I 1. Approved Documents L I A and L1 B

Numerous new legal requirements on

installing heating and hot water systems

came into effect on 6 April 2006.

Chanaes to the cl

Building Regulations (England i L Wales)

The new requirements are the result of the revision of Part L of Schedule 1 of the Building Regulations for England and Wales. (These do not apply to Scotland and Northern Ireland which have their own jurisdiction and building provisions.) Other regulations on the energy performance of dwellings and their heating systems have also been revised.

Part L concerns the conservation of fuel and power in buildings. It is supported by two Approved Documents for dwellings, LIA and L1 B: these provide guidance on how to satisfy the energy performance provisions for new dwellings (Approved Document LIA) and existing dwellings (Approved Document L1 B).

'The Domestic Heating Compliance Guide' LIA and LIB provide guidance only. They rely on 'second tier' documents to provide detailed information on the minimum provisions needed to comply with the Regulations. 'The Domestic Heating Compliance Guide' is the 'second tier' document that covers conventional means of providing primary and secondary space heating and domestic hot water for dwellings in England and Wales. It also identifies the standards that must be met by system installations in both new and existing buildings. (Generally, the level of provision is the same for both; it differs for existing buildings only when practical constraints arise.)

This guidance is not statutory, and as such does not have to be followed: alternative means of complying may be used. There is, however, a legal presumption that following the guidance is evidence of compliance with the Building Regulations.

'The Domestic Heating Compliance Guide' also refers to 'third tier' publications. These include codes of practice, standards, and industry guides which provide information on good practice for design and installation over and above the minimum regulatory provision.

'The Domestic Heating Compliance Guide' comprises four sections that cover all the requirements for primary

RA Aspect JUNE 2006

2. 'The Domestic Heating Compliance Guide' and secondary space heating and hot water technologies for any given fuel. Five further sections provide guidance on the minimum provisions for specialised space heating and hot water technologies, including: heat pumps; micro-CHP; community heating; underfloor heating; and solar water heating.

New requirements

Most requirements of Part L are as those introduced on 1 April 2005. The 2006 edition introduces, amongst others, revised requirements for heating controls; space heating appliances; gas fires; and the installation of supply water treatment devices in hard water areas. There is also greater emphasis given to system flushing and commissioning.

From 6 April 2006 it will also be a requirement of Part L that when exchanging a hot water cylinder fed by gravity flow and return circulation, the system must be upgraded to include a method of temperature control for the stored domestic hot water. This applies to all cylinder exchanges, whether part of a planned upgrade or an emergency exchange due to leakage.

All gas appliances must be installed by a competent person in accordance with the current issue of the Gas Safety (Installation and Use) Regulations (GSIUR). Installation should follow the manufacturer's instructions and comply with all other relevant parts of

the Building Regulations and, for wet systems, the Water Regulations.

Zone controls

From 6 April 2006 Part L requires that new and replacement heating systems must provide 'zone' control of areas that have different heating needs. Single- storey open-plan dwellings with a living area greater than 70 per cent of the total floor area may be treated as a single- space heating zone. Dwellings with a total usable floor area up to 150m2 should be divided into at least two separate space heating zones: typically, the living area and bedroom area. Each zone should be provided with independent temperature control. This is achieved using thermostatic radiator valves (TRVs).

In general, to meet the requirements of the Regulations, central heating installations should be a 'Y' or an 'S'-plan system, with each zone having thermostatic valves fitted to all radiators bar one. The space where the radiator without the thermostatic radiator valve is fitted should be controlled by a room thermostat independently wired to a zone valve.

Dwellings with a total usable floor area greater than 150m2 should again be provided with at least two space heating zones, but each zone must be provided with both independent time and thermostatic controls. Where independent time control is required,

Fused isolation switch Time control

volts

a single multi-channel programmer, multiple heating zone programmers or programmable room thermostats may be employed, or, alternatively, a series of single-channel clocks.

. .

Upgrading and ex='e~f~ons

Where a boiler is being exchanged, there are a number of new requirements which i e e d k be considered. If the work comprises solely of the exchange of a boiler already on a fully pumped system that currently uses a 'Y'- or 'S'-plan . type control system, the boiler may be exchanged without further consideration to upgrades (except for insulation - see later).

