Sam Jump, Head of Business Development at Wunda Group, separates some of the most common heat pump myths from the reality:
There is a lot of conflicting advice when it comes to heat pumps, underfloor heating and zoning, but how much of it still holds true for today’s heating systems?
Some of the advice installers encounter is based on older heat pump technology, while other recommendations are intended to compensate for poor system design or installations that haven’t been properly sized and commissioned. This results in a number of myths surrounding zoning and heat pump efficiency.
The reality is that a well-designed heating system can deliver both high efficiency and excellent room-by-room comfort. The key is understanding how the components work together, rather than treating zoning as inherently incompatible with heat pump operation.
Myth 1: Zoning makes heat pumps less efficient
The myth: Having multiple heating zones or individual room thermostats will make a heat pump less efficient, particularly when only one or two rooms are calling for heat.
The reality: Zoning doesn’t inherently reduce heat pump efficiency, however it can when systems are poorly designed. Issues such as short cycling, high flow temperature operation or inefficient operation can occur when a heat pump is oversized for the system, when there isn’t sufficient system volume, when there are poor control strategies, or when very small zones are calling for heat on their own. In these circumstances, the heat pump can produce more heat than the active zone can absorb, causing it to switch on and off repeatedly. This can reduce efficiency and place additional strain on the system.
However, modern inverter-driven heat pumps can modulate their output to match the heating demand. Rather than operating at full capacity before switching off, they can reduce their output and run steadily at a lower level. Also, other zones and controls should not be ‘on or off’ and should be utilising setback temperatures (often in the realm of 16-18 degrees) and comfort temperatures (often in the realm of 20-22).
Heat pumps perform best this way: steady operation, low flow temperatures and gradual heat delivery. Bottom line is, the idea that zoning inherently reduces heat pump efficiency is outdated. With the right heat pump, controls and system layout, zoning can work with the heat pump not against it.
Myth 2: One thermostat is better for heat pump efficiency
The myth: A single thermostat controlling the whole property is the simplest and most efficient approach for a heat pump.
The reality: A single thermostat cannot necessarily deliver the right level of comfort across an entire home.
Different rooms have different uses and heating requirements. A bedroom may be more comfortable at a lower temperature than a living room, while a bathroom may benefit from a higher temperature for shorter periods. With a single thermostat, the location of that thermostat can also have a significant impact, and can lead to overheating or underheating of areas, poor comfort and wasted energy.
If it is positioned in a warmer hallway, for example, it may satisfy the heating demand before colder rooms have reached their desired temperature.
Room-by-room or zoned control allows the system to respond to how individual spaces are actually used. This doesn’t mean every room needs to operate as a completely independent heating system. Logical zoning can group rooms with similar requirements, helping to maintain sufficient demand while still giving occupants greater control.
Myth 3: Heat will “leak” into cooler rooms, making zoning pointless
The myth: If one room is heated and the room next to it isn’t, heat will simply move between the two spaces, cancelling out any energy savings from zoning.
The reality: Heat transfer between rooms does happen, but that doesn’t mean zoning is ineffective. Heat can move through internal walls, floors and ceilings, as well as through open doorways and gaps. However, the amount of heat transferred will depend on the construction of the property and how the rooms are used.
For installers, the important consideration is how the zones are designed and for users how the controls are used. Using sensible comfort and setback temperatures rather than on / off settings is a good practice. As well as using closer temperatures between adjacent rooms can help prevent the system from having to work harder to compensate.
Keeping internal doors closed between warmer and cooler areas can also reduce unwanted heat transfer. For example, bedrooms may be set slightly
cooler than living areas, while a rarely used guest room can be reduced when it isn’t occupied.
Myth 4: Heat pumps should always be left running 24/7
The myth: A heat pump should never be turned down or switched off because it will always be more efficient to run continuously.
The reality: This advice has some grounding in how earlier underfloor heating systems behaved: traditional screed underfloor heating was slow to respond or older heat pumps struggled with stop-start operation.
Heat pumps generally perform well when they can deliver heat steadily at low flow temperatures, and large temperature swings can mean the system has to work harder to recover the property to thedesired temperature.
However, modern heating systems can be used more flexibly when they are designed correctly. Rapid-response underfloor heating systems use lower thermal mass constructions than traditional screed underfloor heating, allowing heat to reach the room more quickly. This makes room-by-room scheduling and sensible setbacks more practical, without needing to keep every room fully heated all day.
Installers should consider the heat emitter, property, controls, insulation and heat pump together.
Final takeaway
Zoned heating and heat pumps are not in conflict. Poorly designed systems with the wrong heating emitter, or a misunderstanding of the past can create problems, but well-designed systems using the correct heat emitters can deliver excellent efficiency and better comfort. Modern heating standards such as ISO 7730 and ISO 11855 recognise that thermal comfort is determined within individual occupied spaces, reflecting the reality that bedrooms, bathrooms and living areas often have different comfort requirements. The best systems often combine enough open flow for the
heat pump with enough zoning for the homeowner. With the right combination of heat pump, control setup and modern underfloor heating, end users do not have to choose between comfort, control and efficiency, they can have all three.
Find out more at: Wunda – Underfloor Heating and Energy Efficiency Specialists
