© stroma development ltd 2013 | version 1.1 stroma – heating systems space heating

© Stroma Development Ltd 2013 | Version 1.1Stroma – Heating Systems

Space Heating


Heating in RdSAP

• RdSAP allows you to include:– A main heating system (e.g. boiler)– An additional main heating system, (2nd main system)– A secondary heater (room heater)

• The additional heating system allows two main heating systems to be included in the EPC. This means a wider variety of heating setups can be specified in RdSAP.

• The secondary heating must be based on fixed room heaters e.g. gas/ solid fuel fires, electric heaters

• it is not possible to select a central heating system as secondary heating.


Main heating• The main heating system is defined as:

– A system which heats the largest proportion of the dwelling– A system which is not usually based on individual room heaters (although it can be)

– A system which usually also provides the water heating

• A typical main heating system would be a central heating boiler

• If there is more than one heating system or device in a property use the following process to decide which is the main heating system– The main system usually provides both space and water heating and should

heat at least 30% of the dwelling– If no system provides space and water heating then select the system which

heats the greatest part of the dwelling– If there is still doubt then select the system which supplies useful heat to the

dwelling at the lowest cost– If the costs are the same then select the system which heats

the living room


Additional main system

If a dwelling has an additional main system then the proportion of the property heated by each system should be calculated. This should be based on heated floor area to the nearest 10%

– If two systems serve the same heating circuit then assume there is a 50/50 split– The main system should be the one which heats the living area

• Examples where an additional main system can be used– A large property has two different boilers fitted so the whole property can be heated.

One boiler is the main system the other is the additional main system.– A property has a boiler fitted to replace storage heaters, but some functioning storage

heaters are left in the property, the boiler is the main system and the storage heaters are the additional system

Previously only one main heating system could be entered, which restricted RdSAP and meant some properties could not be accurately modelled.


Secondary heating• Secondary heating must be based on fixed room heaters.

– A fixed room heater is an independent heater not on a central system, such as a gas fire or electric panel heater. The heater must be fixed in place, so portable heaters are not included in the assessment.

• This means it is only possible to select the following – Oil room heaters– Electric room heaters– Solid fuel room heaters– Gas room heaters

• If there is more than one secondary heater in a property then use the following process to identify the heater which should be selected:

1. Select the type of heater which heats the greatest number of habitable rooms2. If that does not resolve the choice then select the heater which is cheapest to run,

based on fuel cost3. If that still does not narrow it down, select the device with the

lowest efficiency


Secondary heating• Portable heaters can be specified in particular circumstances:

– When the main heating system is an off-peak storage system (this is covered later in this section) and no other type of secondary heating is present

• The software will automatically include portable heaters in the EPC in particular circumstances:– If the main heating system is not deemed sufficient to heat a dwelling, and no

secondary heating is specified.– If there is no heating system present in the dwelling at all

• Portable heaters are defined as– Completely free-standing and self-supporting– Contains a built in fuel store, or for electric heaters, has a lead and plug– Can be easily moved between rooms– Focal point electric fires designed for the located in a fireplace can be included in the

assessment as a fixed heater


Main Heating Types

• Central heating systems– Gas boilers– Oil boilers– Range cookers– Solid fuel boilers– Electric boilers– Heat pumps– Community heating– Electric storage heating– Electric underfloor heating– Warm air systems– Room heaters


Types of boiler

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The most common type of boiler you will encounter will be Mains Gas as is it the most widely available fuel.

The boilers will either• Regular boiler• Back boiler • Combi boiler• Condensing boiler• Combined Primary Storage Unit


What does a regular heating system look like

• Hot water tank• Cold water tank• Feed and expansion tank• Expansion pipe- heating • Expansion pipe – hot water

tank• Pump• Programmer• Room thermostat


Regular Boiler

Key features of a regular boiler

– It can provide heating and hot water for a dwelling

– The hot water must be stored in a cylinder

– There are usually 3 pipes coming out of a regular boiler, gas supply, flow and return)

– The boiler heats water which then flows around the heating system and to the hot water tank


Back Boiler

• A back boiler is a type of regular boiler, these are fitted behind a fire.

• It provides space heating and hot water.

• As with a regular boiler the water is stored in a cylinder.


