One day they came home to their empty house and found the fire was on, but the flue, which had to be manually controlled, was closed. Since the flue was closed, the hot gases had been going into the house and the wall near the fireplace was starting to burn. My friends were lucky--just some localized fire and smoke damage--but if the fire had burned much longer, their home would be ashes.

The store says there have been similar incidents in the area. Apparently, some remote-controlled toys operate on the same frequency.

Jeffrey Mattox
Madison, WI

Editor's reply: Remote-controlled gas fireplaces are increasingly common all over the United States. Heat & Glo, the company that pioneered the devices, now produces five types of remotes with various amenities, including thermostats, thermometers, and variable controls for the blower and gas. As you note, there is a potential problem: toys, garage door openers, and lightning can all turn the fireplaces on by accident. The Consumer Products Safety Commission has one other complaint on file: a lightning storm turned on the fireplace, and the remote was unable to turn it back off. According to Rob Sloan, an engineer at Heat & Glo, it is technically possible, but rare, for remote controls to malfunction.

In your friends' case, there is an additional complication. Why, or rather how, was the flue closed? Most mechanical codes require gas fireplaces to have the flue dampers permanently fixed open (see Letters, Damperless Fireplaces, HE May/June '96, p. 4, and Opening up to Fireplace Dampers, HE July/Aug '96, p. 4). Leaving the flue open all the time won't help the house's airtightness, but then, neither will a big charred hole in the ceiling.

Housewrap is made to repel bulk water while allowing water vapor to pass through. No housewrap is waterproof. Therefore, it is best to make sure that moisture problems are under control prior to installation. Make sure that exterior drainage around the building carries water away from structure. In some regions, a ground cover is required. Make sure the installation is not exposed to runoff, ponding, leaky plumbing, or sweating HVAC ducts. If the installation is a retrofit installed flush with exterior wall sheathing, as may be the case in mobile homes, be sure to appropriately flash the edges.

For fastening, DuPont suggests 1-inch crown staples at most 12 inches apart along each supporting member. The large staples minimize the chance of rupture in woven materials. Some contractors have successfully used much smaller staples at very tight spacing (5/16-inch staples at 3 inches OC along the joists). You could also mechanically attach the housewrap with strapping (1x furring strips at 16 inches OC) laid perpendicular across the framing. This method is more wasteful and difficult than the others, but it should work well for skeptics. If you're using staples in challenging crawlspace conditions, make sure they are guaranteed for at least 15 years.

The edges of the housewrap fastened to the joists should overlap the prior layer by at least one bay to minimize insulation gapping, loss, and rupture at the seams. An alternative method would be to create a French seam where the edges are rolled together into a seam (like metal roofing) that may be turned flat and mechanically fastened to the joist. Both techniques are reasonably acceptable and airtight.

Securely install the housewrap along the entire bay (or bays) to be insulated. Then cut holes for hoses, insulate to the proper density, and carefully close up the holes. To seal the holes, use either tape approved for use with the housewrap, or 18-inch x 30-inch patches of housewrap secured to the joists.

In addition to Tyvek, there are several other brands of housewrap available that may provide satisfactory performance when properly installed. There are also specialized plastic sheetings designed to support insulation in exposed locations common in metal buildings. Tightly woven fish netting, butterfly netting, or insect screening will also work to prevent blow-back of the cellulose, but be sure to check the product for strength, longevity, and price before opting to use one of these.

Cameron Duncan
Technical Specialist
Energy Efficiency and Renewable Energy Clearinghouse (EREC)
Merrifield, VA

Chris Delikatny
Port Coquitlam, BC, Canada

Editor's response: Yup--you caught an odd situation. The filament lives of high-voltage lamps are indeed longer--rated lives of 8,000 hours aren't unheard of. And that can reduce the energy it takes to produce, transport, install, and dispose of the lamps. But using 130V lamps on 120V circuits causes them to lose about 15% of their rated efficacy.

According to Francis Rubenstein, staff scientist at the Lighting Research Group at Lawrence Berkeley National Laboratory, the U.S. Energy Policy Act outlawed several types of reflector lamps and tube fluorescents. However, it was silent on A lamps of any voltage. 130V lamps are useful in areas with consistently high voltage, such as some rural areas.
 
 

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