This article below is from The ASHI Reporter. Homeowners need to know the seriousness of maintaining the water heater. Retrofitting or installing TPR valves can prove disastrous & dangerous.

The most important part of your client’s domestic hot water system

“The steam-powered tank hurtled across the busy intersection at First Avenue South and South 152nd Street — over at least six lanes of traffic — before landing more than 439 feet away in the parking lot of a Pizza Hut.”

This excerpt from a July 28, 2001, article in the Seattle Post-Intelligencer describes what happened when a water heater with a capped Temperature Pressure Relief (TPR) valve overheated and exploded.

High limit controls

Water heaters have thermostatically controlled devices that keep them from overheating. Both gas and electric water heaters have temperature-limiting devices that shut off the energy source when their regular thermostat fails. Electric heaters have a high-limit switch that interrupts the power when overheating occurs. Many of us have seen and perhaps reset the device by pushing a small red button under the cover plate and just above the thermostat dial.

Thermostatically controlled gas valves found on most residential gas water heaters have a safety shutoff built into the gas valve itself. When they react to excessive temperature, the gas flow to the burner is stopped. Generally not resettable, the entire control valve has to be replaced to get the water heater up and running again.

These devices are the first line of protection against water heater explosion. Should they fail, a temperature pressure relief valve, which should be installed within the top 6 inches of the tank, should prevent the heater from suddenly becoming a bomb or launching like a rocket. In both of the explosion events described earlier, it appears a properly installed TPR valve would have prevented the carnage.

Austin Texas - ASHI Home Inspector

All septic systems are either anaerobic or aerobic type systems. Most homes built prior to the early 90’s have a conventional (anaerobic) system. In recent years many homeowners are spending the extra money to install an aerobic system. There are advantages and disadvantages to both systems.

Conventional septic systems are the least expensive type of system to install and maintain. They are designed to settle waste in the bottom of a tank that is buried in the ground. Bacteria then processes the waste. Effluent (liquid waste) is drained out into lateral lines that are buried in crushed rock below the ground. The earth cleanses the contaminated effluent. One major problem with this type of system is that clay soils are dense and will not absorb the effluent. It is recommended that the tanks be pumped and inspected approximately every 2-3 years.

An aerobic system has the ability to process waste within the system at a very high rate. Once the effluent has been cleansed and chlorinated it can then be used to water the yard. These systems are popular in areas that have heavy amounts of clay in the soil or on small lots that cannot support enough lateral line to effectively operate a conventional system. In order to have an aerobic system installed, most areas require that you maintain a quarterly maintenance schedule with a licensed professional.

Water leaks are constant problems home inspectors face. Bathtubs and showers need to be kept grouted and caulked. This is typically somewhat of an ongoing maintenance issue. You don’t want water entering behind the tiles and becoming trapped in the wall. This will cause the tiles to become loose on the wall and the wall itself to deteriorate. It will be best to use the original type of grout or caulk when making repairs. The one exception is, you should use a silicone caulk at the base of the tile around the bathtub. Getting in and out of the tub tends to separate grout at this seam. A soapy finger or spoon will leave a smooth finish when applying caulk.

Water heaters should be flushed every year. The first thing that you will need to do is shut of the gas or power to the unit. Connect a garden hose to the valve at the base of the unit and begin draining the water heater. Exercise caution while doing this, as the water will be hot! Leave the cold side shut off valve open in order to flush the unit properly. You will want to flush the water heater for about 5 minutes. If the drain valve drips slightly after being closed, take a metal hose cap and a washer and place it on the valve fitting. All water heaters have thermostats to regulate the temperature. Do not set it all the way up, especially if you have young children in the house. Someone could get burned. All water heaters should have a temperature and pressure relief valve installed somewhere near top of the unit. The relief valve is designed to relieve pressure in the tank if the thermostat fails and the unit continues heating beyond the preset temperature. The drain line from that valve should empty to the outdoors. Make note and check that area occasionally for indications of leakage. The T&P drain line should never empty under a pier & beam house.

The plumbing lines that penetrate through the roof are vent pipes to your sewer system. Dangerous gases are vented out of the home through these vents. Sometimes they can be used to run a plumbing snake through to clear a clogged drainpipe.

Outside faucets play an important role in maintaining a home’s foundation and landscape. Leaky exterior faucets can lead to foundation problems if repairs are not made in a timely manner. Remember to disconnect all hoses from faucets before freezing weather sets in or the pipes in the wall may freeze and break. During exceptionally cold weather, open the sink cabinet doors at exterior wall. This will also help keep pipes from freezing.
It is a good idea to have a water meter key and wrench in the garage. You never know when you may need to shut the water to the home off quickly.

Plumbing cross connections especially in older homes can be a health hazard that should be evaluated by a licensed home inspector. In Austin, Texas we have several communities where the age of homes range from the 1920’s - 1960’s. Most cross connections will be found in the bathroom tubs or toilets, but not excluding sprinkler systems & hose bibs. Cross connections can be repaired simply and should not be ignored. Ask your ASHI home inspector about cross connections.

As an experienced home inspector in Austin, my advise to clients when buying an older home (pre 1974) on slab foundation is that metal supply pipes & cast iron drains be evaluated by a licensed plumber performing a “hydrostatic test”. This test reduces, but does not eliminate all risk of undetected faulty pipes that could cost $10,000’s to repair. Make sure your home inspector identifies the type of drain pipes, approximate age & recommends a “hydrostatic test” of the pipes prior to your purchase.
Below is an article from Russell Strahan, an Austin based P.E. who put well into words the crisis of metal & cast iron drains. Read his article to know what you are getting before you close on the pre 1974 home.

