FAQs

With so many radiator types available to heat your home, we understand it can be a difficult choice when buying radiators. Follow the link to read Stelrad’s Radaitor Buying Guide. Click here.

With this guide, we hope to make this a bit easier for you by explaining all you need to know, guiding you through the different types to choose from and how to decide on the best radiators for each room of your home.

Yes, radiators are often more efficient and have lower running costs than a combination of radiators and underfloor heating. Radiators offer flexibility through responsive and targeted heating and are typically more cost effective than alternative heating solutions. You can turn radiators on for short bursts of heat or turn them on for longer periods. By comparison, underfloor heating takes longer to heat up and warm rooms, while being more expensive to run for extended periods of time. In a recent report, it was discovered homes that have air source heat pump with radiators throughout cost an average of 11% less to run than underfloor heating.

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With radiators, you have more flexibility with your heating. You can use the controls for targeted heating in one room or set the timer to activate the heating at certain times, with options such as one-hour boosts. Comparatively, underfloor heating takes longer to heat up. Underfloor heating is best suited to constant heating, but this isn’t a viable option for many households due to the high running costs. It’s 25% to 35% more expensive to have underfloor heating on 24 hours a day than radiators on during typical hours (7am to 9am and from 4pm to 11pm).

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Radiators allow you to use targeted heat with a locally mounted TRV. You can quickly turn a radiator on and heat a room in a short space of time. With underfloor heating, it takes much longer to heat a room and has a higher running cost if you only want the heating on briefly.

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In most properties, homeowners generally prefer targeted heating rather than constant heating throughout. Many radiators offer a one-hour boost control, which is a quick and efficient way to raise the temperature of the room outside of the usual heating routine. By comparison, underfloor heating has low response times and lacks the flexibility that radiators offer. You have to be committed to turning on the underfloor heating for an extended period of time, rather than a short burst as you can with radiators.

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Due to the in-depth installation required for underfloor heating, the best time to install it is when you are having renovations. Any other time, the installation can be very disruptive to your home.

When choosing between radiators and underfloor heating, there are various factors to consider. This includes the size and type of property, along with your heating requirements. Radiators are more affordable and less complex to install than underfloor heating. They also warm up more quickly than underfloor heating, which is perfect for short bursts of heat or to swiftly take the cold edge off a room.

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Radiators give you more flexibility when it comes to a sudden cold snap. You can quickly give the heating a boost and heat a particular room or the whole house. Radiators have intuitive and simple temperature control that can provide targeted heat to a particular room or area in the home.

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Radiators are generally a better option for smaller rooms and properties. You can choose to heat one radiator in a single room, providing fast and efficient heat in the small space.

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P1 also known as Type 10, is a type of radiator with 1 radiator panel and no convection fins.

K1 also known as Type 11, is a type of radiator with 1 radiator panel and 1 set of convection fins.

P+ also known as Type 21, is a type of radiator with 2 radiator panels and 1 set of convection fins.

K2 also known as Type 22, is a type of radiator with 2 radiator panels and 2 sets of convection fins.

K3 also known as Type 33, is a type of radiator with 3 radiator panels and 3 sets of convection fins.

It is an important and sometime complex calculation when determining what size radiator is required to heat a room to the correct level. STARS (Stelrad Technical Advanced Radiator System) heatloss calculator offers a simpler way to get sizing of radiators right, first time. Both fabric heat loss and ventilation heat loss is also calculated in order to establish the radiator output and size required.

Stelrad measure output in Btu/hr, British Thermal Unit per hour which is the standard measurement used to state the amount of output of any heat generating device. Heat output can also be measured in Watts, 1 watt is equivalent to 3.412 Btu/hr.

You can download the full Stelrad Radiator book from the downloads page. You can also contact us to request a hard copy brochure.

Most horizontal steel panel radiators come with a 10 year warranty, the Softline has a 15 year warranty but all other radiators have a 5 year warranty.  The warranty covers any defect that is attributable to a manufacturing, assembly or material fault only, further details are available on request or download our warranty statement for full details.

Standard steel panel products, which are installed in toilets or any areas of high humidity (including bathrooms, Kitchens and
shower rooms, etc) are limited to a twelve months parts and labour warranty. The Stelrad Compact XP range is excluded
from this limitation and comes with a full five year warranty, when installed in these locations.

Suitable and sufficient ventilation should be maintained to prolong the life and finish of the product.

