Plumbing Vents andTraps

Once again, The Word invites you to travel into the dark realm of subjects that are sometimes misunderstood by home inspectors. The Word hopes you will find this trip informative and maybe a little entertaining.

The Word's subject this month is plumbing vents and traps. The Word finds this subject interesting because these components often don't get the full attention they deserve as protectors of our clients' health and safety.

Remember, when reading all The Word columns, that we're discussing general principles. Something you see in the field isn't always wrong just because it doesn't comply with a general principle. Local building codes, manufacturers' instructions and engineered designs trump general principles.

Why traps?

Traps keep sewer gas out of the home. So, what's the big deal about an occasional obnoxious odor? Well, sewers contain all sorts of nasty organisms that make people sick, and a dry trap provides a path for these organisms into the home. This is a health hazard. Sewers also contain methane, the same stuff that flows through the gas meter. Try sticking your combustible gas detector into a sewer pipe; your detector might go off. While unlikely, sewer gas can explode and cause a fire. This is a safety hazard. So, traps are a good thing and protecting them is important. That's where vents come in.

Why vents?

When stuff flows through the drainpipes, the air pressure in the pipes increases in front of the stuff and decreases behind the stuff. The air pressure increase can blow sewer gas through the trap's water seal and even force water out of the trap. The air pressure decrease can suck the water seal from the trap. Both can happen in homes if the venting system isn't properly installed. Vents admit air into the pipes that helps equalize the air pressure in the pipes to prevent blowback and siphoning of the water seal in the trap.

The trap

All fixtures need one, and only one, trap that is set level. Fixtures with an internal trap, like a toilet, do not need and should not have a separate trap. One trap provides the water seal to keep out sewer gas. Two or more traps impede flow and are more likely to become clogged.

Between the fixture and the trap is the tailpiece. This pipe should be smooth-walled material that is compatible with the trap material. The flexible, ribbed material available at big-box retailers isn't allowed because the ribs hold unsanitary materials, and this material is prone to clogging. The vertical distance between the fixture and the trap should be less than 24 inches. This helps prevent stuff from building enough force to blow out the trap's water seal.

A trap may serve more than one sink, but only if the sinks are less than 30-inches-on-center apart. The horizontal distance between the fixture outlet and the trap inlet also is limited to 30 inches. These limits also help avoid trap seal blowout. Figure 1 demonstrates this rule. These distances sometimes are exceeded in bathroom remodels when one sink is replaced with two sinks.


Figure 1

Trap size

The trap serving most sinks and separately-trapped dishwashers should be at least 1½ inches diameter. Bathroom (lavatory) sinks should be at least 1¼ inches diameter. Clothes washing machine standpipes should be at least 2 inches diameter. Bathtub and most shower traps should be at least 1½ inches diameter. This is a recent change for shower traps, which used to be at least 2 inches diameter. Shower traps may need to be up to 4 inches diameter depending on the flow-through multiple shower heads and body sprays. Most of us rarely, if ever, will see this type of shower, so the 1½ inch diameter trap is a good number almost all the time.

Prohibited traps

Several trap configurations that once were allowed no longer are allowed. You may see these traps in older homes. Drum traps were used for bathtubs. You still can get them. The problem with these traps is that they are prone to clogging, and they are less sanitary than the modern P trap. Bell traps were used for floor drains. They also are prone to clogging and are less sanitary. These traps are a reportable deficiency in newer homes. In older homes, The Word just advises clients that these traps are prone to problems and should be replaced if and when it's convenient.

Then there's the S trap. (Cue Darth Vader's theme.) You'd think from all the negative talk about these traps that they are some evil product from the dark side of the force. S traps are used in other parts of the world and there's nothing wrong with an S trap if it is properly installed and vented. Note the caveat. S traps often are not properly vented. The problem with the S trap is its sensitivity to proper installation and venting compared to the P trap; thus, it is more prone to losing its seal. Like drum and bell traps, S traps are a deficiency in newer homes, but can continue to serve in older homes. You might want to make your clients aware of the potential problems. Figure 2 shows the drum, bell and S traps.


