i inspected a house yesterday (c.1890 bungalow) and the cold air return was about 8 inches away from the furnace. old small, unfinished, cellar basement. the duct extended to about 5 inches to the floor. hot water tank was about 12-15 feet away. i didnt see anyplace upstairs where air could also be drawing from. ive seen a few lately.
im telling my clients and noting that maintenance may be required to maintain safe operation around other fuel burning appliances. i dont want to give the impression that these issues must be addressed ASAP, but we cant really expect sellers to modify these old systems. this obviously doesnt fly in modern building, but what are you all recommending on these 50 year old installations?