“Hai il riscaldamento a terra? Non toccare mai il termostato, ecco perché.” If you’ve got warm floors and a mind that keeps reaching for the dial, this line might save you money and mornings. Underfloor heating isn’t a radiator with better shoes. It plays by different rules, and your thermostat finger is often the problem, not the solution.
A hand hovered near the thermostat, hesitating, then nudged it up two degrees — an anxious little ritual on cold mornings. We’ve all known that moment when the floor feels slower than our patience and the coffee hasn’t kicked in yet.
Half an hour later, the room was warm, but the bill for last month still sat like a warning on the fridge. Underfloor heating feels luxurious until it doesn’t. The twist is simple and a bit annoying: the more you chase the heat with your thumb, the worse the system behaves. Leave it alone.
The thermostat trap with underfloor heating
Underfloor heating isn’t slow because it’s weak — it’s slow because it’s designed to move heat through a big thermal mass. Your slab or screed is a giant battery that charges gently and releases steadily. Turn the thermostat up and it won’t heat faster; it will just aim higher, later, with more energy.
Picture a Milan apartment on a windy January evening. The owner bumps the setpoint up from 20°C to 23°C at 6 p.m., hoping for a quick warm hug. By 9 p.m., the floor finally catches up, the room overshoots, and the boiler or heat pump has worked harder than it needed to. Reports from energy auditors show a pattern like this everywhere: fiddling drives overshoot and spikes.
There’s a physics story hiding here. When you ask for big, sudden changes, a heat pump raises its flow temperature to deliver, and its efficiency drops — a typical COP can slide from around 3.5 at 35°C flow to near 2.5 at 50°C. Gas condensing boilers lose their condensing sweet spot when return water gets too warm, trimming efficiency just when you’re pushing. It feels wrong, but it works.
So what should you do instead?
Pick a base temperature and stick with it — usually 19–21°C for living spaces — and let the floor do the slow, even work it’s great at. A tiny night setback of 0.5–1°C is fine in many homes, not more. Use weather compensation or lower your flow temperature until comfort is met on a typical cold day, then stop tweaking. Underfloor heat loves stability.
Watch out for classic mistakes. Big day–night setbacks make the system chase itself and chew energy. Thick rugs, stacked boxes, or a low sofa with no legs can smother the floor and create cold corners. A thermostat on a cold exterior wall will lie to you, and drafts will make it overreact. Let’s be honest: nobody does that every day.
Think in rhythms, not jolts. Your floor wants gentle, predictable inputs, like a good sourdough starter. Set a steady base, keep doors ajar for balance, and allow a couple of days for each change to settle.
“With underfloor, the smartest move is often to do nothing fast,” says Marco, a Bologna heating tech who’s spent 20 winters fixing hot-cold homes.
- Start with 20°C setpoint, hold for 48 hours, then adjust by 0.5°C if needed.
- Lower flow temperature until comfort dips, then nudge back up one click.
- Avoid thick rugs in key zones; use lighter textiles that breathe.
- Keep zones simple; fewer, larger zones are easier to balance.
- Give every change time; underfloor reacts in hours, not minutes.
Why leaving the thermostat alone works in real life
Homes are not laboratories. Kids run in from the park, the oven door stays open, the dog steals the warm spot by the window. That’s exactly why your floors should be your calm constant. Set it and leave it.
Small, steady heat builds comfort that doesn’t vanish when a gust hits or the bathroom door swings. The slab buffers those little shocks. Your system runs at lower temperatures, which is kinder to a heat pump and lets a boiler condense day after day. Small, steady beats big, sudden.
There’s also the human side. When the house just feels right all the time, you stop the anxious micro-management. Mornings become predictable. Even the air feels softer because underfloor warmth lives where you live — at your feet, not scorching the ceiling. The thermostat stops being a button and becomes a background setting. Quiet, invisible, effective.
Here’s the twist most people only believe after a week of trying it: comfort climbs when you stop chasing it. Set a sensible temperature, dial in the flow, and let the system coast. If you’re on a heat pump, pairing 24/7 operation with weather compensation turns the outside into a guide rather than a threat. If you’re on gas, staying in the condensing zone shifts your bill down without drama. You feel fewer swings. You spend less. You argue less with the thermostat. That’s a win in any language.
| Point clé | Détail | Intérêt pour le lecteur |
|---|---|---|
| Thermal inertia is your ally | The slab stores heat and releases it slowly at low temps | Stable warmth, fewer spikes, lower energy use |
| Set-and-hold beats fiddling | One base setpoint with tiny setbacks (0.5–1°C) | Better comfort and predictable bills |
| Tune flow, not room swings | Use weather compensation or manual flow temp trimming | Higher heat pump COP and boiler condensing efficiency |
FAQ :
- Should I turn underfloor heating off at night?No. The system is slow and efficient at low temperatures, so shutting it off forces big morning catch-ups. A small setback of 0.5–1°C is usually enough if you want cooler nights.
- Will turning the thermostat up warm the room faster?No. It only changes the target, not the speed. Underfloor output depends on flow temperature and surface area, not a higher number on the wall.
- What’s the best setpoint for most homes?Start at 20°C in living areas and 18–19°C in bedrooms. Hold for 48 hours, then shift by 0.5°C if you genuinely feel cold or warm after that period.
- How long does underfloor heating take to respond?Typically several hours for noticeable change, a day or two for the slab to fully settle after a big adjustment. That’s normal for a high-mass system.
- Can rugs and furniture really make rooms feel cold?Yes. Thick rugs and low, solid furniture block heat from rising. Choose breathable rugs, add legs to sofas, and keep clear zones where you want warmth.