Back Boilers

• Back boilers can be – Gas, – solid fuel – Oil

• In RdSAP gas and solid fuel back boilers can be identified as central heating systems

• Gas and solid fuel back boilers are sometimes listed in the PCDF but not always


Identifying a back boiler

• How can you tell if a gas fire has a back boiler?– Look for a plate at the bottom

of the fire, this may come away to reveal the boiler controls

– Back boilers are usually more substantial than a normal gas fire

– There will usually be a control dial, sometimes with the boiler name on it

– There may be a cylinder with no boiler unit


Solid Fuel Back Boiler


Combi Boiler

• A combi or combination boiler provides heating in the same way a regular boiler does

• It provides domestic hot water on demand, rather than storing it in a cylinder.

• A combi boiler is easily identified as it usually has 5, 6 or 7 pipes.

• Combi boilers also have more controls on the front of them e.g. heating, hot water and sometime a programmer


Combi Boiler pipework


What does a Combi Boiler system look like


Condensing Boiler

• A condensing boiler is a highly efficient type of boiler• Most non-condensing boilers emit hot combustion gases, but a condensing

boiler extracts the heat from the combustion gases before they are emitted, pre-warming the water in the boiler.

• This means the flue gases emitted are a lower temperature• There is some condensation of flue gases as they leave the boiler, these are

drained out of the boiler through a plastic condensate pipe. This is the key identifying feature of most condensing boilers

• Because the flue gases are cooler a plastic flue can be used, rather than a metal flue

• On a cold day you may be able to see a plume of water vapour coming from the flue.


Condensing Boiler pipework

A. Central Heating FlowB. Domestic Hot Water C. Gas InD. Mains Cold InE. Central Heating ReturnF. Overflow/ Pressure Relieve Valve G. Condensate Pipe


Condensing Boiler


Condensing Boiler- Flue and Condensate Pipe


Combined Primary Storage Unit

• This is an appliance which incorporates the provision of space heating and hot water; the hot water store should be at least 70L and integral to the appliance.

• This type of appliance is usually floor mounted and larger than a conventional boiler


Underfloor Heating

• Underfloor heating can be fitted to a boiler if it is fitted there will be a manifold such as the one pictured.

• This manifold distributes the hot water amongst the underfloor heating loops• If both underfloor heating and radiators are present in a property it is not

possible to include both as the heat emitter. Radiators should be specified as they require a higher flow temperature, making them the worst case scenario


Underfloor Heating System


Underfloor Heating System Layout


Underfloor Heating – Floor Construction


PCDF

• Product Characteristic Data File• The PCDF is a searchable database which includes the following types of

heating systems– Gas and oil boilers– MicroCHP*– Heat Pumps *– Solid fuel boilers *

• The PCDF contains specific technical details about heating devices, including their seasonal efficiency

• RdSAP software incorporates the PCDF when searching for heating systems

* Covered later in this section


PCDF

• Make sure you collect the device make and model information so you can accurately identify it in the PCDF.

• If a device cannot be found in the PCDF then there is a list of types of heating systems in RdSAP, the device should be selected from this generic list, known as the alternative method in Stroma’s software.

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Boiler ID Plate

The boiler ID plate is a very useful way of finding out all the information needed to find the specific boiler in the PCDF


Flue Types

• The flue can help identify the boiler type and it’s location.• There are a 3 flue types

– Open flue– Balanced flue– Fan assisted flue


Open Flue

• Open flues are usually found with older, floor mounted boilers• The combustion gases are taken from within the room the boiler is in.• The combustion gases are drawn up from the boiler by wind passing over

the top of the flue


Open Flue

This is the more common type of open flue, these are found on the top of converted chimneys.


Open Flue


Balanced Flue

• This type of flue uses air from outside the dwelling for combustion.• It relies on natural air movement to draw the hot air back outside from the

boiler• The flue must be located as close to the boiler as possible to keep the flue

length short• A balanced flue is classed as ‘room sealed’


Balanced Flues


Fan assisted flue

• This is a room sealed flue which uses a fan to assist the movement of the air through the flue

• This means the flue doesn’t have to rely on natural air movement and can be located further from the boiler


Fanned Flue for Regular Boiler


Plastic Fanned Flue

• A plastic fanned flue indicates that the boiler fitted must be condensing


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 two principle ways:

– Instantly – 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



FGHRS can either be integral to the boiler 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 calculationFGHRS can be fitted to existing boilers, in which case the system will be separate from the boilerThe FGHRS should be visible above the boiler, where the flue outlet is located.In order to include the FGHRS it must be in the PCDF


Flue Gas heat Recovery

A flue gas heat recovery system will normally be found just above the boiler unit.

