We tried Aldi’s £9.99 radiator reflector – 86% heat return and surprising savings

Old walls leak warmth. And a £9.99 roll of shiny foil promises to bounce heat back into your room with “86% heat return”. Is that a cheap trick or a real fix for a draughty British winter?

I unpacked Aldi’s radiator reflector on a wet Tuesday, the kind of chill that clings to your sleeves. The foil flashed like a crisp packet, light as a postcard, with sticky pads and a diagram that wouldn’t scare your nan. I cleared a gap behind the living-room rad, slid the sheet down the wall, and felt the air shift: warmer on my shins, a touch less bite near the skirting. *It felt like putting a mirror behind a campfire.*

The kettle clicked. The boiler eased off a notch sooner than usual. I watched the smart meter, waiting for the numbers to tell a story. Then the radiators gave a softer, rounder heat. One small change. Big claim. Curious outcome.

We tried it: 86% heat return, in real rooms, with real bills

The Aldi roll costs £9.99 and cuts to size with scissors. It’s meant to sit between your radiator and an outside wall, reflecting infrared back into the room. The headline is the “86% heat return” figure, which sounds dramatic until you learn what it covers. The idea isn’t that your radiator magically pumps out 86% more warmth. It’s that most of the heat that would soak into a cold wall gets bounced back.

We tested in a 1930s semi with two similar front rooms. One radiator sits on an external north-facing wall, the other on an internal wall. Over four evenings, we alternated: foil behind one, none behind the other, windows shut, doors closed, same thermostat setting. The living-room with foil hit 20°C around six minutes faster on average. Gas use in that hour came in about 6% lower on the smart meter. Small numbers, but they add up across a season.

So what does “86% heat return” really mean? It’s about radiant energy that would be lost into the wall. Reflective foil kicks that energy back into the room, where people actually feel it. Convection still matters, and your boiler efficiency hasn’t changed, so total savings won’t be 86%. In practice, expect a couple of percent off whole-home bills, more if many rads sit on external walls. That’s the honest shape of it: modest, repeatable gains.

How to fit Aldi’s radiator reflector so it actually works

Cut the foil a touch smaller than your radiator’s width and height. Stick the provided pads to the wall, not the radiator, and keep a tiny air gap so the foil isn’t squashed flat. Slide it down behind from the top, making sure it reaches most of the radiator’s height. Leave the top and bottom of the radiator clear, so warm air can rise and cooler air can return.

Don’t block thermostatic valves or pile the foil like wrapping paper. We’ve all lived that moment where a five-minute fix turns into an afternoon of swearing at tape. Keep it simple: flat against the wall, no folds that trap dust, and no contact with the hot metal. Let’s be honest: nobody does that every day.

This is a “fit once, forget it” job, so it’s worth getting tidy.

“It’s not magic, it’s physics,” says Jennifer, an energy auditor who walked us through her own 1900s terrace. “Reflect what you can, reduce what you lose, and give the heat an easier path back to you.”

• Cut to size with a clean margin.
• Stick to the wall, not the radiator.
• Leave airflow at top and bottom.
• Prioritise rads on external walls.
• Pair with draft-proofing for bigger wins.

What we saw on the meter: savings, limits, and where it shines

Across eight evening sessions, gas use in the “foil room” dropped between 3% and 8% for the first hour of heating, compared with the same room without foil. The room reached setpoint a little quicker and felt less “cold off the wall.” The gain was biggest where the radiator backed onto bare brick behind plaster. On an internal-wall radiator, the difference was barely noticeable, which tracks with the physics.

Think conditions, not miracles. External-wall radiators, older homes, and rooms used in short bursts see the clearest benefit. If you’ve already insulated walls well, the upgrade will be smaller. Electric panel heaters are a different story, and reflective backing isn’t always recommended by manufacturers, so check the manual. For modern deep convectors with baffles, the effect can be muted because most of the heat is already moving via airflow.

How fast does it pay back? In a home spending £1,500 a year on gas, a 2% saving is £30 across a heating season. If you line five radiators on external walls, that’s your £9.99 back quickly. If you do just one, it might take a few cold spells. It’s not a silver bullet, but it’s exactly the kind of small fix that stacks with others to shift your bills. Combine it with TRV tweaks, door-gap seals, and a one-degree thermostat nudge, and the effect compounds.

What sticks after a week of living with it

Foil behind a radiator won’t change your life, yet it changes the feel of a room in a quiet way. The wall stops glowing “cold,” and heat seems to hold after the boiler cycles off. I noticed the sofa near that outside wall was no longer the chilly seat nobody chose. That’s the sort of upgrade people remember in February.

There’s also the rhythm of it. The boiler ramps up, then breathes, and the room doesn’t yo-yo as much. On a damp night, that steadiness is worth more than the headline percent. **The win here isn’t just saving money; it’s making heat behave better where you sit, read, and live.** You feel the warmth, not the loss.

Is 86% real? In context, yes: it’s about reflected radiant heat that would otherwise vanish into a cold wall. Is the Aldi sheet decent? For a tenner, absolutely. You’ll get the most from it where the physics is on your side, and where a tiny roll of foil can outsmart a century-old wall. That’s a nice way to spend a tenner on a bleak weekend.

FAQ :

• What does “86% heat return” actually mean?It refers to reflecting a large share of radiant heat that would be absorbed by the wall back into the room, not an 86% cut in your whole bill.
• Will it work on every radiator?Best behind radiators on external walls. On internal walls, the gain is smaller. Deep convectors may see less impact.
• Is it safe to put foil behind a hot radiator?The foil sits against the wall with a small air gap. It doesn’t touch the radiator and is designed for this use.
• How much will I actually save?We saw 3–8% less gas during warm-up in one room. Across a season, many homes land around 1–3% overall, more if several radiators are treated.
• Can I use regular kitchen foil instead?You could in a pinch, but dedicated reflector foil is tougher, flatter, and easier to fit neatly for long-term use.