Heat your home: central heating, radiators, stoves, fireplaces and underfloor heating

Old houses often have outdated and ineffective heating systems. Renovation expert Michael Holmes advises on the potential costs, and how to modernise yours while making your home more energy efficient at the same time

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Princess H56cm radiator in Aged Gold, from Castrads  

Updating the heating system can seem a daunting and possibly expensive prospect, but it presents a good opportunity to improve your home’s energy efficiency and cut the cost of fuel bills. As well as making a more comfortable place to live, having a properly heated and insulated home can help prevent damp and rot. If you are fully renovating an old house, it is worth going back to basics and investing in a completely new system.

At the same time as updating the heating, you should look for ways to reduce heat loss and improve insulation levels. Period homes have a reputation for being draughty and inefficient, but with modern technology, they can be just as comfortable and eco-friendly as new builds.

Central heating

If your central heating and hot-water system is more than 10 years old, then the boiler, radiators and even the pipework may not be performing to their full potential and might be unsuitable for the needs of both your lifestyle and the building. Alterations or additions to the system over the years may not have helped and, if you are planning a major renovation or an extension, it is almost certainly time for a rethink.

Most systems have a boiler or sometimes a stove at their heart, although eco options, including solar thermal panels and ground- or air-source heat pumps, are increasingly common, and can be integrated sensitively into a period home.

Pipes, cylinders and radiators store and distribute the heat, while control systems ensure all the other elements work together effectively, regulating temperature levels to maintain comfort and efficiency.

Which type of boiler do I need?

Your boiler accounts for about 60 per cent of your home’s total energy spend, so ensuring it is right for your needs is vital. There are three basic types of heating system:

• conventional open-vented gravity-fed, with tanks in the loft

• a high-pressure system fed straight from the mains, which stores hot water in a cylinder

• a combination (“combi”) boiler, which produces hot water to demand

Each system has its pros and cons. Combi boilers are usually the cheapest to install and run, and take up the least space, but they can’t supply more than one bathroom simultaneously unless they have an integrated hot-water cylinder or ‘thermal store’.

For large households with more than one bathroom, a high-pressure mains-fed system is a good solution.

Since 2005, condensing boilers, which use the waste heat in the flue gases to pre-heat cold water entering the boiler, making them much more efficient than older models, have been mandatory.

An issue for owners of period homes is that these boilers require a condensate pipe to drain away the condensed water. Sometimes this links to the waste under the kitchen sink, but it usually drains externally. This is an important aesthetic consideration and should be thought through before the installation of the boiler.

Likewise the position of boiler flues must be carefully planned, otherwise they can spoil the facade of a building. They are also prone to freezing, so need insulating.

What boiler size?

Correctly sizing a boiler is crucial. This is decided by means of a heat loss calculation, completed by a heating engineer. It will be affected by the house’s size and building materials, the level of insulation and airtightness, and your hot water requirements.

Before replacing a boiler, install other energy-efficiency measures, such as insulation and draught-proofing; this should mean the house is warmer, so the boiler can be smaller.

Heating engineers have a tendency to slightly oversize boilers, rather than risk them underperforming, but try to ensure it’s not excessively powerful for your needs.

Servicing old pipework

Simplifying, upgrading and flushing through old pipework, and adding corrosion and limescale inhibitors to radiators, will make a heating system more efficient. Try to minimise the length of pipe runs to prevent unnecessary heat loss and water use.

To retain heat, hot and cold pipes, as well as water tanks, must be thoroughly insulated, including joints and bends.

Invariably joinery and floorboards will be disturbed when upgrading a heating system, so employ a skilled joiner to work alongside your heating engineer. Boards above fragile ceilings or those that may have to be taken up again in the future are best fixed with screws. Avoid notching the tops of joists to fit new pipes or cables, as this will weaken the floor structure.

Controlling your heating system

Good control is vital to the efficiency of a heating system and will ensure greater comfort. Thermostatic radiator valves are now common but further control can be gained by dividing a building into separate heating ‘zones’. This is particularly useful in larger houses where only a limited area might be used regularly, or spaces are used at different times of the day.

Wireless technology is increasingly used for control systems and saves the need to run cables. Where cables or pipes do need to be run, carefully plan their route to minimise disturbance. Redundant chimney flues can be a good path from the top to the bottom of a building.

