Ceramic tile and stone are popular flooring materials, but each is subject to damage if not properly maintained.

• uneven tiles. Examine the tiles to see how level they are in relation to each other. Uneven tiles probably weren’t set correctly in the mortar, and reinstallation may be necessary;
• cracks, loose tiles and splitting. Cracks in ceramic tile are the result of movement in the tile underlayment, excessive expansion or contraction of the building during freeze-thaw cycles, abuse, or improper installation. Minor cracks can be repaired with grout that matches the color of the tile, but larger cracks may require replacement of the tile;
• crazing. If tiles were cooled too quickly after kiln-firing, they can develop fine surface cracks, most often appearing as a fine, web-like network akin to cracked ice. Crazing is much more common in older, historic tiles than in modern tiles, but it still happens today. Crazing increases the rate at which tiles hold dirt, leading to discoloration; and
• cracked or discolored grout lines. Unsealed or improperly sealed grout will readily absorb moisture from the air or standing water, especially around showers and sinks. Some types of porous tiles may actually powder or spall if subjected to constant moisture. Damaged or discolored grout can be removed and replaced.

Natural stone tiles have a beauty that is difficult to recreate. They add an air of elegance and character to any home. Stone is more durable than ceramic tile, too, as it’s less likely to scratch, and holds up well under foot traffic. The unique and complex patterns can appear busy and overwhelming in large, empty rooms, however.  Stone is also more difficult to maintain than ceramic tile. The following maintenance and repair tips are recommended:

• Apply an impregnating sealant. An oliophobic sealant will repel both oil and water, and it’s especially helpful in the kitchen. Try to use a solvent-based sealant, as they’re generally better than water-based varieties.
• Quickly clean up any acids. Some of the more common stone tiles are marble and limestone, which are calcite-based, meaning that they will corrode when exposed to acids, such as vinegar or lemon juice. Unfortunately, sealants cannot protect stone against these substances, which will etch into the stone if left standing. Igneous stones, such as basalt and granite, as well as ceramic tile, are less vulnerable to acid damage.
• Lay walk-off mats or area rugs on either side of exterior entrances and instruct people to wipe their feet before they enter the home. The main cause of surface scratching on stone floors is dirt from outside that becomes caught under shoes and scraped across the floor. Scratching can dull the stone’s natural polish and damage its natural crystals, causing it to lose its shine and reflection.
• Use a good-quality stone soap, preferably one containing linseed oil, for regular maintenance and cleaning. In most cases, you can simply mop the soap and leave it to dry.

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by Nick Gromicko

A bug zapper is a popular exterior appliance installed by a homeowner or food handler to attempt localized control of flying insect populations. Its name comes from the characteristic “zap” sound produced when an insect is electrocuted. Around homes, they are primarily used to kill biting (female) mosquitoes, which create itchy bumps and can transmit the West Nile Virus or encephalitis, malaria and yellow fever. While Popular Mechanicsproduced a sketch of a bug zapper as early as 1911, it wasn’t until 1934 that parasitology professor Dr. W.B. Herms introduced the electronic insect killer that became the model for all future bug zappers.

Bug zappers typically consist of the following components:

• the housing, which is a plastic or grounded metal exterior casing that contains the zapper’s parts. It may be shaped liked a lantern, a cylinder or a rectangular cube. A grid design may be incorporated to prevent children and animals from touching the electrified grids inside the device;
• a light source, which is usually fluorescent-type, such as mercury, neon or ultraviolet light;
• wire grids or screens, which are electrified layers of wire mesh that surround the light source. These grids are separated by a tiny gap roughly the size of a typical insect (several millimeters); and
• the transformer, which is the device that electrifies the wire mesh, changing the 120-volt, electrical-line voltage to 2,000 volts or more.

