Frequently Asked Questions
1 What does P1, K1, P+, K2 & K3 mean?
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.
2 When do I need to use Low Surface Temperature radiators?
LST radiators are an ideal choice wherever high efficiency heating is required, yet where safety demands a low surface temperature i.e. where people may injure themselves if left in contact with a standard radiator. The range of Stelrad LST radiators reach a maximum 43°C and are ideal for residential homes, hospitals, schools, nurseries and children’s bedrooms.
3 How do I calculate the heating requirements of a house/room?
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.
4 Do you run CPD (Continuing Professional Development) courses?
Stelrad are proud to offer RIBA (Royal Institute of British Architects) and CIBSE (Chartered Institute of British Service Engineers) accredited CPD (Continuing Professional Development) training sessions.
Learn about the latest developments in radiators with a CPD training session led by a fully qualified specialist from Stelrad. The one-hour training session counts towards your 35 hour annual CPD requirement and can be arranged for you on a one-to-one or group basis at your practice, at a time to suit you.
5 Where can I find Stelrad BIM products?
6 How can I order a radiator brochure?
7 What is your product warranty?
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.
8 Which radiators come in colour?
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. 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 a colour chart please email firstname.lastname@example.org.
9 Where can I buy Stelrad Radiators, spare parts and touch up paint from?
10 Do you bend radiators to fit a room?
Stelrad does not bend radiators, and if this is done your warranty will be invalidated.
11 What does Δt mean and should I use Δt50?
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.
12 What clearances should I leave around my radiator to ensure maximum efficiency and air flow?
Stelrad recommends clearances of 100mm either side, 50mm 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.
13 Which LSTs come with a TRV and lockshield valve?
14 What does TBOE/BOE mean?
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.
15 What pressure are your products tested to?
Most models are high pressure tested to withstand 188 psi (13 bar). Strictly controlled independent laboratory testing ensures that all Stelrad radiators are guaranteed to perform to a maximum working pressure of 145 psi (10 bar) at a maximum temperature of 95°C. All Stelrad radiators conform to BS EN 442 – the European Standard for radiators.
16 What connections do your radiators have?
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.
17 What is included in the radiator packaging for installation?
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.
18 Which of your products can I fit feet on?
19 What is the difference between Compact and Elite radiators?
20 How do you bleed a Stelrad radiator?
21 What is the best way to prevent corrosion in your 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.
22 How do you clean a Stelrad radiator?
You can follow the simple step by step instructions on how to clean a Stelrad Elite by using the following link to download the ‘Cleaning a Stelrad Elite radiator’ advice sheet
23 How do you fit a Stelrad radiator?
Installing a Stelrad radiator is simple, you can view how these can be done on the following link
24 Who stocks Stelrad Radiators?
There are many plumbers’ merchants who stock our products, to find your nearest stocking branch click here
25 Where are Stelrad radiators made?
To find out more about Stelrad, please click here
26 How do you clean inside an LST?
By pressing the ring clip between the top grille, allowing the user to remove the fascia, thus making access to the complete product easy for cleaning purposes.