Central heating dos and don’ts

• Do be aware of the risk of fire if blow torches are used to solder joints on pipework. Stop ‘hot works’ an hour before the end of the working day and ensure the area is checked before it is left unattended. During works, fit carbon monoxide and smoke alarms.

• Do ensure your boiler is serviced annually by a registered engineer to maintain its performance and safety.

• Do position thermostats so that they have a good air flow around them and are not subject to draughts or direct heat from radiators.

• Don’t allow anyone to work on your boiler unless they are properly qualified. Only engineers on the Gas Safe Register may work with gas.

• Don’t tamper with asbestos. It is a health hazard and often found around old pipes and heating installations. If you suspect it is present, seek specialist advice.

• Don’t forget to think of the future. If you are likely to want to install solar thermal panels or other renewable energy sources, check that the system you fit now will work with them.


Traditional-style cast iron radiators give a nod to authenticity. Fortunately, there is a fabulous choice of designs on offer, and modern versions are far more effective and efficient than original 19th-century models, which were heated by steam.

The main choices are between school-style pillar cast-iron designs, and more ornate decorative models, which may be polished or painted. Alternatively, modern stainless-steel designs can be chosen to make a contemporary statement.

Getting the right sized radiator

It is vital to get the size right – calculate the output you need in BTUs (British Thermal Units) using the online calculator at The Radiator Company. A heating engineer can also work this out for you.

Antique radiators

For the most authentic look, invest in original radiators that have been restored and updated to work alongside modern heating systems. Buying non-reconditioned models from a salvage yard or at auction might seem budget-conscious, but do find out refurbishment costs before investing.

Old cast-iron radiators can still be used but are best not disturbed during renovation work. Flush out debris with a garden hose. Areas of rust may indicate leaks, but it is always worth a pressure test to ensure there isn’t a problem.

Bear in mind that the connections between modern pipework and old radiators may be of different sizes.

Click here to find out how to reduce heat loss from your radiators and improve energy-efficiency


The ultimate cosy centrepiece for a room, a woodburning or multi-fuel stove is also a highly efficient way of heating a space. While the majority of heat from an open fire disappears straight up the chimney, stoves are sealed and designed to burn fuel as efficiently as possible.

Ranging from freestanding appliances positioned in the corner of a room to those designed to sit within traditional fire surrounds, stoves are a flexible choice, too. They are mainly available in cast iron or steel, and can be enamelled with a coloured finish.

If you have an old stove, cleaning it and maintaining it properly will help improve performance.

Fuel options for stoves

  • Wood
  • Coal
  • Oil
  • Gas
  • LPG
  • Electricity
  • Pellets

If you choose a multi-fuel stove, it can be used with wood or coal, and you will need a grate when burning coal/smokeless fuel. This grate is removed when using logs, as they burn better on a ‘hotbed’ of ash. Generally, solid-fuel stoves tend to produce large amounts of heat, but are less controllable than gas, oil and pellet models. If you live in a smoke control area, you’ll need a Defra-approved stove.

heat your home with a Arada ecoburn heat option

How to choose the right sized stove

For a basic estimate of the size of stove you need, calculate the volume of your room in cubic metres by multiplying its length x width x height. You need 1kW heat output for every 14 cubic metres to give a consistent room temperature of 21°C when the temperature outside is zero. Before making your final choice, consult a HETAS-registered installer or retailer, who will make a more accurate assessment of your needs.

Where a room has a large fireplace or hearth, don’t be tempted to opt for a bigger stove that will be visually in proportion. Running a stove with too high a heat output for the space it occupies will make the room uncomfortably hot.


While traditional open fires are not as efficient as stoves, they are an authentic option for many period homes, and if you have an original surround or grate in place, you should look to restore rather than replace and check that the structure of the chimney is still sound. Find a local chimney sweep at HETAS.

If you are specifying a new fire and concerned about efficiency, consider a hi-tech gas-fuelled fire that is highly controllable and offers a realistic effect. If you don’t have a chimney, you could opt for a flueless gas or electric fire, or one that burns bio ethanol, which doesn’t emit harmful gases.

