Furious residents fed up with the sound of a leisure centre heat pump humming outside their homes fear the noise will get worse when two more are switched on.

Neighbours living on a new-build estate next to Tenterden Leisure Centre say their homes were peaceful when they first moved in, but now they are blighted by an "unnatural buzzing".

They say the noise – which is coming from an air source heat pump and an air conditioning unit just 50 metres from their gardens in Mercer Drive – is so loud it is "driving them crazy".

The pumps have been installed behind the leisure centre as part of Ashford Borough Council's (ABC) plan to reduce its carbon footprint.

But while residents support the environmental benefits, they say the pumps must come with proper soundproofing.

Chris Bathew, 57, said: "We have got one pump working at the moment which is extremely noisy and disturbing.

"The acoustic barrier doesn’t go all the way around so the noise is being reflected off the building.

"When the other two heat pumps are running as well, it’s going to be a significant increase in noise.

"Bat boxes have been put up but the sound of the machinery will disturb them or prevent them from nesting."

Initially the pumps were planned to be installed to the north of the leisure centre on a footpath between the building and pitches on the recreation ground.

But instead they have been placed to the east in an overflow parking area, closer to the homes than expected.

Objector Doreen Ryan hopes the pumps can be moved to their original location to reduce noise or that they are encased in proper soundproof barriers.

"My biggest concern is listening to it overnight," she added.

"I'm 83 now, I don’t want to lose my sleep. I don’t want to be unreasonable, but it has not been very well thought out.

"It's going to affect people coming to visit a house for sale, it’s going to put them off."

Rebecca Feaver, who is recovering from a car accident, says she already struggles to sleep because of constant pain.

She fears the added noise from the pumps will make sleeping even more difficult, adding: "It's usually so peaceful and I just can’t believe this monster is going to take over.

"The noise pollution is just going to be horrendous.

"I thought they would be put on the side of the building yet all these beautiful houses are going to be affected.

"I'm awake all night so I’m very sensitive to noise and sleeping is bad for me."

One neighbour said she recorded the current sound on a decibel reader in her garden which gave a reading of 70db.

That is the equivalent of a washing machine or a dishwasher and according to the Decibel Pro sound-recording app, it is considered a "moderate noise level" that could be "disturbing or annoying" overtime.

The neighbour: "It's just awful, I have got children doing their A-levels next month and they can’t have their windows open because of the existing heat pump which is a lot smaller than the ones they have installed now.

"Even opening my windows now you can hear this constant whirring and it's completely outrageous and unacceptable.

"It was peaceful when we moved in but now this horrendous noise chugging away in the background is driving everyone crazy."

Earlier this year, ABC submitted a planning application to install the two additional pumps but a decision on the scheme is yet to be made.

'It is driving everyone crazy...'

Tenterden Town Council has objected to the move, saying the units are "very big beasts" that would only "exacerbate the noise".

A spokesperson explained: “Tenterden Town Council’s planning committee has objected to the installation of two air source heat pumps (ASHPs) to the north east side of the Tenterden Leisure Centre, due to concerns over the noise impact on residents in particular.

"It is our understanding that ASHPs fall within the category of permitted development and ABC would not have been required to consult on this.

"Due to the proposed installation of three-metre acoustic barriers around the pumps, this would require planning permission.

"Our objection also highlighted ABC’s breach of their own Local Plan Policy ENV10 and central government’s noise mitigation guidance which states that good acoustic design needs to be considered early in the planning process, which had not happened.

"We hope that the concerns raised with ABC can be resolved, particularly regarding the noise impact on residents.”

If the plans are approved, the town council has suggested one condition should be that they are not used between 11pm and 7am.

In a statement, a spokesman for ABC said: “We are aware of concerns about noise being expressed by people living near Tenterden Leisure Centre.

"More details of our response will be made public in the next few days.”

Last week, it was confirmed Freedom Leisure will run the centre from May 1, taking over from current operator Serco.

It comes weeks after Tenterden Leisure Trust (TLT) confirmed it would hand back control of the building after months of clashing with ABC over the continued closure of the site's swimming pool.