How to Measure Pipe Centres for a Towel Radiator (UK Guide)

If you're installing or replacing a towel radiator, knowing how to measure pipe centres for a towel radiator correctly is essential. Accurate measurements help ensure your new radiator works with your existing pipework, potentially saving you from unnecessary plumbing adjustments.

In this guide, you'll learn exactly how to measure pipe centres, understand the difference between radiator width and connection centres, avoid common mistakes, and choose the right radiator size. Once you know the available wall space, you can also use our BTU Calculator to work out how much heat your bathroom needs, helping you choose a radiator that is suitable for both your space and heating requirements.

Quick Answer: How Do You Measure Towel Radiator Pipe Centres?

To measure pipe centres, measure the distance from the centre of one radiator pipe to the centre of the other radiator pipe.

For many standard side-connected towel radiators, the manufacturer's stated pipe centres are narrower than the radiator's overall width. However, this can vary depending on the radiator design and connection type.

👉 Pipe centres are NOT the same as radiator width.

What Are Pipe Centres?

Pipe centres refer to the distance between the centre points of the two pipe connections supplying your towel radiator.

This measurement is normally given in millimetres (mm) and is an important specification when choosing a replacement radiator.

For example, a towel radiator may have an overall width of 500mm, while the distance between its connection centres may be approximately 450mm.

The exact measurement depends on the radiator's design. This is particularly important when choosing between narrow towel radiators designed for compact bathrooms and wide towel radiators intended for bathrooms with more available wall space.

Why Does Measuring Pipe Centres Matter?

Getting the measurement right can help you:

• Ensure your new towel radiator is compatible with existing pipework
• Reduce the need for pipes to be moved
• Avoid unnecessary flooring or wall work
• Choose suitable radiator valves
• Save time and installation costs
• Achieve a neat, professional-looking installation

Pipe centres become especially important when replacing an existing radiator with a different width. For example, moving from a compact model to one of our wider towel radiators for larger bathrooms may require you to check whether your existing pipework can accommodate the new connection spacing.

What Tools Do You Need?

You don't need specialist equipment. Usually, you will only need:

• A tape measure with millimetre markings
• A notepad or mobile phone to record measurements
• A pencil or marker if required
• Optional: a spirit level

How to Measure Pipe Centres for a Towel Radiator

Step 1: Identify Your Existing Pipe Positions

First, locate the two pipes that will connect to your towel radiator.

Depending on your bathroom installation, the pipes may come up from the floor, out from the wall, or through the wall behind the radiator.

Make sure you identify the two pipe positions that will connect to the radiator valves. You should also consider the valves and fittings required, as choosing the correct towel radiator accessories for your installation can help ensure everything connects correctly.

Step 2: Measure From Centre to Centre

Centre of Pipe A → Centre of Pipe B

This gives you the centre-to-centre distance, which is the measurement normally used in radiator specifications.

If the centres of the pipes are easy to identify, place your tape measure at the centre of one pipe and measure directly to the centre of the other.

Record the measurement in millimetres (mm).

Step 3: How to Measure Pipe Centres When You Can't See the Centre

If it is difficult to identify the centre of each pipe, there are alternative ways to calculate the measurement.

• Measure Outside Edge to Outside Edge: If both pipes are the same diameter, measuring from the outside edge of one pipe to the outside edge of the other pipe can give you the same measurement as the centre-to-centre distance.
• Measure Inside Edge to Inside Edge: If both pipes are the same diameter, measure the distance between the two inside edges and add the outside diameter of one pipe. For standard 15mm pipework: Inside edge measurement + 15mm = approximate pipe centre measurement.

Always measure carefully and compare your measurements with the radiator manufacturer's specification.

Step 4: Check Your Existing Pipe and Valve Setup

If radiator valves are already installed, you can also use the existing valve positions to help assess compatibility.

However, different valves can have different dimensions and offsets, so the most accurate method is to measure the actual pipe centres wherever possible.