If exchanging a boiler that is currently on gravity circulation then the system must be brought up to the standard as if the system was new. This means upgrading to fully pumped, using a 'Y'- or 'S'-plan system (see Figure 3) and fitting TRVs to all existing and new radiators bar the one where the room thermostat is fitted. In both cases the exposed primary pipework between the boiler and cylinder should be insulated (if not a combi) and then all the pipeworl, connected to the cylinder lagged for at least one metre. This includes primay flow and return, cold water feed, hot water draw-off and pumped shower connections via Essex flanges.

A separate hot water zone, in addition to space heating zones, should be provided (except where hot water

"HWthermostat 3. 'S'-plan system (the pump on 7 modern systems is normally controlled via the boilerlpump overrun device, not shown)

Control elements 2 channel time control DHW thermostat Room thermostat 2 port zone valves (2 off)

b DHW zone valve 1 thermostat

N

HTG zone valve I T & l Pump Boiler

oanel

J U N E ~ O O ~ Aspect 8,

4. Typical boiler F& isolation interlock switch Time control

j

volts

DHW thermostat I

Control elements 2 channel time control DHW thermostat Room thermostat 2 port zone valve (HTG)

for domestic use is being supplied instantaneously, such as via a combination boiler).

The heating and hot water circuits must be able to be independently controlled. The exception to this is for replacement systems where only the hot water cylinder is being replaced and a separate time control for the hot water circuit is not present: here it is permitted to have a single timing control for both space heating and hot water. However, where the cylinder being replaced is on a gravity circulation system and the installation is planned (rather than an emergency replacement due to a leak, etc.) a cylinder thermostat should be fitted and wired so that boiler interlock is provided.

Cylinder replacements

Pump

Boiler panel

Stored water tempemturn control To control the temperature of the stored hot water on new and replacement systems, a cylinder thermostat and a zone valve or three-port valve should be fitted. In dwellings with a total floor area greater than 150m2, however, it could be reasonable to provide more than one hot water circuit, with each having separate timing and temperature controls.

A non-electric hot water controller does not meet Building Regulations requirements for temperature control unless the cylinder is replaced in an emergency. Also, in some circumstances, such as thermal stores, fitting a zone valve may not be appropriate. In these cases the zone valve could be substituted by a second pump.

Where cylinders heated by gravity circulation are replaced in an emergency situation (leaking, for instance), the customer should be advised to upgrade the controls to incorporate boiler interlock (cylinder thermostat and motorised valve linked to the boiler, see Figure 4). If this is declined the minimum provision shall be a thermo-mechanical valve (Tapstat) which will allow the thermostat on the boiler to be turned up, increasing the heat transfer of the coil. A cylinder must not be changed unless the minimum provision is provided.

C I

System requirements Both new and replacement heating systems must be fully pumped, with separately controlled circuits to the hot water cylinder and radiators. All associated system contro!~ (such as room thermostats, cylinder thGrmoststs, programmers and time switches) must be wired so they are interlocked with both the boiler and pump to prevent their operation when there is no demand

'. :>,

for heat o i hot Water.

Note The use'oY-thetmoStatic radiator valves alone does not provide interlock. Where manufacturers specify a bypass, this should be of an automatic type.

An acceptable alternative for controlling heating and hot water is by means of any boiler management system that delivers the specified zoning, timing and temperature and boiler interlock control provisions.

System and water decrning

While already good practice, Part L places a requirement for all wet central heating systems to be thoroughly flushed and cleaned in accordance with BS 7593 before installing a new boiler. The system should be flushed and cleaned either before the old boiler is removed or by means of bridging the flow and return pipework before installing the boiler on new and replacement systems. The heating system fill water should also be chemically treated to control corrosion and scale and sludge formation by using a corrosion inhibitor. Always follow boiler manufacturer's instructions for

5. Applying cherni- cal via a radiator

Aspect JUNE 2006

appropriate treatment products and special requirements for individual models.

Where mains water hardness exceeds 200 parts per million, provision shall be made - by installing a supply water treatment device, such as a scale reducer - to treat the feed water to water heaters and the hot water circuit of combination boilers. This will reduce the rate that limescale accumulates and will help to maintain boiler efficiency. Once again, boiler manufacturer's guidance should be sought as to the type and location of such a device.