The warranty does not cover any defect that is due to misuse during the handling, transportation or storage processes.

Please be aware the warranty is void if you paint your own radiator.

None of these conditions or limitation affects your statutory legal rights.

Stelrad radiators are available in white as standard with a 60% gloss finish; the white is RAL 9016. RAL is a European wide colour matching system.

Each Stelrad radiator is subjected to a multi stage cleaning process before the paint is applied. This involves several rinsing stages, including an iron phosphate and demineralisation rinse. The first coat of paint is applied by electrophoresis and the radiator is then stoved and cooled. The second powder coat is applied and the radiator goes through a final curing stage. It is then allowed to cool, prior to packaging.

Stelrad also offers specific radiators in a variety of colours with varying lead times. Please check on the product page for your chosen product or contact Customer Services on 0800 8766813.

Please note that once ordered, coloured radiators cannot be cancelled.

The colours shown on this website and in the Stelrad Radiator Book are reproduced as accurately as the process will allow and can be made to order on the identified products only. To request individual colour swatches, please complete the online request form here.

Stelrad supplies these products to all major plumbers’ merchants, to find your nearest stockist use our handy find a stockist map, or you can purchase directly from us through the website.

Stelrad does not bend radiators, and if this is done your warranty will be invalidated.

Δt refers to the difference in temperature between the water circulating in the central heating system and that of the ambient temperature. It is important to use the correct Δt when selecting your radiators, as the same radiator will have different outputs at different water temperatures due to the heat source.

Δt50 is the UK standard for domestic gas boilers, however Stelrad also quotes at Δt30 and Δt40 for lower water temperature systems, such as renewable systems.

Stelrad recommends clearances of 100mm either side, 150mm above and 150mm minimum from the floor to the base of the radiator. This allows adequate airflow when the radiator is placed on the bracket.

TBOE / BOE refers to which position the pipes are connected to the radiator, OE means opposite end i.e. 1 pipe on each side, TB is top bottom i.e. 1 pipe is connected to the top and 1 to the bottom, B is both pipes connected to the bottom.

The standard piping connections for all Stelrad products are ½ inch bsp.  A 3/4 inch valve adaptor is also available, providing a ¾ inch connector option to the valve without reducing performance.

Our electric radiators don’t need to be connected to a central heating system and must be electrically connected to a fused fixed spur, which is fitted with a 13amp fuse.

For specific air vent and blanking plug requirements, please check our Air Vents and Blanking Plug Technical Specifications.  Please note the Radical has different connections.

Everything required for installation can be found within each radiator’s packaging. Brackets are of a strong design, with open top and deep slots, which facilitate easy and secure installation. Plastic inserts seat the radiator precisely on the bracket, minimising expansion and contraction noise.

The neat nickel-plated plug and vent provide a watertight joint, whilst complementing the superior finish. To facilitate easy one off replacement, nickel-plated brass extension pieces are also available, complete with sealing washer, in 20mm, 30mm and 40mm options.

All steel panel type radiators, including K3 and Concord have optional feet, however these must be specified when ordering.

You can follow the simple step by step instructions by downloading the ‘How to bleed a radiator’ advice sheet or watch a short video on how to bleed a Stelrad radiator.

Firstly a well designed and commissioned system is assumed.

Rusting of iron is a complex but well understood process and requires the presence of 3 ingredients; iron (present in all steel alloys), water and oxygen. Rust is hydrated iron oxide.

The first step in a closed central heating system is to focus on the oxygen component. A well designed and commissioned heating system will initially have dissolved oxygen in the system water which will produce rust. By preventing the addition of new air (air ingress) to the system then the cycle of rust production is limited. Clearly the continued addition of new air to a system will exacerbate the rust production cycle. This must be prevented in the first place and a de-aerator will help remove new air in the undesired event it is introduced.

Secondly the production of rust deposits in a system (often resulting in a sludge known as magnetite) will cause a concentration of corrosion locally / in the area that the sludge is deposited. Therefore the fitting of a magnetic filter may prevent the local build ups of sludge and therefore alleviate concentrated / localised corrosion.