Homes with 10mm microbore pipework may need an adaptor when using standard 15mm radiator valves. In this situation, a 15mm-to-10mm reducer for radiator valves allows compatible standard valves to be connected to smaller microbore pipes.

Typical Pipe Centre Measurements for Standard Side-Connected Towel Radiators

Many standard side-connected towel radiators have pipe centres that are related to their overall width. However, the exact measurement can vary depending on the radiator design, manufacturer and connection configuration.

Typical examples include:

*Many standard side-connected towel radiators and traditional towel rails feature bottom connections rather than side tappings. Always verify the manufacturer's technical specifications and connection type before ordering.

If your measurements show that wall space is limited, choosing from a range of space-saving narrow towel radiators may make installation easier without overcrowding the bathroom. Larger bathrooms, on the other hand, can often accommodate wider towel radiators with more towel-hanging space.

Pipe Centres vs Radiator Width: What's the Difference?

This is one of the most common areas of confusion when buying a replacement towel radiator.

• Radiator Width: The overall width is the total measurement from one outside edge of the radiator to the other.
• Pipe Centres: The pipe centres measure the distance between the centres of the two radiator connection points.

Never assume that a radiator with the same overall width as your old radiator will automatically have the same pipe centres. Always check both measurements before ordering.

Do Your Existing Pipe Centres Need to Match Exactly?

Not always.

The amount of flexibility depends on:

• The type of radiator valve
• Whether you use angled or straight valves
• The valve design and available adjustment
• Whether pipework can be repositioned slightly

Some valve installations provide a small amount of flexibility, but you should not rely on a large tolerance when selecting a radiator.

If your existing pipe centres are significantly different from the radiator's required connection centres, pipework adjustments may be necessary.

Check Your Radiator Connection Type

Before buying a towel radiator, check how it connects.

• Side Connections: Traditional towel radiators usually have connections at the bottom on either side. These normally require suitable valves and fittings, so it is worth checking the available radiator valves, reducers and installation accessories before planning the installation.
• Central Connections: Some modern designer radiators have connections positioned closer together in the centre. These require different measurements and may need specific valve arrangements.
• Bottom Connections: Some radiator designs use dedicated bottom connection points, which may have different pipe centre requirements.

👉 Always check the manufacturer's technical drawing or product specification before ordering.

Common Mistakes to Avoid When Measuring Pipe Centres

Avoid these common mistakes:

• ❌ Confusing the radiator's overall width with its pipe centres
• ❌ Measuring valve handles instead of the actual pipe positions
• ❌ Measuring from inside edge to inside edge without allowing for pipe diameter
• ❌ Assuming all towel radiators have identical connection centres
• ❌ Forgetting to check whether the radiator uses side or central connections
• ❌ Ordering a radiator before checking the manufacturer's dimensions

Pro Tips for Measuring Pipe Centres

• ✔ Measure in millimetres for the most accurate result
• ✔ Measure twice before ordering
• ✔ Check the radiator's technical specification
• ✔ Measure the actual pipe centres where possible
• ✔ Consider the type of radiator valves you plan to use
• ✔ Check both the overall radiator width and the connection centres
• ✔ Before choosing a larger or smaller radiator, use our bathroom BTU Calculator to check the heating output you need
• ✔ If replacing an existing radiator, take a photo and note all measurements before removing it

Conclusion

Measuring pipe centres correctly is one of the most important steps when replacing or installing a towel radiator.

Measure the distance from the centre of one pipe to the centre of the other, then compare this measurement with the manufacturer's stated connection centres.

Remember to check the overall radiator width, pipe centres and connection type before ordering. If your bathroom has limited wall space, a narrow towel radiator may provide a practical solution, while larger bathrooms may benefit from the increased capacity and towel space offered by wider towel radiator designs.

Finally, make sure your chosen radiator is not only the right physical size but also produces sufficient heat by checking your room requirements with our free BTU Calculator.