Insulation

Insulate pipework in new systems with insulation labelled as complying with 'The Domestic Heating Compliance Guide' (the labelled insulation is being introduced in line -with the TIMSA guide) in the following situations:

Primary circulation pipes for heating and hot water circuits should be insulated wherever they pass outside the heated living space or through voids which communicate with and are ventilated from unheated spaces.

Primary circulation pipes for domestic hot water circuits should be insulated throughout their length, subject only to practical constraints imposed by the need to penetrate joists and other structural elements.

All pipes connected to hot water storage vessels, including the open vent pipe, should be insulated for at least one metre from their point of connection to the cylinder (or up to the point where they become concealed).

Where secondary circulation is used, all pipes kept hot by that circulation should be insulated.

Similarly, whenever a boiler or hot water storage vessel is replaced in an existing system, any pipework (in the above situations) that is exposed as part of the work, or otherwise accessible, should be insulated either with insulation labelled as complying with 'The Domestic Heating Compliance Guide' or, where practical constraints dictate, to a lesser standard.

When to notify Building Control

Unwnted hot water systems

Work solely comprising of a minor nature need not be notified to Building Control: for example, insulating pipework; replacing defective heating control components, such as programmers, room thermostats; replacing radiators, radiator valves or circulating pumps.

The installation of a boiler or hot water cylinder is a notifiable service and should be done through the installer's competent persons scheme provider (e.g. CORGI). However, if the installer is not a member of a competent persons scheme, work involving an emergency repair to a failed boiler or hot water cylinder must be notified directly to Building Control; a notification form must be raised as soon as the job is completed.

It is a requirement of the CORGl's competent persons scheme that only competent persons holding a recognised qualification in Energy Efficiency, such as City & Guilds 6084 or equivalent, are permitted to change or install central heating boilers or cylinders. (Without this qualification they will have to notify local Building Control. The operative will also need to hold a valid certificate of gas competence, under the current ACS arrangements, specific to the work categories being undertaken.)

When work is complete, the system must be commissioned correctly. The emphasis of the commissioning has been elevated to that of the Statutory Instrument (the law) which now requires conformation that it has been correctly undertaken. This means that the boiler should be set correctly, checking the gas rate, burner pressure (if possible) and flow and return temperatures. The radiators also need balancing to ensure the correct temperature difference is set across the radiator (normally 11 "C in the UK). The auto bypass needs setting correctly to ensure the correct flow rate at the boiler. The Benchmark certificate also has increased importance and shall be completed at commissioning, recording the relevant readings and settings. The Benchmark certificate shall be left with the customer as evidence of compliance with the Building Regulations. In addition, it is a requirement to instruct the customer on the efficient use of the system.

Unvented hot water systems are a 'controlled service' and fall within the scope of Part G of the Building Regulations in England and.Wales (although not applicable in lid . or Northern Ireland) and therefore are notifiable. The revised Building Regulations extend the 'competent persons,' self-certification scheme to include the i?&allatiiih. of both new and replacement unvented hot water systems. If this wot'kls undertaken by a member of the CORGI competent ; persons scheme, CORGI must be notified (notification being by electronic means, as CORGI does not accept paper). CORGI electronically collates all unvented hot water systems installation information on behalf of local building authorities.

6. Fire and back boiler unit

Combined fire and back boiler units

Combined fire and back boiler units (BBU) are not allowed on new installations. However, they may be installed as a replacement in existing dwellings, providing that a combined fire and back boiler unit is already in situ and an assessment of the building (following the Condensing Boiler Assessment Procedure) shows that the installation of a condensing boiler would, in exceptional circumstances, be impractical or too costly. The new BBU must also meet a minimum SEDBUK

JUNE2006 Aspect

rating of 78 per cent (D) and the system must be fully pumped.

To comply with Part L, the gas fire provided with the BBU must conform to BS 7977-2: 2003. If the fire is an inset live-fuel effect type it must have a minimum efficiency of 40 per cent or 41 per cent respectively for natural gas and LPG, with all other types of gas fires having a minimum efficiency of 63 per cent or 64 per cent respectively.

Decorative fuel-effect appliances (DFEs) to BS EN 509: 2000 are designed for decorative rather than heating purposes, so they have poor energy efficiency. A minimum thermal efficiency is therefore not specified. Part L, however, limits the installation of these appliances to one appliance per loom2 of dwelling floor area or part thereof. (For the purposes of SAP 2005 the efficiency of DFEs is classed as 20 per cent for use in the Space Heating Requirement calculation.)

