The £200 Mistake on Your Wall
That sleek smart thermostat looked great in the store. The app is beautiful. Alexa integration? Check. But if you've connected it to a heat pump, you've probably made an expensive mistake.
Designed for the Wrong Job
Today's smart thermostats are clever updates to 1950s technology. They're digital versions of mechanical thermostats, built for systems that blast heat when cold and stop when warm. They excel at controlling boilers.
Heat pumps are different beasts entirely.
The Fundamental Mismatch
What Smart Thermostats Do:
- Measure room temperature
- Compare to setpoint
- Send on/off signals
- Look good doing it
What Heat Pumps Need:
- Continuous modulation signals
- Flow temperature adjustment
- Defrost cycle management
- Load prediction algorithms
- Multi-zone coordination
See the problem?
The Efficiency Killer
When you control a heat pump with an on/off thermostat, you force it into the least efficient operating mode possible:
- Thermostat calls for heat → Heat pump starts at maximum output
- Room reaches temperature → Heat pump shuts down completely
- Temperature drops → Violent restart cycle begins again
Each cycle wastes significant high-consumption startup energy. Multiple cycles per day can dramatically increase your running costs.
The "Smart" Features That Aren't
Scheduling
"Save energy by turning off heating when you're out!" Except with heat pumps, the recovery energy to reheat your home often costs more than keeping it warm.
Geofencing
"Automatically heat when you're near home!" Translation: Force your heat pump into its least efficient rapid-heating mode when you need heat quickly.
Learning
"Learns your habits!" But doesn't learn your building's thermal mass, heat loss coefficient, or solar gain patterns - the things that actually matter.
Room Sensors
"Control individual rooms!" By cycling your entire heat pump on and off based on the coldest room. Your efficiency just died.
What's Really Happening
Your "smart" thermostat is making your heat pump stupid:
- Destroys COP - Forcing high flow temperatures instead of optimal low temps
- Increases wear - Constant cycling ages components prematurely
- Wastes energy - Startup losses significantly reduce overall efficiency
- Reduces comfort - Temperature swings instead of stable warmth
The Weather Compensation Band-Aid
Some installers suggest adding weather compensation alongside your smart thermostat. This creates a new problem: two control systems fighting each other.
- Weather compensation says: "It's mild, reduce flow temperature"
- Smart thermostat says: "Room is cold, maximum heat now!"
Result? Confusion, inefficiency, and a heat pump that satisfies neither master.
The Zone Control Disaster
Multi-zone smart thermostats compound the problem:
- Living room calls for heat → Entire system fires up
- Bedroom reaches temperature → Tries to shut down
- Kitchen still cold → Overrides shutdown
- System cycles frantically between zones
Your heat pump becomes a ping-pong ball, never finding its efficient steady state.
What Heat Pumps Actually Need
Continuous Communication
Not just "on/off" but nuanced control of capacity and flow temperature while monitoring return temperature and outside conditions.
Predictive Control
Starting gentle heating well in advance, not blast heating at the last minute.
Whole-System Thinking
Understanding how solar gain in the living room affects heating needs in the bedroom.
Building Learning
Understanding how quickly your specific building gains and loses heat based on its construction and insulation.
The Warm Energy Approach
We threw out the thermostat model entirely. Instead of room-by-room on/off control, we built system-wide optimization:
Real Heat Pump Communication
Direct integration with heat pump controllers, speaking their language, not translating from boiler-speak.
Physics-Based Prediction
We model your actual building, not generic "learning" that takes months to maybe work.
Multi-Source Intelligence
Your heat pump knows when the sun will warm the living room, when you're cooking dinner, when the wood burner is lit.
Efficiency First
Every decision optimizes for COP, not just reaching setpoint fastest.
The Integration Reality
If you already have a smart thermostat, you have three options:
- Remove it - Let proper heat pump controls take over
- Bypass it - Set to constant "on" and use proper controls
- Replace it - With controls designed for heat pumps
The Bottom Line
Smart thermostats are fantastic for boilers. They're disasters for heat pumps. The technology inside that sleek plastic case was designed for a different era, a different fuel, a different physics.
Your heat pump is a Formula 1 car. Don't drive it with a tractor's steering wheel.
Ready for controls actually designed for heat pumps? Join our early access list and experience the difference proper integration makes.