Pipe centres are the distance between the centres of a radiator's two connection points, measured from the middle of one to the middle of the other. It is one of the most useful numbers to know before you buy a replacement, because it tells you whether the new radiator will line up with the pipes already in your wall or floor.
This article supports our radiator buying guide.
How to measure pipe centres
- Turn the heating off and let the radiator cool before you touch it.
- Find the two connections. They are where the valves meet the radiator, either at the bottom corners, the sides or the back, depending on the design.
- Measure from the centre of one connection to the centre of the other. Use a tape measure and measure to the middle of each, not the edge.
- Note the position. Record whether the connections sit at the bottom, the side or the back, and the height from the floor.
- Measure the pipes too. Where pipes rise from the floor or leave the wall, measure their centres as well, because they are what the new radiator must reach.
Why the radiator and the pipes must agree
If the new radiator's connections do not match the existing pipes, the installer has to alter the pipework. That is possible, but it adds work and can affect the finished look, especially with exposed floor pipes. Checking before you order avoids surprises.
Connection types and valves
Radiators can connect in different ways, for example at the bottom, at the side or through the back. Valves also come in different forms such as straight, angled or corner. Make sure the valve type suits the connection and pipe direction. Browse radiator valves, including thermostatic straight valves, traditional angled valves and thermostatic corner double angled valves. Check each product page for compatibility.
When to ask an installer to confirm
- Your measurements do not match any product exactly.
- The pipes are hidden, corroded or in an unusual position.
- You are changing the radiator's type, position or size by a lot.
- You are replacing valves or draining the system. Work on a heating system should be carried out by a suitably qualified heating engineer or plumber.
Common mistakes
- Measuring edge to edge instead of centre to centre.
- Measuring the radiator but not the pipes.
- Forgetting that valves and tails add to the overall dimensions.
- Ordering before checking the connection position.
In short
Measure centre to centre on both the radiator and the pipes, record where the connections sit, and ask a professional to confirm anything that does not fit neatly. Also check heat output with our BTU calculator before you decide.