heating basics.
We all know that a warm home is a happy home! Heating plays a vital role in our lives — it affects our comfort, health, finances, and the environment. For too long, we’ve ignored the impact of energy waste and fossil fuel use on our planet. But now, in the mid-2020s, there’s a growing awareness that both individual and collective action are essential.
Education is at the heart of this change. Our heating section is here to share practical insights and reliable information to help you make informed choices, ones that keep your home cosy and inviting while supporting a more sustainable future.
From boiler to heat pumps, we all have to do our bit in this ever-changing world. Hopefully below will give you the information to make informed decisions.
Understanding KWh (kilowatts per hour).
Energy value.
Combustion fuel has an energy value called the (CV) calorific value. Calorific value refers to the amount of heat produced by unit volume of a substance by complete combustion, the higher CV, the more heat.
The CV of gas can change regional as does the price, the higher the CV of gas the more the gas company charges us per unit. Help with reading your gas meter here.
Butane gas 121.8MJ/m3
Natural gas. 38.1 MJ/kg (can change regional)
Dry wood 18.5 to 19 MJ/kg (changes with moisture content)
LPG 46.3 MJ/kg
Oil 42.5 MJ/kg
House coal 27-31 MJ/kg
Wood pellets 17 MJ/kg (10% moisture content)
Health and safety.
You may need specialist advice from tradespeople and professionals regarding things like,
Nesting. Bees, wasps, bats.
Vermin. Rats, mice, squirrels
Asbestos. Vermiculite, flues, fire check boards, loft hatches.
Special care must be taken if there are any nesting bats, as well as bees or wasp nests.
If vermin are present in any area where pipework or electrics are to be installed then it’s a good idea to try to seal areas to prevent access as cables can be gnawed or snagged by vermin, if you notice a strong ammonia (rat urine) smell, be cautious of Weil’s disease.
Consideration and advice will also need to be sought with flues in lofts, areas of limited access and flue routes.
Some older houses may contain asbestos, which only a trained eye can recognise. Never disturb anything you’re unsure about. The health and safety section has more details.
Installation project.
For any insulation or heating project funded through a UK grant scheme, the current PAS (Publicly Available Specification), best practices, and relevant building regulations should be strictly adhered to. The works should be guaranteed and warranted as part of the current PAS standards, MCS or protected by consumer law which can be a little bit daunting in this area, especially for the privately funded installations. A good guide is here.
Privately funded projects will decide on how to install and what guidelines to follow to suit budget and personal achievements.
A Pre-installation building inspection should be performed on either privately funded or grant funded installations. This should highlight any potential areas of concern and the property’s suitability for the proposed installation.
The current PAS requires Installers to undertake a pre-installation building inspection by the requirements set out in B1-l2 of Table B.1
The system.
The Fuel. Solid fuel, Gas, LPG, Oil, Electricity, Environment (air, water, ground)
The source. Boiler, solid fuel with back boiler, heat pump,
The emitters. Radiators, blowers, underfloor emitters.
The delivery. Fully pumped, gravity.
The controls. Analogue, smart, zoned.
The technology. Weather compensation, optimisation, apps.
The water delivery. Stored (HW tank) on demand (combi).
The safety devices. Expansion relief, overflows, shut off valves, switches, and stats.
A heating system can be powered by natural gas, LPG, biomass, electric, solid fuel, oil, and electricity. Depending on our personal choices, preferences, limitations and finances, the choice is down to the individual.
Some areas of the UK have no natural gas (like parts of Anglesey for example) so choices are limited if you have no access to say the safe delivery of LPG or oil, solid fuels or electric may be the only choices.
Most heating systems contain the same components depending on their design and characteristics, which we go into in each section. The main differences are fuel source, space and hot water delivery. So let’s look at typical components that domestic heating systems have.
The Fuel.
Solid fuel, Gas, LPG, Oil, Electricity, Environment sourced with the use of refrigerants.
Natural gas.
Natural gas is more efficient than other fuels like oil and LPG, and natural gas produces less carbon dioxide than coal. It is currently cheaper than electricity and oil for heating and provides a reliable source of fuel for the UK domestic heating market. It is delivered to most properties in the UK via pipelines, so also very convenient.
Solid fuel.
Solid fuel can be a cost-effective way to heat a home, especially in rural areas without mains gas. However, solid fuel is usually more expensive than mains gas and can be a labour-intensive affair. Solid fuel boilers can be over 90% efficient. However, solid fuels have a lower calorific value and poor thermal efficiency than liquid fuels.
Solid fuel can be a sustainable heating option, especially if you use biomass boilers that burn wood chips, pellets, or logs. You may also be eligible for the Domestic Renewable Heat Incentive (RHI) if you use a biomass boiler.
LPG.
LPG boilers can be more efficient than oil boilers, producing fewer carbon emissions and using less fuel. LPG is more expensive than natural gas, and the cost of LPG has been increasing. LPG storage tanks need to be kept pressurized and stored securely, and delivery can be problematic.
Oil.
Kerosene is the most widely used fuel used in oil domestic central heating systems in the UK. It’s chosen for its winter performance, affordability, and because it offers a cleaner and more efficient burn compared to diesel. A large storage tank is required that can be problematic if access and space is a problem.
Environment.