ANTIQUATED PLUMBING MATERIALS IN CENTRAL TEXAS
Background
Slab-on-grade construction appeared in central Texas in the late 1950’s. Once the materials handling equipment (ready-mix plants and trucks) become available, slab foundations quickly became much less expensive than wooden floor structures used in pier/beam houses. By the early 1960’s pier/beam no longer could compete in specification housing.
As with any new technology, the adoption of residential slab foundations was progressive and conservative. Some desirable aspects of these older foundations include:
Heavy conventional reinforcement.
High-quality concrete (no admixes and relatively little shrinkage).

Accurate formwork.
Excellent finishing techniques.
In general, these slabs can be remarkably damage-tolerant. They often flex without rupture better than their modern counterparts.
But as is also typical for new technology, some problems have also become apparent with the passage of time. These include:
Poor attention to mudsills, reveals and freeboard, placing the walls close to the ground (esp. at garages). Inferior fill practice, placing soft, erosive bank sands beneath slabs.
Poorly sealed plumbing penetrations, creating concealed foraging areas for termites.
Antiquated plumbing materials (primarily cast iron drain lines, although some galvanized supply).
All of these can be intractable, but the most problematic issue is plumbing materials. Most of our local soils are alkaline, resistive and remarkably corrosive to uncoated ferrous materials. Any iron piping buried in these soils inevitably corrodes away. After drain piping fails water is introduced into supporting fill and soils. On deep clay soils, this can lead to substantial foundatiqn movement.
Cast iron drain lines were used almost exclusively in old houses. In the early 1970’s metallic drains were displaced by ABS, then PVC plastics. The only other common alternative was wrapped terra cotta pipe (and most of these failed right away). A few houses also have galvanized iron supply piping, but modern, seamless copper tUbing was already prevalent by 1960.
The structural consequences of subslab leakage are highly variable, potentially affecting both settlement patterns and slab integrity. Observed examples in houses known to have subslab leaks:
No measurable effect, other than clogging drains.
No measurable movement, but large voids formed beneath slab (fill erosion). Sudden heaving without rupture (occasionally recovered after leak repair). Sudden heaving and rupture (severe foundation damage).
Progressive subsidence (permanent without expensive repairs, but ruptures are rare).

Cast Iron Drain Replacement
Once a section of piping has corrosion failures, the only substantial repair is to replace all of the wet-service piping beneath the house. This is a relatively expensive repair, largely due to the difficulty in accessing the piping. Replacement costs can range from $20,000 to $100,000+. Four basic techniques have been developed in the last decade:
Chipping through the Floors - Literally trenching the interior floors of the house.

Subslab Tunneling -Excavating access tunnels to the plumbing fixtures beneath the house.

Horizontal Boring - Tunneling to drain connections, then machine-boring for new pipe runs.
Route Around - Chipping or tunneling to drain connections, then running pipe around the house.
The most appropriate technique depends upon specific conditions such as local geology, the plumbing layout and available fall to the sewer hook-Ups. Because some of these operations can obviously affect foundation integrity, it is advisable to have a Professional Engineer oversee the process.

Homeowner’s Insurance in Texas
In earlier years there was variable homeowners’ insurance coverage for subslab piping. Some companies simply rejected all claims, others would replace the piping, and the best would replace piping and repair any foundation damage. This inconsistency led to many disputes and a few lawsuits.
In the late 1990’s a Texas Supreme Court ruling ordered that the promulgated insurance policies for owneroccupied properties must cover both the piping and consequential foundation damage. For a few years the situation was clear-cut - Detect a leak, file the claim and get new piping installed. Thousands of systems were replaced and it was during this period the replacement techniques were established and refined.

HOWEVER, Texans were also filing a phenomenal number of mold claims during this period, forcing a crisis in the insurance industry. Although never associated with mold, mildew or indoor air quality problems, subslab piping coverage has been removed from the most common promulgated policies in Texas.

The Situation for a Texas Homebuyer
State regulations do not require real estate inspectors to identify plumbing materials, much less assess their condition. If considering an older home with cast iron drain lines it is possible leaks are already present but undiscovered. A simple test to hydrostatically verify the drain lines can be conducted for $200-300 by a master plumber if a yard line clean-out is available. Installation of a clean-out can quadruple this cost.
If no insurance coverage is available, there is a triad of options:

Functionally Test Prior to Purchase
This is a simple test to verify the pipes will hold water. An exterior clean-out must be present. The plumber will block the outfall and fill up the drain system (usually by pulling out a commode), then watch the water level. If the water level consistently drops, then the system is leaking. Once disclosed, this becomes a ‘discovered’ leak and the house is effectively uninsurable for purposes of resale.
Note that even if no leaks are detected, future failure is still foreseeable.
Replace the Plumbing Regardless of Condition
This is obviously very expensive. Be advised that the liability associated with antiquated plumbing is generally not considered in current house valuations (this may change with time).
Ignore the Plumbing Until Damage Becomes Apparent
In this case the owner should be prepared to finance both a plumbing replacement and a foundation repair. Remember, some houses never show any distress (if you are feeling lucky).

Conclusion
Due to a combination of time-dependent material incompatibilities and recent regUlatory changes in Texas, the potential structural liability associated with older slab foundations has clearly increased for homeowners.
Cast iron plumbing systems are fairly easy to test (or even observe using camera equipment), but repair and replacement requires accessing components beneath the house foundation. This is expensive.
No regulatory changes are anticipated in the foreseeable future.
Good luck.

RDS August 2004