Your Weheat heat pump can cool, but its success depends on your heat distribution system, sufficient cooling surface area, and the status of the power grid.

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1. You have high-temperature radiators  

High-temperature radiators are not very suitable for cooling. Here is why: Cooling requires a water temperature of approximately 18 °C.

Consequence: At low water temperatures, they provide almost no cooling. You will feel very little effect, even though the heat pump has to work very hard.  

Solution: Replace them with low-temperature radiators, fan coils, or underfloor heating. These are efficient enough for both cooling and heating. A double win: it also improves the efficiency of your heat pump.

2. There is insufficient cooling surface area  

Your heat pump can only dissipate heat through the available surface area of your radiators, floors, and convectors. Cooling only works if the relatively cold water has enough surface area to absorb and remove the heat from your home. If that surface area is too small, the heat pump cannot reach the requested temperature.

Consequence:  It will start cycling on and off rapidly (see point 3) and eventually stop cooling altogether.

Solution: Increase the cooling surface area – for example, by adding an extra convector in the living room or additional loops to your underfloor heating.  

3. 'Short cycling' (rapidly switching on and off)  

When the heat demand is low but the heat pump still operates at full capacity, it rapidly switches on and off. This is called short-cycling.  

Consequence: Short-cycling puts strain on the compressor, shortens its lifespan, and can cause malfunctions.  

Solution: Weheat Intelligence has completely solved this problem. Our software detects short-cycling in real-time. If the system notices that the water temperature in your system is dropping too quickly (e.g., due to insufficient cooling surface area), it disables the cooling mode until the water in your system has warmed up further. This prevents wear and tear on the system caused by unnecessary cooling cycles.  

If your system proves unsuitable, the cooling cycles will eventually be disabled. We do this to protect the system.

4. Grid congestion and voltage spikes  

On sunny, hot days, the electricity grid sometimes becomes overloaded; this is called grid congestion. The grid voltage can then become (briefly) too high.  

Consequence: During such a voltage spike, the heat pump shuts itself off to avoid electronic damage. You will then temporarily have no cooling because the system is turned off.

Solution: Weheat has found a way to handle voltage spikes. New systems have this as standard; for existing installations, a simple upgrade is available.  

5. System volume too small: the water gets cold faster than your house

To cool, your heat pump extracts heat from the central heating water. Even at the lowest setting, the compressor still delivers a minimum cooling capacity: it cannot go any lower. All that cold has to go somewhere, and that is the water in your system.

And that is where the physics comes in: the less water involved, the faster it cools down. The energy required to make water one degree colder is simply the amount of water multiplied by the heat capacity and the temperature difference. If there is only about 50 liters of active water in your system, a cooling capacity of 3 kW will cool that water by roughly one degree per minute. The heat pump therefore reaches the requested temperature almost immediately and must then stop, because the water cannot get any colder (think of the risk of condensation). A little later, the water has already warmed up again and the cycle starts over.

This is essentially the same story as the short-cycling in point 3, but explained through physics: it is not that the heat pump is too slow, but that the water volume is too small to absorb the cooling capacity.

Consequence: short cooling cycles, little noticeable effect in the house, and eventually Weheat Intelligence will disable the cooling mode to protect your system.

Solution: ensure that the cold water can actually release its cold, meaning there is enough heat coming in from the other side.

Open all zones. The more floor zones or low-temperature radiators involved, the greater the water volume and the heat exchange surface area. The water cools down more slowly, allowing the heat pump to run for longer.

Ensure air circulation. Stagnant warm air transfers its heat to a cool floor very slowly. A small fan that blows warm room air across the floor or convector significantly increases heat transfer. The water stays at the right temperature, the heat pump keeps running, and you feel the coolness at eye level instead of just around your ankles.

This turns your system from a small glass that gets ice-cold instantly into a large vat that steadily continues to absorb heat from your home. Exactly what you want on a hot day.

How do I know if this applies to me?

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What can you do right now?

Check your heat distribution system. Do you have low-temperature radiators or underfloor heating? Great. Only high-temperature radiators? Consider adding low-temperature radiators. Cooling with high-temperature radiators alone is not possible. Unsure if you have enough cooling surface area? Ask your installer for a capacity calculation.  

We continue to actively monitor your system, provide upgrades when necessary, and assist your installer with clear advice. This keeps your home cool, quiet, and energy-efficient – even during those lovely summer days.

Please note: cooling doesn't feel cold immediately

Underfloor cooling works differently than air conditioning. The heat pump reaches the requested water temperature very quickly, but the floor itself must cool down before you notice the effect. This can take a few hours. Furthermore, cold air tends to stay low to the ground, while warm air rises. A small fan helps circulate the air so that the coolness is also felt at eye level.