Climsom heated & cooled mattress topper: our tester's first impressions (heating mode)
- Test
- Andrea R.
- Maison connectee
- 01 Nov, 2026
- 0
First impressions — cooling-mode test to follow
The heatwaves of summer 2026 reminded many of us how badly we sleep in a hot bed — and in winter, the problem flips. Climsom, a company from Nantes, France, makes a mattress topper that circulates heated or cooled water. We handed it to a couple of testers in Chaville, near Paris, in their sixties, with very different body heat at night: two units, one each. Here is the first feedback from our tester in Chaville after her first nights in heating mode.
How it works
- A thin topper (70 × 190 cm for the Personal), threaded with fine medical-grade silicone tubes, sits between the mattress and the fitted sheet.
- A 1 m hose connects it to a control unit (24 × 29 × 17 cm) that heats or cools the water in its tank and circulates it.
- Adjustable to the degree from 18 to 48 °C "in normal conditions"; Climsom notes that the felt temperature in cooling mode depends on the room, the mattress and your own body heat.
- 160 W electrical power (under 100 W on average, per Climsom), infrared remote (2 AAA batteries).
- Stated noise: around 30 dB when cruising, 35 dB max. Climsom sells a 2 m extension to move the unit away, even out of the bedroom.
- No dual zone in a single topper: the Duo bundle is two single toppers and two control units, each set independently.
How much power does it use? Climsom vs air conditioner vs electric blanket
| Climsom (Personal) | Portable air conditioner (bedroom) | Electric underblanket | |
|---|---|---|---|
| Power draw | 160 W max, ~100 W on average, 80 W to hold temperature | ≈ 1,010 W (9,000 BTU, class A model) | 60 W max (Beurer UB 60) |
| kWh per 8-hour night | ≈ 0.8 kWh (1.28 kWh max) | ≈ 3.5–5 kWh (8 kWh max) | ≤ 0.48 kWh |
| Cost per night* | ≈ €0.16 (€0.26 max) | ≈ €0.70–1.00 (€1.62 max) | ≤ €0.10 |
| Cost per month (30 nights)* | ≈ €4.80 (€7.68 max) | ≈ €21–30 (€48.50 max) | ≤ €2.90 |
| Heats / cools | Both | Cools (heats only if reversible) | Heats only |
| Noise | ≈ 30 dB cruising, 35 dB max (Climsom) | 60–70 dB claimed for single-unit models (Que Choisir) | No motor |
| Best for | People who want warmth in winter and cool in summer, in bed only | Cooling the whole room, if noise isn't a problem | Tight budget, warmth only |
Bottom line: over a night, the Climsom uses roughly five times less electricity than a portable air conditioner and is far quieter. But it only cools the bed, not the room. In winter, a basic electric underblanket uses even less and costs much less to buy. The Climsom's appeal is doing both jobs with one device.
* French EDF Tarif Bleu, Base option: €0.2001/kWh incl. tax (3–6 kVA, in force since 1 August 2026), excluding standing charge. Assumptions: 8-hour night; Climsom at its stated ~100 W average (160 W as the upper bound), same figure for heating and cooling since no separate figure is published; 9,000 BTU class A portable AC (EER 2.6), running about 2 hours flat out to cool the room, then 25–50% of the time; underblanket at full power all night (it actually steps down a level after 3 hours). A Duo uses twice as much as a Personal.
Sources: Climsom press release (160 / 80 / ~100 W) · Climsom product page (noise) · Wisiko, portable AC power and duty cycle (EU Regulation 626/2011, Trusted Reviews measurements) · ADEME (portable AC: ~710 kWh/year with heavy use) · Que Choisir (portable AC noise) · Beurer UB 60 spec sheet (60 W) · EDF Tarif Bleu
Our tester's feedback (translated from French)
Why she wanted to try it
"I suffer from the cold but also from the heat. The various heatwaves of summer 2026 had a very negative impact on the quality and length of my sleep.
The idea of a mattress topper with built-in air conditioning won me over. Here is my first feedback on the Climsom topper, which offers built-in climate control with a temperature range from 18 °C to 48 °C.
In other words: a bed temperature you can tailor to the seasons — bliss!
First try: 38 °C for 30 minutes
It's autumn, so I tested the heating function at 38 °C for 30 minutes before going to bed. At first, the warmth didn't seem very intense.
But once I slipped into bed, I felt a gentle, very diffuse warmth that gradually enveloped me. Nothing like the heat of an electric blanket: the sensation is far more subtle and enveloping.
The result: I fell asleep within seconds! 😊
Can you leave it on all night?
I switched the device off when I went to bed, but you can also leave it running all night, placing the climate unit outside the bedroom if you're sensitive to noise.
Her verdict so far
I think this topper could be particularly useful during heatwaves, when you want a way to make the bed more comfortable without resorting to conventional room air conditioning, which doesn't affect how warm the sheets are!
A very positive first experience that makes me want to test its cooling function too!"
— Our tester in Chaville
Takeaways so far
- Gentle, diffuse warmth, very different from an electric blanket (no heating element in the bed).
- Fell asleep almost instantly on this first 38 °C try.
- One device for summer and winter, adjustable to the degree.
- Duo bundle: each sleeper picks their own temperature.
Watch points
- Control-unit noise: our tester suggests placing it outside the bedroom if you are sensitive (extension needed).
- Cooling mode not tested yet — that's the one that must deliver during heatwaves.
- No app or Wi-Fi announced: remote control only, so no known native Home Assistant integration.
About the study Climsom cites
Climsom highlights a 2011 pilot study with Prof. Damien Léger (Hôtel-Dieu Sleep and Vigilance Centre, Paris) on 15 people without sleep disorders, cooling mode vs placebo: +58% perceived night quality and +23 minutes of sleep, according to the brand. A very small sample — a lead, not proof. Read the study (French).
Next: we'll test cooling mode and the two-person (Duo) setup in the coming weeks, then publish a full review with measurements and a verdict.
Where to buy
See the Climsom Personal (1 person)
See the Climsom Duo (2 people, independent settings)
Disclosure: Climsom lent us two refurbished units for this test. The "See the Climsom" links in this article are affiliate links: if you buy through them, Rocks on Galaxy may earn a commission at no extra cost to you. Climsom did not review this article.