Remember that the system must be included in the database in order to be included in the assessment


Flue Gas Heat Recovery - Software

Select whether a FGHRS is present

Select the fuel type

Then select the FGHRS make and model information



• A FGHRS can be fitted to a separate hot water store• If this is the case it may be powered by PV• Make sure you check for a solar PV array installed specifically to power the

FGHRS • There is a section in the software for FGHRS and a PV array

specific to it

Record the standard PV data, kWp, tilt, orientation and overshading



RdSAP Convention 9.06 states:– Include [FGHRS] only if found in database, identified in same way as

for heating systems. When the model cannot be found no default option is available but the presence of the device should be recorded in site notes


Electric Central Heating

• Provides heating and hot water• Generally for smaller properties such as flats• No flue


Electric Central Heating

• This is an electric direct acting boiler

• The unit is about 1metre long and can provide heating and hot water, if a cylinder is fitted

• Common examples of this type of boiler are the Heatrae Sadia Amptec and the Trianco Aztec Classis


Electric central heating

• This is an electric water storage boiler

• It uses cheap rate electricity over night to heat water for space and water heating

• There is a water cylinder within the unit

• The cylinder must be less than 270L, if it is bigger the device is classed as a Electric CPSU



• Electric CPSU – like a gas CPSU this device has a hot water tank within the device

• The water store must be over 270L for it to be classed as a CPSU, otherwise it is an Electric water storage boiler

• These units are generally quite large, around 1.8m tall so will be found in cupboards.

Electric CPSU



• Electric dry core storage boiler ; this works in a similar way to storage heaters, using cheap rate electricity to heat bricks inside the unit

• The heat is transferred from the bricks to water via a heat exchanger to provide space and water heating

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Solid Fuel Boiler

• These can be either manual or auto (gravity) feed

• Solid fuel boilers run on traditional solid fuels such as anthracite, or they can run on biofuels such as wood pellets

• Solid fuel boilers are usually regular boilers capable of providing heating and hot water for a property.


Range Cookers

• To be accounted for as a heating system a range cooker must incorporate a boiler capable of providing space heating

• Range cookers can run on solid fuel, gas or oil


• Gas and oil range cookers can either be– Twin burner – has two burners one for heating and one for cooking– Single burner – one burner which does heating and cooking

• If the range cooker is just supplying hot water it can be specified in the RdSAP software. This will be covered in more detail in the water heating section.

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Range Cookers


Warm Air System – Gas Fired

• Warm air systems blow warm air out of vents located around the property• The main unit is floor mounted and about 1.5-2m tall• Warm air systems can run on gas, oil or electricity• Electric warm air systems use off peak electricity to store heat

overnight, so the property should have a dual rate electricity meter


Warm Air – Typical Vent

Extra care should be taken when looking for the vents, many can be hidden behind wardrobes, sofas etc.


Electric Storage Heaters

• Storage heaters use cheap rate electricity over night to store up heat in bricks within the heaters. This heat is then released during the day

• Storage heaters make use of off-peak/economy 7 electricity which is sold at a much cheaper rate

• Storage heaters use drift heat, and are often placed in hallways and landings, as well as the main living area


Inside of Storage Heater

Ceramic plates


Old (large volume) storage heaters

• Old storage heaters are usually quite large, around 20-25cm deep• They sit directly on the floor due to the weight of the bricks inside the

heater


Modern Slimline Storage Heater

• Modern storage heaters are narrower, around 10-15cm• They are sometimes attached to the wall with small feel to support their

weight


• 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 over-night charging

Modern Fan Assisted Storage Heater


Integrated storage and direct acting

• These storage heaters 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 heating

• When certain types of storage heaters are the main heating a secondary system should be specified.– Old (large volume) storage heaters– Modern (slim line) storage heaters– Fan storage heaters– Electric underfloor – in concrete slab

• Because integrated storage heaters and integrated underfloor heating have direct acting heaters included in the device there is no need to specify any secondary heating


Electric underfloor heating

• In concrete slab (off-peak)– This system uses the floor to store heat, much like storage heaters use the bricks– There should be a dual electricity tariff available to the property

• In screed above insulation (standard tariff)– Cables are laid just under the floor surface and provide on-demand heat.– This system uses peal rate electricity and is often installed in one

room, usually a bathroom or kitchen)


Electric underfloor heating

Integrated (storage and direct acting)– This system combines the off-peak and on-peak systems– Two sets of cables are laid in the floor, one placed lower than the other to

provide the off-peak heating

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Electric ceiling heaters

• This form of heating is very unusual in domestic properties.• It was most commonly fitted in the 1970s and 1980s.• It works in a similar way to underfloor heating, with panels embedded in

the ceiling construction, with insulation fitted above.


