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  • 2026 EDITION

Guidebook of
Home Heating Systems

The essential guide to boiler efficiency. Maximize performance, minimize costs, and ensure compliance.

Read the Guide
Check Grant Eligibility
Table of Content

1.0 Introduction

You shouldn’t have to break the bank or continuously pray that your old boiler doesn’t give out on you just so you can keep your home warm. A hardworking heating system is vital to reducing bills and keeping your carbon emissions down in the UK. Your boiler is the center of all this, and it can make a huge difference to your comfort, running costs and the planet.

Homes up and down the country sit on ageing boilers which are wasting money, energy and heat. By replacing it with a modern, high-efficiency new boiler, you can save as much as £345 a year and won’t ever have to worry about your boiler letting you down.

Eligibility Check

Programs such as ECO4 and the Free Boiler Grant exist to get people on a better deal. These government-backed schemes enable eligible households to switch old boilers, and to improve or install central heating – usually at no cost.

Guide Objectives

This document serves as an essential resource for homeowners and property managers. Its primary objectives are to:
  • Educate on the fundamental principles of boiler operation and system types.
  • Empower you to identify signs of boiler inefficiency and evaluate performance.
  • Detail actionable strategies for maximizing efficiency through maintenance.
  • Clarify opportunities for financial assistance through the ECO4 scheme.

2.0 Understanding Boiler Systems

The three most common boilers in UK households are Combination (Combi), System, and Conventional. Choosing the right one affects efficiency, installation complexity, and footprint.

Combination

Heats water straight from the mains. No storage cylinder needed.

  • Saves space & money
  • Reduced flow if multiple taps used

System Boiler

Heats central heating and produces hot water for a storage cylinder.

  • Multiple taps simultaneously
  • Needs cylinder space

Conventional

Includes boiler, cylinder, and loft tanks. Ideal for older systems

  • Good for low pressure areas
  • Needs loft space, less efficient

Core Components

  • Heat Exchanger: Transfers combustion heat to water.
  • Burner: Provides the heat using fuel (oil/gas).
  • Pump: Moves hot water through pipes/radiators.
  • Controls & Thermostat: Manages temperature and cycles.

3.0 Evaluating Current Performance

Reading Your Boiler's Label

All new boilers since 2015 show an ERP label.

  • Rating A-G: A-rated condensing boilers are ~92% efficient. G is least efficient.
  • Output (kW): Ensures the unit is sized properly for your property.
  • Sound (dB): Indicates noise level during operation.
A+++

Efficiency Goal

Identifying Signs of Inefficiency

Symptom

Implication

Rising Energy Bills

Unexplained increases indicate the unit is consuming more fuel to produce the same heat.

Frequent Repairs

Increasing service calls suggest the boiler is nearing the end of its lifespan.
Inconsistent Heating
Cold spots or unreliable hot water suggest internal wear or blockages.
Visible Pilot Light

A constantly burning blue pilot light is an obsolete source of energy waste.

4.0 Strategies for Maximising Efficiency

Combination

An annual service by a Gas Safe registered engineer is crucial. It includes component checkups, safety precautions (carbon monoxide), and pressure adjustments.

System Balancing

Balancing: Adjust lock shield valves to ensure equal hot water circulation.

Bleeding: Release trapped air from radiators to fix cold spots.

Thermostat & Controls

Smart Thermostats: Control heating remotely and optimize settings.

TRVs: Fit Thermostatic Radiator Valves to control individual room temperatures.

Pro Tip: Reducing your main thermostat by just 1°C can save up to 10% on heating bills annually

  • Government Initiative

5.0 The ECO4 Scheme

The Energy Company Obligation (ECO) is the UK Government’s initiative to eradicate fuel poverty. The ECO4 phase focuses on replacing poor heating systems in low-income and vulnerable homes.

Eligibility Checklist

  • Property EPC rating D to G
  • Owner-occupied or Private Rental
  • Receipt of eligible benefits (see below)

Eligible Benefits

  • Universal Credit
  • Income Support
  • Housing Benefit
  • Pension Credit
  • JSA / ESA
  • Tax Credits

How to Apply

The process involves an eligibility check, a property survey by a certified engineer, and finally, the installation of approved measures.

Check My Eligibility

6.0 Selecting and Fitting a New Boiler

Undersized or oversized, a boiler will run inefficiently. Use these criteria:

Property Size & Layout

Larger properties need higher kW output.

Hot Water Demand

Multiple bathrooms? Consider System or Conventional.

Fuel Type

Gas, Oil, LPG, or Electric depending on grid connection.

Installation

Must be Gas Safe registered.

