A manufactured home has a compact oil fired forced air furnace in one corner oc a 40x28 manufactured home. A large central duct runs down the middle of an unfinished basement and perpendicular ducts run in the joist spaces. The joist spaces in the basement are insulated with faced fiberglass. The home is in south eastern PA. Seemed like a lot of heat was wasted because the central duct was not insulated. The owner of the home complained of cold and one heating contractor installed a larger central duct (slows down flow further increasing heat loss?)
Should the duct work be insulated and if so roughly how many years to payback?
Thank you for any help!