Not mentioned is a good system inhibitor. These are effective because they interrupt the part of the chemical process that allows dissolved oxygen to combine with the iron content of the steel and ‘inhibits’ the production of hydrated iron oxide. A layer (film) of inhibitor is formed over the steel of the radiator. A good inhibitor will also contain ingredients that will prevent the formation of biological contamination which can introduce new oxygen or carbon dioxide to the system. The effectiveness of the inhibitor can be significantly reduced if the protective layer is disturbed respectively by the circulation of air and / or system debris (including magnetite) in the system. Therefore the prevention of air ingress / removal of air will ensure the action of any inhibitor. Additionally the prevention of any magnetite deposition (sludge) via a magnetic filter will also ensure the action of the inhibitor.

You can follow the simple step by step instructions on how to clean a radiator outlined here.

Installing a Stelrad radiator is simple, watch our simple video on installing a radiator.

Stelrad radiators are built in facilities in both the UK and the Netherlands. To find out more about Stelrad, please read our About Us page.

Read our online purchase information to find all the answers to this question.

Delivery is within UK Mainland only.

Your existing radiators should have been sized to suit the existing boiler installation, if you are changing the boiler to an air source heat pump or similar then the existing radiators will still be alright but will need checking to see if they are adequately sized for the new heat source, this can be conducted by the installer or competent person.

If you are changing your radiators now, they will be sized to suit your existing boiler installation, if later you change your boiler installation to an air source heat pump or similar the radiators will still work, however as they should have been sized for the existing boiler installation these may need checking to see if they are adequately sized for the new heat source.
If you are contemplating changing your boiler to an air source heat pump or similar at a later date you may want to discuss this with an installer or competent person to size the radiators for the future installation of an air source heat pump or similar.

When sizing radiators it is advisable to consult with a competent installer to determine what temperatures your heat source works at, you will also need to know the desired room temperature you require, for the radiators to heat the room to.

It is advisable to use a Thermostatic radiator valve and lock shield valve on radiators, certain radiators can be installed with a centre tap Thermostatic radiator valve and Lock shield valve combined, with many radiators requiring a single Thermostatic radiator valve and lock shield valve.

Step 1 – Installing a Concord Vertical & Slimline radiator:
Install / plumb the Concord Vertical & Slimline radiator with the flow and return either side, this is due to a ‘baffle’ incorporated into the radiator within the bottom horizontal header bar. The air vent should be fitted diagonally opposite the lock shield valve with which the radiator will be filled. If using a TRV (Thermostatic Radiator Valve) the TRV must be fitted on the flow unless it is bi-directional.

Step 2 – Filling the radiator with water:
Once the radiator is correctly installed and with both valves shut off (no water should be in the radiator), ensure the heating is turned off, the water is cool, and the system pressure is maintained. Fully open the air vent which will allow the air to be evacuated when the radiator is being filled with water.

Using the lock shield valve, gradually fill the radiator with water. You will start to hear the water passing through the valve (lock shield valve), by slowly allowing the continuous flow of water to fill the radiator, this will ensure that no air becomes trapped within the tubes and the entire radiator will become completely full of water. The valve should remain open for the duration of the radiator being filled, and this may take a few minutes to complete. Once water starts to bubble and spurt out of the air vent, wait until all bubbles have stopped and then close the air vent. When the air vent is closed, this is the time to open both valves (lock shield and the TRV).

Once the above steps have been completed, turn on the heating and check the entire radiator is evenly heated.

Step 3 – If the radiator doesn’t heat evenly:
If the radiator starts to make a dripping or trickling noise or is not evenly heated across all the tubes, this suggests that the radiator is not entirely full of water and has air gaps, therefore, you will need to isolate both sides of the radiator, drain and then repeat step 2.

Please note:
This is only a guide, if in doubt please seek professional advice from a qualified heating engineer.

Panel radiators: All brackets and fittings are housed within the radiator fins in a plastic bag for transportation. This is to avoid scratching or damaging the outer paint work.

Designer radiators and towel rails: All brackets and fittings are housed within the packaging in a plastic bag or cardboard box for transportation. This is to avoid scratching or damaging the outer paint work.

If you cannot find them please call 0800 876 6813 or email [email protected].

At Stelrad, every radiator is crafted with precision, pride, and a touch of British engineering excellence. If you’re curious about how we bring warmth to your home, we offer exclusive behin-the scenes factory tours at various times of the year.

Groups will be taken on a tour of the production and distribution areas, then they will have the opportunity to hear all about Stelrad and look at our showroom to see the vast portfolio of radiators we have to offer.

Please note that tour groups numbers are limited and health and safety rules apply.

Whether you’re renovating, building, or simply passionate about quality, come and see how it all comes together.

For information about the next factory tour, please email [email protected].