Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 1: Regulatory requirements and efficiency standards for gas- fired and oil-fired heating appliances connected to ‘wet’ heating circuits

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 1- regulatory requirements and efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits During the session you will: Be able to use college computers to conduct online research Learn where to find regulatory requirements and sources of guidance for energy efficiency standards for gas-fired and oil- fired heating appliances connected to ‘wet’ heating circuits Find examples of regulatory requirements and sources of guidance for energy efficiency standards for gas-fired and oil- fired heating appliances connected to ‘wet’ heating circuits Report back to the group on the websites and information you find Session Objectives and Activities

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 1- regulatory requirements and efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits If you are unsure where to look for regulatory information and guidance, try one or more of the following websites: UK government Planning Portal Building and Engineering Services Association (B&ES) connections/technical/ connections/technical/ Energy Saving Trust Scottish and Northern Ireland Plumbing Employers’ Federation Welsh Government Chartered Institution of Building Services Engineering Do not feel you must limit your search to these sites if you have ideas of others worth exploring. Key websites

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 1- regulatory requirements and efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits You may have found a range of websites that contain relevant information. Note the key websites in your course folder for future reference including: –Building Regulations Part G (Sanitation, Hot Water Safety and Water Efficiency) –Building Regulations Part J (Heat Producing Appliances) approved approved –Building Regulations Part L (Conservation of fuel and power) Websites, regulations and standards are frequently updated so you may want to revisit websites and conduct further research in future to ensure you are always using the latest information. Key web pages

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems During the session you will: Research requirements and sources of guidance for boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Be able to find examples of requirements and parameters for boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Complete calculations related to boiler efficiency Provide feedback regarding the websites and information you find regarding calculations and strategies to improve energy efficiency Next session: minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 2: Minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 2 – minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits During the session you will: Research requirements and sources of guidance for boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Be able to find the requirements and parameters for boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Complete calculations related to boiler efficiency Feed back to the group regarding the websites and information you find and the calculations and strategies to improve energy efficiency Session Objectives and Activities

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 2 – minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Key websites If you are unsure where to look for regulatory information and guidance, try one or more of the following websites: UK government Planning Portal Building and Engineering Services Association (B&ES) connections/technical/ connections/technical/ Energy Saving Trust Scottish and Northern Ireland Plumbing Employers’ Federation Welsh Government Chartered Institution of Building Services Engineering Do not feel you must limit your search to these sites if you have ideas of others worth exploring.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 2 – minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits You may have found a range of websites that contain relevant information. Note the key websites in your course folder for future reference. Tutor to add specific websites if felt helpful Websites, regulations and standards are frequently updated so you may want to revisit websites and conduct further research in future to ensure you are always using the latest information. Key web pages

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 2 – minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Students should work individually to complete the session worksheet, with access to either hard copy or online versions of the Domestic Heating Compliance Guide. Answers are given on the following slides. Statements to support questions Boiler efficiency may be indicated by: –Combustion Efficiency - indicates a burner’s ability to burn fuel, measured by unburned fuel and excess air in the exhaust –Thermal Efficiency - indicates the heat exchanger’s effectiveness to transfer heat from the combustion process to the water or steam in the boiler, exclusive radiation and convection losses –Fuel to Fluid Efficiency - indicates the overall efficiency of the boiler inclusive thermal efficiency of the heat exchanger, radiation and convection losses - output divided by input. Boiler efficiency is, in general, indicated by either Thermal Efficiency or Fuel to Fluid Efficiency depending on the context. Worksheet

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 2 – minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Question 1 SEDBUK stands for Seasonal Efficiency of a Domestic Boiler in the UK. Question 2 Boiler rate data information should be on the boiler data plate and in the boiler manual/instructions. Solutions

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 2 – minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Question 3 A result of insufficient supply of mixed fresh air to the combustion of natural gas can be soot deposits and increased carbon monoxide. Question 4 The following types of gas-fired heating systems are addressed under section 2.1 of the Domestic Heating Compliance Guide: Range cookers with integral heating boilers Wet heating central heating systems Solutions

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 2 – minimum boiler efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits Question 5 The CO 2 emissions factors should be taken from table number 12 of the SAP 2005 when installing gas-fired replacement systems in existing dwellings. Question 6 The seasonal efficiency (SEDBUK) value of an oil-fired range cooker, with integral central heating boiler, should not be less than 80%. Solutions

