The best way to clean a furnace is to do a complete job-including the taking down and cleaning of the stove pipes. Use a long, stiff wire brush to scrub the interiors of the pipes.
If your basement is damp during the summer, it is well to store the pipe sections in a dry place where they will not rust. After thoroughly cleaning the pipes-inside and out-give the outsides a coat of stove pipe paint or rub them with kerosene.
Replace any that are in poor condition due to rust, for a leaky pipe interferes with the draft and is a fire hazard as well. If you do not disconnect the pipes, be sure that all connections to the chimney are tight and the pipe is flush with the wall of the flue. See that all joints are tight, particularly where the pipe enters the chimney.
If the pipe is shaky and tends to sway, reinforce it with wire or metal bands attached to the ceiling rafters.
Each furnace has one or more clean-out doors, making possible the removal of soot and fly ash from any of the heating surfaces. Work from the top opening down, so that any soot and ash not removed will fall into the ash pit. Remove all the ashes from the ash pit.
Brush the outside of the furnace to remove soot, dirt, and rust particles. It is a good plan to give both the inside and outside of the furnace a thin coat of oil or grease. A spray gun can be used for this purpose, and old crankcase oil makes an inexpensive rust preventative.
Oil door hinges and see that they are tight and that the door shuts firmly. A poorly fitting ash pit or fire box door will impair the performance of the furnace.
Examine the fire grates. If they are warped or in poor condition, replace them.
Remember that if soot is left on any metal portions of the furnace, it will absorb moisture and form sulphuric acid. This will corrode the metal.
The furnace doors should be left open during the summer to allow free circulation of air through the furnace and prevent moisture from collecting.
Check all automatic dampers for any sign of wear, or maladjustment in chains or rods. Apply oil where necessary.
Oil storage tank
The storage tank for oil burning furnaces should be filled at the end of the season. This will prevent the inside of the tank from rusting.
When preparing a boiler for the summer, remember to keep it full of water to prevent the inside from rusting. In a steam boiler, add water until the glass gauge indicates that the boiler is completely full. In a hot water system, leave the same amount of water in the system as is required during the heating season. Do not completely drain and refill until fall, or just before turning on the furnace.
Loosen the tie rods that hold the sections of the boiler together, to allow for contraction. This is done by loosening the nut at the end of the rods.
Some automatic steam boilers are provided with an aquastat, and continue to operate during the summer to heat hot water for the plumbing system. The aquastat regulates the amount of steam so that enough is generated to heat the water but not enter the radiators. Obtain the right setting for the aquastat from the dealer, along with the necessary operating instructions for the boiler.
Oil burners and coal stokers should be cleaned and prepared for summer in accordance with directions supplied by the manufacturer. If you do not possess the necessary information, have the work done by a serviceman.
Warm air furnace
To clean a warm air furnace completely, first remove the outer casing from around the fire pot. The casing is in several sections held together with bolts. The sections are comparatively light, and the only difficulty encountered will probably be rusty bolts which need a few drops of oil before they turn easily. Clean the inside of the casing as well as the outside, and clean the fire pot by the same method used for the boiler furnace. Apply a coat of oil or grease to all metal surfaces and check the condition of doors, hinges, and dampers.
While the casing is off, inspect the cemented seams between the sections that make up the fire pot. The cement used to make these seams airtight will not last indefinitely, and when it finally breaks down, coal gas or oil fumes will enter the heating system.
The fire pot is made up of several sections, and if the cement appears to be in poor condition, you will do well to remove the sections of fire pot and recement them. This work will require assistance, as the individual sections of the fire pot will probably be too heavy to handle alone. Remove all the old cement with a cold chisel and scrub down the surfaces of the joint with a wire brush. Put furnace cement on the joint and replace the sections.
While the furnace is apart, give the entire system a good cleaning. Remove dirt and dust from the fresh air intake line, ducts, and registers. A vacuum cleaner is very useful for much of this work.