Insulating jacket for a filter

An insulating cover for a central heating system filter, the insulating cover being made from a resilient insulating material, and being provided in two parts, the two parts of the cover being releasably attachable to each other by resilient clips, and the two parts of the cover surrounding at least part of the filter, and being retained around the filter, when the two parts of the cover are attached to each other by the clips, and the cover being removable from the filter by releasing the attachment of the two parts of the cover to each other, in which an arrangement of magnets is provided on an inside surface of the cover, the magnets facing towards the filter when the cover is installed on the filter, wherein the magnets are arranged in one or more pairs, each magnet being in the form of a substantially cylindrical billet, and the magnets of each pair being joined together by a ferromagnetic carrier, the magnets are mounted on springs which urge the magnets towards the filter in use, wherein a force transfer element is provided to a side of the carrier facing towards the filter in use, the force transfer element being arranged to push the magnets away from the filter when the cover is removed from the filter, the force transfer element is fixed to the cover by at least two screws, and an apertured plate is provided on the side of the cover facing away from the filter, the screws fixing the force transfer element to the cover passing through the apertures in the plate.