Figure 2

The fixture arm
The fixture arm (also known as the trap arm) is the pipe that connects the fixture trap to its vent. Figure 3 demonstrates this. Most amateur plumbers, and a few professionals it seems, don't realize that the length and slope of the fixture arm is important to avoid siphoning the trap. It makes sense when you think about it. If the fixture arm outlet is below the trap outlet, it's like putting a hose in a gas tank to siphon some of the gas into a can. The trap will be siphoned and lose its seal. Figure 4 demonstrates this.

Figure 3



Figure 4

Pipes smaller than 3 inches diameter should slope at least ¼ inch per foot and ideally not much more. At ¼ inch per foot, a 1¼-inch fixture arm for a bathroom sink will be below the trap outlet after 5 feet. This, coincidentally, is the maximum allowed length for a 1¼-inch fixture arm. The maximum length for a 1½-inch fixture arm is 6 feet and a 2-inch fixture may be no longer than 8 feet. Remember, rules may be different in your area.

Vents

Unless you're performing a pre-drywall inspection, it's unlikely you will be able to inspect most of the vent system. There's no point in going into the details of venting systems, but a quick summary may give you some perspective. There are many ways to configure a vent system to protect multiple traps with one vent pipe. Wet vents protect multiple traps by using one strategically placed vent near the beginning of the vent system and by using an oversized drain/vent pipe to let stuff flow while providing enough air to protect the traps.

Figure 5 shows a horizontal wet vent. 


Figure 5

Branch vents are dry vents that connect two or more individual or common vents above the flood-rim level of the highest fixture served and let one vent pipe serve several traps. These are some of the most common vent systems protecting multiple traps.

Air admittance valves are an alternative to extending multiple vents outdoors. Air admittance valves can be used to protect one trap. They also come in types for protecting multiple fixtures. You should see the listing ANSI/ASSE 1051 on single fixture and branch AAV or ANSI/ASSE 1050 on stack AAV. If you don't see this listing information, call for evaluation by a licensed plumbing contractor. You may be looking at a check vent.

Beware of a device that looks like an air-admittance valve but really is a check vent (also known as a cheater vent). Check vents are approved for use only in manufactured homes and recreational vehicles. You should not see them in site-built homes. They usually don't last as long as air-admittance valves and are more prone to failure. Look at the label on the device.

Air-admittance valves should be installed at least 4 inches above the fixture arm and should be installed within at least 15° of vertical. An air-admittance valve installed too close to the fixture arm might be damaged or leak if the fixture arm backs up. An air-admittance valve that isn't level might not open and close properly. Air-admittance valves should be installed at least 6 inches above the flood rim level of the highest fixture served and at least 6 inches above insulation in attics. Air-admittance valves should be accessible for replacement.

Air-admittance valves are great for situations where extending a vent outdoors is impractical or undesirable, but they have some use restrictions. They are not allowed in some jurisdictions. They should not be used to vent any sump or sewage ejector. They should not be located outdoors. At least one vent in every home must terminate outdoors.

The bottom line

Sewer gas needs to be kept in the sewer for health and safety reasons. But don't assume that a foul smell is evidence of a problem. Frequently, it's nothing more than a trap where the water seal has evaporated due to lack of use. The Word sees this frequently in foreclosed homes and sometimes in his own home where the shower in the hall bathroom is rarely used. Running water in seldom-used fixtures solves that problem.

Fixing real problems with traps and vents can be simple or it can be difficult and costly. The Word hopes that you now have a better handle on how to inspect the visible parts of these components.

Memo to Poseidon and the other water gods: The Word does not reside on Mt. Olympus (just at its base) and welcomes other viewpoints. Send your lightning bolts or emails toBruce@DreamHomeConsultants.com. The thoughts contained herein are those of The Word. They are not ASHI standards or policies.

From the ASHI Reporter 

Dryer Vent and You

What we want to focus on in this tutorial is showing you how to remove dangerous lint build up in your dryer and dryer venting. Excessive lint build up occurs slowly and gradually. You don't realize it is happening. You think that by cleaning out the lint filter after each use you are doing your job and maintaining the dryer. Not quite!

A full load of wet clothes contains about a half gallon of water.Lint is created from the clothes as water is removed during the drying process. This lint will build up in crevices deep down inside the lint filter trap, and all along the dryer vent hose. At the end of the day, your dryer is the number 1 source of fire in the home.

