Heat Pump Sizes Compared: Every Brand in One Visual

"Will it fit?" is one of the most common questions from homeowners considering a heat pump. The answer, in almost every case, is yes — but seeing the actual dimensions helps. This guide puts every major UK heat pump brand side by side so you can compare physical sizes at a glance. As our 50-installation survey proved, modern heat pumps fit in terraces, semis, and even small urban gardens.

The Complete Size Comparison Table

Dimensions from manufacturer technical specifications as of March 2026. Noise figures are manufacturer-stated sound power levels at 1m. Actual installed noise may vary — see our real-world noise measurements.

The Most Compact Models

If space is tight, these are the brands to consider:

The Mitsubishi Ecodan at just 300mm deep is the slimmest major brand — ideal for narrow side passages. The Samsung EHS Mono at 310mm is another excellent option for tight spaces. For homeowners who want the quietest operation, the Stiebel Eltron and Vaillant lead despite being slightly larger.

Size by Output Rating

An important finding from our comparison: within the same brand, different output ratings often share similar physical dimensions. Vaillant's 5kW, 7kW, and 10kW units are all the same physical size — only the 12kW is taller. Daikin's 6kW, 8kW, and 11kW share the same body. This means you do not necessarily need more space for a larger output unit.

Average ground footprint across all brands at each output range. Excludes clearance space.

Weight Comparison

Heat pump weight matters for base preparation and access logistics. Most residential units weigh 48-120kg — manageable for two installers. Heavier units (Nibe, Stiebel Eltron) are typically also the quietest, as the additional mass helps dampen vibration.

Clearance Requirements by Brand

From manufacturer installation manuals. Front clearance is for air intake — can sometimes be reduced with professional guidance.

Indoor Cylinder Dimensions

The indoor hot water cylinder is the other space consideration. Typical dimensions:

Placement Planning Tips

• Measure your available space including clearances before committing to a brand
• If side passage width is tight, prioritise Mitsubishi (300mm) or Samsung (310mm)
• If noise is the priority, prioritise Stiebel Eltron or Vaillant regardless of size
• Consider wall mounting for ground-level space constraints
• Ask installers about acoustic screening options if the unit faces neighbours

Frequently Asked Questions

Which brand is smallest?

Mitsubishi Ecodan (300mm depth) and Samsung EHS (310mm depth) are the most compact for tight spaces.

Do bigger units need more space?

Only slightly. A 5kW and 10kW unit from the same brand often share the same casing. Even 16kW units need less than 1.5m² including clearance.

How much clearance is needed?

Typically 300mm sides, 100-300mm rear, 1-2m front (air intake). Specific requirements vary by brand — always check the installation manual.

Are heat pumps getting smaller?

Yes. R290 refrigerant and improved compressors are making each generation more compact.

Does size affect noise?

Not directly. Some of the largest units (Stiebel Eltron) are the quietest. Fan design and compressor quality matter more than physical size.

How heavy are they?

48-120kg depending on brand and output. Two installers can position them. They need a solid, level base but no special structural support.