heating, around 4.2m households are not connected to the mains gas network. In parts of the UK where there is no mains gas network to connect to, such as rural areas, some homes use heating oil instead. The main difference between mains gas and heating oil is that it is delivered by road and stored in a tank, which you may have to buy or rent from your supplier. Heat-only and combination condensing oil-fired boiler types are both available. Most oil-fired combination boilers have an internal hot water store to supply domestic hot water rather than the instantaneous heating more common in gas boilers.
Oil Heating Systems Advantages Oil is a highly efficient fuel, giving a good return on every unit of energy. Modern condensing boilers, which use hot flue gases that are wasted in a standard boiler, now achieve efficiencies of 90% and more. Replacing a standard oil boiler with a highly efficient modern condensing boiler is relatively straightforward. Oil boiler – wall-hung
Oil Heating Systems Disadvantages High oil price. As oil is delivered by road there is a possibility the supply could run out. However, systems that monitor the amount of oil in the tank and automatically notify the supplier when it needs topping up are available. . The storage tank can also be unsightly (although this can be resolved by opting for an underground tank). Oil boilers need annual servicing to ensure they run efficiently Most condensing oil-fired boilers are floor standing so it may be difficult to find a wall-mounted model. Oil boilers generally limit the hot water flow rate to ensure the water is as hot as it should be, meaning the hot water flow rate is lower than a gas boiler and that the hot water temperature will decline as more water is used. As a fossil fuel, oil produces carbon dioxide when it’s burnt and can’t be considered a clean source of energy.
Secondary Heating Secondary heating is used to supplement a main system within a dwelling. It can be used to top up the heating from the main system although this usually means the main system is under heating the dwelling. Under-heating may be solved by insulating or reprogramming. Secondary heating is best used to heat a smaller section of the dwelling when there is no need to heat the entire dwelling e.g. on a cold summer evening.
Underfloor Heating or Radiators The standard/traditional and usually cheapest option is to use wall-hung radiators. Normally one radiator is placed in each room, perhaps two in larger rooms. The size is worked out according to a heat-loss calculation. With underfloor heating, plastic pipework is buried within the cement screed or under a timber floor, and the whole floor is used as an emitter. It is a more expensive system to install though more efficient. The heat radiates slowly upwards. It is therefore, thought to be much more pleasant. There are no hot spots or draughts. There are no unsightly radiators. There are energy-efficiency benefits as UFH operates at low temperatures.
Underfloor Heating or Radiators Older UFH systems were less controllable than radiator-based heating systems, so much so that many systems would be left to run 24/7. As technology has improved, more sophisticated controls have made it possible to manage two or three temperature regimes. UFH can take a long time to get a house warm. UFH can take an equally long time to cool down, which can cause overheating. One frequent compromise is to fit UFH on the ground floor and radiators upstairs. UFH tends to suit houses in constant occupation, rather than those where everyone is out all day.
Upgrading a Boiler Same Fuel Upgrading a boiler is usually straightforward when swapping like for like. Where the boiler type is changed (regular to combi) there will be some inevitable disruption, as the pipe work and components of the system will not be compatible: • Cylinder. • Header tanks in the loft. • Pipework runs.
Header tanks Indirect hot water cylinder Sink Sink Boiler Mains water supply Pipework Open Vented System
Pipework Sealed System
Combi Boiler Combi Boiler
Radiators Radiators need to be sized for the room they are installed in by: • Heating type • Size of the room • Location Heating engineers agree that the best location for a radiator is in the coldest part of the room. In addition, they traditionally specify that radiators should be installed on the external wall beneath the window. This allows the cold air coming in via the window to be warmed up. It should also be noted that a double radiator has less heat output than two single units, though the overall size may be the same i.e. two singles are more efficient.
Central Heating Problems Is the heating system slow to warm up? Are some radiators completely or partially cold? Is the radiator water dirty and discoloured? Are there ‘kettling’ noises from the boiler? Are there repeated pump failures? If a customer complains of any of the above they may need their heating system: • Bleeding (DIY) • Balancing (DIY) • Flushing (£300)
Radiator Reflector Panels Radiator reflector panels are a good low-cost option for reducing energy consumption. Fixed behind radiators, they reflect heat from the radiator back into the room, instead of letting the heat out through an external wall. They have the most benefit when installed on walls which are not insulated.
Flue Gas Heat Recovery Flue Gas Heat Recovery Systems (FGHRS) are designed to recover heat in the flue gases discharged from a condensing boiler. The boiler can be fired by natural gas, LPG or oil. They use the cold temperature of the domestic cold water supply to recover extra heat that is not extracted by the boiler. This recovered heat is used to heat the hot water supply in one of two principal ways: • Instant: recovered heat is immediately used to pre-heat to the domestic water supply before it enters the boiler or external hot water cylinder. • Deferred: heat recovered during space heating production is stored for later use to pre-heat the domestic water supply before it enters the boiler or external hot water cylinder the next time hot water is required.