• Female (biting) mosquitoes and other biting insects are more attracted to the carbon dioxide (CO₂) and water vapor in the breath of animals than to ultraviolet light. As a consequence, standard bug zappers typically kill large numbers of harmless and beneficial insects, such as beetles and fireflies, and ultimately fail to reduce the number of the types of insects that prompt the purchase of a bug zapper in the first place. In fact, one study found that just 0.22% of the insects killed by bug zappers were biting insects, while nearly half of those killed were harmless, non-biting aquatic insects from nearby rivers and streams. The study even found “the probability of being bitten by mosquitoes increases in the vicinity of these traps,” perhaps because the biting insects are actually lured by the ultraviolet light but become distracted by the far more attractive human prey nearby. Some newer bug zappers address this issue by incorporating a CO₂ container at the bottom of the lamp. Other designs attract mosquitoes into a netting device on the outside of the bug zapper that traps the mosquito, and eventually the insect dies of dehydration.
• The electrocuted insects are blasted into a fine mist that contains insect parts as well as unkilled bacteria and viruses up to 7 feet (2.1 m) from the device. The air surrounding the zapper may become contaminated with campylobacter jejuni, staphylococci, serratia marcescens, enterococci, and other potentially dangerous organisms commonly carried by flies. For this reason, a bug zapper should never be placed over a food preparation area or in a hospital or any other sterile environment to prevent the potential spread of disease. Children should not be allowed to play beneath an operating bug zapper. Models that contain a tray to catch insect debris are less of a health risk.

Inspectors may pass on the following mosquito-control techniques to concerned homeowners:

• Do not allow water to accumulate anywhere in your yard for more than a few days. Eliminate sources of standing water, especially old tires, flower pots, clogged gutters, tin cans or buckets. Fill in or drain ruts, puddles and other low places in the yard. Even holes in trees from rot and hollow stumps can collect water that can harbor mosquitoes. Cover trash containers to keep rainwater out, and drill holes in the bottom of trash containers to allow any water to drain. Repair leaky pipes and outdoor faucets.
• Bug zappers should be cleaned out at least annually to prevent the accumulation of bug parts on the wire mesh, which will decrease the effectiveness of the unit, and may lead to illness if the bug parts contaminate foods, drink or items used by people or pets.
• Keep grass cut short and any shrubbery well-trimmed, as adult mosquitoes use these places to rest and hide.
• Encourage the presence of bats by installing a bat house. These winged mammals pose little danger to humans, and a single brown bat can consume up to 600 mosquitoes per hour.
• Install a fan. Mosquitoes and other flying insects will avoid moving air.
• Wear long-sleeve shirts and pants. The pesticide permethrin may be applied to clothing to protect against mosquitoes and ticks. Beware that while permethrin is relatively safe for people and dogs, it is toxic to cats.

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Brominated flame or fire retardants (BFRs) include a wide range of chemicals added to household furnishings and products to inhibit their ignition and reduce the chance of fire. In recent years, concern surrounding the toxicity of this class of chemicals has risen due to the widespread accumulation of several types of BFRs in humans and in the natural environment.

There are more than 175 different types of flame retardants, which are generally divided into classes that include brominated, chlorinated, phosphorus-containing, nitrogen-containing, and inorganic flame retardants. Producing BFRs, at a rate of 5 million metric tons annually, is a $2 billion business, and this particular arm of consumer fire safety is currently the industry leader. For several decades, BFRs have been routinely added to consumer products, including computers, TVs, electrical cables, carpets, furniture and textiles, in a largely successful effort to reduce fire-related injuries and property damage.

The World Health Organization has called for disuse of PBDEs where adequate alternatives are available, and the Swedish Chemicals Inspectorate has called for the chemicals to be entirely phased out.  By contrast, the UK Department for Trade and Industry calls fears over PBDEs “chemical paranoia,” arguing that there is no conclusive proof that BFRs are harmful to humans. Still, the European Union has banned PBDEs in electronic devices, and in the United States, PBDEs are now heavily regulated, notably in Washington state, Maine and California.

