Heating Systems

Report
ABBE Level 3 Diploma in
Domestic Green Deal Advice
7. Heating Systems
Presented by
① Comparing Heating Types
⑥ Hot Water Cylinders & Insulation
② Fuel Storage, Heat Recovery and
Ventilation
③ Storage Heaters
④ Heating Controls
⑤ Changing Heating Systems
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Comparing Heating Types
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The Measures
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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.
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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.
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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.
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Gas Heating Systems
Annual fuel cost for heating and hot water (not including
installation costs):
Heating Unit
Running Cost per year
Non Condensing Boiler
£950
Condensing Boiler
£720
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.
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Gas Heating Systems
Old boiler rating
Annual saving
CO2 per year
G ( < 70%)
£310
1,200kg
F (70–74%)
£205
810kg
E (74–78%)
£155
610kg
D (78–82%)
£105
430kg
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
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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.
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Storage Heaters - advice
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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.
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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.
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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.
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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 singlerate 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.
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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
Heating System
Install Cost
Savings per year
Slimline fan assisted
storage heater
£200 - £500
£120 - £180
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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.
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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)
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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.
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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.
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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.
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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.
Heating System
Annual fuel cost
Oil Boiler
£1,360
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Oil boiler – wall-hung
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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.
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Secondary Heating - advice
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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.
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Underfloor Heating or Radiators
The standard/traditional and usually cheapest option is to use wallhung 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.
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Underfloor Heating or Radiators
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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.
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Changing Systems, and Heating
Problems - advice
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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.
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Pipework
Open Vented
System
Header tanks
Indirect
hot water
cylinder
Sink
Sink
Boiler
Mains water supply
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Pipework
Sealed System
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Combi Boiler
Combi Boiler
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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.
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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)
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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.
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Heat Recovery and Ventilation- advice
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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.
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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.
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Flue Gas Heat Recovery
A flue gas heat recovery system
will normally be installed just
above the boiler unit.
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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.
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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.
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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.
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Mechanical Ventilation
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Heating Controls - advice
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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.
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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.
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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.
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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.
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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.
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TRV Settings
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Room Thermostat
This controls the general temperature of the property. It is usually on
the wall in the hall or in a cool part of the home. A comfortable and
economic temperature is between 18 and 21°C. Once a temperature is
set, the thermostat checks the temperature in the air around it.
If the temperature falls below the set temperature, it switches the
heating on to bring the house temperature back up. If the temperature
rises above the set temperature, it switches the heating off until the
house temperature drops to the set temperature.
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Room Thermostat
Remember:
• Constantly adjusting the thermostat never allows the thermostat to
do its job - a heating system needs a period of time to settle into a
suitable pattern.
• Digital remote thermostats should be kept in one place to allow the
boiler to interpret the correct temperature required to heat the
property.
• The higher the temperature is set, the more fuel will be used.
• In very cold conditions it may be more efficient to leave the heating
on constant at a lower temperate.
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Digital Programmer
A timer/clock or digital programmer automatically turns the heating and
hot water on and off at set times. They can be set to come on once,
twice or stay on all the time, as required. They tend to incorporate three
switches.
To get the best from a room programmer:
• Check the clock is showing the correct time. If not, put the timer
switch to ‘Clock’ or ‘Time’ and adjust the time using the + and buttons.
• Set the switch to ‘On’ and ‘Off’ in turn, adjusting the times to reflect
when heating and hot water are required.
• Reset the timer switch to ‘Auto’ and check that the settings
on display show the times have set.
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Analogue Programmer
Check the clock is showing the correct time and adjust it if necessary.
Set the times needed for heating and hot water to come on and go off.
The clock may have pins or arrows to do this.
• Pins: Push them in opposite the times needed to switch on, and
pull them out opposite the times when not required.
• Arrows: Slide the ‘On’ arrows (usually red) around to the times for
on. Slide the ‘Off’ arrows (usually blue) around to the times for off.
