Radiator FAQs: Your Questions Answered

Choosing, positioning and looking after a radiator raises more questions than you'd think. We've pulled together the questions we're asked most often, covering everything from stock and delivery through to valves and installation, so you can find a clear answer without having to dig through a manual.

Stock & Delivery

Are all radiators kept in stock?

We hold the most popular sizes of white and chrome models in stock, as well as various other finishes depending on the product. Our website indicates which models are stock items, and in our brochure the stock sizes are listed in bold.

What is "Made to Order"?

You can have a radiator made to order to best fit your design and space requirements, simply by choosing from one of the thousands of sizes available and selecting a colour or finish. We will have your radiator made specifically for you.

How long will I have to wait for my radiators?

Expected delivery time depends on whether you order a stock radiator or a Made to Order radiator. Stock radiators can be delivered within 48 to 72 working hours, whereas Made to Order models generally take around 3 to 6 weeks. Small delays can be expected for deliveries to Scotland and the offshore islands. Check the delivery information on each product page for exact stock and lead time details.

How will my radiators be delivered?

We deliver radiators and towel rails free of charge to UK mainland addresses, using our own fleet of vehicles or specialist couriers where appropriate. Orders under £50 incur a nominal £5 postage and packing charge, and deliveries to non-mainland addresses incur an additional charge, confirmed at the time of order.

Choosing the Right Radiator

How much heat do I need?

To establish how much heat your room needs, consult your Gas Safe registered installer or heating engineer, or use our Heat Output Calculator. All our radiators are shown with their heat outputs, so you can choose a radiator, or combination of radiators, whose combined output matches your heating requirement. Outputs are calculated in line with the European BSEN442 Testing Standard at Delta T50C. To convert Delta T50C to Delta T60C, multiply by 1.264.

How do I convert between BTUs and watts?

To convert BTUs to watts, divide your BTU figure by 3.412. To convert watts to BTUs, multiply your watts figure by 3.412.

Do different radiator designs affect output?

Altering the size, shape or number of tubes or columns in a radiator changes the output it achieves. Our Ancona Radiator range, for example, offers a huge variety of options, giving flexibility in achieving the right output within a limited space.

The radiator I want doesn't have enough output for my room, what can I do?

Depending on the range, you can select an alternative model with more columns, or single or double rows of elements, to increase output within the same space. You may also need to add a second radiator to the room to make up any shortfall in output.

What is the difference between cast iron, steel and aluminium radiators?

Cast iron radiators have a dense, heavy structure that takes time to reach optimal temperature but stays hot long after the heating is turned off, making them ideal for cold, draughty period homes. Steel radiators use a lighter, less dense material that heats up and cools down quickly, giving more manageable control. Aluminium is a highly conductive material that heats up almost instantly, giving total control over your heating system. Read more in our blog to learn more about the differences in radiator material.

What is the difference between single and double radiators?

Models with additional rows of tubes, or multiple columns, maximise heat output within the same wall space. For example, our Water Lily Vertical Radiator at 2020mm x 312mm outputs 2,238 BTUs in the single version, compared with 3,180 BTUs in the double version, for the same footprint.

What are electric or dual fuel radiators?

A number of our towel rails can be converted to work as dual fuel models using an element and T-piece. Your installer will need to be aware of this to adjust pipe centres accordingly. Product pages and our brochure note where a towel rail is suitable for dual fuel conversion.

Positioning

Where should I position my radiators?

In modern homes, radiator positioning is less critical, though advice is always available. In traditional homes, radiators are best placed in the coldest part of the room, usually under a window. Larger spaces are more effectively heated with two or more smaller radiators rather than one large one. A common rule of thumb among installers is one radiator roughly every four metres.

Should I choose a horizontal or vertical radiator?

Many of our designs are available in horizontal or vertical options. Which you choose depends on the space available and how you want to make use of ceiling height and wall length without losing heat output.

What clearances do I need above and below my radiator?

We recommend leaving at least 50mm of clearance above and 100mm below the radiator, so heat can be effectively distributed around the room.

Can I curve or bend a radiator to fit an existing bay window?

Our Ancona range can be curved to fit a bay window, provided the dimensions fall within tolerance. Our online specification tool and [LINK: Ancona Curved Specification Instructions — insert URL] will help establish what can be achieved in your space.

Colours & Painting

What colour options are available?

Each product belongs to a colour group, showing the range of colours it's available in, on the product page and in our brochure. For a copy of our RAL or Special Finish chart, contact us via our [LINK: Finishes page — insert URL] or by phone. Please note that screen resolution, printing and manufacturing tolerances mean the finished colour of a radiator, including white, may vary slightly from what's shown online or in print, and between colour groups or production runs.

What should I paint my radiators with?

Radiators with a factory painted finish have a durable baked on powder coat that will not fade and should not be repainted, as this voids the warranty. Most cast iron radiators need painting to protect against rust; we can supply cast iron radiators pre-painted in popular RAL colours with a powder coat guaranteed for at least 10 years. If painting yourself, apply a zinc based rust inhibitor primer, followed by an acrylic based undercoat and topcoat. Do not use water or emulsion based paint, and match undercoat and topcoat colours for the best finish.