Gas fires

With the exception of flueless appliances, fixed independent space heating appliances (gas fires) may be installed as a means of primary or secondary space heating. To comply with Part L, gas fires in new dwellings which are the primary heat source should be one of the types given in Figure 7 and have an efficiency of no less than 58 per cent.

Each gas fire should also be able to independently control the temperature - by room thermostats or other suitable temperature-sensing devices - in areas that have different heating needs, such as separate sleeping and living areas.

Note: Wherever practical, gas fire installations in existing dwellings should be upgraded to the standards required for new dwellings.

A gas fire that is a replacement in existing dwellings or provided as the secondary heat source in new or existing dwellings should be one of the types given in Figure 8; its efficiency being no less than the coinciding value given.

In all cases the appliance must be accompanied by a manufacturer's declaration of appliance performance.

7. Gas fire tvnar that cnmnlv with Pad L

Warm-air units

Gas-fired warm-air units should meet the requirements, as appropriate to the design of the appliance, of BS EN 778: 1998 or BS EN 131 9: 1999.

Part L requires new warm-air heating systems - and, where practical, on replacement systems - to provide zone control of areas with different heating needs. Dwellings with a total usable floor area up to 150m2 should be divided into at least two separate space heating zones, one being the living area, each with independent timing controls. Dwellings with a total usable floor area greater than 150m2 should again be provided with at least two space heating zones, but each zone must be provided with both independent time and thermostatic control.

Zoning may be achieved by fitting electric/mechanical dampers in the ductwork; however, additional care must be taken to ensure the system is correctly balanced.

Time and temperature control may be provided either by: an external time switchlprogrammer and room thermostat; a programmable room thermostat; or, alternatively, by an integrated appliance time switch1 programmer and room temperature

lritish Standard designation (appliance type)

- ....-.

BS 7977-1 : 2002 Specification for safety and rational use appliances. Radiantlconvectors. SS EN 613: 20Q1 Independent gas-fired convection heater!

sensor linked to the appliance burner and fan speed controller.

If the warm-air unit is fitted with an integral gas-fired circulator to provide domestic hot water, the circulator should be able to deliver,full- and part- load efficiency at least equal i o that prescribed by BS EN 483. This applies to both new and replacement systems.

As ~i th~other domestic hot water systems,"primai circulation to the hot water cylinder must-be pumped. lndependenf dohtrol of the hot wziter circuit must be provided, consisting of a cylinder thermostat and timing device, wired so that when there is no demand for hot water both the pump and circulator are switched off.

Note: The installation or replacement of a warm-air unit does not require the installer to hold the Energy Efficiency qualification unless the unit is fitted with an integral hot water circulator, in which case the installer must have City & Guilds 6084 or equivalent.

Gas-fired range cookers/ boilers

For both new and replacement systems any gas-fired range cooker with an integral central heating boiler for space heating and hot water should have a SEDBUK value in excess of 75 per cent. It must also have the manufacturer's declaration of appliance performance and SEDBUK value, including case heat emission value, test data from which the values have been calculated, and identification of the notified body certifying the test data.

To comply with Part L, the appliance should have two independently controlled burners: one for cooking and one for the boiler.

The integral central heating boiler must meet the minimum provisions for gas- fired central heating systems. Appliance performance data should be included in declarations to local Building Control and in the commissioning information given on job completion.

Electric boilers

If an electric boiler is installed on a

g, Aspect JUNE 2006

the boiler uses a different fuel, Part L requires that the efficiency of the new service should be multiplied by the ratio

S

L+,+&fggg of the CO2 emission factor of the fuel

L= used for the old boiler to that used for .

5 % the new boiler. These emission factors =?W.% -c*-.

, are published in Table 12 of SAP 2005 and are shown in Figure 10. w e r e the -

!:gi resultant efficiency of the new boiler is p:g: c;'gE'& greater than 2 per cent below that of the old boiler, the boiler cannot be replaced.

-

p =-:':?~. -p -=-=c---2 = - . . - . - 1 L=-- . _ . -

ritish Standard designation (appliance type) ~ . $ ~ ~ ~ F 5 - ~ < $ - ~ ~ 7 ~ ~ : ~ - ~

. - L7. .~- - . ..