Classical style stone fireplace to heat your home

Mid-18th-century-style fireplace with classical ornamentation, £6,480, Jamb

Click here to find out how to maintain your fireplace and your chimneys in your home

Choose the right surround for your home

  • In Georgian homes, fireplaces were often open – inglenooks were introduced – with a fire basket or hob grate. Surrounds were of brick or stone. In later years, and in grander houses, marble, slate or wood were used.
  • In the Victorian era, hob grates were popular, but from 1850 the cast-iron register grate appeared. Corbels were often used to support the mantel and from 1880 the smoke hood was introduced. Tiled cheeks were popular between 1880 and 1900.
  • In Edwardian times cast-iron register grates were common, before Art Nouveau designs came into fashion. Simple, classical models were also popular, often using marble or enamelled slate. Glazed bricks were also often used, as were ornate oak surrounds with mirrors and shelves.

Bear in mind that all fires, solid or gas, require a hearth that meets the building regulations.

Underfloor heating

Both very comfortable and space-efficient, underfloor heating (UFH) is becoming an increasingly popular choice. The downside is that it does not provide instantaneous heat, so you need good controls with timers, and a regular, predictable occupancy pattern, to maximise comfort and energy efficiency.

Underfloor heating types

Electric UFH: Electricity is a relatively expensive fuel source and consequently the most commonly used form of electric UFH is for small areas such as bathrooms, where it is ideal for retrofit because the mats are very thin.

Hydronic UFH: While warm-water UFH is well suited to many period properties, the maximum floor temperature is limited, so its output is not always enough to heat space effectively, unless the building is renovated to improve the thermal efficiency of the floor and roof, and, where possible, the walls and door and window openings. UFH is ideal for installing in extensions, though, and for conversions where there is no existing ground-floor structure.

Installing underfloor heating in an old house

Underfloor heating works well with hard flooring, such as stone, terracotta and quarry tiles, but is not recommended for use with solid timber flooring, and the heat output is reduced when it is fitted under carpet.

Where the existing floor structure is timber joists, typical of first storeys upwards and the ground floor of many period homes from the 18th century onwards, the usual solution is to lay coils of UFH pipe fitted over insulation cut to fit between the joists.

Continued ventilation of the joists needs to be considered at the design stage, and insulation should be breathable. Metal plates suspended over and between the joists, with channels into which the UFH pipe can be laid, can help to distribute heat evenly.

Warmup StickyMat: great for retrofitting

'Not many people know that they could easily and cost-efficiently install an underfloor heating system in a bathroom (and many other rooms) when they renovate and change the flooring. Applying insulation boards on the subfloor, then installing electric underfloor heating on top of that, and finishing it off with the floor finish of your choice is not difficult or laborious, but brings inevitable comfort to your bathroom.

The most common and popular floor heating system for retrofitting is electric underfloor heating. The availability of ultra-thin electric systems that only marginally raise the floor height (a few millimetres) means that owners of older houses can now fully enjoy the benefits of underfloor heating throughout their entire home.

Underfloor heating generates radiant heat distributed evenly from the floor up and, unlike radiators, does not overheat the space. This makes underfloor heating more efficient to run than radiators as no energy is wasted overheating the room.

Warmup StickyMat underfloor heating in a kitchen

The most popular system in the market for retrofitting is Warmup StickyMat. A 3m² bathroom heater can be self-fitted and installed for less than £250 and cost £20 each year to run

Remember to get a heat loss calculation done prior to buying a system to confirm the efficiency of your home. The key is to check that the heat output of underfloor heating is higher than the heat loss of a room.'

Andrew Stimpson, CEO Warmup PLC

Click here to read our ultimate guide to installing underfloor heating in an old property

Installing underfloor heating directly onto the ground

The task of retrofitting underfloor heating where the existing floor is laid directly onto the ground, typically in the case of flagstones, clay pamments or quarry tiles, is usually harder.

  • You will need to remove any skirting boards
  • The flooring will need to be removed carefully
  • The ground will need to be excavated to a depth suitable for a new ‘breathable’ limecrete oversite slab to be laid. (Usually 400–450mm plus the depth of the floor finish)
  • Care must be taken not to undermine existing walls.

An alternative is to lay an independent UFH system over the existing floor structure with a thin layer of insulation bonded beneath it. This will increase the height of the floor, but only by 15–30mm, so minimising disruption.

