I'm doing some fix-up work at a house, and learned that the furnace has been off for 3 years. The furnace is in a closet next to the water heater. Both sit on a raised section in the closet about a foot from the floor. The furnace draws air from the hallway through an enclosed box that is underneath both furnace and water heater.
It turns out that the water heater had leaked and was then drained and disconnected, and a new water heater was installed in the garage. I didn't see any sign of water damage inside, outside or from underneath, and don't see or smell any mold anywhere, including in the box.
Still, I'm hesitating firing up the furnace because I don't want it to spread any spores through the ducts and into the rest of the house. If the house was empty, I would open the windows and run it long enough to purge it out. But the house is being lived in with the usual furniture, etc.
So what I'm thinking of doing is closing all the vents and sealing them except the one nearest the furnace, and then connecting a large OD hose from the vent to outside thru a window. Then emptying a few cans of Lysol into the intake area and running just the blower for awhile. Then turn on the furnace and run that for awhile. Then seal that vent, and repeat the fan & furnace with the next closest vent, until all the ducts are purged.
I first tried rigging up a box to cover the vent with a vacuum cleaner hose, and then running the vacuum, but the blower puts out way more air than the vacuum can handle.
Anyway, that's my story. Does anyone have any ideas of a better way to be sure the ducts get reasonably dust-free?
Thanks in advance!