I have an old gas furnace, and my utility bills are high. My budget for improvements is limited. What can I do to get it ready for winter and make it last a few extra years? -- T.R.
A -- Doing a simple tune-up each fall can keep your furnace running at maximum efficiency and improve comfort. An annual utility bills savings of at least $100 is reasonable. It should only take an hour or so, and you can check your central air conditioner at the same time.
A gas or propane furnace should be checked by a qualified technician every two or three years. Their equipment detects actual and potential problems.
Always switch off the electricity to the furnace first. As a safety check, put a few drops of soapy water on all the gas line fittings. Bubbles indicate a small gas leak.
Your fall furnace tune-up should include a filter change and then a change monthly thereafter. A dirty filter reduces air flow over the heat exchangers, which is necessary for maximum efficiency.
Remove the blower cover on the side of the furnace. This provides access to the blower motor, belt (if your model has a belt drive) and some of the heat exchanger surfaces. Vacuum clean all the interior surfaces. (The fine layer of dust and dirt that collects acts like a layer of insulation and lowers efficiency.)
If the blower motor has oil cups over the bearings, squirt in just a drop or two of oil. If there is a belt drive, check the tension on the belt. At the proper tension, the center of the belt should flex about one-half inch. Tighten or loosen it by adjusting the motor position.
Check the air inlet opening to the furnace. It should be clean with no soot. Soot deposits indicate incomplete combustion and/or back-drafting. If there is soot, do not use the furnace until it is checked by a technician.
Start the furnace and observe the color of the pilot flame and burners. The flames should be blue and steady, not yellow and dancing. This area is sealed on some newer furnaces, so you may not be able to see it.
Turn the thermostat up and down to make sure it's working. It is normal to have a short delay before the blower starts. Check to make sure all the duct dampers and registers are fully open. You can readjust them later to control the amount of heat going to each room.
Write for Update Bulletin No. 798, a do-it-yourself gas furnace tune-up guide, plus trouble-shooting guides and a furnace sizing evaluation chart. Include $2 and a business-size, addressed, stamped envelope, and send your request to James Dulley, Buffalo News, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.
Shortening a hollow core door
Q -- I added new deeper carpeting in my house. I have to shorten a hollow core door to clear the carpeting, and then I plan to add retractable weather stripping. What is the best way to shorten the door? -- R. E.
A -- Shortening a hollow core door can be a little tricky to get a clean appearance. Remove the door and mark a cut line for the amount to be removed. Saw slightly below the line and finish file it to the line. Using a chisel, drive the cardboard core up inside the door. Peel the plywood veneer from the sides of the old bottom block in the cutoff piece. Put glue on the bottom block and insert it back up into the door.