Can I change radiators by myself?
With the rising cost of tradespeople in 2025, many UK homeowners are looking for ways to save money by tackling home improvement projects themselves. Changing a dated or inefficient radiator for a stylish new heated towel rail is high on the wish list for many bathroom renovations. It seems achievable, and the satisfaction of completing such a tangible upgrade is immense. This leads to the big question: can you actually change a radiator yourself?
The answer is a qualified yes. For a confident, experienced DIYer with the right tools and a methodical approach, a straightforward, like-for-like radiator swap is one of the more advanced but certainly achievable plumbing tasks. However, it is not a job for a novice. A small mistake can lead to a significant leak and costly water damage.
This honest guide from Company Blue will act as your DIY litmus test. We'll help you assess if you have the skills and tools required, provide a clear step-by-step overview of the process, and, most importantly, explain when you absolutely must put the tools down and call a professional plumber.
The DIY Litmus Test: Should You Really Do This Yourself?
Before you start, ask yourself these crucial questions. If the answer to any of them is "no", we strongly recommend hiring a professional.
- Is your DIY skill level appropriate? Have you successfully completed simpler plumbing tasks before, like changing tap washers or fittings? Are you generally confident and methodical in your approach to DIY? This should not be your first ever plumbing project.
- Do you have the essential tools? You cannot do this job without the right kit. The absolute minimum you will need is: two good-quality adjustable spanners, a radiator bleed key, a bucket, plenty of old towels, a spirit level, and PTFE tape.
- Is it a simple, like-for-like swap? The key to a successful DIY radiator change is replacing an old radiator with a new one where the "pipe centres" (the distance between the two pipe inlets) are the same or very similar.
- Does your new radiator require pipework alteration? If the new radiator is a different size and the pipes need to be physically moved, extended, or re-routed, this immediately becomes a job for a professional plumber. Cutting and soldering copper pipe is a skill that requires experience to get right.
- Do your radiator valves work correctly? Can you successfully turn both the main valve and the lockshield valve off to completely stop water from entering the radiator? If the valves are seized or weeping, you should not proceed.
A Step-by-Step Overview for a Like-for-Like Swap
If you've passed the litmus test and are confident to proceed, here is the methodical process to follow. For a more detailed breakdown, see our full 'How to Install a Towel Rail' guide.
- Preparation: Turn off the central heating and let it cool. Lay down dust sheets and towels. Have your bucket and all your tools ready.
- Isolate and Drain: Close both the main valve and the lockshield valve (counting the turns on the lockshield!). Slowly loosen the large nut connecting the main valve to the radiator, catching the draining water in your bucket. Open the bleed valve at the top to speed up the process.
- Remove the Old Radiator: Once empty, fully undo the nuts on both valves and lift the old radiator off its wall brackets.
- Prepare the New Radiator: If the wall brackets are different, remove the old ones and mount the new ones, ensuring they are perfectly level. Before hanging the new rail, wrap the threads of the new radiator tails in PTFE tape and screw them into the bottom inlets. Fit the bleed valve and blanking plug to the top.
- Mount and Connect: Hang the new towel rail on its brackets. Connect the valves to the new radiator tails, ensuring a firm, watertight connection.
- Refill and Re-pressurise: Slowly open both valves (opening the lockshield by the exact number of turns you noted down). Go to your boiler and use the filling loop to bring the system pressure back to the correct level (usually around 1.5 bar).
- Bleed and Leak Check: Bleed all the air from your new towel rail until water comes out. Now, perform the most critical step: meticulously check every single joint you have touched with dry kitchen roll to ensure there are no leaks.
- Turn On and Test: Once you are 100% certain there are no leaks, turn the central heating back on and enjoy your new, warm towel rail.
When You MUST Call a Professional Plumber
Knowing your limits is the most important part of DIY. Do not attempt the job yourself and call a professional if:
- The pipework needs to be moved or altered in any way.
- You have very thin 8mm or 10mm pipes (known as 'microbore'), which are more delicate and prone to kinking and blockages.
- Your existing valves will not fully close, are stuck, or are leaking. Trying to force a seized old valve is a common cause of DIY disasters.
- You cannot successfully re-pressurise your boiler or you are unsure how your heating system works.
- You encounter any problem you are not 100% sure how to solve. A plumber's fee is a small price to pay to avoid a flood.
A Note on Electric & Dual Fuel Models: While the physical mounting of these radiators is a DIY task, the final electrical connection is never a DIY job. It legally requires a qualified electrician to ensure the connection is made safely in a bathroom environment.
FAQ: Your DIY Radiator Change Questions
Here are our answers to the most common questions about tackling this project.
What is the most common mistake DIYers make?
The two most common mistakes are not sealing the radiator tails correctly with enough PTFE tape, and over-tightening the nuts. Overtightening can crack the brass fittings or damage the internal 'olive', which will guarantee a leak. The correct approach is to be firm but gentle.
How long should it take me to change a radiator?
A professional plumber can often do a simple swap in about an hour to an hour and a half. For a first-time DIYer, you should set aside at least 3-4 hours to allow you to work slowly, methodically, and to double-check every step without rushing.
Do I need to turn the main water supply off to the house?
No. Your central heating system is a sealed circuit, separate from your mains tap water. You only need to switch off the boiler and isolate the specific radiator you are working on (or drain the heating circuit if the valves don't work).
What if my old valves are stuck and won't turn?
If you cannot close the valves with a reasonable amount of force, you should stop immediately and call a plumber. Using excessive force, especially on old pipework, can cause the pipe or valve to fracture, leading to an uncontrollable leak.
Is the cost saving really worth the risk of a leak?
This is the ultimate question. If you are a skilled and confident DIYer and the job is a simple swap, saving £150-£200 on labour can be very worthwhile. However, if you are a novice, the risk of a leak from a poorly made joint—which could cause thousands of pounds of damage to floors and ceilings—far outweighs the potential saving. The golden rule of DIY is: if in doubt, get a professional out.