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems During this session you will Familiarise yourselves with the ‘Guide to condensing boiler installation assessment procedure for dwellings’ and associated parameters Complete calculations relating to boiler installations Research requirements related to space heating primary circuits types and design for gas-fired and oil-fired wet heating systems Discuss websites and information you have found Next session: non-condensing and condensing boiler installations, and requirements in relation to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3: Non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems During the session you will Familiarise yourselves with the ‘Guide to condensing boiler installation assessment procedure for dwellings’ and associated parameters Complete calculations relating to boiler installations Research requirements related to space heating primary circuits types and design for gas-fired and oil-fired wet heating systems Discuss websites and information you have found Session Objectives and Activities

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems Gas-fired and oil-fired domestic central heating must use condensing boilers in most circumstances Where installation of a condensing boiler may be difficult, an assessment should be completed to see if a non-condensing boiler would be allowed ‘The Guide to the Condensing Boiler Installation Assessment Procedure for Dwellings’ explains the assessment procedureThe Guide to the Condensing Boiler Installation Assessment Procedure for Dwellings If it is suspected that a building may not be suitable for a condensing boiler, a standard form must be completed to assess whether a non-condensing boiler can be fitted for a specified fuel. Appendix G of Part L of the Building Regulations is the formPart L of the Building Regulations for assessing when non-condensing boilers are permitted. Introducing the condensing boiler installation assessment procedure for dwellings

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems The condensing boiler installation assessment procedure for dwellings – assessment criteria The following criteria must be considered: Dwelling type Existing boiler fuel New boiler fuel Existing boiler type Existing boiler position In the lowest cost option, is the new boiler positioned in a different room from the existing boiler? New boiler positioned in a different room to the existing boiler? Extended flue (longer than 2m) necessary? Condensate pump or soakaway necessary? This will lead to an assessment score.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems Circumstances when non-condensing boilers are permitted in domestic heating systems In residential buildings, a non-condensing boiler is allowed only if: an existing boiler is being replaced within 3 years of installation under the manufacturer’s or installer’s guarantee OR The assessment form shows a score above 1,000 giving evidence that installation of a condensing boiler has been assessed as impractical or uneconomic. Note that a score above 1,000 does not prohibit installation of a condensing boiler.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems Possible difficulties with condensing boilers There are a number of possible difficulties with installing condensing instead of non-condensing boilers. Compared to non-condensing boilers, condensing boilers: discharge gasses from the flue terminal which are cooler, less buoyant and often form a visible plume discharge gases which may wet surfaces too close to the terminal, or be a nuisance to neighbouring property or people passing nearby cannot use a flue designed for a non-condensing boiler or share a flue with a non-condensing boiler form liquid condensate within the boiler which must be discharged to a suitable drain or soakaway

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems Key websites If you are unsure where to look for regulatory information and guidance, try one or more of the following websites: UK government Planning Portal Building and Engineering Services Association (B&ES) connections/technical/ connections/technical/ Energy Saving Trust Scottish and Northern Ireland Plumbing Employers’ Federation Welsh Government Chartered Institution of Building Services Engineering Do not feel you must limit your search to these sites if you have ideas of others worth exploring.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems From 1 st April 2005, revised Approved Document L1 of the Building Regulations sets down revised guidance for the efficiency of hot water central heating gas and oil boilers installed in new and existing dwellings. Appendix G of the revised Approved Document L1 is the Condensing Boiler Installation Assessment Procedure, which is to be used in cases where it is expected to be impractical or too costly to install a condensing boiler. Key points from ‘Guide to condensing boiler installation assessment procedure for dwellings’

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems Key web pages You may have found a range of websites that contain relevant information. Note the key websites in your course folder for future reference. Tutor to add specific websites if felt helpful Websites, regulations and standards are frequently updated so you may want to revisit websites and conduct further research in future to ensure you are always using the latest information.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 – non-condensing and condensing boiler installations, and requirements relating to space heating primary circuits type and design for gas-fired and oil-fired wet heating systems Students should work individually to complete a heat loss / demand / boiler sizing worksheet with a set of example parameters. Example worksheets are available from various energy providers, manufacturers, trade associations and/or government websites. One example suggested for use in this session is available from The Energy Saving Trust – CE54, available to down load via this link: professionals/Heating-systems/Domestic-heating-sizing-method edition Worksheet

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 3 Potential Solutions Property 1Property 2 A = W/KA = 155 W/K B = W/KB = 321 W/K C = 87 W/KC = 250 W/K D = 288 W/KD = 250 W/K E = W/KE = W/K F = 1080 W/KF = 1190 W/K G = 32,400 WG = 35,000 W H = -H = 39.9 W/K I = -I = 255 W/K J = -J = 255 W/K K = - L = -L = 5830 W/K M = 3000 N = 3000N = 5830 Property 1 U = 28.5 WK T = 35.8 KW V = 35.8 KW Property 2 U = 30.5 WK T = 41.2 KW V = 41.2 KW