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What is a Blower Door?

Inspectors should become familiar with blower doors, as they can be a valuable tool in energy audits. A blower door is a powerful, variable-speed fan that can be temporarily mounted into an exterior door frame to provide controlled air flow for analysis.  The way that air flows through a building can have a serious impact on air quality, comfort and energy expenses.  The use of a blower door allows air flow through a structure, and the resulting loss of heat can be immediately quantified, providing a way to pinpoint the location of air leaks.

Blower doors were originally developed in the 1970s for use as a research tool.  As technology has evolved, allowing for the development of more portable equipment, blower doors have transitioned into use as a valuable field tool, as well.  The first portable blower doors weighed as much as 200 pounds and took up quite a bit of space, and were also very expensive.  Today, they are much more affordable and are built lighter and smaller.  The reduced set-up time allowed by their more compact designs has led to the standard use of blower doors as part of energy audits for measuring air flow.

When air pressure and air flow are controlled and measured, they can provide data about how airtight a building is.  The three variables involved are pressure, flow and holes or leaks.  A change in one of these factors will produce a change in at least one other factor.  Since the goal of a blower door test is to locate air leaks in the building envelope, data regarding air pressure and flow can provide information about the holes, which may otherwise be tough to find.

The blower door utilizes controlled differences in air pressure to collect data.  Once installed in an exterior door frame, the air pressure inside a building can be changed in relation to the outside pressure by forcing air into or out of the interior.  The difference in pressure forces air through holes or leaks in the building envelope.  The pressure and air flow are measured by gauges, which are part of the blower door equipment.  By measuring the pressure and air flow in relation to each other, the airtightness of the building envelope can be quantified.  The amount of air flow needed to create a change in pressure increases as the airtightness of the building envelope decreases.  A well-sealed building requires less air flow to generate a change in pressure.

During a blower door test, the interior air pressure needed to be maintained in order to gather useful data is 50 pascals, which is roughly equal to the pressure created when a 20-mph wind hits the building.  The blower door equipment has a gauge to indicate when this pressure has been achieved, as well as a gauge to indicate the cubic feet per minute (CFM), which is the standard unit of measure for air flow.  Air flow in a well-sealed building will generally be less than 1,500 CFM at 50 pascals.  Air flow above 4,000 CFM would be considered leaky.  This is valuable data that can be acquired in about half an hour with the use of a blower door.

Since the blower door forces air through cracks and holes, the locations of the leaky spots can be identified.  The draft of air entering through the holes can often be felt with the hand. Smoke and infrared imaging can also be employed to locate smaller, more subtle leaks.  It is often assumed, especially by homeowners, that poorly sealed windows and doors are the major culprits of air leaks. In reality, leaks in other areas are usually much more significant.  The difference in air pressure between the interior and the exterior is greater both at ground level and up high, so leaks in basements and crawlspaces, as well as in attics, are the most important to locate.

When looking for air leaks, check through basement rim joists, holes for plumbing traps under tubs and showers, cracks between finish flooring and baseboards, utility chases, plumbing vent-pipe penetrations, kitchen soffits, fireplace surrounds, recessed can lights, and cracks between partition top plates and drywall.  These are all common places where significant leaks can develop.

Accounting for Outside Factors

Wind and temperature can have an effect on the test data. Wind blowing on the outside of the building can add to pressure differences between the interior and exterior.  It can also affect the flow rate of the blower fan.  It is best not to conduct blower door tests in windy conditions.  But if wind is not severe, tests can be conducted at multiple points in the building and then averaged together.

Differences in temperature can create differences in pressure. Accounting for a baseline stack-effect pressure will ensure that the test results are not skewed.  The stack-effect pressure is a function of the height of the building and the difference in temperature from the interior to the exterior.  A 15-foot tall building with a 50º-temperature difference between the inside and outside will have a 5-pascal pressure difference from the top of the building to the bottom.  Some blower door equipment has a gauge with a built-in baseline feature, so this difference can be easily determined at the outset of the test.