UFH installation can be linked to an existing heating system by adding a separate circuit from the boiler outflow, with a mixer valve to regulate the flow temperature. Separate thermostatic controls in each zone will be required, ideally with night setback mode, as UFH is most efficient when it is run constantly and just turned down at night rather than turned off.

Installing underfloor heating in a listed building

Installing underfloor heating in a period property inevitably involves removing floor coverings, and consideration should be given to any potential loss or damage to these materials, including the removal of skirting boards and other decorative features. If the work involves an alteration to the character of a listed building or loss of historic building fabric you will need listed building consent.

Energy options

Choosing a the right heating system for your home is the key to reducing running costs and making it a comfortable place to live, therefore it should be designed to suit your property, lifestyle and budget. It’s also important to consider heating in the context of your home’s overall energy efficiency — installing insulation and controlling ventilation could reduce running costs significantly. Below are the main options when it comes to providing energy to your property

 Click here to read our essential guide to central heating

For most homes, a combination boiler will be suitable, providing heating to radiators and hot water on demand. For larger homes with higher hot water demand, a system boiler may be more suitable, providing heating to radiators, or underfloor heating, towel rails and hot water via a storage cylinder.

A gas-fired heating system will cost around £3,000–£5,500 for a typical 93m2 three-bedroom terraced house.

If you live in an area without mains gas, your options for a heating system are oil, liquefied petroleum gas (LPG), electricity, solid fuel, or biomass fuel. With the exception of electricity, all these options require fuel storage on site. The default option where no mains gas is available is usually oil-fired central heating. 

The capital cost for a 93m2 property is around £4,000–£6,500, which includes a boiler, oil storage tank, hot-water cylinder, radiators, parts and labour.

The installation cost for a bulk LPG heating system is slightly lower than for oil, as the tank is usually provided by the gas supplier on lease, but the running costs are slightly higher. An LPG tank can be buried, making it a good choice for those with limited space for an above-ground oil tank. LPG also offers options for a gas hob and real-flame-effect gas fires.

A renewable option, the most common and practical choice of biomass fuel is wood pellets, or wood chip. Systems are also available that burn logs and even straw bales.

The cost of installing a biomass system is relatively high and you also need lots of space for the boiler, thermal stores and for fuel storage — which is relatively bulky. This means it’s usually an option only for properties with larger gardens and space for a plant room and fuel store, or an outbuilding to convert.

As biomass heating is subsidised currently under the renewable heat incentive (RHI), it can be a very cost-effective option when well designed. Although the upfront investment is high compared to alternatives, the payback can be fast and the long-term running costs fairly low. To qualify for the RHI subsidy, your home must be energy efficient, so you will need to consider a major renovation upgrade insulation levels in the roof and floor and, where possible, the walls — not always practical in a period home.

A relatively expensive fuel option for home heating, electricity is typically only used where there is no mains gas available and no space to store other fuel options, or nowhere to install a flue for a heating appliance.

The most common electric option is storage heating powered by cheaper-rate off-peak electricity, such as Economy 7 and Economy 10. It’s worth exploring options for an alternative system that could reduce running costs.

Electricity is commonly used as a retrofit underfloor heating solution in small rooms, rather than a heating option for a whole home.

Using the cooling technology of conventional refrigeration, heat pumps extract renewable solar energy from the air, the ground or a body of water. A heat pump is only a cost-effective option when carefully designed to ensure the average performance (the ratio of usable energy extracted per kWh of electricity consumed) offsets the high fuel cost.

It is most economical if your home has a very low heat requirement because it has high levels of insulation and airtightness, and is combined with low-temperature heat emitters such as underfloor heating — none of these are easily achieved in a period property. When powered by green and or clean electricity, a heat pump is a sustainable heating option.

Active solar panels that produce hot water, and photovoltaic panels that generate electricity, are both subsidised at the moment. Therefore they both make financial sense over the medium to long term when designed, sized and positioned correctly, as long as you have spare funds available to invest in the relatively high upfront capital cost.

If they are not to compromise the building’s character, solar panels will need to be very carefully sited on a period home. Planning permission is not usually required to fit solar panels, although they must not face the highway if your home is within a Conservation Area. If your home is listed, you will need consent.