Central Heating Radiators

Aluminium Radiators

These multicolumn radiators in aluminum and steel are a popular range available in 200 colours. Sectional products allow you to create a size to suit your specification.


Bathroom Towel Rails

Convectors heaters have unique qualities that allow them to fill specific roles. Low profile aluminium heating elements make them perfect for LST radiators, Trench and premier heating.

Cast Iron Radiators

Our range of hand welded and hand finished stainless steel designs can be used as one off statement pieces or throughout the home.

Convector Radiators

Classic designs for a designer home or for period restoration of Victorian houses and Georgian style homes.

Designer Radiators


Steel Multi Column Radiators

Use throughout the home, reflecting the latest in interior design trends you can select from a range of tube designs, vertical and horizontal to find a solution.

Stainless Steel Radiators

High thermal efficiencies make them perfect for heating systems, smooth clean lines and slim profiles make them perfect for both new builds and refurbishments.

Radiator Valves

Stylish and easy to install electric radiators are perfect for single room projects, extensions of flats. Easy to control via built in thermostats or centrally via pilot wire.


Radiator Accessories

Designed to deliver form and function in the bathroom. With space often at a premium a wide choice of heights and widths provides maximum opportunity.

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Radiator Questions and Answers

Are ZD radiators / towel rails compatible with my system?

ZD radiators / towel rails are compatible with normal central heating systems and have British Standard fittings.

On an existing system, you can replace all the radiators or just the ones you want.

ZD radiators work with all types of boiler, and with all types of circuit including sealed systems, combination boiler systems and condensing, closed-circuit systems with an expansion tank. (If you have an expansion tank, the top of the highest radiator must be at least 60 cm two feet below it.)

Note that ALL ZD radiators must be placed on the central heating system and never on the hot water system that feeds the taps i.e. a Direct system (which is separate). The water flowing to taps is constantly refreshed and its high oxygen content will rapidly corrode any radiator. Only stainless steel or solid Brass products can be used with Direct systems. back to top

Are the cast iron radiators from ZD compatible with my system?

All of our Cast Iron radiators are compatible with normal central heating systems and have British Standard fittings. On an existing system you can replace all the radiators or just the ones you want. Confirm with your installer that your pipe work and system set up is suitable for additional radiators. back to top

Can I get any colour I want?

ZD have radiators in stock that come in white and chrome finishes, but a huge range is available by special order. Many of our designs are available in a large selection of RAL colours (188 internationally recognised paint colours) and Special Finishes. If you would like a copy of our RAL or Special Finish chart please contact us on 01342 302250.

Some Cast Iron radiators are only available in primer, so you can paint them any colour yourself. Special radiator paints are readily available from all the major DIY retailers and come in a wide choice of colours. Please check the colour symbol by each product to see what is available.

Please note that due to Screen settings and manufacturing tolerances the colour (including white) of a finished radiator may vary slightly from the colours represented here and from one colour group to another as well as from our Special Finish & RAL charts. It should also be noted that if the same type of Radiators are ordered and produced they may also differ in finished colour from any previously ordered.back to top

What should I paint my radiators with?

The radiators supplied with painted finishes have a very durable baked-on powder coated finish that will not fade. They should not be re-painted as this will void the warranty.

Cast iron radiators supplied in a primer coating will need to be finished with acrylic water based enamel. This is the best solution, as it will stop any rust from appearing or the paint colour to fade. Alternatively synthetic dissolvent enamel can be used; again this will stop rust from coming through but will not be as resistant to fading in the future. In all cases the primer coat should be in excellent condition with all traces of surface rust removed before the finishing coat is applied. Further priming coats may be required to achieve this.

We do not advise the use of nitro dissolvent enamel or paints not designed specifically for use on radiators i.e. emulsion, they can adversely affect the primer coat and allow rust generation. back to top

Can I fit decorative covers over my radiators?

Decorative covers can be utilised, however they will significantly reduce the output of a radiator. The amount of heat reduction is dependent on the actual design of the cabinet so we cannot give an exact heat reduction figure. Thermostatic radiator valves should not be fitted inside covers. back to top

Can I remove and refit my radiators for decoration purposes?