Can I remove and refit my radiators for decorating?

Yes. With the heating system off, protect the floor, close both valve heads fully, loosen the nut connecting the valve tail to the valve and drain the radiator into a shallow container, then disconnect the valve tail and remove the radiator. Use decorator caps on thermostatic TRV heads to keep them fully closed, and blank off valve tails as an extra precaution.

Can I fit decorative covers over my radiators?

Decorative covers can be used, but they will reduce a radiator's output. The amount of reduction depends on the cabinet design, so we can't give an exact figure. Thermostatic radiator valves should not be fitted inside covers.

Valves

What is the difference between a TRV and a manual valve?

A TRV (thermostatic radiator valve) controls the radiator's temperature by sensing room air temperature and automatically opening or closing the flow to maintain a preset level. A manual valve controls the radiator's temperature regardless of the room's current warmth. TRVs are now required under Building Regulations, so check with your installer that you have the correct valves fitted.

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

The wheelhead valve provides temperature control, while the lockshield valve balances the system so all radiators heat up at a similar rate. Without balancing, a radiator closer to the boiler would heat faster than one further away, so lockshield valves are opened progressively wider the further the radiator is from the boiler.

Should I install my valves on the flow or return pipe?

Even though some of our valves are bi-directional, we recommend fitting all valves on the flow pipe rather than the return pipe, to avoid the noises that can occur when valves are fitted on the return.

Will old twin entry radiator valves fit new radiators?

Older twin entry valves have both pipe connections on one side of the radiator. If you're fitting new radiators, these valves need to be replaced with a pair of single entry valves.

Technical

What heating systems are our radiators compatible with?

All radiators and towel rails featured on this website are suitable for indirect (closed) systems complying with BS5449 Section 1 forced circulation hot water systems.

What is the difference between an indirect and direct system?

An indirect system uses water that stays within the system, circulating through the boiler and radiators. A direct system uses mains water that is continually replaced, introducing more oxygen and bacteria, meaning stainless steel or brass radiators should be used to avoid rusting or contamination.

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

Aluminium radiators install in the same way as steel or cast iron models. As with any central heating system, a suitable quality and quantity of inhibitor must be used to prevent corrosion; mixed metal inhibitors are widely available from plumbers' merchants.

Are cast iron radiators compatible with my system?

All our cast iron radiators are compatible with normal central heating systems and have British Standard fittings. You can replace all radiators on an existing system, or just some, though your installer should confirm your pipework and system set-up is suitable.

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

Yes. Cast iron's mass means it takes longer to reach temperature, but it stays warm long after the heating is turned off, giving gentler temperature changes than steel radiators. If mixing cast iron with standard radiators, a thermostat sited near a standard radiator may shut off the heating before the cast iron radiators reach full temperature; partially closing the lockshield valve on the standard radiator helps balance this. Cast iron also helps retain warmth in the building's fabric, which can counteract dampness and condensation.

Are your radiators suitable for a single pipe system?

All our radiators are compatible with a single pipe system, though depending on your setup you may need specialist valves. Contact us if you're unsure about compatibility.

Do my radiators need venting, and how do I do it?

Pockets of air naturally build up in central heating systems, making radiators less efficient. A radiator that's cold at the top and hot at the bottom usually needs venting (bleeding). With the heating off and the system cold, protect surrounding surfaces, then open the air vent slightly using a radiator key or small screwdriver until water appears, indicating all air has been purged. Close the vent gently and switch the system back on. If venting is needed frequently, ask a heating engineer to check the system for a fault.

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

This usually indicates an insufficient flow of water, which can be caused by incorrect balancing, incorrect pipe size, an under-performing or under-sized pump, a blockage, or trapped air needing venting. A heating engineer should investigate further.

Installation

Who will install my radiators?

Our radiators can be installed by any competent plumber or installer, or an electrician for electric models, preferably Gas Safe registered.

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

Radiators are heavy and must be securely fastened to the wall. Identify the wall construction and use the appropriate fixings for the brackets. All our radiators are supplied with the correct brackets and detailed fitting instructions, also available online. For the Ancona range, stud wall brackets are available where standard brackets aren't suitable.

How do I fit valves?

Switch off the heating system and drain the radiator. Remove the current valve by loosening the connecting and securing nuts, then wrap at least five turns of PTFE tape around the threaded tails of the new valves and screw them into the radiator and pipework, keeping the tape on the thread as you tighten. Tighten the connecting and securing nuts to secure the valve, and repeat if replacing the lockshield.

Should I prepare my pipework before my radiators arrive?

We aim to ensure all pipe centres are correct, but manufacturing tolerances must be considered. We strongly recommend pipework isn't installed or altered until your new radiator or towel rail has been delivered.

Can I use microbore pipework?

Yes, though on large cast iron radiators over 3500 watts it can prove problematic when balancing the central heating system. Check with your plumber or installer if in doubt.

Still have a question we haven't covered? Get in touch and our team will help you find the answer.