Temperature and barometric pressure affect both air density and viscosity, which is its resistance to flow.  Because of this, an adjustment for density is required. Some software packaged with blower door equipment is designed to make these calculations, and if it is not available during the test, the manual supplied with the equipment should have information about making the necessary adjustments and applying it to the results.

Preparation and Safety

In order to ensure accurate results, as well as safe conditions for performing the test, some preparation is necessary before beginning. Any fireplaces or stoves used for heating should not be operating, and all furnaces and pilot lights should be turned off.  There should be no open flames anywhere indoors.  Ashes in fireplaces or stoves should be removed so they do not get sucked into the building.  Dampers should be closed.  Every door and window must be closed tightly so that air flowing through them does not affect the test, while all interior doors should be left open.

If there is a basement, it must be determined whether this area is to be considered part of the building envelope for testing purposes. Generally, if there is heat in the basement, even if only because the furnace is located there, it will be considered part of the envelope, and access to it should be left open during the test.  Sometimes, the test may be done both ways — with the basement access open and with it closed, and this is quick and simple to accomplish.

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Bed bugs are small, flightless, rust-colored parasites that feed on the blood of humans and other warm-blooded animals. Inspectors should learn the telltale signs of these pests and be capable of providing information to their clients.

Bed bugs were diminished to an historical footnote after their near-eradication in the 1950s, but they are re-emerging in a big way. At the EPA’s National Bed Bug Summit in 2009, researchers decided that the parasite’s revival is more appropriately termed a pandemic rather than an epidemic, noting its rapid spread across large regions and different continents. For those afflicted by the bug, humiliated and defeated by its persistence, many prefer to refer to the infestation as “house herpes.” The United States has seen a 50-fold increase in bed bug infestations over the last five years, according to the National Pest Management Association. An entomologist told MSNBC, “It’s like the return of the wooly mammoth,” as many of his peers had previously never seen a single bed bug in their careers. The outbreak has affected most parts of North America and Europe, especially in urban areas.

Researchers believe bed bugs have roused from a half-century of hibernation for two reasons:  the termination of the use of the pesticide DDT; and a rise in international travel. DDT, a powerful synthetic pesticide, was used widely in agriculture until a public outcry concerning its safety lead to a US-ban of the chemical in 1972, followed by international bans. Unbeknownst to the environmentalists of the time, these laws would permit future outbreaks to grow unchecked, which is precisely what happened when travel increased from countries where bed bugs were never subjugated, such as India.

Hotbeds of international travel, such as New York City, have hosted the bulk of the carnage. The bugs hitch rides from country to country in suitcases, and creep into hotel rooms where other guests are then exposed and unknowingly spread the parasites to movie theatres, cabs, buses, hospitals, houses, and everywhere in between. In New York City, bed bug reports increased 800% from 2008 to 2009, a year in which the Department of Housing Preservation and Development received 13,152 bug infestation complaints.

The unpleasantness of a typical rodent or insect extermination is largely the fee charged by the exterminator.  But with bed bugs, this fee is just one piece of a greater nightmare. Because bed bugs are adept at hiding almost anywhere, an alarming quantity of possessions, from curtains to books and picture frames, must be discarded or quarantined. In one posh New York City rental tower, a tenant was forced to part with carpets, bedding, curtains, 20 cashmere sweaters, an Armani suit, a couch, a headboard, a night table, a bedframe, and an exercise bike, according to the New York Daily News. Other victims have had to throw away their books unless they were willing to inspect each one, page by page. Some possessions may be salvaged if they are sealed in special casing long enough for the bed bugs to die, which can takes many months. During this time, residents may be forced to move to temporary housing elsewhere.

