How to Clean Your Radiators


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Jun 19, 2023

How to Clean Your Radiators

Who knows what evil lurks in the hearts of cast-iron radiators? Given their cave-like interiors, it could be anything—dust piles, pet and human hair, toenails, candy wrappers, even chunks of drywall

Who knows what evil lurks in the hearts of cast-iron radiators? Given their cave-like interiors, it could be anything—dust piles, pet and human hair, toenails, candy wrappers, even chunks of drywall from long-ago renovations. All of which can contribute to foul odors and decreased efficiency in your home’s heating system.

Cast-iron radiators are often found in older houses and apartment buildings. They typically come in one of two designs—column and thin tube. The internal heating mechanics differ slightly when it comes to distributing steam and/or hot water throughout the radiator. Externally, however, these two types essentially work the same. As their name implies, they radiate heat. But convection does the real work, with air warming a room as it naturally circulates through the fins (the individual columns that look like tall slices of bread).

These radiators don’t have motors. But when it comes to understanding the problem of debris buildup, Dan Holohan, author of The Lost Art of Steam Heating and founder of, suggests picturing how a hair-dryer filter becomes full of hair and dust. “Anything that gets stuck between those fins is going to slow the convection,” he said. This causes radiators to become less efficient because the boiler has to use more fuel to get the room to your desired temperature. And if you don’t like the way your home smells, radiators might be the culprit.

Given that radiators are so difficult to clean and the worst grime is typically hidden (unless you go looking for it), they often go years without attention. Wirecutter editor Jon Chase calls this having “grotty rads,” a phrase no one wants associated with their home.


A long brush: I used two different kinds, one of which was designed specifically for radiators.

Vacuum cleaner or wet/dry vac with crevice and brush attachment: Be warned—dust will spew everywhere while you’re working. Having a vacuum on hand will help you clean as you go and clean up once you’re done. I started out with our vacuum cleaner pick, the Shark Navigator Liftaway NV352, and I liked its extra-long crevice tool. But ultimately my job required the stronger suction of a wet/dry vac.

Non-abrasive sponge: Use these to wipe down the radiator’s outer surfaces.

Dish towels: Any thin dish towel will do, but I’m partial to these and use them for a variety of household tasks.

Larger, old towel: Use an old towel to catch drips on the floor.

Mild dish soap: You’ll need only a couple of drops of a gentle cleanser like Seventh Generation Dish Liquid.

Two buckets: One is to hold soapy water, the other is for rinsing.

Dust mask with filters: Use a respirator mask to protect your lungs from all the dust you’re about to kick up.

Large, flattened cardboard box: Protect your wall from splashes by placing one of these behind your radiator, held in place with painter’s tape.

Rubber gloves: The insides of a cast-iron radiator can sometimes be quite rough if they’ve been painted many times over the years. You’ll want to use rubber gloves to protect your skin.


Old bed sheets or sheets of plastic: If your radiators are extra-dusty, you may want to cover nearby furniture.

Headlamp: A bright, hands-free light can help pinpoint problem areas deep within a radiator.

Safety glasses: Wear these to protect your eyes from any unexpected projectiles launched by a brush.

Toothbrush: If you don’t have a straw brush on hand, an old toothbrush with soft bristles can reach tricky spots (as long as they aren’t too deep within the radiator).

Pen, pencil, or any other thin narrow tool: Depending on how deep your radiator is, you can use one of these to thread a dish towel through the fins, to navigate hard-to-reach crevices.

Dowel or yardstick, rubber bands, microfiber cloth: Fashion a DIY radiator brush by attaching a cloth to any type of long, thin stick.

There’s no simple answer here. Whether you’re doing a deep clean or a maintenance touch-up, the time it takes depends entirely on the size and style of your radiators. You need to factor in width and height, as well as the amount of fins on your model, the number of crevices on each fin, and how many units you have in your home.

I recently moved into a house built in 1934, and the radiators look as though they haven’t been cleaned in a decade. During my first attempt, completing about 2½ feet of an almost 5-foot-long radiator took me about 45 minutes, including prep.

This sounds extreme, but I was working on a thin tube radiator, which typically has more crevices than a column style does. So 24 inches of radiator meant cleaning 12 fins, pressed close together, each containing eight narrow slots laden with crud. That’s a total of 96 hard-to-reach openings, all requiring a thorough cleanse. And I’d only just begun—my house contains a combined total length of 41 feet of radiators dispersed throughout its rooms.

Tackling a deep clean of this magnitude is not a chore for the faint of heart or the bad of back. A column radiator with wider spaces between its fins and fewer crevices would likely be a much quicker job, and I’m confident that next year’s maintenance clean will be a lighter lift. (Another 2-footer in a different room that wasn’t quite as dirty took me only about 30 minutes.)

Holohan recommends doing this once a year, prior to turning on your radiators for the first time each cold season. But performing touch-ups throughout the year certainly won’t hurt.

If you’ve just purchased or rented a new home and the radiators look especially dirty, I strongly recommend tackling this chore before moving in, if possible, due to how much dust can get kicked up in the process.

Make sure your radiators are turned off and completely cool. Use painter’s tape to attach a flattened cardboard box against the wall behind the radiator. This will protect your walls from errant splashes of dirty water. If your radiators are especially dusty inside, you might want to consider covering nearby furniture with plastic or a sheet.