Heat pumps

Heat pumps are becoming increasingly common in the UK• They can be used as part of a wet central heating system or a warm air

system• Heat pumps work by extracting heat from a low temperature source and

increasing the temperature so it can be used for heating.• This results in greater than 100% efficiency as the amount of energy used

is less than the heat energy generated


Ground Source Heat Pumps

A ground source heat pump is a device for converting energy in the form of low level heat to heat at a usable temperature.The heat pump consists of three main parts;

- ground collector loop, - compressor, - condenser heat exchanger


Ground Source Heat Pump


Air Source Heat Pumps

Operating in a similar way to Ground Source Heat Pumps, Air Source Heat Pumps are an alternative way of extracting useful thermal energy from the air if ground space is not available.


Community heating

Community heating is a system which provides heat to more than one dwelling

• Typically community heating would be available in a block of flats

• The system in place would be a large industrial size boiler system housed in a boiler room

• It is unusual to get access to the boiler room, but the system can usually be identified by the lack of a boiler in the dwelling, but a wet heating system is present.


Community heating

• Three types of community system are available in RdSAP

– Community boilers only: a standard heating system which can provide space and water heating

– Community CHP and boilers: a more complex system which includes Combined Heat and Power. You must have evidence this is present to include in the survey. (more details in the next few slides)

– Community heat pumps – large heat pump system which runs on electricity, often a warm air system with vents visible in the dwelling. Fan-coils can be selected as an emitter for community heat pumps


Community heating

• Try and determine the fuel type of the community heating system, if this is not possible assume the fuel is Mains gas.

• Additional fuel types are available to community heating as well as the standard fuels such as mains gas and oil– B30D – a form of biofuel made up of 30% bio diesel and 70% oil– Waste combustion – heat produced at incinerators and similar waste

disposal sites can– Biomass– Biogas – landfill and sewage gas

• If community heating provides hot water only and the space heating comes from an alternative source, such as electric panel heaters, then the community heating can be specified as the water heating.

• Further details on this are covered in the Water Heating slides.


Combined Heat and Power (CHP)

• When electricity is generated in central power stations around 60-65% of the primary energy is rejected as waste heat into the atmosphere.

• Combined heat and power units generate electricity locally so that waste heat can be used for beneficial purposes for heating or hot water.

• Where all waste heat generated can be used, CHP units will have overall efficiencies of up to 80-85% compared to 35-40% for conventional power stations.

Bristol City Council Community Heating


Combined Heat and Power Systems

CHP systems produce roughly twice as much waste heat as they generate electricity. To be viable and economic, CHP require a large constant demand for heat.Current insulation standards mean the requirement for space heating is very low and demand is present only part of the year. The only constant source of heat demand is for domestic hot water and in terms of reducing CO2 emissions some of the demand could be met by the use of solar water heating instead. For large CHP systems to be economically viable they need to run for at least 4,000 hours per year. They are most suited to leisure centres with swimming pools and hospitals


MicroCHP

Micro Combined Heat and Power units are systems designed on a smaller scale than standard CHP

• Micro CHP mainly generates heat, with some electricity generation

• If the electricity is not used in the home it can be sold back to the grid


MicroCHP

• Most micro CHP systems run on mains gas or LPG• The latest micro CHP devices are similar in size to a domestic boiler• Some micro CHP systems are now listed on the PCDF. If they cannot be

found on the database they should be listed as a condensing boiler used the alternative method.