Fortunately, the health dangers posed by bed bugs seem to be limited to temporary skin irritation and inflammation, akin to mosquito bites. There are no known cases of disease transmission from bed bugs to humans, despite the fact that the parasites seem similar to other parasites that do transmit disease, such as fleas and ticks. Anaphylactic shock, however, may be experienced by a small percentage of the population, and measures should be taken to prevent bacterial infection of bitten areas.

Adult bed bugs are flat, apple-seed sized with rusty-colored, oval bodies. Newly hatched bed bugs are semi-transparent, light tan in color, and the size of a poppy seed. Yet, due to their elusive nature, their presence is usually discovered through peripheral clues rather than by seeing the bugs themselves. Some of these signs include fecal spots, blood smears, crushed bugs, or the itchy bumps that may result from bites. Bugs may be disturbed while feeding and leave a cluster of bumps, or they may bite in a row, marking the path of a blood vessel. The parasites emit a characteristic musty odor, although the smell is sometimes not present in even severe infestations. The bugs also emit a smell that is detectable by dogs, which has lead to the implementation of dogs in bed bug detection. Properly trained dogs can find bed bugs in wall voids, furniture gaps, and other places that humans may overlook and, in doing so, they focus on the area in which exterminators must spray.

• Remove bed skirts, as they provide easy access for the bugs to travel from the floor to your bed. If you must have bed skirts, make sure they do not reach the floor.
• Move your bed away from the wall. Bed bugs cannot fly, but they can climb walls in order to fall onto the bed.
• Place furniture legs in tin cans coated with talcum powder, petroleum jelly or a non-evaporative liquid, to deter the bugs from climbing.
• Place a strip of duct tape at the base of furniture with the sticky side out. This tactic can be used to confirm the presence of bed bugs because it will trap them in place.
• Spray cracks and crevices with an insecticide designed to control bed bugs. Follow the label’s directions carefully. However, do not treat bedding, towels or clothing with insecticide.

 

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by Nick Gromicko and Kenton Shepard

Bats are nocturnal mammals found in most inhabited places throughout the world. Bat infestation in homes, especially in attics, can be a health hazard, as well as a nuisance, for homeowners.

• Due to its high levels of phosphorous and nitrogen, guano (bat feces) is an effective fertilizer and gunpowder ingredient. Guano has been such a critical resource that in 1879, a war between Chile and Bolivia, called the Guano War, was waged over rights to the guano-rich western coastline.
• Despite how large they appear in flight, bats are remarkably small. Some can fit through openings smaller than ½-inch wide. Even the largest bat – the golden-crowned flying-fox — with a wingspan of up to 5 feet, may weigh as little as 3 pounds.
• Roughly 20% of all known mammal species are species of bats.
• Bats are the only mammals capable of sustained flight.
• Contrary to popular belief, bats are neither rodents nor birds, and they are not blind.

• the accumulation of guano. Bat guano resembles rodent droppings but can be distinguished in several ways:  guano tends to cluster as it piles up beneath the exit of the bats’ roost; guano often has a shiny, speckled appearance due to the ingestion of insect wings; and guano can be easily crushed into smaller fragments, while rodent droppings will not. Of course, it is not safe to touch any animal droppings with unprotected hands;
• milky white urine stains on windows;
• stains around entry holes, such as cracks and crevices;
• mouse-like droppings under eaves and overhangs;
• stains and odors caused by urine and guano;
• noises such as squeaking, scratching and crawling in attics and walls shortly before dusk and dawn; and
• grease and dirt. Bats often leave smears of grease and dirt from their coats on the entry point to their roost.

Due to their high mobility and social behavior, bats are often hosts for diseases, such as rabies. Rabies is perhaps the most serious disease transmitted by bats in North America. Most of the human rabies cases in the United States have been caused by the rabies virus from bats. Awareness of the facts about bats and rabies can help homeowners protect themselves, their families, and their pets.

