abbe level 3 diploma in domestic green deal advice 7. heating systems

Domestic GDA Training – 7. Heating Systems 1Training Material © Stroma Certification 2013 | Version 1.3

ABBE Level 3 Diploma in Domestic Green Deal Advice7. Heating Systems

① Comparing Heating Types

② Fuel Storage, Heat Recovery and Ventilation

③ Storage Heaters

④ Heating Controls

⑤ Changing Heating Systems

⑥ Hot Water Cylinders & Insulation

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Comparing Heating Types


The Measures


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.

Heating Unit Running Cost per year

Non Condensing Boiler £950

Condensing Boiler £720


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

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


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.


Storage Heaters - advice


Electric Heating

Night Storage HeatersThe 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 10Many 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

Heating System Install Cost Savings per year

Slimline fan assisted storage heater

£200 - £500 £120 - £180


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

Heating System Annual fuel cost

Oil Boiler £1,360


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 - advice


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.



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.


Changing Systems, and Heating Problems - advice


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.


Pipework

Open Vented System

Boiler

Sink

Sink

Mains water supply

Header tanks

Indirect hot water cylinder


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.


Heat Recovery and Ventilation- advice


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.



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.



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.


Mechanical Ventilation


Heating Controls - advice


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.


TRV Settings


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.


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.


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.


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.


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.

55

Full control of a heating system could save up to 20% on existing energy bills.


Changing Heating Systems


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.


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.


Community Heating

community heating system are available in Green DealA specialist assessment would need to be carried out to determine suitability

GuidanceTo get a the most accurate assessment Its is recommended for the community heating is modelled using full SAP


Hot Water Cylinders & Insulation


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.


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.


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.


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


Questions?


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abbe level 3 diploma in domestic green deal advice 7. heating systems

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