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Secondary Heating

Room HeatersGas firedSolid fuelElectric


Secondary Heating

• Room heaters can be specified as the main heating system or a secondary heater

• Only room heaters can be specified as secondary heaters

• Room heaters should not be specified as the main system or additional system unless the only heating in the dwelling is from room heaters

• Room heaters are not listed in the PCDF, so they have to be entered into the software using the alternative method


Gas Fires

There are a range of gas fire options in RdSAPThe options available have descriptive titles which can be used to help identify the type of gas fire you have


Gas Fires

Selecting the correct gas fire is important as the efficiencies vary between the appliances

– Gas fire, open flue, pre-1980 (open fronted) with or without back boiler– Gas fire, open flue, 1980 or later (open fronted), sitting proud of and sealed to

fireplace opening, with or without back boiler unit– Flush fitting live fuel effect gas fire (open fronted), sealed to fireplace opening,

with or without back boiler unit– Flush fitting live fuel effect gas fire (open fronted), fan-assisted, sealed to

fireplace opening.– Gas fire or wall heater, balanced flue– Gas fire, closed fronted, fan assisted– Condensing gas fire– Decorative fuel effect gas fire, open to chimney– Flueless gas fire, secondary heating only

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Gas Fires

Gas fire, open flue, pre-1980 (open fronted) with or without back boiler– An older style of gas fire, often with the ceramic blocks which radiate the heat

when lit


Gas Fires

Gas fire, open flue, 1980 or later (open fronted), sitting proud of and sealed to fireplace opening, with or without back boiler unit

– This type of gas fire is a bit more modern, it must be sat in front of the fireplace, rather than being built into it

– Open fronted in this case means the combustion gases are taken from the room, so the heater is not sealed. There may be a glass panel in front of the coals on this type of appliance, but it does not seal the unit.


Gas Fires

Flush fitting live fuel effect gas fire (open fronted), sealed to fireplace opening, with or without back boiler unit

– This appliance sits in the fireplace, it is usually a single unit which fits in the fireplace and controls the airflow up the chimney


Gas Fires

Decorative fuel effect gas fire, open to chimney– This type of gas fire is similar to a flush fitting live fuel effect gas fire, but there

is no control of the airflow, so the efficiency of the appliance is quite poor


Gas Fires

Gas fire or wall heater, balanced flue– This type of appliance will have a balanced flue on the external wall


Gas Fires

Condensing gas fire– Should have a condensate pipe and fanned flue– These types of gas fire are not particularly common, the main

manufacturer is Mantis


Gas Fires

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Gas fire, closed fronted, fan assisted– the appliance must be sealed from the room– A glass panel which does not seal off the appliance is not considered a ‘closed

fronted’ appliance


Gas Fires

Flueless gas fire, secondary heating only– This is a very efficient type of gas fire– There should be no flue coming from the appliance, so it can be freestanding


Oil Room heaters

There are less oil room heaters to choose from– Room heater, pre 2000, with or without back boiler– Room heater, 2000 or later, with or without back boiler– Bioethanol heater, secondary heating only


Oil Room heaters

• Take care to ensure they use oil, there should be an oil tank present at the property

The age of oil room heaters should be based on how old they look


Oil room heaters

Bioethanol heater– These appliances must use bioethanol fuel– the bioethanol is in liquid or gel form– They can be freestanding because they do not need a fixed fuel

supply or flue


Solid Fuel Room Heater

• Solid fuel room heaters are generally quite inefficient appliances as the majority of the heat is lost up the chimney or flue

• The following options are available– Open fire in grate with or without back boiler– Closed room heater with or without back boiler– Stove (pellet fired) with or without back boilerUse house coal, smokeless fuel, wood, dual fuel

• These appliances can burn a variety of solid fuels, but the exact options are determined by whether or not a property is located in a Smoke Control Zone


Open fire in grate– Fuel options include coal, wood logs, and smokeless fuel– This is a highly inefficient heating appliance, at 37%



Closed room heater– Can use coal, wood logs and smokeless fuel– This is a more efficient solid fuel appliance than an open fire, at 65%



Wood pellet stove (Biomass)– This device is designed

specifically to burn wood pellets

– This device is 65% efficient



Electric Heaters

• There are three types of electric heaters– Panel, convector or radiant

heater– Water or oil-filled radiators– Portable electric heaters

• Portable electric heaters should not be specified unless they are secondary heating to a storage heating system


Electric panel, convector or radiant heaters– This includes fixed panel heaters and electric fires

Electric Heaters


Water or oil filled radiators– These should be fixed heaters– They look like normal wet radiators but have electrical wires where you would

usually see pipe work

Water or oil filled radiators


Portable electric heating– This type of electric heater should not be fixed– The heater should be self-supporting and have a flex and plug– This type of heater should be ignored unless the dwelling has electric storage

heating

Portable


Fuel Types

There are a variety of fuels available in RdSAP

• Most heating systems are designed to run on a specific fuel, so make sure you know the fuel type of the heating device.


