Through Wall Ins Kit (TW-KIT) 22mm-28mm helps run pipe work from an externally mounted air source heat pump or biomass boiler into a property. The pipe work requires to be run through the exterior wall.  Without the correct insulation the hot pipe work will be affected by cold bridging and heat loss. MIS 3005 requires that external pipework running through external walls to be adequately insulated. The TW-Kit is ready made for such installations and also comes with the elbows to cover the external copper pipe connection.