Flue Gas Heat Recovery FGHRS can either be integral too or separate from the boiler. An integral system is known as a Passive Flue Gas Heat Recovery Device (PFGHRD), and selecting the correct boiler from the PCDF database will include the heat recovery system in the calculation. FGHRS can be fitted to existing boilers, in which case the system will be separate from the boiler. The FGHRS should be visible above the boiler, where the flue outlet is located, or there should be enough room to install one.
Flue Gas Heat Recovery A flue gas heat recovery system will normally be installed just above the boiler unit.
Waste Water Heat Recovery A waste water heat recovery system (WWHRS) uses a heat exchanger to recover heat from waste warm water as it flows through the waste plumbing system. This is used to pre-heat the cold water feed of a shower, combi boiler or hot water cylinder. The energy recovered depends on the temperature of the cold water feed to the dwelling (which varies by month) and the number and type of systems that are installed. It is unlikely to be retro-fitted at a property, so it is more likely to be found in modern properties. It is unlikely to be visible as it will run in the building fabric.
Ventilation There is clear guidance in Part J of the building regulations about the required ventilation of combustion appliances (oil, gas, LPG, solid fuel): Room sealed appliances don’t need to take air for combustion from the room. Generally older appliances using gas, oil, and LPG are open-flued, and need adequate permanent internal ventilation. All solid fuel appliances are open-flued because they cannot be switched off. The ventilation requirements are determined by the capacity of the appliance and the size of the room they are in.
Mechanical Ventilation Mechanical ventilation systems circulate fresh air using ducts and fans, rather than relying on airflow through small holes or cracks in a home’s walls, roof, or windows. BENEFITS OF MECHANICAL VENTILATION Better Indoor Air Quality: Indoor air can be many times more polluted than outdoor air. Ventilation systems can significantly improve a home’s air quality by removing allergens, pollutants, and moisture that can cause mould problems. More Control: When homes rely on air flow through walls, roofs and windows for ventilation, there is no control over the source or amount of air that comes into the house. In fact, air leaking into the house may come from undesirable areas such as the garage, attic or crawl space. Mechanical ventilation systems provide controlled fresh air flow with appropriate locations for intake and exhaust. Improved Comfort: Mechanical ventilation systems allow a constant flow of outside air into the home and can also provide filtration, dehumidification and conditioning of the incoming outside air. Typical use - Homes where condensation is problematic.
Heating Controls Old heating controls are unlikely to be adequate after a boiler upgrade for a number of reasons: The thermostat is less responsive. The timer/programmer is likely to be less accurate with less programs available. Lock shield radiator valves aren't thermostatically controlled. It is unlikely to be zone controlled by multiple room stats and motorised valves.
Heating controls For a central heating and hot water system to operate efficiently it must be possible to control it so that heating and hot water are provided at a suitable temperature, as and when required. Most systems include: • Boiler (which can be a regular/system/combi off of which can be condensing models). • Cylinder stat. • Room thermostat. • Motorised valves. • Thermostatic radiator controls. • Programmer.
Boiler Thermostat Most boilers have a dial marked in numbers or from Min to Max. This sets the temperature of the water that will be pumped from the boiler through the radiators. The higher this is set, the quicker and more effectively the system will heat the property. In fact, if this is not set high enough, when it is very cold outside the home may not reach the desired temperature. The boiler control thermostat should always be set to a higher temperature than the cylinder thermostat. In most boilers, a single boiler thermostat controls the temperature of water sent to both the cylinder and radiators, although in some they are separate.
Hot Water Tank If your hot water is stored in a cylinder, the thermostat will prevent it being hotter than it needs to be. Once the water has reached the temperature you have set, the heat supply from the boiler will be turned off. Turning the thermostat higher will not make the water heat up any faster, and the water heating will not come on if a time switch or programmer has switched it off. Cylinder thermostats are usually fitted between one quarter and one third of the way up the cylinder. They have temperature scales marked: you should set them at between 60ºC and 65ºC This is hot enough to kill off harmful bacteria in the water, To retain as much heat as possible the cylinder should have 80mm of insulation.
TRVs TRVs are mechanical controls found on radiators in rooms other than where the room thermostat is placed. The TRV senses the air temperature in the room and can be set higher in the rooms that are used most and lower in rooms used least, such as bedrooms. They usually have a fat valve at one end, marked with a * and numbers from 1 to 5. The * setting is to protect against frost. This will typically leave the radiator switched off unless the temperature falls below about 8°C on the proviso the system is on. For a normal living room, the setting of 3 or 4 is likely to be about right. For a bedroom a cooler temperature will normally be enough.