In 1999 the U.S. Consumer Product Safety Commission (USCPC) developed a report called the “Report on Electric and Gas Clothes Dryers.” In that report they determined that of the 15,000 fires studied in one year, electric dryers were over 2.5 times more likely to be the cause of the fire than gas dryers. Fires originated most frequently from two places: dryer venting and the lint trap.

What are the warning signs that dangerous lint build up is occurring in your dryer and venting system? Well, the symptoms may include:

• Clothes take longer and longer to dry;
• Clothes don't fully dry;
• Clothes are hotter than normal at the end of the drying cycle;
• The outside of dryer gets very hot;
• The outside exhaust vent flapper does not open very much indicating low exhaust velocity;

• Laundry room becomes more humid than it is usually;
• Burnt smell is evident in the laundry room.
• 
  
• Dryer Vent Cleaning Brush Kit
  To effectively clean your dryer and dryer vent hoses / venting system, you will need a special brush for this dryer repair. Vacuum attachments alone do not work as well because they do not agitate the lint to separate it from the duct and it is this physical agitation that is important.
  There are a few different dryer duct cleaning brush kits or tools out there, but I've found the best value to be a great little kit called the LintEater® Jr.

Remove the Lint Trap FilterThis is the step you are most familiar with and probably do on a regular basis such as after each load. As a matter of fact, this step is probably all you have ever done, just like 90% of the population. Although this step of cleaning the lint filter is important, it does not solve the problem of lint build up in the dryer or in the ducting. However it is important as a first line of defense and we need to do it, so:

• Remove the lint screen by pulling it straight out;
• 
  
• Clean the screen of any lint by gently brushing it with the fine bristled cleaning brush.

Vacuum Lint Trap Housing CavityOK, now we start getting to areas of the dryer where you're going to find all kinds of lint hidden away. The next area you want to clean is the lint trap housing cavity, the cavity from which you pulled the screen out. You'll need the long flexible fiberglass handle of the brush kit to get into this area.

• Extend the brush all the way into the bottom of the cavity;
• Using a gentle and slight twisting motion, pull out the brush to expose the clumps of lint it has removed;
• Using a household vacuum cleaner or shop vacuum, vacuum the brush head clean of any lint;
• Repeat this process until there is no more lint that can be removed from the cavity.

This can be a DIY project...but we recommend a professional inspect and clean. They have the tools and experience to do this right.

We recommend DUCTZ of West St. Louis

What is a Broken Seal in Windows

WHAT IS DOUBLE-GLAZING?

Double-glazed doors and windows are made up of two sealed sheets of glass with an insulating void between them. This gap is either in the form of a vacuum, or more commonly, filled with a heavy inert gas such as argon. Together, the panes of glass and the void between them are very effective at preventing heat loss – in fact the U-value for a new double glazed window can be as low as 1.7, while a single glazed window in comparison has a u-value closer to 5.

However, overtime the effectiveness of the double-glazing can wane, especially if the seal goes around one of the panes of glass allowing air to replace either the vacuum or the inert gas between the panes.

The most common side effect of a seal going is that the window will fog up, as water vapour condenses on the inside surface of the window. So once you start describing your windows as foggy, misty or steamy when you try to look through them – it means that the seals have failed, or at least have started to fail.

WHY HAVE MY DOUBLE-GLAZING SEALS BECOME DAMAGED?

This can happen due to a number of reasons, however the most common tends to be general wear and tear as the double-glazing unit ages. Continuous changes in temperature cause fluctuations in the sizes of the glazed unit, since they expand in the warmth and contract in the cold, and over time this can loosen and damage the seals.

Particularly strong cleaning products can also sometimes eat away at the seal, so even though we all like being able to see through a really clean windows, make sure the cleaning product you are using is not chemically abrasive.

Other reasons for your double-glazing unit failing include faulty installations or faulty production methods, however on the whole these should be covered by your window installer, so it is key to make sure you keep your FENSA certificate and a receipt of any work carried out.

As the perimeter seal goes, then this moisture will start to enter the double-glazing unit. Normally there is a silica strip within the void, that absorbs small amounts of moisture and separates the glazing units, however, as soon as this becomes saturated the condensation rapidly increases leading to it misting up the entire unit.