-

p

~. . - .. .

--. - I I dS EN 1266: 2002 Independent gas-fired convection I heaters incorporating a fan to assist transportatin of combustion air andlor flue gases.

I (All types except inset live-fuel effect) BS 7977-1 : 2002 Specification for safety and rational use of energy of domestic gas appliances. Radiant1 I

/ BS EN 613: 2001 lndependent gas-fired convection j heaters. ++._in. :;:,;m:' l l l .nT wt.=: I S a) Gas system being replaced .by . -

electric boiler: . ..

BS EN 13278: 2003 Open-fronted gas-fired l

, independent space heaters.

Inset live-fuei effect) BS 7977-1 : 2002 Specification for safety and rational I use of energy of domestic gas appliances. Radiant

Existing gas boiler - 67% SEDBUK efficiency New electric boiler - 99% efficient Gas emission factor - 0.194 Electric emission factor - 0.422 99 X (0.19410.422) = 45.5% Boiler may not be replaced Thermal efficienw

requirements for Ws type of: appliance are n&,spbmed as all the heat p r ~ d ~ & by the combustion pn&-- is released into h e spBW : '- to be heated. In &&P 2005 the efficiency of these ' appliances is classed 90% and an adjustmeil made for ventilatlrm inttte Space Heating WWMe1

b) Oil boiler being replaced by gas (non-condensing):

Existing oil boiler - 85.3% New gas boiler 78% Oil emission factor - 0.265 Gas emission factor - 0.1 94 78 X (0.26510.194) = 106% Boiler may be replaced

l (Flueless) BS EN 449: 2002 Specification for dedicated liquefied petroleum gas appliances. Domestic

, flueless space heaters (induding diffusive catalytic I combustion heaters).

calculation.

Note. At the time of writing prEN 14829 is in draft but it may not appear as a European standard. Tht type of appliance for which this standard is proposeu is on the market, having been certified as comptying with the essential requirements of the Gas Appliance Directive. The BSI is producing a parallel UK safety installation standard for appliances designed to

1 9. AMTEC electrlc boiler

8. Appliance types and efflciencies

electrical heating elements or immersion heaters. The lower element should be capable of heating up at least 85 per

new or replacement wet central heating system, it should be fitted with a flow temperature control and be capable of modulating the power input to the primary water, depending on space heating conditions. If the boiler also supplies domestic hot water, the system should have boiler control interlock so wired that when there is no call for heat from either the space heating or hot water circuits (where appropriate) then the boiler and pump are switched off.

cent of the cylinder contents, and the upper element should be capable of heating at least 60 litres of water. The lower element should be so connected as to utilise the off-peak electricity tariff and the upper for boost operation. The cylinder should also be designed so that following reheating to 60C from the off-peak element, at least 80 per cent of the contents can be drawn off at 45C or above at a flow rate of 0.25 11s. I If domestic hot water cylinders are

electrically heated they should either be factory-fitted with, or have provision for, two thermostatically controlled

Note: While particularly relevant to electric boilers, on boiler exchange, i f

JUNE2006 Aspect 51

c) Wood loglpellet solid fuel boiler being replaced by gas condensing:

Emissions (kg C02 Per kWh)

Existing solid fuel boiler - 70% New gas boiler - 90.2% Solid fuel emission factor - 0.025 Gas emission factor - 0.194 90.2 X (0.02510.194) = 11.6% Boiler may not be replaced

Mains gas -LP,G j;: *$$rA:::.3,-. ---P":

,..-,p 0.: . ~ : ~ * ~ y & ~ j $

L:.:.% ._I.u.. ~. ~

ttled LPG .- .

Heating oil Underfloor heating systems House coal

thnclte

~ 9 n u k r e d smokeless fuel All underfloor heating systems, whether electrical or warm-water types, should be fitted with suitable controls to ensure safe system operating temperatures. These include a separate flow temperature high-limit thermostat for warm-water systems connected to any high-temperature water supply operating at more than 60C. Similarly, mixed systems containing both radiators and floor heating connected to a common high-temperature water supply should be provided with a separate means of reducing the water temperature to the floor heating system.

)ad @l& (in bags, b r secondary

Wood pellets (bulk supply in bags, for main heating) W