I have two very cold rooms in my house. This winter I purchased register blowers and they brought the temperature in the rooms up to the same as the rest of the house. Does this mean that the problem is related to HVAC? The ducts in the open basement had lots of gaps which we sealed up, so it wouldn't surprise us if the rest of the ductwork was done just as slopily. I'm just not sure if it would be bad enough to create a 4-6'C difference in these rooms. I would love if the register blowers were an easy solution - however they are very noisy. Is there anything I can try without opening the ceiling below the rooms to inspect the ductwork? If the only solution is to take the ceiling down, are there any quiet register blowers out there for at least a temporary fix?