Compare heat pump size, side by side

See the real size of 3 well-known heat pump brands, grouped by the heating capacity your home might actually need.

Compare heat pump size, side by side

See the real size of 3 well-known heat pump brands, grouped by the heating capacity your home might actually need.

Comparing 3 well-known heat pump brands

This page compares 3 well-known heat pump brands: Octopus Energy, Vaillant, and Aira. It looks at their size, noise, and footprint side by side, so you can see how they stack up before speaking to an installer.

Octopus Energy

Vaillant

Aira

Comparing size, brand by brand

Grouped by roughly the size heat pump your home might need, so you can compare brands at the same size, not just by name. Each tier shows two views: height first, then depth. Both are shown next to a grey outline of an average adult and a 6ft scale mark. Depth figures match the Footprint tool. Fan positions are approximate. Scroll sideways on a narrow screen if a row doesn't fit.

~6kW tier

for smaller or well-insulated homes

Octopus Cosy 6

Height

Octopus Cosy 6

855 × 1125mm

58 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Octopus Cosy 6

595 × 1125mm (depth × height)

58 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Vaillant 5kW

Height

Vaillant 5kW

1100 × 765mm

54 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Vaillant 5kW

450 × 765mm (depth × height)

54 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Aira 6kW

Height

Aira 6kW

1216 × 1005mm

57 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Aira 6kW

425 × 1005mm (depth × height)

57 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

~8-9kW tier

for medium-sized family homes - see the note below on Vaillant's gap here

Octopus Cosy 9

Height

Octopus Cosy 9

855 × 1375mm

56 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Octopus Cosy 9

595 × 1375mm (depth × height)

56 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Vaillant 7kW

Height

Vaillant 7kW

1100 × 965mm

~54 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Vaillant 7kW

450 × 965mm (depth × height)

~54 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Aira 8kW

Height

Aira 8kW

1216 × 1005mm

56 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Aira 8kW

425 × 1005mm (depth × height)

56 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

~11-12kW tier

for larger or older, less-insulated homes

Octopus Cosy 12

Height

Octopus Cosy 12

855 × 1375mm

61 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Octopus Cosy 12

595 × 1375mm (depth × height)

61 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Vaillant 12kW

Height

Vaillant 12kW

1100 × 1565mm

60 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Vaillant 12kW

450 × 1565mm (depth × height)

60 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Aira 12kW

Height

Aira 12kW

1152 × 1503mm

57 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Depth

Aira 12kW

416 × 1503mm (depth × height)

57 dB(A)

For scale

Average adult, 5′9″ (1.75m)

Scale

6ft (1.8m) marked

Tiers group models with roughly similar real-world heating output, not identical labelled kW. The exact size your home needs depends on a proper heat-loss survey, not this page. Depth figures come from each manufacturer's installation guidance, the same source used on the Footprint tool. Figures may vary by exact model or revision, always confirm with your installer. This is a size comparison only, not an endorsement of any brand.

Frequently asked questions

What if my home falls between two sizes?

Keep reading

Compare heat pump footprint

See the ground space and clearance each brand needs.

Compare heat pump noise

See how loud each brand gets next to everyday sounds.

How to compare quotes

Check certification, sizing, the grant and aftercare.

Just Ask: Heatpump

Just Ask: Heatpump is an independent companion to Visit a Heat Pump and Get a Heat Pump. Built from real installation experience to give honest, practical guidance before you commit. Everything here is about air-to-water air source heat pumps.

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