The programmer may need to be switched to ‘Timer’ or ‘Auto’ to
activate the new regime.
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Savings
The right controls will allow heating and hot water to come on and off as
required. Average savings which could be made in a typical three-bedroom
semi-detached home, heated by gas:
•
•
•
Install a room thermostat: £70 and 280kg carbon dioxide a year.
Fit a hot water tank thermostat: £30 and 130kg carbon dioxide a year.
Fit a hot water tank insulation jacket: £40 and 170kg carbon dioxide a
year.
Further savings could be made through more effective use of controls. Upgrade
or installation of heating controls can take place without replacing a boiler.
This is a particularly good idea if controls are over 12 years old. Room
thermostats, for example, are much more accurate than they used to be.
Full control of a heating system could save up to 20% on existing
energy bills.
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Changing Heating Systems
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Changing to a Heating System
Installing a central heating system where none previously existed is a
way of:
•
•
•
•
Controlling the cost of fuel.
Improving the thermal comfort.
Improving fuel efficiency.
Improving controllability.
If room heaters and water heaters were previously independent, they
will be inefficient and have individual losses inherent within each
appliance.
This applies to both fuel switching and upgrading a system.
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Changing to a Heating System
Installing a central heating system where none previously existed will
require a level of disruption to the property. In particular:
• Floors will need to be lifted to install new pipe work.
• Ducting may need to be installed (surface mounting of pipe work).
• There must be careful consideration of boiler/cylinder siting.
• Disruption to external land is possible if a fuel switch is to take place,
with possible additional costs.
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Community Heating
community heating system are available in Green Deal
A specialist assessment would need to be carried out to determine
suitability
Guidance
To get a the most accurate assessment Its is recommended for the
community heating is modelled using full SAP
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Hot Water Cylinders & Insulation
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Hot Water Cylinder Insulation
In most homes, the hot water is supplied by
the main central heating boiler either directly
if it is a combi boiler, or from a hot water
cylinder. Often there will be an electric
immersion heater in the cylinder as well.
Advice: Use the boiler to heat the water,
even in the summer. The immersion heater
will be more expensive and should only be
used as an emergency back-up.
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Hot Water Cylinder Insulation
Insulating the hot water cylinder is one of the easiest ways to save
energy.
If there is already a jacket fitted, check the thickness. It should be at
least 80mm thick. If not a recommendation will be made to increase
insulation.
A well-fitting jacket around your cylinder will cut heat loss by over 75%
and save more than the cost of the jacket!
Spray foam cylinder insulation can also be topped up with a jacket if it
is < 25mm.
A hot water cylinder jacket costs around £15, and fitting
it is a straightforward job i.e. green tick.
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Pipe Insulation
There is a complex network of water pipes in most homes in
the UK. As many of these pipes are located in the loft, they
are more likely to freeze in the winter (if cold water pipes),
but also they can lose heat if hot water is sitting in them.
To minimise the risk of both freezing and heat loss, the
copper pipes (excellent conductor of heat but a poor
insulator) can be insulated fairly cheaply with pipe insulation,
often referred to as pipe lagging.
Lagging is simply a tube of insulating material with a slit all
the way down it’s length, that is fitted over the pipe and then
held in place with electrical tape if necessary (it should be a
snug fit, so this isn’t necessarily needed).
Fitting insulation to pipes is easy if the pipes are accessible
and will cost from around £10. Professional help may be
required to fit insulation to harder to reach pipework, which
would incur extra cost.
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Potential Savings
Measure
Annual saving
per year
DIY cost
Time taken to
pay for itself
CO2 per year
Hot water
tank jacket
Around £45
Around
£15
Less than six
months
Around 170kg
Primary pipe
insulation
Around £15
Around
£10
Around a year
Around 60kg
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Questions?
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Web Links
www.stroma.com/certification
Contacts
Stroma Certification Ltd.
4 Pioneer Way, Castleford, WF10 5QU
0845 621 11 11
[email protected]
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