clean flooded heating system before use

Any heating system exposed to floodwater must be cleaned before reuse, said Tom Greiner, Iowa State University Extension agricultural engineer.

Even if the heating system works after its "bath," dirt-clogged chimneys & smoke boxes could cause the furnace to explode. Check the inside of a flooded furnace before starting any fires. Flush sediment from the chimney w/ a hose or a swab tied on a long stick. Most flues can be reached through a clean-out door above the fire door.

If the heater is jacketed, clean out all mud between the stove & the outside casing. The casing may be removed to give working space. Take the smoke pipe out of the chimney & reach through the thimble to remove any mud from the lower portion of the chimney flue. This assures a draft for the fire.

In oil burning systems, inspect the fuel storage tank for opened seams. Dismantle the burner & clean all parts w/ kerosene. Inspect & clean the air blower. Replace fuel filters & clean & dry out the fuel pump. Remove housings that enclose gears & clean the gears thoroughly w/ kerosene. Grit in the gears will cause undue wear.

Be extra careful that the fan motor, electric ignition system & wiring are completely clean & dry before you turn on the electricity. Electric motor cleaning should be left to electricians & repairpeople.

Check any chimney that has been in contact w/ water for leaks that may have developed from dissolved mortar. Most chimneys have a foundation in the ground. Check the foundation & make sure it has not been undermined.

"A good way to check for small leaks in the chimney or furnace is to buy an inexpensive smoke candle from your local heating contractor," Greiner said. "Follow the instructions furnished. After lighting the candle, trap the smoke in the chimney by restricting the top of the chimney. Leave a small opening so the smoke will rise. Smoke escaping through the masonry will indicate leaks you may not see otherwise. The best repair is a new flue liner."

Natural & bottled gas heating systems should be checked by a serviceperson to make sure that no water leaked into the controls or pressure regulator. You can remove the burner elements & clean them, but leave the electric controls & regulators to a serviceperson. Replace severely soaked electric blower motors.

When the system is in good shape, have it "okayed" by a serviceperson, Greiner said. Then restart the furnace to see if it works, keeping the heat low. If weather permits, turn the furnace off. High heat may dry the house out too fast & cause excessive warping in the floors & other parts of the building.