Heat pumps have been around for a long time but are now becoming common place in the UK. They produce no emissions and are a clean energy. They may not give off the instant heat we are used to with carbon fuels as they work at a lower temperature and are best suited to large surface areas for radiating heat like underfloor systems and larger radiators.
The Source.
System. Pump and diverters contained within unit. (Stored hot water tanks). Pumped delivery of hot water circuits to provide heating. Pressurised system (will have a pressure gauge). Typically, gas but can be electric.
Regular. Water tank fed with external pumps, diverters, and feed and expansion tanks. (Stored hot water tanks). Pumped delivery of hot water circuits to provide heating. Non pressurised system. Typically, gas but can be electric.
Heat pumps. Can come in different types, and use environmental sources for energy, ground, water, and air.
Biomass. Can come in the following different types. (page coming soon)
- Pellet boilers. Use wood pellets as a renewable fuel to provide hot water and central heating for homes. Stored hot water and combination.
- Wood chip boilers. Burn wood chips as fuel, but can also run on pellets or energy crops like grain. Provide hot water and central heating for homes. Stored hot water and combination.
- Log boilers. Also known as batch boilers, these boilers burn wood logs or briquettes to heat a large water tank.
Provide hot water and central heating.
The Emitters.
Firstly, what we are all used to, is radiators. They come in all different sizes and colours, but It’s how they radiate the heat that matters. The term Delta T (ΔT) is the difference in temperatures between two measuring points. The temperature differs either in time and/or position. In the world of radiators, this is all about the design temperature for the room. More information and a better explanation is here. All the systems mentioned here can use radiators, but for a better and steady output on low temperature systems, then underfloor is the way forward. Remember, a well-insulated house is a must for optimum performance and cost savings. Below are some links to emitter types.
- Radiators
- Fan heaters (blowers)
- Underfloor
The Delivery.
Fully pumped.
A fully pumped heating system uses a pump to circulate heated water through a home’s heating and hot water circuits. The pump moves water through valves that direct it to the appropriate part of the system. When the system goes to off mode, a lot of pumps will carry on for a certain time (pump overrun) to remove some of the heat from the components. A pumped system can be a combi (on the heating side), system (for heating and hot water)
Gravity.
A gravity fed heating system uses water supplied by a tank in the loft. One of the tanks will supply the HW tank (large one) and a smaller tank (feed and expansion) will feed the central heating system. A pump moves water through pipework, valves and usually into the hot water tank coils. The gravity part is because of the head of pressure in the loft pushing down on the hot water tank and also the heating system. When the system goes to off mode, a lot of pumps will carry on for a certain time (pump overrun) to remove some heat from the components.
A gravity system usually incorporates a regular boiler.
The water delivery.
Combi boilers have a heat exchanger that can deliver water almost instantaneously. Stored hot water comes from hot water storage vessels that are either gravity fed or non-vented (sealed). With any HW tank system, insulation and temperature control are paramount.
The controls.
The controls have a dedicated section here.
Some Boiler manufacturers.
Installation Guide.
Accreditation.
All heating systems either renewable or fossil fuels will need to be installed by accredited installers and all electrical work performed by competent tradespeople.
Fire regulations need to be adhered to regarding materials and electrics.
PAS needs to be adhered to if funded on UK scheme.
Conservation of fuel and power regulations need to be adhered to regarding pipework insulation and building.
Electrical regulations need to be adhered to regarding high-powered cables and lighting.
MCS accreditation is required on funded renewable energy schemes.
Other regulations regarding gas appliances, solar inverters and stored water within the loft space are also to be referenced when required.
PAS 2035 is a comprehensive standard and not a regulation. It was introduced in 2019 as part of the UK government’s commitment to improving energy efficiency in buildings. If work being carried out on a UK funded scheme, then the current PAS and building regulations should be followed.
Part B contains guidance on fire safety, including means of escape, fire spread, structural fire protection and fire service access.
Click here for more on regulations,
Part L address the conservation of fuel and power in new and refurbished dwellings in the UK. The upgraded Part L Building Regulations aim to reduce carbon emissions for new and refurbished buildings by at least 31%. The latest version of Part L was updated in June 2022, and the new requirements have been in force since June 2023.
Click here for more on regulations,
Part F of the UK Building Regulations, sets out requirements for ventilation in buildings to ensure adequate indoor air quality and prevent issues such as condensation, mould growth, and the build-up of pollutants.
The primary objectives of Part F are to.
Provide Sufficient Ventilation, Control Condensation and remove pollutants.
Click here for more on regulations
Electrical certificates.
The two types of electrical certificates you will come across as a customer who is having any electrical work as part of installing EEM’s (energy efficient measures)
- Electrical Installation.
- Minor Works Certificate.
Electrical Installation Certificate.
An electrical installation certificate is the type of certificate a customer receives after an electrician has installed one or more new circuits. Other examples include a complete rewire, a replacement consumer unit or an additional consumer unit. Generally, any time electrical work is done at the consumer unit, a new installation certificate will be issued.
Minor Works Certificate.
A minor works certificate is issued after an electrician has made an alteration to an existing circuit. Minor works certificates are often used to certify work such as adding additional sockets to an existing circuit or increasing the number of light fittings in a room. It can also be where a fused spur has been installed for an appliance or boiler connection.