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems During the session you will: Research compliance standards and parameters for hot water storage vessels Research requirements relating to the preparation and water treatment of hot water systems and wet central heating systems Research requirements relating to the commissioning of hot water systems and wet central heating systems Next session:

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 4: Hot water storage, hot water systems and wet central heating systems

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 4 – hot water storage, hot water systems and wet central heating systems During the session you will: Research compliance standards and parameters for hot water storage vessels Research requirements relating to the preparation and water treatment of hot water systems and wet central heating systems Research requirements relating to the commissioning of hot water systems and wet central heating systems Feedback to the group about what you found Session Objectives and Activities

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 4 – hot water storage, hot water systems and wet central heating systems Key websites If you are unsure where to look for regulatory information and guidance, try one or more of the following websites: UK government Planning Portal Building and Engineering Services Association (B&ES) connections/technical/ connections/technical/ Energy Saving Trust Scottish and Northern Ireland Plumbing Employers’ Federation Welsh Government Chartered Institution of Building Services Engineering Do not feel you must limit your search to these sites if you have ideas of others worth exploring.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 4 – hot water storage, hot water systems and wet central heating systems Key web pages You may have found a range of websites that contain relevant information. Note the key websites in your course folder for future reference. Tutor to add specific websites if felt helpful Websites, regulations and standards are frequently updated so you may want to revisit websites and conduct further research in future to ensure you are always using the latest information.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems During this session you will Research definitions and requirements for boiler interlock Research relevant requirements relating to space heating zone control and water heating zone control Research relevant requirements relating to time and temperature control, including the use of non-electrical (thermo-mechanical) hot water controllers Feed back to the group about what you found Next session: control of gas-fired and oil-fired wet central heating systems

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 5: Control of gas-fired and oil-fired wet central heating systems

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 5 – control of gas-fired and oil-fired wet central heating systems During the session you will: Research definitions and requirements for boiler interlock Research relevant requirements relating to space heating zone control and water heating zone control Research relevant requirements relating to time and temperature control, including the use of non-electrical (thermo-mechanical) hot water controllers Feed back to the group what you found Session Objectives and Activities

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 5 – control of gas-fired and oil-fired wet central heating systems Key websites If you are unsure where to look for regulatory information and guidance, try one or more of the following websites: UK government Planning Portal Building and Engineering Services Association (B&ES) connections/technical/ connections/technical/ Energy Saving Trust Scottish and Northern Ireland Plumbing Employers’ Federation Welsh Government Chartered Institution of Building Services Engineering Do not feel you must limit your search to these sites if you have ideas of others worth exploring.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 5 – control of gas-fired and oil-fired wet central heating systems Key web pages You may have found a range of websites that contain relevant information. Note the key websites in your course folder for future reference. Tutor to add specific websites if felt helpful Websites, regulations and standards are frequently updated so you may want to revisit websites and conduct further research in future to ensure you are always using the latest information.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems During this session you will: Be briefed on the end of course assessment Revise topics covered throughout the course Complete practice calculations Have opportunities to ask about anything from the course you are unsure about Next session: revision

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6: Identify requirements of the minimum standards for the insulation of pipework Relating to stand-alone glandless heating system circulators

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6 – Identify requirements of the minimum standards for the insulation of pipework By the end of the session the learner will be able to: Identify the key requirements of the minimum standards for insulation of pipework for gas-fired and oil-fired wet central heating and hot water storage systems. Relating to stand-alone glandless heating system circulators. Session objectives and activities

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6 – Identify requirements of the minimum standards for the insulation of pipework By the end of the session the learner will be able to: Identify the key requirements of the minimum standards for insulation of pipework for gas-fired and oil-fired wet central heating and hot water storage systems Relating to stand-alone glandless heating system circulators. Session outcomes

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6 –Identify requirements of the minimum standards for the insulation of pipework Key websites If you are unsure where to look for regulatory information and guidance, try one or more of the following websites: UK government Planning Portal Building and Engineering Services Association (B&ES) connections/technical/ connections/technical/ Energy Saving Trust Scottish and Northern Ireland Plumbing Employers’ Federation Welsh Government Chartered Institution of Building Services Engineering Do not feel you must limit your search to these sites if you have ideas of others worth exploring.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6 – Identify requirements of the minimum standards for the insulation of pipework Key web pages You may have found a range of websites that contain relevant information. Note the key websites in your course folder for future reference. Tutor to add specific websites if felt helpful Websites, regulations and standards are frequently updated so you may want to revisit websites and conduct further research in future to ensure you are always using the latest information.

