Attic 'thumps' may just be fluctuations in the wood

Q. Every once in a while, when it is quiet in the morning, I hear a thump that seems to come from my attic. There are no animals in my attic, so where does that thump come from? I have things in my attic, like everyone else. I also have vents in the soffit all around the attic, plus two vents near the top of the side roof. This thumping does not happen all the time. A. My guess is that you hear the thumping in the fall and spring, which would be caused by changes in the moisture content of the rafters or trusses straining against the fasteners. It's nothing to worry about.My brown Kohler bathtub needs refinishing. I can't seem to get the shine back in it. There are two methods that I am aware of: a liner or epoxy paint. Which would you recommend? A. One method is porcelain repair. A specialist prepares the tub and sprays a porcelain coating on it. The other is a complete liner that is fitted inside your tub. Either method is fine. Be aware that you should not use any abrasive cleaners with either of these processes, as they are not as durable as the original finish.I need your opinion on some things. When I first run the hot water in the bathroom sink, it smells musty at the start and then it will go away. It will repeat during the day. Also, do ultrasonic pest repellers really work? I am deathly afraid of mice. A. If it happens only at that one faucet, it's obviously not a water problem. Do you have a plastic faucet instead of a brass one? That could be your problem. Some people say that ultrasonic pest repellers work, while others say they don't. You just have to try one for yourself. Mice are disease carriers; you have a right to be concerned.I have a problem with an area on my roof that always melts the snow. It seems to be over the bedroom closet that is on the front of the house. I had a guy go in the attic, and he said I have plenty of insulation: 12 inches of batts and 12 inches blown-in. He questioned if there was enough of a gap between the roof and the soffit. He took a rake and tried to get a bigger airflow between the two. When we get a snowstorm, it is still melting in the same area. What do you suggest I do to correct the problem? A. There is an obvious heat loss either through the closet ceiling or the outside wall. Do you have a recessed-ceiling light in it? Is the insulation covering the outside wall plate? From your sketch, it looks as if your house has two stories. It is possible that a duct, plumbing pipe or electric wire from the main floor allows some heat loss through the exterior wall to work its way into the attic, since the melting occurs at the eaves. It is difficult to pinpoint the problem without actually checking the site conditions. Could you ask the person who looked at it to take a closer look? Or call an energy auditor to have him or her look into it.Please give us advice on chimney cleaning. We get annoying calls all through the year from chimney-cleaning companies. One such caller said that every two years, by law, we are required to have our chimneys cleaned. Is this a fact? What are the facts about chimney cleaning when oil, coal, gas or wood is used for home heating? A. To find out if regular chimney cleaning is required by your town or state law, call your local fire department. I am sorry that you are being annoyed by these phone calls. I would hang up after asking them to get you off their list. I don't recommend that anyone hire any firm or person calling to offer services. It is always best to select someone who has a solid reputation, people who don't need to generate business by calling people cold. You do not need to have your chimney cleaned regularly if your heating appliance is oil- or gas-fired and is properly maintained. You do need to have an oil-fired furnace or boiler serviced yearly, which should include a chimney inspection, and a gas-fired one checked yearly for safety. Coal and wood are a different story. Coal burning results in a small amount of fly ash, and the chimney should be inspected regularly. Wood burning creates creosote that sticks to chimney walls and can become a fire hazard. If the wood stove has a catalytic converter, it should not generate much, if any, creosote. A non-catalytic wood stove can generate a lot of creosote. A simple way to eliminate this problem is to spray all firewood with ACS (Anti-Creo-Soot). It is a liquid catalyst that turns what would be harmful creosote deposits into a harmless light brown ash, similar to what an oil-fired heating appliance would generate. You should be able to buy ACS from chimney sweeps or by contacting ChimneySaver, (800) 860-6327. You should still have the chimney cleaned yearly or every other year, depending on the type of wood you use and how much you burn, just to be safe.I have a south-facing sunroom with oak trim that has become stained by moisture that collects during the winter months. We try to keep up with it by wiping off the moisture, but over time the oak trim has become stained and is a very dark black in some areas. The manufacturer (Duckback Products) used a seaside formula treatment. Is there a product available to bleach the stains before I attempt to refinish the trim? Is there a finish I should use in place of the original finish?A. Remove all existing finish. Make up a saturated solution of oxalic acid crystals in hot water, using a glass or plastic container and a wood or plastic spoon or spatula. A saturated solution means that the water is no longer able to absorb more crystals, leaving undissolved crystals. Do not use metal instruments. Apply it on the stained oak with a small nylon brush, and let it do its work. You may need to repeat. When you are satisfied with the results, wipe any residue with a white cloth dampened with white vinegar. You should be able to get oxalic crystals in a well-stocked paint store. You will need very little, but be very careful with it: it is a very strong chemical. Use rubber gloves, wear old clothes and eye protection. Dispose of any leftover solution in an environmentally safe way. The varnish applied by the manufacturer appears to be a marine varnish, so it should be good.I have a few questions about water heaters. I have an 11-year-old Rheem 40-gallon gas heater. The only problem is that when I drain a few gallons out every six or seven weeks, the water that comes out always has a little rust color to it, which never clears no matter how much I drain out. I've been told to replace any heater over 10 years old, but from the research I've done it's apparent that these things can last 20 to 30 years. If almost all leaks start as small drips that can be seen if you're vigilant, then why not wait until the leak starts before replacing the heater? What percentage of heaters will actually burst and flood the area? Many people claim they replaced a perfectly good heater due to age and now have a "leaker" or other problems with the new units. Which heaters do you like? I hear Bradford White, Rheem, A.O. Smith and Kenmore are OK. A. Water heaters usually fail as you mention when a small leak develops. I have not heard of heaters bursting suddenly. However, few heaters last 20 to 30 years, but that does not mean that you should replace yours pre-emptively. Any of the brands you mention should be fine. Follow-up from a readerI may be able to offer an alternative answer to a heat-pump question that appeared in a recent column. As you probably know, a heat pump is an air conditioner that works two ways. In the summer, it removes heat from inside the house. In the winter it works in reverse, extracting heat from the outside and bringing it in. During this process, the outside condenser coils can begin to form ice, as it becomes colder than the air temperature. The ice inhibits the ability of air to flow over the condenser coil and prevents the unit from extracting any heat. To remove the ice, the air conditioner will go into a defrost cycle, where the unit basically goes back to its "summer mode" and begins to take warm air from inside the house and sends it back outside to defrost the unit. The cold air the homeowner is experiencing may have several causes. First, the defrost cycle may not be working, which means the unit may need servicing. More than likely, the defrost unit is working correctly and the homeowner is simply experiencing the cold air from the unit being in "summer mode." Some heat pumps have electric strip heaters installed in the ductwork that activate when the unit is in its defrost cycle. In this case, the homeowner would not notice the cold air. However, depending on the manufacturer or the installer, these electric heaters may not come on if the outside air is above a certain temperature. In warmer climates, electric heat strips are often not installed at all, which would again cause the homeowner to feel the cold air during the defrost cycle. It is also possible that the electric strip heaters are not working at all, but the homeowner would probably notice this whenever the outside temperature was below 30 degrees because the heat pump by itself would not heat the home. I believe it is the defrost cycle of the heat pump that is causing the homeowner to experience cold air after an hour of operation, rather than the heat anticipator of the thermostat.bull; Thank you for a very detailed explanation. It should help anyone with this problem. bull; Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via e-mail at henridemarne@gmavt.net.#169; 2009, United Feature Syndicate Inc.