Can a radiator be replaced without moving the pipes?
Often, yes. If the new radiator has the same pipe centres as the old one, it is usually a straight swap on the same valves or new valves in the same place.
Pipe centres are the distance between the two valve connections. Older imperial radiators may not line up exactly with new metric ones. Small differences can usually be taken up with adaptors or short lengths of pipe. A bigger difference, or a move to a new position on the wall, means altering the pipework. That might mean lifting a floorboard or two, or running pipe along the skirting.
Most jobs start the same way: photos of the old radiator, the valves and where the pipes come up. From those we can usually tell whether it is a like-for-like swap or needs new pipework.
- Like-for-like swap
- Same position and similar size. Usually the quickest job.
- Different size, same wall
- Pipework shortened or extended to meet the new valves.
- New position
- New pipe runs from the nearest flow and return.
- Pipes from the floor or the wall
- We match the new radiator to how your pipes arrive.
What size radiator do I need for my room?
It depends on how much heat the room needs, measured in watts or BTUs, not on the width of the wall. A radiator that is too small will leave the room cold even with the heating up full.
Heat output is usually shown on the radiator's label or listing in watts or BTU per hour (one watt is roughly 3.4 BTU). The output a room needs depends on its size, its windows, how well it is insulated and whether it has outside walls. Online radiator calculators give a reasonable starting point. We can check your figures and suggest a sensible output, but treat any calculation as a guide rather than an exact answer.
Outputs are usually quoted at a high water temperature. If your boiler runs cooler, the radiator gives out less heat than the label says, so a slightly larger one often helps.
Can you fit a towel radiator in a bathroom?
Yes. A towel radiator can replace a standard bathroom radiator or go in a new spot, connected to the central heating like any other radiator.
Be aware that towel rails usually give out less heat than a panel radiator of the same size, and chrome ones less than white. Towels hanging on the rail reduce the heat further. In a larger bathroom, a towel rail on its own may not keep the room warm.
A dual-fuel rail has an electric element as well, so it can warm towels in summer when the heating is off. That needs a fused electrical connection, and electrical work in bathrooms must follow the current Wiring Regulations (BS 7671, 18th Edition) and may need to be notified to building control. Because we handle the electrics as well as the plumbing, one visit covers both.
Does the whole heating system need draining to change a radiator?
Not always. A straight swap can often be done by closing the valves and draining just that radiator. New valves, new positions or new pipework usually mean draining down the system.
How we drain and refill depends on your system:
- Sealed (pressurised) systems
- Usual with combi and system boilers. Refilled through the filling loop to the right pressure.
- Open-vented systems
- Fed by a small tank in the loft. The tank's supply is isolated before draining.
- Refilling
- Done slowly, with air bled from each radiator in turn.
- Inhibitor
- Added after refilling to protect against corrosion and sludge.
Why do radiators need bleeding, balancing and inhibitor?
Bleeding lets trapped air out, balancing makes every radiator heat at a similar rate, and inhibitor protects the inside of the system. All three matter after a radiator is changed.
Air gets into the system whenever it is drained, and it collects at the top of radiators, leaving them cold there. Balancing means setting the lockshield valve on each radiator so the ones nearest the boiler do not take all the hot water while those furthest away stay lukewarm.
Inhibitor is a chemical added to the heating water. It slows the corrosion that turns into black sludge. Industry guidance recommends keeping inhibitor at the right level, and draining the system dilutes it, so we add more when we refill.
We also fit thermostatic radiator valves (TRVs) where agreed. A TRV controls the temperature of each room on its own. The room with the main thermostat is usually left without one, so the thermostat can do its job.
Why is my radiator cold at the bottom?
A radiator that is warm at the top but cold at the bottom usually has sludge settled inside it. A radiator cold at the top usually just has air in it and needs bleeding.
Sludge is mostly rust and debris. It builds up over the years, especially where inhibitor has run low. Sometimes the answer is to take that radiator off and flush it through outside. When several radiators are affected, the whole system may need cleaning. Power flushing pumps cleaning chemicals through the system at speed.
When does the boiler need a Gas Safe engineer instead?
Whenever the problem involves gas, the boiler's burner or its internal gas parts. We do not do gas work, and nobody should unless they are Gas Safe registered.
We look after the water side: radiators, valves, pipework, draining, refilling and system pressure. If the boiler shows a fault code, will not fire, smells of gas or has a flue problem, you need a Gas Safe registered engineer. If you smell gas, leave the property and call the National Gas Emergency number on 0800 111 999.
If we find a problem on the boiler side while we are with you, we stop, explain what we have seen and recommend you call a Gas Safe engineer before the system is used.