Mains Gas

• Mains gas is piped to individual properties and one of the cheapest and cleanest fuels widely available in the UK

• You musts state whether mains gas is present or not in an EPC. If a property has a gas meter or gas burning appliance within the property it has mains gas.

• A closed of gas pipe does not mean mains gas is available• If mains gas is available in the local area, but has not been piped to the

specific property, then mains gas is not available


Heating Oil• Heating oil is commonly used in

areas which do not have a mains gas supply

• The oil is stored in a large tank on site and must be delivered in bulk

• Oil tanks are usually metal or moulded plastic

• Oil boilers are usually larger and more heavy duty than gas boilers

• It is possible to get, regular, combi and condensing oil boilers

• The boiler pictured is a regular oil boiler.


Oil Fired Combi Boiler


Condensing oil boiler


Oil Tank

This is typically the type of tank you will find with heating oil. They are usually plastic. But can be sunk into the ground meaning you will only see the filling cap.


Bulk LPG

• LPG – Liquid Petroleum Gas• This is an alternative to oil in areas which are not on mains gas• Boilers are manufactured to run on LPG specifically.• Several boiler manufacturers have a mains gas and LPG version of some of

their boilers, so it is important to confirm whether or not it is LPG• LPG is stored in a tank and will be delivered in bulk to the property


LPG - Bottled• Some properties may use LPG

cylinders rather than a bulk tank.• LPG is a manufactured fuel, which

means both bottled and bulk LPG have a much higher costs than most other fuel types.

• The manufacture process also increases the carbon emissions.

• This results in a poor EPC rating, usually 2 or 3 bands lower than a property with a mains gas equivalent boiler.

• It may be worth advising your client of this during the survey


Underground Bulk LPG

• Some properties may have their LPG tank buried in their garden.• You will only be able to see a man hole cover.


Electricity

• There are a few electricity meter options in RdSAP– Single– Dual– Unknown– 24 hour (Scotland Only)


Electricity

• Single meter– This indicates the property is on a standard tariff– the meter should only show one reading– A few examples of single meters are shown below


Electricity

• Dual meter– This means a property has two electricity rates

• a standard rate, charged for electricity used during the day• an off peak rate, charged for electricity used over night and electric storage

systems have been developed to take advantage of this– This type of electricity tariff is also known as Economy 7, this is because

the tariff applies to 7 hours overnight


Electricity

• A dual tariff can be identified by the meter present at the property.– Originally properties with a dual tariff would have two electricity meters, one for

each tariff– More modern meters tend to have both readings in one meter, either a mechanical

meter with two readouts visible, or a digital meter with a button to switch between the two readings

• Some modern meters have ‘single phase’ printed on them, this does not indicate the tariff, as most dwellings have a single phase supply.


Electricity

• 24 Hour Meter

– The 24-hour tariff option, which is almost exclusive to properties in Scotland, does have some exceptions for England.

– Specifically, there are properties in Northumbria that are supplied by Scottish Power and use the 24-hour tariff

– It is highly unlikely the 24 hour tariff will be found anywhere else in England, Wales or Northern Ireland

• Unknown meter– this option should be used if it is not possible to access the meter. – The software will assume a single meter, unless the main heating or

water heating require an off-peak tariff (such as storage heaters)


Solid fuel• Coal

– can be used in open and closed room heaters– cannot be used in Smoke Control Zones

• Anthracite– used as a replacement for coal in Smoke Control Zones– Supplied in grains or nuts, smaller than coal– Can be used in solid fuel central heating boilers

• Smokeless fuel– Used as a replacement for coal in Smoke Control Zones– Can be used in open and closed room heaters– Much more expensive than coal– Is a manufactured fuel, the coals are usually a uniform shape


• Wood – also known as biomass– Comes in various forms

• Wood logs• Wood chips• Wood pellets

– When biomass fuel is combusted is releases carbon dioxide, but no more than it absorbs whilst the tree grows. Biomass is therefore considered to be carbon neutral

– Wood pellets and wood chips can be used in biomass boilers– Wood logs are used in open and closed room heaters

Solid fuel


Biomass & Biofuel Boilers


• Biomass can be burnt directly to provide heat in buildings. Wood from forests, urban tree pruning, farmed coppices or farm and factory waste, is the most common fuel and nowadays is used commercially in the form of wood chips or pellets, although traditional logs are also used.