It is possible to reseal your damaged double glazed windows and there are many sources on the Internet that will tell you how to do it yourself. However, to be honest we are pretty against this.

In the first instance, give your double-glazing installer a call. Most double-glazing companies will not attempt to reseal a window fitted by another company, however if you can get hold of the original installer, you may find that they charge a fraction of the price for resealing, compared with replacing the whole window unit.

The true fix though is sadly also the most expensive – simply replacing the window unit altogether. To be honest this is definitely not the most cost effective fix – replacing any form of double glazing (working or not) with a new double-glazing unit will obviously allow you to see through the window and it will have some impact on energy efficiency, however the energy savings you will make will go no where near to covering the installation costs.

However if the view out of your window is your pride of joy, unfortunately you only have one choice and that is to pay for a replacement. We really do recommend getting hold of the original installer if you can though, since they might be able to re-seal it or offer you a repeat-order discount.

WHAT ABOUT WARRANTIES?

Whatever you do, check to see if you have a warranty/guarantee left of the windows. If you do and the windows are still showing signs of inner pane condensation, then presume that the cause was faulty installation and you may be able to replace them free of charge using the same company. However, if the warranty has expired then expect wear and tear to be the main contributor, and brace yourself for the replacement of double glazed units.

Air Conditioners

One of the most common air conditioning problems is improper operation. If your air conditioner is on, be sure to close your home's windows and outside doors. For room air conditioners, isolate the room or a group of connected rooms as much as possible from the rest of your home.

Other common problems with existing air conditioners result from faulty installation, poor service procedures, and inadequate maintenance. Improper installation of a central air conditioner can result in leaky ducts and low airflow. Many times, the refrigerant charge (the amount of refrigerant in the system) does not match the manufacturer's specifications. If proper refrigerant charging is not performed during installation, the performance and efficiency of the unit is impaired. Unqualified service technicians often fail to find refrigerant charging problems or even worsen existing problems by adding refrigerant to a system that is already full. Learn what to ask for when hiring a technician to maintain your air conditioner.

Air conditioner manufacturers generally make rugged, high quality products. If your air conditioner fails, begin by checking any fuses or circuit breakers. Let the unit cool down for about five minutes before resetting any breakers. If a central air conditioner's compressor stops on a hot day, the high-pressure limit switch may have tripped; reset it by pushing the button, located in the compressor's access panel.

REFRIGERANT LEAKS

If your air conditioner is low on refrigerant, either it was undercharged at installation or it leaks. If it leaks, simply adding refrigerant is not a solution. A trained technician should fix any leak, test the repair, and then charge the system with the correct amount of refrigerant. Remember that the performance and efficiency of your air conditioner is greatest when the refrigerant charge exactly matches the manufacturer's specification, and is neither undercharged nor overcharged. Refrigerant leaks can also be harmful to the environment.

INADEQUATE MAINTENANCE

If you allow filters and air conditioning coils to become dirty, the air conditioner will not work properly, and the compressor or fans are likely to fail prematurely.

ELECTRIC CONTROL FAILURE

The compressor and fan controls can wear out, especially when the air conditioner turns on and off frequently, as is common when a system is oversized. Because corrosion of wire and terminals is also a problem in many systems, electrical connections and contacts should be checked during a professional service call.

SENSOR PROBLEMS

Room air conditioners feature a thermostat sensor, located behind the control panel, which measures the temperature of air coming into the evaporative coil. If the sensor is knocked out of position, the air conditioner could cycle constantly or behave erratically. The sensor should be near the coil but not touching it; adjust its position by carefully bending the wire that holds it in place.

DRAINAGE PROBLEMS

When it's humid outside, check the condensate drain to make sure it isn't clogged and is draining properly. Room air conditioners may not drain properly if not mounted level.

Home Inspection Tips

There are some home maintenance and repair issues that, given a choice, most property owners are likely to procrastinate, whether because they take time, cost money, or just don't seem all that urgent.

If it's not an entirely apparent or nagging issue, it might take some time to be addressed. But some of the most serious problems hide masked behind a beautiful facade and could turn any dream home into a nightmare on Elm Street.

The following are some top structural and mechanical time bombs that experts say have the potential to blow up in order to spot and squelch them in a own home, before the big boom.

Foundation

A small crack in the brick veneer on the exterior of their home is no big deal, right? Not always. What looks like it can be solved with a cosmetic fix can sometimes indicate a deeper problem with moving foundation.

Hire a structural engineer immediately to evaluate a home's foundation. If caught early, a repair might only cost a few thousand, but if it's too late homeowners are looking at one of the most expensive home repair jobs possible with a whopping $50,000 price tag.

Roof

A roof can appear completely fine from the front while still crumbling elsewhere. That's why most people end up making the tragic mistake of waiting until they see water leaking through the ceiling to identify roofing issues.

Water usually enters the attic first, so regularly inspect for stains around the chimney and vents. To be on the safe side, have a roof inspected every five years.

Septic system

Many rural homeowners rely on septic tanks for their sewage systems, which operate by breaking down solids and liquefying them. That liquid then goes out into the lines and is dispersed into the surrounding ground.

While extremely useful, these tanks are also highly susceptible to clogs from other materials, like cigarette butts and food waste. Save the cost of digging up the yard to repair the whole system and opt for a cheaper maintenance alternative: regularly pumping the tank every three-to-five years, checking for signs of clogs and leaks routinely between inspections

Old electrical system

Homes built prior to World War II didn't have to meet the same requirements for power that are now a standard in home construction of recent years. With all of this generation's high-tech amenities, older wiring just can't handle today's electrical demands.

Sockets and switches can wear out, breakers grow less reliable as they age and heavy use of extension cords could lead to a fire. Squelch worry about these larger problems with a thorough electrical system inspection every 20 years. If a home doesn't meet the code, people will want to replace the entire electrical system to avoid a major fire hazard.

Crawl space

When it comes to maintenance and repair, the out-of-the-way and untraveled crawl space is one of the most overlooked areas of the home. But because the crawl space is like the window into the belly of a home, it could also hold the key to revealing any number of problems before they get bigger and expand to other areas: weakening floors, termite damage, and even issues with heating and cooling ducts.

Grab a flashlight and routinely take a peek at this so-often storage spot; even call in a home inspector, if looking for a second opinion.

Furnace, HVAC unit

When someone's heating goes, the only real fix it is to replace the furnace, which will cost upwards of $6,000. But keep up maintenance on a current unit about every six months and they won't need to break into emergency savings.

Hire an HVAC professional to come and inspect everything to make sure the system is running smoothly. Another easy way to improve air quality, efficiency and extend the life of a unit is to replace the filter at least every 90 days, or less, if people have allergies or pets.

Deck

Building a deck is sure to boost the value to a home, but if homeowners don't keep up with maintenance, their piece of curb appeal could unexpectedly fall apart.

While deck maintenance runs roughly $100 a year, the average cost of replacing it from the ground up is closer to $10,000. Save big bucks by simply keeping it clean, re-securing any nails, and reapplying sealant as needed.

A full inspection at least once a year will help people determine what work looks necessary and catch any early signs of rot.

                  Good information from The American Society of Home Inspectors

How Serious is a Cracked Heat Exchanger?

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By Reuben Saltzman

It's an industry standard: if a furnace has a cracked heat exchanger, it gets replaced.  The American Gas Association has even put this in writing - they say "Any visible crack or hole is reason for requiring replacement of the heat exchanger or furnace."  When I inspect a furnace and I find a cracked heat exchanger (and I find a lot of them), I always say to replace it.

So what's the big deal with cracks or holes?  A cracked heat exchanger could allow exhaust gas from the furnace to contaminate the household air with carbon monoxide.   In order for this to happen, the furnace must be producing high levels of carbon monoxide AND the exhaust gas must be mixing with the household air.  For a good example of a hazardous heat exchanger, check out the photo below showing a large rust hole in the heat exchanger of this high-efficiency furnace that was only ten years old.

Cracks, on the other hand, I'm not so sure about.  With the majority of the cracked heat exchangers that I've seen, I've always been curious how the exhaust gas from the furnace could possibly leak out of those tiny cracks enough to contaminate the househouse air.  Of course, what I'm curious about doesn't matter... but sometimes my curiosity gets the best of me, and I have to find out for myself.

So I did. I took home a furnace that had a cracked heat exchanger, tore it apart, and removed the heat exchanger cell that had the largest cracks.  You can see the cracks for yourself below - click on any of the photos for a larger version.  This first photo shows the cracks as seen from inside the heat exchanger cell - this is what we saw during our inspection.

I wanted to see if water would leak through these cracks, so I doused the outside of the heat exchanger and looked inside for any signs of leakage.  Nothing. I've heard that penetrating oil, such as WD40, will get through the cracks, so I tried that next.  Nothing. Feeling pretty disappointed at this point and determined to get some results, I filled the heat exchanger with water.  I laughed like a mad scientist at what happened next.

Water began to leak out of the factory seam in about ten different places, but the crack never leaked.

Why does this tiny crack mean the furnace should be replaced?  Because the American Gas Association says so.  Don't argue. 

Apparently, when heat exchangers get very hot the metal expands and the cracks open up, allowing air to leak in to or out of the heat exchanger.  Just because my test didn't allow any water to leak doesn't mean that this furnace was safe, and it doesn't mean that a different furnace will behave the same way... but I sure found it amusing.

Winterizing Your Sidewalks and Driveways

As a homeowner, there will always be tasks that need to be done at least once a year. When was the last time you really looked at your sidewalk and driveway? Are there any cracks? Are there any weeds growing through those cracks? Winter moisture in the form of snow and rain can worsen existing cracks in pavement. With some prevention now, you can save yourself major repairs in the spring.

Cracks in Sidewalks

The cracks are an easy fix. For concrete sidewalks some of the supplies you’ll need include a stiff brush, concrete crack filler and a putty knife. You can find these items at any home improvement store. The crack filler is usually in a caulk-like tube, so make sure you have a caulking gun.

Clean out the cracks with a stiff brush. Rinse with a high pressure water hose, or if you have a compressor blow the area clean. If you are using water pressure, make sure to let the area dry thoroughly before filling with the concrete filler. Squeeze the concrete repair material into the crack and smooth with a putty knife. Please be sure to read all the directions ion the concrete repair material before beginning your project.

Expansion Joints in Sidewalks

Cracks are not the only things you should maintain on the sidewalk. Expansion joints (the spaces between the sections of sidewalk) will also need maintenance. When sidewalks are first laid, there is a felt-like material that goes in between the joints. This material breaks down after a few years so something needs to fill this area to protect it from freezing and thawing. The items you need for maintaining this area include foam window insulation and liquid tar (in a squeeze bottle).

Prep work for expansion joints is the same as for cracks, but the finishing is very different. Do not use concrete repair filler in this area. Liquid tar is the item of choice here. If the groove is very large or deep it can get expensive to fill it entirely with tar. The alternative is to use window insulating rolled foam. This material can be used as a back filler in the joint. It comes in many different diameters, so measure the width and depth of the groove so you’ll know what size to get.

The joints are easier to do than cracks. All you have to do is push the foam into the cleaned space and then cover it with tar. The foam and tar are flexible enough to take all that winter has to throw at it.

Shifting or Leaning Slabs

If you notice any leaning, upheaval or shifting of your sidewalk, it is time to call a contractor. They may need to mudjack your sidewalk to make it level again.

Driveways-Blacktop/Concrete

If you have blacktop, sealing is suggested at least every 2 to 3 years. Temperatures should be above 50 degrees to do this. Get all the grass overgrowth off the edges of the driveway. Sweep with a stiff brush and hose off any leftover dust. Scrub any grease or oil spots with a strong detergent and rinse again. Let it dry thoroughly. Apply a thin coat of sealer with a squeegee. Follow the manufacturer’s directions. Do not walk or drive on the area for at least 24 hours. It may look and feel dry, but resist the urge and wait the full 24 hours.

If your driveway is concrete, follow the same procedure as for the cracks in sidewalks.

Gravel Driveways

What about gravel driveways? The biggest problem with gravel is that most of it ends up in the lawn by spring. A remedy for that is to leave the first snowfall on the driveway and use your car to pack down the snow. The packed down snow will hold all that gravel in place. Now you can take care of the next snow fall by either blowing or plowing without throwing all the gravel into the lawn.

Annual tasks aren’t all that difficult, and doing them maintains the value of your property. Simple maintenance of sidewalks and driveways could save you costly repairs down the road.