Rabies is a virus that affects the nervous system of humans and other mammals. Once symptoms of the disease develop, it is almost always fatal. Humans contract rabies from animal bites. Some bats have teeth so sharp that a sleeping person may not realize that they have been bitten. It is recommended that those waking up with bats in the bedroom undergo a series of preventative (and sometimes painful and expensive) rabies inoculations. The alternative is to capture the bats (without being bitten) and take them to a laboratory for testing.

Indications that a bat has rabies:

• The bat is in an unusual place, such as a bedroom or in the lawn. Healthy bats do not rest on the ground.
• The bat is approachable. Healthy bats are scared of humans and will flee long before they can be approached.
• The bat is active during the day.
• The bat appears unable to fly.

For these reasons, rabid bats are often most likely to come into contact with humans.

This respiratory disease, caused by the fungus Histoplasma capsulatum, is transmitted through the inhalation of fungal spores found in bat guano and bird droppings. Although generally not fatal, histoplasmosis can cause flu-like symptoms. For individuals with compromised immune systems, such as those with AIDS, histoplasmosis can be fatal.

• The entry point for the bats should be identified. Holes as small a human thumb are large enough for some bats to squeeze through. The homeowner can seal off most of these holes with caulk, leaving one hole intact for resident bats to exit at night.
• The homeowner can then plug this hole at night so that bats cannot return to the house. Alternatively, the homeowner can install a one-way “check-valve” from wire mesh that will allow bats to exit the house but not allow them to return.
• “Bat houses,” which can be constructed or purchased, can be placed next to the house during bat removal to provide bats with an attractive alternative to the house.

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• Propane grills present an enormous fire hazard, as the Consumer Product Safety Commission (CPSC) is aware of more than 500 fires that result annually from their misuse or malfunction. The following precautions are recommended specifically when using propane grills:
  • Store propane tanks outdoors and never near the grill or any other heat source. In addition, never store or transport them in your car’s trunk.
  • Make sure to completely turn off the gas after you have finished, or when you are changing the tank. Even a small gas leak can cause a deadly explosion.
  • Check for damage to a tank before refilling it, and only buy propane from reputable suppliers.
  • Never use a propane barbecue grill on a terrace, balcony or roof, as this is dangerous and illegal.
  • No more than two 20-pound propane tanks are allowed on the property of a one- or two-family home.
  • To inspect for a leak, spray a soapy solution over the connections and watch for bubbles. If you see evidence of a leak, reconnect the components and try again. If bubbles persist, replace the leaking parts before using the grill.
  • Make sure connections are secure before turning on the gas, especially if the grill hasn’t been used in months. The most dangerous time to use a propane grill is at the beginning of the barbeque season.
  • Ignite a propane grill with the lid open, not closed. Propane can accumulate beneath a closed lid and explode.
  • When finished, turn off the gas first, and then the controls. This way, residual gas in the pipe will be used up.

• Charcoal grills pose a serious poisoning threat due to the venting of carbon monoxide (CO). The CPSC estimates that 20 people die annually from accidentally ingesting CO from charcoal grills.  These grills can also be a potential fire hazard. Follow these precautions when using charcoal grills:
  • Never use a charcoal grill indoors, even if the area is ventilated. CO is colorless and odorless, and you will not know you are in danger until it is too late.
  • Use only barbeque starter fluid to start the grill, and don’t add the fluid to an open flame. It is possible for the flame to follow the fluid’s path back to the container as you’re holding it.
  • Let the fluid soak into the coals for a minute before igniting them to allow explosive vapors to dissipate.
  • Charcoal grills are permitted on terraces and balconies only if there is at least 10 feet of clearance from the building, and a water source immediately nearby, such as a hose (or 4 gallons of water).
  • Be careful not to spill any fluid on yourself, and stand back when igniting the grill. Keep the charcoal lighter fluid container at a safe distance from the grill.
  • When cleaning the grill, dispose of the ashes in a metal container with a tight lid, and add water. Do not remove the ashes until they have fully cooled.
  • Fill the base of the grill with charcoal to a depth of no more than 2 inches.