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6 – Identify requirements of the minimum standards for the insulation of pipework Please work individually to complete the work sheet. Answers are shown on the following slides. Work sheet

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6 – Identify requirements of the minimum standards for the insulation of pipework Question 1 For new systems, if secondary circulation is used, all pipes kept hot by that circulation must be insulated. Question 2 Where the pipe diameter size is 22mm OD the permissible heat loss is 9.12 W/m. Question 3 All pipes should be insulated to 1 metre from their point of connection to the hot water cylinder in new systems. Solutions

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6 – Identify requirements of the minimum standards for the insulation of pipework Question 4 When installing a replacement oil boiler, you should insulate any pipe work exposed as a result of your work. Question 5 Where insulation is labelled as complying with the Domestic Heating Compliance Guide it must not exceed the maximum permissible heat loss (W/m) level for pipework with outside diameter of: -  10mm = 7.23 W/m  15mm = 7.89 W/m  22mm = 9.12 W/m  28mm = W/m Solutions

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session 6 – Identify requirements of the minimum standards for the insulation of pipework Question 6 You will find additional guidance for insulation of heating and hot water pipework in unheated areas against freezing in: BS 5422:2009 Method for specifying thermal insulating materials for pipes, vessels, ductwork and equipment operating within the temperature range -40°C to +700°C BRE Report No 262 Thermal insulation: avoiding risks, 2002 edition Solutions

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems During this session you will: Be briefed on the end of course assessment Revise topics covered throughout the course Complete practice calculations Have opportunities to ask about anything from the course you are unsure about Next session: B revision

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session B: Course recap and revision

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session B – course recap and revision During this session you will: Be briefed on the end of course assessment Revise topics covered throughout the course Complete practice calculations Have opportunities to ask about anything from the course you are unsure about Session objectives and activities

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session B – course recap and revision The end of course test is designed to confirm your knowledge of topics covered throughout the course. Keep calm and read each question carefully. We will review key points from the course today and go through some practice calculations. It is recommended that you complete additional revision outside of class. You may find it useful in your revision to: review materials in your course handbook revisit key regulations and associated guidance online make sure you are familiar with key regulatory criteria (including important numbers) ensure you are familiar with key calculation methods talk to colleagues and other students about the course End of course assessment

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session B – course recap and revision Having completed this course you should know about: the regulatory requirements and sources of guidance for energy efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits the requirements of minimum boiler efficiency standards for gas- fired and oil-fired heating appliances connected to ‘wet’ heating circuits how able to determine if a non-condensing boiler installation would be acceptable the requirement relating to space heating primary circuits type and design for gas-fired and oil-fired ‘wet’ heating systems the compliance standards requirement for hot water storage vessels End of course assessment

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session B – course recap and revision End of course assessment (continued) Having completed this course you should know about: the requirements relating to the preparation and water treatment of hot water systems and wet central heating systems the requirements relating to the commissioning of hot water systems and wet central heating systems the requirements of the minimum standards for the control of gas- fired and oil-fired wet central heating systems the requirements of the minimum standards for insulation of pipework for gas-fired and oil-fired wet central heating and hot water storage systems the requirements relating to stand-alone, glandless heating systems circulators

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session B – course recap and revision Key websites: communities-and-local-governmenthttps:// communities-and-local-government Key points to remember: Revision documents are available to you via the resource material or web link previously given. Regulatory documents L1A (New Dwellings) and L1B (Existing Dwellings) should be researched / read. Regulatory document Domestic Building Services Compliance Guide is the key document to the majority of information required for this course. Regulatory requirements and sources of guidance for energy efficiency standards for gas-fired and oil-fired heating appliances connected to ‘wet’ heating circuits

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session B – course recap and revision Key points to remember: Where installation of a condensing boiler may be difficult, an assessment should be completed to see if a non-condensing boiler would be allowed If it is suspected that a building may not be suitable for a condensing boiler, a standard form must be completed to assess whether a non-condensing boiler can be fitted for a specified fuel. Compared to non-condensing boilers, condensing boilers: –discharge gases from the flue terminal which are cooler, less buoyant and often form a visible plume –discharge gases which may wet surfaces too close to the terminal, or be a nuisance to neighbouring property or people passing nearby –cannot use a flue designed for a non-condensing boiler or share a flue with a non-condensing boiler –form liquid condensate within the boiler which must be discharged to a suitable drain or soak away Key websites: The Guide to the Condensing Boiler Installation Assessment Procedure for Dwellings Appendix G of Part L of the Building Regulations – form for assessing when non- condensing boilers are permitted Non-condensing and condensing boiler installations

Energy efficiency for gas-fired and oil-fired domestic heating and hot water systems Session B – course recap and revision Example calculation: Use the form - Appendix G of Part L of the Building Regulations and the following example to work out whether a condensing boiler would be allowedAppendix G of Part L of the Building Regulations Non-condensing and condensing boiler installations