Check under the radiator (to clear away any hidden large objects), and then vacuum the area. After you vacuum, place a towel beneath and around the radiator, to capture falling debris and dripping water.

Put on your dust mask (and goggles and gloves, if you’re working with those). Using the brush attachment on your vacuum cleaner or wet/dry vac, gently remove larger dust piles, hairballs, and anything else that’s easily reachable.

For vintage radiators, it’s especially important to use a brush that has soft bristles because you want to minimize disturbing the paint, in case it’s lead-based (more on that later). Be sure to vacuum up all chips that easily flake off with your brush.

This initial loosening of debris is a good test run for becoming familiar with the needs of your radiator for the wet cleaning stage. If you have a thin tube model, you’ll start to get a sense of the specific angles required in order to access the more-difficult spots, like the innermost crevices. The light from a headlamp can help pinpoint hidden clumps deep in the recesses.

If you don’t have a radiator brush, a microfiber towel affixed tightly to the end of a dowel (or any sort of thin, mildly flexible rod) with rubber bands is a decent DIY hack, particularly if your radiator isn’t too dirty to begin with.

I tried several radiator brushes, and my favorite was Konex’s Premium Flexible Medium-Soft Natural Goathair Radiator, Coil, and Vent Brush because of its tapered bristles, flexible wire base, and comfortable-to-grip wooden handle. The brush also features a smart design trick: A clear plastic tube covers the wire space between the bristles and the handle. This prevents the wire from bending during vigorous brushing (which is what caused the handle on another model I tried to quickly snap off).

Fill one bucket with warm water and a few drops of mild dishwashing soap, and fill a second one with regular tap water. Use a soft sponge or dish towel to gently wipe down the radiator’s exterior with lightly soapy water, reaching inward as far as your hand allows. Follow that with a second swipe using regular water, to help remove any soap left behind. Dry thoroughly with a dish towel.

Once you’ve finished wiping every space you can reach with just your hand, dip a dishcloth in the clear water and “floss” the interior sections, pulling the cloth back and forth to get at any stuck-on grime. Rinse the cloth and repeat (over and over and over).

I didn’t use soapy water for my interior flossing because that would have required a second round of rinsing, and I simply didn’t have the time. The water alone did a good job of getting dirt out. But had I been dealing with just one or two radiators, I would have used soap to be extra-thorough. It’s your call, based on your needs and how much time you have.

You might find yourself growing frustrated if it looks like certain areas aren’t getting clean enough—especially if your radiator is painted a light color. But what appears to look like stubborn gunk is possibly just a stain or worn-away paint. Repainting will help, and Bob Vila’s website has good step-by-step instructions.

I found that wrapping the end of my dish towel around a capped pen or the eraser side of a pencil helped maneuver the cloth through tricky areas, until I could get a proper grip on it from the other side of a narrow space for flossing.

A dampened straw brush allowed me to get into extremely tight spots—like the space between the horizontal thin tubes and the base—to get at more-stubborn, stuck-on grime. An old toothbrush would work just as well on easier-to-reach areas, but the longer handle on the straw brush allowed me to have much more access to the interior.

Before you turn the heat back on, dry your cleaned radiator with a dry dish towel as thoroughly as possible.

I thought I’d done a great job of capturing everything that came flying out of my radiators with my vacuum cleaner and wet/dry vac. Yet once the literal dust had settled, 24 hours later, many nearby surfaces still needed a good wipe-down with a microfiber cloth. This might not happen to everyone, but it’s something to keep an eye out for.

Many old radiators were covered with lead paint, but Holohan said fumes are nothing to worry about because radiators don’t get hot enough for lead air pollution to become an issue. If your radiator is shedding paint flakes, test them with a home lead-test kit before you start to clean. If the test comes back positive, take extra precautions, as outlined by the Environmental Protection Agency.

We’ve seen folks suggest using compressed air to help clean a radiator. I’m personally not a fan of this idea because the forced expulsion would cause dust to spread all over the place, far too widely and quickly to catch with a vacuum as you go.

Lastly, I think it’s important to note that “good enough” is likely fine when it comes to cleaning inside a vintage radiator. This can be an extremely difficult, time-consuming, and frustrating task. Chances are high that after you’ve spent a considerable amount of time working, you’re still going to see some areas you simply can’t reach or don’t have the energy to tackle. Cut yourself some slack, and know that if you’ve followed even a couple of the steps above, you’ve likely gotten the worst out of the way.

If you have some tips or hacks to make it easier to clean your radiator, share it in the comments.

Joshua Lyon

Lead Editor

Joshua Lyon is the supervising editor of emergency-preparation and home-improvement topics at Wirecutter. He has written and edited for numerous outlets, including Country Living, Modern Farmer, The New York Times, V and VMAN, Marie Claire, Jane, and Food Network Magazine. He’s also a Lambda Literary Award–nominated author and ghostwriter. Learn more at

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Essentials:A long brush:Vacuum cleaner or wet/dry vac with crevice and brush attachment:Non-abrasive sponge:Dish towels:Larger, old towel:Mild dish soap:Two buckets:Dust mask with filters:Large, flattened cardboard box:Rubber gloves:Optional:Old bed sheets or sheets of plastic:Headlamp:Safety glasses:Toothbrush:Pen, pencil, or any other thin narrow tool:Dowel or yardstick, rubber bands, microfiber cloth: