The heating comfort problem nobody measures

You can spend £2,000 on a heat pump and still feel oddly on edge in your own living room. The missing piece is often room temperature stability, and it lives or dies by the control logic inside your thermostat, boiler, heat pump or TRVs. It matters because people don’t complain about “18.7°C”; they complain about the swing-warm for an hour, chilly for the next, and never quite settled.

A homeowner will tell you they want “cosy”. An installer will tell you the system is “to spec”. And both can be right, while the house still feels wrong.

Because the comfort problem nobody measures isn’t the average temperature.
It’s how much it moves.

The comfort gap hiding inside “average temperature”

Most homes are effectively judged on a single number: setpoint achieved, yes or no. The app shows 20°C, the room is technically 20°C, and the job is done. Yet many people feel drafts, peaks of stuffiness, and those little cold dips that make you pull a jumper on and off all evening.

That’s room temperature stability in plain English: how steady the room feels over time, not where it lands for one moment.

Two houses can share the same average temperature across a day and deliver completely different comfort. One stays within a tight band; the other bounces around like a yo-yo. The second is the one where arguments about the thermostat begin.

Why nobody measures it (and why that’s convenient)

Measuring stability is awkward because it forces you to look at behaviour, not labels. A boiler can be “efficient” on paper and still create comfort chaos if it cycles hard. A heat pump can be “sized correctly” and still feel disappointing if it’s controlled like an old on/off system.

It’s also inconvenient for the industry. Most of the common handover checks happen in minutes, not days. Stability needs time-series data: what happens at 7am, after the school run, when the oven’s on, when the wind picks up.

And if you don’t measure the swings, you can pretend they aren’t there.

The real culprits: cycling, overshoot, and slow rooms

A lot of comfort problems are not “lack of heat”. They’re control problems.

Here are the usual patterns people live with:

• Short-cycling: the system fires, stops, fires again. Rooms get pulses of heat rather than a steady input.
• Overshoot: it pushes past the target, then backs off too far, then chases again.
• Lag: the room warms slowly, so the system overcompensates, then the building “catches up” later and you get stuffy.
• Room-to-room fights: one space hits target early and shuts the system down, while another never quite gets there.

These aren’t mysteries. They’re predictable outcomes of mismatched emitters, sensor placement, and control logic that was never tuned to the building.

A simple way to think about stability

Forget the marketing terms for a moment and ask one question: How wide is the comfort band in daily life?

If your living room spends most evenings between 19.5°C and 20.5°C, it will generally feel calm. If it swings between 18°C and 22°C, you’ll feel it in your shoulders, your feet, and your patience-especially in draughty UK weather.

You don’t need laboratory kit to get a first read. A £10 temperature logger or a couple of cheap sensors in the right spots will show you the shape of your heat: smooth and flat, or spiky and reactive.

A quick stability check you can do this week

• Put a sensor away from radiators, about 1–1.5m off the floor.
• Log temperature every 5 minutes for 48 hours.
• Note when heating is “on”, when you cook, and when doors/windows open.
• Look for repeated patterns: sharp climbs, sharp drops, saw-toothing.

If you see a repeated spike-and-dip pattern, you’re not imagining the discomfort. Your system is doing it.

Where control logic goes wrong in real homes

Most heating controls are designed to be easy to understand, not to be gentle. “If below X, turn on; if above X, turn off” is simple. It’s also a recipe for swings in many UK houses, especially with modern insulation changes or mixed emitters.

Common traps include:

• Thermostat in the wrong place: a hallway that warms fast shuts the heat down while lounges and bedrooms still cool.
• Smart TRVs fighting the main thermostat: each room “requests heat”, but the heat source can’t modulate smoothly, so you get bursts.
• Weather compensation set too aggressively: flow temperature swings create room swings, just delayed.
• Heat pumps controlled like boilers: high flow temps and on/off behaviour create the very peaks and dips low-temp systems are meant to avoid.
• Night setbacks that are too deep: the morning recovery is a heat sprint, not a gentle climb.

None of this requires ripping the system out. It often needs calmer decisions: better sensor placement, smaller setpoint steps, and control that modulates instead of slamming.

What “better” looks like (without making your home cold)

Stability doesn’t mean living at a lower temperature. It means delivering heat in a way that matches how a house actually loses it-gradually, continuously, with weather and occupancy.

Practical moves that often help:

• Reduce the size of temperature jumps (e.g., 20°C day / 19°C night rather than 21°C / 16°C).
• Enable modulation where possible (OpenTherm, proper heat pump curves, or a controller that can ramp).
• Balance radiators and lockshields so rooms warm at similar rates.
• Treat TRVs as “fine tuning”, not primary control if the heat source can’t respond smoothly.
• Move the reference sensor to where comfort is judged (often the living room), not where it’s convenient.

If you want one guiding principle: aim for fewer dramatic decisions per hour. A stable home is usually one where the system makes small corrections, not big reactions.

A tiny metric that changes the conversation

If you ever speak to an installer, a landlord, or even just your partner about why the house feels off, it helps to name what you mean.

Here’s a compact way to describe it:

What you track	What it tells you	Why it matters
Temperature range (max–min) over evening hours	How “swingy” the room is	Swing drives perceived comfort
Number of heating on/off events per hour	Whether the system is pulsing	Pulsing often feels draughty
Time to recover 1°C	Whether the room lags	Lag leads to overshoot and stuffiness

You don’t need perfect data. You need enough to stop arguing about feelings and start talking about patterns.

Why this will matter more in the next few years

As more UK homes add heat pumps, smart TRVs, zoned controls, and time-of-use tariffs, the complexity rises. The irony is that complexity can reduce comfort if it’s layered without a stability goal.

Room temperature stability is the missing performance measure: it’s what people actually live with, and it’s the thing that decides whether “efficient heating” feels like a win or a daily nuisance.

And until we measure it, we’ll keep “fixing” heating by changing setpoints-when the real fix is teaching the system to behave.

FAQ:

• Is room temperature stability only a “smart heating” issue? No. Old on/off thermostats can create big swings too, especially in smaller or well-insulated rooms. Smart kit can help, but only if the control logic is set up to modulate rather than constantly chase.
• What’s a normal amount of temperature swing in a living room? Many people feel comfortable when the room stays within about ±0.5°C to ±1°C of the target during occupied hours. Larger repeated swings can feel draughty or stuffy even if the average looks fine.
• Will lowering my flow temperature improve stability? Often, yes-particularly with heat pumps and condensing boilers-because gentler heat input reduces overshoot. But it must still meet heat loss on cold days, so adjustments should be tested, not guessed.
• Do smart TRVs automatically improve comfort? Not automatically. If they’re fighting a single central thermostat or a non-modulating heat source, they can increase cycling. They work best as part of a coordinated control strategy.
• What’s the fastest low-cost thing to try? Log temperature for 48 hours in the room you care about most, then reduce big schedule setbacks and avoid large setpoint jumps. If swings shrink, you’ve found the direction of travel.