• Electric grills are probably safer than propane and charcoal grills, but safety precautions need to be used with them as well. Follow these tips when using electric grills:
  • Do not use lighter fluid or any other combustible materials.
  • When using an extension cord, make sure it is rated for the amperage required by the grill. The cord should be unplugged when not in use, and out of a busy foot path to prevent tripping.
  • As always, follow the manufacturer’s instructions.

• Always make sure that the grill is used in a safe place, where kids and pets won’t touch or bump into it. Keep in mind that the grill will still be hot after you finish cooking, and anyone coming into contact with it could be burned.
• If you use a grill lighter, make sure you don’t leave it lying around where children can reach it. They will quickly learn how to use it.
• Never leave the grill unattended, as this is generally when accidents happen.
• Keep a fire extinguisher or garden hose nearby.
• Ensure that the grill is completely cooled before moving it or placing it back in storage.
• Ensure that the grill is only used on a flat surface that cannot burn, and well away from any shed, trees or shrubs.
• Clean out the grease and other debris in the grill periodically. Be sure to look for rust or other signs of deterioration.
• Don’t wear loose clothing that might catch fire while you’re cooking.
• Use long-handled barbecue tools and flame-resistant oven mitts.
• Keep alcoholic beverages away from the grill; they are flammable!

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by Nick Gromicko and Kenton Shepard

Backdrafting is the reverse flow of gas in the flues of fuel-fired appliances that results in the intrusion of combustion byproducts into the living space. Many fuel-fired water heaters and boilers use household air and lack an induced draft, which makes them especially vulnerable to backdrafting when indoor air pressure becomes unusually low. Inspectors should try to spot evidence of backdrafting in homes.

How does backdrafting happen?

Fuel-fired water heaters, boilers, wall heaters, and furnaces are designed to exhaust the byproducts of combustion to the outdoors through a flue. These hot gases rise through the flue and exit the home because they are not as dense as indoor air. The pressure differential that allows for the release of combustion gases can be overcome by unusually low indoor air pressure caused by a high rate of expulsion of air into the outdoors through exhaust fans, fireplaces and dryers. When this happens, combustion gases can be sucked back into the house and may potentially harm or kill building occupants. Improperly configured flues or flue blockages can also cause backdrafting.

How can InterNACHI inspectors test for backdrafting?

• An inspector can release smoke or powder into the draft diverter to see whether it gets sucked into the duct or if it spills back into the room. A smoke pencil or a chemical puffer can be used to safely simulate smoke.
• An inspector can hold a lighter beside the draft diverter to see whether there is sufficient draft to pull the flame in the direction of the flue.
• Combustion gases that back-draft into a house may leave a dark residue on the top of the water heater. The presence of soot is an indication of backdrafting, although its absence does not guarantee that backdrafting has not happened.
• A carbon monoxide analyzer can be used to test for backdrafting of that gas. Inspectors should be properly trained to use these before they attempt to use one during an actual inspection, primarily to avoid false negatives.

  While performing the above-noted tests, it is helpful if inspectors ask their clients to turn on all devices that vent air into the outdoors in order to simulate worst-case conditions. Such devices may be dryers, or bathroom and kitchen fans.

Types of fuel-fired water heaters:

• Atmospheric DraftMost backdrafting is the result of the characteristics of this type of water heater. Combustion gases rise through the ventilation duct solely by the force of convection, which might not be strong enough to counter the pull from dips in indoor air pressure.

• Induced Draft
  This system incorporates a fan that creates a controlled draft. The potential for backdrafting is reduced because the induced draft is usually strong enough to overcome any competing pull from an indoor air-pressure drop.

• Sealed Combustion
  The combustion and venting systems are completely sealed off from household air. Combustion air is drawn in from the outdoors through a pipe that is designed for that purpose. The potential for backdrafting is nearly eliminated because the rate of ventilation is not influenced by indoor air pressure, and the vented gas has no pathway into the home.

