How close to the boundary can a heat pump be?

There's no longer a fixed distance. Since 2024 the test is noise at the neighbour's window — your installer does the MCS noise calculation.

Can I install a heat pump in a conservation area?

Yes, but not on a wall or roof that faces the road and is nearer the road than the house. Round the back is usually fine.

Must comply with the MCS planning standards, including 37 dB at the nearest neighbour's habitable-room window.
Outdoor unit no larger than 1.5 m³.
Not on a pitched roof, and within 1 m of the edge of a flat roof only if it doesn't project over it.
Sited, as far as practicable, to minimise the effect on the look of the area.

Flats & maisonettes
No householder permitted development rights at all.
Listed buildings
Not permitted development — planning permission and listed building consent.
Conservation areas
Not on a wall or roof facing the road where it's nearer the road than the house.
Article 4 directions
Your council may have removed this right on your street.
Planning conditions
An old permission may have removed permitted development rights. Not published anywhere.
New builds
Often have permitted development removed by condition. Check your deeds.

Your exact limits

House type, plot size, Article 4 and trees — worked out for your address.

£14.99one-off

Some councils have Article 4 directions that change these limits. Pick yours to see what applies locally.

How close to the boundary can a heat pump be?: There's no longer a fixed distance. Since 2024 the test is noise at the neighbour's window — your installer does the MCS noise calculation.
Can I install a heat pump in a conservation area?: Yes, but not on a wall or roof that faces the road and is nearer the road than the house. Round the back is usually fine.