How to sound proof the door to our boiler cupboard

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Hello. We have just had a new boiler fitted and part of this involved replacing the door to the boiler room as the old door had an asbestos cement board pinned to the back of it and therefore wasn't particularly safe! The replacement door is just a basic 2 ply door and is letting a lot of noise through (didn't realise how much sound dampening the old door was doing). Rather than purchase another new door I was wondering if one of your products could be attached to the back of the new door to reduce sound transmission, and if so, which one. The dorr is 27" by about 68". Thank you.