Technical Help, Finishes & Design Advice

Radiator Installation & Water Treatment Guide

 

To ensure your premium cast iron radiators look stunning and work perfectly for decades, please share this specific guide with your heating engineer or plumber before any physical work begins on your property.

​

1. Buy Before You Pipe (Crucial Advice)

We strongly recommend having your physical radiators and valves on-site before your plumber installs or alters any pipework.

​

• Because our radiators are hand-assembled and use traditional manufacturing processes, slight variations can occur during production.
   

• To ensure a flawless fit, your plumber should always fit the pipes to match the actual radiator and valves in situ.
   

• Foundry Cast Iron Ltd cannot be held liable for any pipework installed prior to the goods arriving on site. If you already have fixed pipework in place, please contact our team before ordering so we can advise on the best fit for your space.

​​

2. Not All Radiators Arrive Fully Assembled

To comply with health and safety regulations, strict courier weight restrictions, and transport manoeuvrability, larger sectional radiators cannot always be shipped fully assembled.

​

• If your chosen radiator exceeds our maximum safe transport size, we will assemble it up to the maximum possible size and supply the additional sections separately.
   

• We can hire out specialist assembly tools if your plumber requires them on-site.
   

• Size Tolerance: Because our sectional radiators are hand-assembled, there is an acceptable industry measurement tolerance of plus or minus 5%. Longer radiators may also have a very slight curvature from transportation; this is entirely normal and naturally settles over time once fitted with the correct wall stays and brackets.

​​

3. Water Treatment & Guarantees (Don't Void Your Warranty!)

Our radiators are designed exclusively for closed, sealed central heating systems. They are NOT suitable for installation on secondary hot water service (HWS) circuits.
 

To keep your manufacturer's guarantee completely valid, your installer must follow these steps:
 

• Flush the System: Upon completing the installation, the entire heating system MUST be thoroughly cleaned and flushed to remove all building debris, sludge, and flux residues. If a chemical cleanser is used, it must be completely flushed from the system.
   

• Add Corrosion Inhibitor: The system must then be dosed with a premium water treatment inhibitor (such as Fernox or Sentinel) in accordance with British Standards (BS 5449: 1990, BS EN 12828: 2003, and BS 7593: 1992). The inhibitor must take into account the specific combination of metals within your unique heating system.

​​

​​

Guide to Cast Iron Textures, Colours & Finishes

 

Cast iron is a beautiful, traditional material, meaning every single item possesses its own unique character. Here is what to expect from our artisan finishes and custom paint options.

​

1. The Natural Texture of Cast Iron

Cast iron is naturally rough and porous because it is created using a traditional sand-casting process.
 

• Lumps, bumps, pits, and surface textures are completely normal and form an essential part of the product's historical, period charm.

​

• This natural texture is particularly visible underneath lighter-coloured paint finishes, which tend to highlight the metal's profile. Different batches of the same radiator style may also vary slightly depending on the age of the sand cast mould used.

​​

2. Minor Transit Scratches & Touch-Up Paint

Due to the sheer weight and bulk of cast iron radiators and baths, minor surface scratches can occasionally occur during transit or when manoeuvring them into position. This is almost impossible to avoid entirely and is not considered a fault. Most manufacturers include a complimentary pot of touch-up paint with your order so you can easily blend these in. (Please note: major or obvious transit damage is handled differently—see our Deliveries page).

​

3. Important Paint & Colour Advice

 

• The "Wet Clothes" Rule: Never hang wet garments or damp towels directly over a cast iron radiator to dry. The moisture can severely interfere with the curing process of the finish and will void your warranty. This is especially damaging to water-based designer paints.

​​

• Screen vs. Reality: Digital screen resolutions vary significantly, meaning colours can look slightly different in person compared to how they appear on an LED monitor. If you are ordering the same paint finish across separate batches or at different times, slight variations in shade can occur.

​​

• Primer Finishes: If you order a radiator in a standard primer finish, it is supplied unsealed and unfinished (the primer coat starts life as black, grey, or a shade of white). It is expected that you will re-prime and paint this yourself. Please note that the final paint finish will not be covered by the manufacturer's warranty—we highly recommend choosing a professional factory finish instead.

​​

• Industrial RAL vs. Designer Paints:

  • Our RAL finishes use a durable, industrial 2-pack paint mixed with professional hardeners.

  • Designer paints (such as Farrow & Ball® Flat Eggshell or Little Greene® Intelligent Eggshell finishes) contain natural or water-based pigments. While they look stunning, they do not contain industrial hardeners, meaning they are less hard-wearing, scratch more easily, and are generally not recommended for humid bathroom or wet room environments unless specified by the manufacturer.

​​

4. Polished & 'Living' Finishes

A polished radiator brings out the beautiful, raw aesthetic of the raw metal, but it is classified as a 'living finish'—meaning its appearance will naturally change and age over time.

​

• Patina & Oxidation: Surface rust, patinas, and minor oxidation are completely normal over time and are not considered product faults.

​​

• Oiled Finishes: These require regular, minor maintenance to prevent heavy oxidation. You can keep them looking pristine by gently rubbing them down with fine wire wool or metal finishing pads and a lint-free cloth, followed by a coat of non-silicone based 3-in-One multipurpose oil.
   

• Lacquered Finishes: Lacquer helps slow down surface oxidation, but it will not completely stop a natural patina from forming, particularly if placed in a humid environment or if wet items are placed on it.
   

• Hidden Areas: Radiators are not polished between the individual sections, on the joining collars at the bottom, or on the wall-facing back as standard, as these areas are completely hidden from view once installed.

​

5. Antiqued, Highlighted & Hand-Gilded Finishes

Because special effects like highlighting (using guild paste applied by hand onto ornate models like Daisy or Rococo), antiquing (two-tone paint removal), and hand-gilding (applying gold or copper leaf) are done entirely by hand, every single piece is unique. Expect beautiful, artisan variations from piece to piece.

​

​

Our Design Service & BTU Calculator

We are delighted to offer a complimentary Home & Online Design Service, alongside our online BTU calculator, to help you find the perfect radiator size and style for your home.

​

Getting the Right Fit for Your Space

 

• A Reliable Starting Point: Our calculator and design advice use standard room assumptions to give you a strong estimate for guidance purposes, based on standard industry values.

​​

• For Absolute Precision: While our guide provides a fantastic foundation for most projects, it is not a substitute for a professional on-site survey. For a precise requirement, please consult a qualified Energy Assessment professional.