7.0 Summary & Actionable Next Steps

Conduct a System Audit

Check your boiler's energy label and record inefficiencies over a week.

Book a Free Home Survey

Contact a Gas Safe engineer for a comprehensive overview.

Determine ECO4 Eligibility

If you have a low EPC and receive benefits, you could get a free upgrade.

Get a Professional Efficiency Report

Call our experts for obligation-free advice.

8.0 ECO4 Cancellation & Warm Homes Plan

The UK Government has confirmed that the national ECO4 grant programme will come to an end, following its announcement in the Autumn Budget – representing a significant shift in how energy efficiency funding is deployed. ECO4 was designed to assist households that could not afford improvements to their heating by making the largest energy suppliers contribute towards boiler upgrades, insulation, and heat pumps. Its primary aims were to cut carbon emissions, end fuel poverty and make homes warmer and cheaper to run.

Key Policy Shift

ECO4 is now closed for homeowner applications under the earlier national framework. Instead, the government has developed a different approach in the Warm Homes Plan. Under this new system, funding moves from a single national programme to local councils doing things as they see fi,t by grants in accordance with the needs of their particular communities.

Under this new system, funding moves from a single national programme to local councils doing things as they see fi,t by grants in accordance with the needs of their particular communities.

Local authorities are now placed under the Warm Homes Plan to design and deliver energy efficiency assistance, which takes account of local housing stock and household characteristics. That means what kind of help is available may vary depending on where a person lives, resulting in a more tailored and nimble system of support for low-income households.

9.0 Introducing the LA Flex Scheme

What is the LA Flex Program?

The LA Flex Scheme (Local Authority Flexible Eligibility) is an expansion of the recommended energy saving scheme ECO4. ECO4 is generally for homes receiving specific state benefits, but LA Flex enables local authorities to assist people who may not be eligible under typical benefit criteria. Under LA Flex, councils would be able to set their own eligibility criteria in order to support low-income households and people with health conditions impacted by cold living environments. This approach helps to ensure that local households can access support more easily if they require assistance with improvements to home energy and heating costs.

Who Qualifies for the LA Flex Scheme

LA Flex eligibility is determined by a few main household factors. You don’t necessarily have to satisfy every one of these conditions, but usually at least one or more apply. Eligibility is often considered if:

Household Income

You have a household income of £31,000 or less per year.

Energy Rating

Your home's EPC rating is from a low band (D, E, F or G).

Health Conditions

A member of your household has a chronic illness which is made worse by living in cold conditions.

If any or all of these apply to you, you could benefit from help under the LA Flex energy grants to make your home warmer and more comfortable.

How To Apply for LA Flex Scheme

Check Eligibility

Ensure that you are eligible by checking the essential requirements on our website.

Gather Papers

Collect your documents, such as income documentation or medical evidence.

Professional Presentation

Have a professional present your application to the council.

Audit & Upgrade

After approval, your home is audited and energy upgrades are made.

Tips for Faster Approval

  • Fill the application form by answering all questions as directed
  • Ensure names, addresses and answers are correct and identical to those of your ID documents.
  • Collect all of your supporting documents in advance, such as evidence of income, ownership and identity – as well as medical evidence if necessary.
  • Before you apply, check your LA Flex eligibility to make sure you meet the basic requirements.
  • Give yourself a head start by preparing documents in advance so that the council can review your application sooner.
  • Keep track of the progress of your application - write or phone to check.

How FreeNewBoiler Helps with LA Flex Approval

Council Liaison

We act as a direct link between you and the council funding team.

Paperwork Management

We manage all paperwork to ensure forms are accurate, complete, and compliant.

Follow Up

We actively follow up on applications to help avoid unnecessary delays.

10.0 LA Flex Review & Preparation

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Preparation Checklist

  • Properly completed application forms.
  • Evidence of income (payslips/bank statements).
  • EPC Rating verification (D, E, F, or G).
  • Income check (approx. £31,000 limit).

Why Prepare?

With this preparation completed in advance, applications can proceed efficiently and with confidence.

Confidence

How Councils May Decide Funding in 2026

A few significant household factors are considered by local councils in determining LA Flex funding. Every council in the country follows national guidance, but overlays its own local priorities.

Key Decision Factors

Financial Circumstances

Household income levels and stability.

Energy Performance

Current EPC rating (targeting D-G).

Vulnerability

Household health and age-related risks.

Local Priorities

Specific community needs and housing stock.

Because each council determines its own funding priorities, eligibility rules,and approvals may be different from one area to another. This localised approach can help verify that the families in greatest need receive support.