This can be easily achieved on most traditional open vented systems, however it can be more complex for sealed systems. An open vented system has a feed and expansion tank, with a ball valve and overflow located at high level in the property. A sealed system should have a pressure gauge located in or near the boiler.

For open vented systems switch the heating system totally off and allow it to cool. Close the radiator valves at each side of the radiator, making a note of how many turns each valve is open. Place a receptacle under one radiator connection (not the valve to pipe connection) and loosen it until water slowly drains. Some radiator valves have an integral drain point that makes this task easier. Once the water has drained from the radiator, loosen the other radiator connection and remove it. To refit, replace the radiator, re-attach the radiator valves and open the valves to their previous settings. The air vent at the top of the radiator will need to be opened until the radiator is full of water. back to top

How much heat do I need?

To establish how much heat your room needs, consult your Gas Safe registered installer or heating engineer. If you want to work it out yourself click for our BTU Calculator page (link), which leads you through the simple calculation and works out the answers for you.

All our radiators are shown with their heat outputs, so you can choose a single radiator or a number of radiators whose outputs add up to the heat you need.

All outputs listed are calculated in line with the European BSEN442 Testing Standard at ∆t50°C (the latest standards for modern boiler systems). To convert Δt50°C to Δt60°C simply multiply x 1.264. (see BTU calculator) back to top

Where should I locate my radiators?

For even heating and the right comfort levels, most radiators are best placed in the coldest part of the room: traditionally found under a window. This is because the cold outside air helps create the right convection inside i.e. pushing the hot air from the radiator into the room.

Large spaces are more effectively heated with 2 or more, smaller radiators rather than one large one. A rule of the thumb often used in the trade is to have one radiator every four metres (about 15 feet) or so in the room.

An alternative could be two tall thin radiators either side of the window or a long low radiator along the wall. back to top

Can I curve or bend radiators to fit into an existing bay window?

ZD column does not provide this type of radiator. Curved radiators are difficult to make and install, requiring templates, hence our decision not to provide this service. For a very similar effect we suggest that you use a series of smaller radiators to make up the total length and shape of the bay. This is also generally more cost effective as curved radiators carry a premium. back to top

How long will I have to wait for my radiators?

Stock radiators can be delivered without delay generally within 3-5 working days from placing an order. Made-to-order-models generally take about 3-6 weeks. Please check the detailed delivery details within the product section to see what we have in stock or how long made-to-order deliveries are for that model. back to top

How will my radiators be delivered?

ZD delivers free of charge, direct to your merchant within mainland UK, using our own fleet of vehicles.

Non-mainland delivery charges are available on application at the time of order. back to top

Who will install my radiators?

ZD radiators can be installed by any competent plumber / installer (electrician for electric models) who is preferably Gas Safe registered. They are compatible with manual and thermostatic valves, to ensure your valves complement your Designer radiator please see our extensive range of valves and accessoriesback to top

What should I use to secure the radiator to the wall?

Radiators are heavy items and should be securely fastened to the wall. Specific care should be taken to identify the construction of the wall and use the appropriate fasteners to secure the radiator bracket. All ZD radiators are supplied with the correct brackets and detailed instructions, which are also available on line. back to top

Can I use microbore pipework?

Yes, but on really big cast iron radiators (over 3500 watts) it can prove problematic on balancing the central heating system. If in doubt, ask your plumber / installer. back to top

The radiator I want has not got enough output for my room, what can I do?

Depending on the range you can select an alternative model with more columns, double or even triple rows of elements to increase output within the same space. You may need to add another radiator into the room to make up the shortfall in output required. back to top

I want to install aluminium radiators, is there anything I need to know?

Aluminium radiators are installed in exactly the same way as steel or cast iron ones, as with all central heating systems a suitable quality and quantity of inhibitor must be used to avoid corrosion. Mixed metal inhibitors are now easily available from most plumbers merchants. Your installer will know all about this. back to top

How do I convert from BTUs to Watts?

Divide by 3.412 back to top

How do I convert from Watts to BTUs?

Multiply by 3.412. back to top

How do I fit valves?

Wrap at least five turns of PTFE tape around the threaded tails of the valves and screw them into the radiator. Make sure the PTFE tape stays on the thread rather than just running along it as you tighten. If it does run, undo the valve and roughen the thread slightly with a hacksaw blade then re-tape the thread.