• Water Heater Location
  The installation of fuel-fired water heaters in particular household locations can increase the chances of personal harm caused by backdrafting. The 2006 edition of the International Residential Code (IRC) states the following concerning improper location:

Fuel-fired water heaters shall not be installed in a room used as a storage closet. Water heaters located in a bedroom or bathroom shall be installed in a sealed enclosure so that combustion air will not be taken from the living space.

In summary, inspectors should try to spot evidence of backdrafting.

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Arc-fault circuit interrupters (AFCIs) are special types of electrical receptacles (or outlets) and circuit breakers designed to detect and respond to potentially dangerous electrical arcs in home branch wiring.

AFCI indicators should be inserted directly into the receptacle. Some AFCI indicators, such as the popular #61-165 model produced by Ideal, offer a number of testing options. This indicator creates eight to 12 pulses of 106 to 141 amp charges in less than a second which should be recognized by the AFCI as a dangerous arc and cause it to open the circuit that it serves. The indicator can also test for nuisance tripping, the annoying tendency of an AFCI to open its circuit when it detects a safe, shared neutral connection. For this test, it produces a 300mA arc that should not cause the AFCI to trip. Some AFCI indicators conveniently incorporate a GFCI indicator into their design.

CAUTION:  AFCIs recognize characteristics unique to arcing, and AFCI indicators produce characteristics that mimic some forms of arcing. Because of this, the indicator may give a false indication that the AFCI is not functioning properly. If this occurs, recheck the operation of the AFCI using the test and reset buttons. The AFCI button test function will demonstrate proper operation.

 

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• lightweight. It is, in fact, the lowest-density solid on the planet. Some types are composed of more than 99% air, yet they still function as solids;
• extremely high in surface area. It can have a surface area up to 3,000 square meters per gram, meaning that a cubic inch of aerogel, if flattened out, could cover an entire football field; and
• strong. It can support up to 4,000 times its own weight. In the picture at right, a 2-gram piece of the material is supporting a 5-pound brick.

The following qualities will also assist with identification. Aerogel:

• appears blue due to Rayleigh scattering, the same phenomenon that colors the sky;
• feels like Styrofoam® to the touch. Although a slight touch will not leave a mark, pressing more firmly will leave a lasting depression or even produce a catastrophic breakdown in the structure, causing it to shatter like glass; and
• is rigid. Despite its name, it is hard and dry, little resembling the gel from which it was derived.

Aerogel is derived from gels, which are substances in which solid particles span a liquid medium. The first aerogel was produced from silica gels, although later work involved alumina, chromia, carbon and tin oxide. Through a process called super-critical drying, the liquid component of the gel is removed, leaving behind the hollow, solid framework. The resulting aerogel is a porous, ultra-lightweight lattice composed of more than 90% air. Ordinarily, drying of a gel results in its shrinkage and collapse (think of Jell-O left out for a few days), but super-critical drying is performed under intense heat and pressure that preserve the structure of the gel.

Manufacturers offer the material in a variety of forms, such as the granules pictured at right, made by Cabot, which are sometimes used as insulation in skylights. Aspen Aerogel® offers 57-inch wide rolls of the material in 0.2- and 0.4-inch thicknesses, while Thermoblok® comes in 1.5-inch wide strips that are used to cover framing studs and help prevent thermal bridging at a cost of about $1.99 per foot.

Safety

Aerogel safety is dependent on the safety of the gel from which it was made; it will be carcinogenic, for instance, if the gel from which it was derived had this quality. Fortunately, silica-based aerogel is not known to be dangerous, although it may irritate skin, mucous membranes, eyes, the respiratory tract, and the digestive system. Aerogel is hydroscopic and extremely dry to the touch, which can, in turn, cause it to dry out unprotected skin. Gloves and goggles are recommended for inspectors and contractors who must handle the material.

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