• Biomass boilers can be designed to burn smokeless fuel to comply with the Clean Air Acts.

• Boilers can be fed automatically by screw drives from fuel hoppers. This typically involves daily addition of bagged fuel to the hopper. Electric firing and automatic de-ashing are also available.

• Biomass boilers replace conventional fossil fuel boilers and come with the automated features mentioned above. Fuels other than wood, such as straw can also be used.

Biomass and Biofuel


Biomass and Biofuel

• Biomass is normally considered a carbon neutral fuel, as the carbon dioxide emitted on burning has been (relatively) recently absorbed from the atmosphere by photosynthesis and no fossil fuel is involved.

• The wood is seen as a by-product of other industries and the small quantity of energy for drying, sawing, pelleting and delivery are discounted.

• Biomass from coppicing is likely to have some external energy inputs, for fertiliser, cutting, drying etc. and these may need to be considered in the future.


Any questions on material coveredso far?

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Heating Controls

Central heating systems generally have some or all of the following controls• Programmer• Room thermostat• Thermostatic radiator vales (TRVs)

Some systems have additional controls:

- Boiler energy manager- Zone control


Boiler Programmer

• A programmer determines the time the heating is switched on and off• Programmers can be mechanical or digital• They usually control the space and water heating


Room Thermostat

• A room thermostat measures the air temperature, if the set temperature has been reached it will feed back to the boiler to switch off

• A room thermostat must be separate to the boiler, they are usually wall mounted.


Room Thermostat

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• A thermostat situated on a boiler is most likely there to control the temperature of the water in the system, rather the actual room temperature

• If a wireless thermostat is fitted then the thermostat may not be in a fixed position, but the transmitter should be located near the boiler.

• Combined programmer and room thermostats are also quite common now, the time and temperature will be shown on the display.


Not a room thermostat

These are examples of Frost stats• A frost stat can be set at a low temperature• They are designed to turn the boiler on when the temperature gets low to

prevent the pipes freezing.• They are usually fitted near a boiler when it is located in or garage or

outbuilding where the temperature can drop very low


Thermostatic Radiator Valves (TRV’s)

• TRVs sense the temperature of individual radiators, the sensitivity can be adjusted by turning the valve

• They will cut off the flow into the radiator if it has got up to temperature• Radiator cut off valves are not classed as TRVs as they are only used to manually

shut off a radiator


Bypass

• If a system has a programmer and TRVs it must have a bypass.

• A bypass is a radiator with no TRV.

• If all other radiators TRVs are turned down there is an outlet (bypass) for the boiler


Boiler Energy Manager

• This device works in conjunction with a programmer and TRVs to adjust the output of a boiler based on a variety of external data including– Weather compensator – this adjusts the output of the boiler based on internal

or external temperatures. Sensors are usually located around the building for this type of system

– Net setback – maintains a low temperature overnight to reduce the warm up time for the system in the morning


Zone control

• A property can be split into zones which can have independent control of the heating

• Each zone should have it’s own room thermostat

• There may be one programmer with the facility to independently control each zone

• This type of system is usually found in larger properties


Boiler Interlock

• This is not a physical device but an arrangement of the system controls so as to ensure that the boiler does not fire when there is no demand for heat.

• In a system with a combi boiler it can be achieved by fitting a room thermostat.

• In a system with a regular boiler it can be achieved by correct wiring interconnections between the room thermostat, cylinder thermostat, and motorised valve(s).

• It may also be achieved by a suitable boiler energy manager.• In systems without an interlock the boiler is kept cycling even though no

water is being circulated through the main radiators or the hot water cylinder.


Boiler Interlock

Programmer

Room thermostat

TRVs

Cylinder thermostat


Other Heating Controls

Storage heaters have either manual or automatic charge control.– Most will have manual controls on the top of the heater.– Some may have automatic control, this means they have sensors which

monitor the difference in temperature in the room and the heater. The temperature is the automatically adjusted to the correct level.

• Appliance thermostats appear on electric heaters and other room heaters, they control the temperature for the individual appliance


Questions

• Name the most common types of gas boiler?• How do they work?• Which are most efficient?• How would you identify them during a survey for an EPC?• How are central heating systems controlled?• What are the main components and how do they contribute to the

efficient operation of the system they control?


Any Questions?

Heating

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