Some of our valves have parallel threads which means that they never tighten against a stop like traditional valves so more PTFE than usual is required we recommend the use of gas type PTFE which is much thicker than the standard. The advantage of parallel threads is that they fit the same depth on all radiators so giving pipe centres is more accurate and also the threads are completely hidden inside the end of the radiator. back to top

Valves are sold in pairs, what is the other valve for?

The wheelhead valve is the temperature control; the other is called a lockshield valve and is used to balance the radiators in the system so that they all heat up at roughly the same rate. Simply put, the radiator closest to the boiler if left unchecked would heat quicker than the one sited at the other end of the house, so the lockshield valves should be set opened at increasing amounts the further away from the boiler the radiator is. back to top

What is the difference between a TRV (Thermostatic Radiator Valve) and a manual one?

The TRV controls the radiators temperature by sensing the room air temperature and automatically opening and closing the flow to the radiator to maintain a preset temperature. A manual valve controls the temperature of the radiator regardless of how warm the room already is. TRVs are now a requirement as part of Building regulations, check with your installer to make sure you have the correct valves. back to top

Will old twin entry radiator valves fit new radiators?

These older valves are identified by having both pipe connections in one radiator valve at one side of the radiator. If new radiators are being fitted it may be advisable to also renew the valves. back to top

When do I need to use Low Surface Temperature radiators?

Although no radiator should ever be too hot to touch, LST radiators are advisable for areas where a person may injure themselves if left in contact with a traditional radiator due to an accident or fall for example. Such applications are generally hospitals, nurseries and homes for the elderly or infirm but they are also great in children’s rooms and other higher-risk areas of the house. back to top

Do cast iron radiators take longer to warm up than standard radiators?

Yes, however, because there is a lot of mass with cast iron, the radiators have the advantage of staying warm long after the central heating has been turned off. This means that the changes in temperature in a room heated with radiators made of cast iron are gentler than those in a room heated with regular radiators. Most people tend to run their central heating twice per day, once in the morning and then again at night, if a third short period is added into the middle of these two times then the warm up time is greatly reduced and the house will remain warm all day and night. When mixing standard radiators with cast iron we find that if the central heating thermostat is sited near a standard radiator the heating may close down before the cast iron radiators sited elsewhere have reached full temperature. The solution is to slow down the standard radiator influencing the thermostat by part closing the lockshield valve on that radiator (the usually covered end valve opposite the temperature control valve on the radiator used to balance the central heating system). Heating a home is partly about heating the fabric of the building. Cast iron radiators are again becoming popular amongst heating engineers and architects (particularly for older buildings) as they tend to retain the warmth in the fabric of the building which in turn counteracts damp and condensation. back to top

What is the difference between a direct and an indirect system?

A direct system is one where the tap water actually mixes with water in the radiators. An indirect system separates the tap water from heating system water used to heat the radiators. Most of ZD radiators are made from mild steel or aluminium and should only be fitted to an indirect system. We do offer a choice of Stainless Steel and Brass ranges however that are suitable for either system. Always check with your installer that your selected radiator is suitable for your system. back to top

Why are my radiators hot at the top and cold at the bottom?

This indicates that the radiator may be receiving an insufficient flow of water; typically large radiators need a higher water flow than small radiators. There may be several reasons for this, such as incorrect balancing, incorrect pipe size or an under-performing or under-sized pump; there may also simply be a blockage in the radiator. A heating engineer should be called to carry out further investigations. back to top

Do my radiators need venting?

If your radiators are cold at the top and hot at the bottom, the radiator needs venting (bleeding). Venting is beast carried out when the system is cold, simply turn off the heating system and slightly open the air vent (some radiators will require a radiator vent key, others may need a small screwdriver) until water is noted at the air vent. Take care to protect decorated surfaces with a cloth prior to opening the air vent. Gently close the vent and switch the system back on. If the radiators need venting frequently, there may be a fault with the system and a heating engineer should be called. Fitting Aladdin HV30c Automatic airvents will help keep radiators vented and improve the efficiency of your system. back to top

What clearances do I need above and below my radiator to ensure maximum efficiency?

We recommend that clearances of 50mm above and 100mm below should be left clear so heat from the radiator can be effectively distributed. back to top


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