It’s Not Always the Contractor’s Fault.

Although the time has come when warmer weather is upon us, the effects of this past winter are still being felt.  Recently, we were involved in an investigation that focused on the cause of damage to a water cooling coil located inside of a cooling tower (see photo below).  This might seem strange to some but, it is possible to require the cooling of a building during the winter.  In the investigation we were performing, the system was comprised of a water cooled water chiller.  This might not mean anything to most people but to those familiar with chiller operation, water was the fluid used to both cool the air and remove the heat absorbed by the refrigerant.  On the condenser side, water was circulated through a shell and tube heat exchanger and then pumped to another coil type heat exchanger located inside the cooling tower.  The problem arose when the local air temperature began to drop below freezing.  As the water temperature dropped below 40 F, water flow between the condenser and water coil was stopped (as part of the automatic control sequence).  As the air temperature continued to drop, the water temperature also dropped until the water froze inside the coil and caused it to burst in several places.  Since this was new construction, it was the engineer’s position that the mechanical contractor had erred and was negligent in their responsibility to protect the equipment.  However, it was later determined that the building had been turned over to the building owner under the substantial completion part of the contract.  As a result, the building owner was responsible for the protection of the building as well as the building’s mechanical systems.  Regardless of the positions taken by the various parties, the design of the HVAC system including the incorporation of freeze protection, was the responsibility of the mechanical engineer.  This responsibility is not an arbitrary assignment.  It has been long recognized by engineers and specifically, those engineers that are involved in HVAC design.  Although freeze protection had been designed into other parts of the system, no provision for freeze protection was made for the cooling coil located inside the cooling tower.  When all was said and done, the engineer failed to incorporate an adequate way to protect the coil and blamed the contractor in order to avoid the appearance of failure on their part.

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Maytag Dryer Electrocution and Fire Hazard

Recently, we investigated the case of a minor fire that occurred in an electric dryer.  The dryer was purchased through a local home improvement store and installed by their crew.  When the dryer was test started, the vent line immediately began smoking and burning.  The dryer was later examined at the retail store where it had been purchased.  It was subsequently determined that one of the line cord connections at the terminal block, apart from the ground wire, was somehow connected to the dryer housing.  This connection, in effect, had made the appliance electrically “live”.  As a result, touching any metal part of the housing and something else such as a metal water pipe could have caused significant injury to the user.  However, since this was a new appliance and had never been used, the installers would not have been aware of the condition.  Instead, when the dryer was started, the housing was not only electrified but, current traveled through the aluminum exhaust duct to ground.  The exhaust duct was burned because it could not withstand the amount of current flow.  The dryer in question is manufactured by Whirlpool under the Maytag brand and is a model number MEDC215EW.  There are currently no recalls for this model.  At present, it is unknown if this is an isolated incident or if other incidents have occurred.

Destructive Force of Ice

As most everyone knows, this winter has been hard on just about every corner of the country.  It’s been a very cold winter and the southeast has had its share of low temperatures.  For this reason, buildings that must be protected against fire sometimes have to use dry sprinkler systems.  Conventional systems that pressurize lines with water up to the sprinkler heads are impractical because the lines are usually routed through areas (such as attics) that are subject to falling below freezing.  As a result, the water in the lines can freeze and cause the lines to beak or burst.  When thawing occurs, water damage will also occur.  In order to prevent such damage, dry systems are employed.  That is, instead of filing the lines with water, the lines are pressurized with air.  Pressurized air serves to keep the main water valve closed until such time as a fire causes the sprinkler heads to open and relieve the pressure.  As the air pressure is relieved, the main water valve opens, water fills the lines, and exits through the open sprinkler heads to fight the fire.  However, there are times when water can get into the branch lines.  Water can enter when there is a loss of air pressure due to a leak in the system or when water is completely removed such as after a hydrostatic test.  The photos below show what happens to an iron pipe tee when water is frozen inside.  In one instance, the tee is broken in half whereas in the second instance, the tee is fractured on one end.  Note that both fittings came from the same job.  Ice typically expands between 9 and 12% by volume and as a result, places a tremendous amount of pressure on the fitting walls to cause failure.

Rheem Water Heater Recall

On May 26, 2016 Rheem recalled approximately 50000 electric water heaters.  The problem with the appliances was that the temperature control could overheat resulting in a fire.  The recall applied to 40, 50 and 60 gallon units.  Recently, we encountered a water heater where a fire had occurred and caused damage to the upper control area including the circuit board that controls the water temperature. In this instance, damage was limited to the upper front of the appliance and the ceiling of the closet where the water heater had been installed.  However, if the fire had gone unnoticed, the fire would have spread to the remainder of the structure causing significant damage.  Water heaters involved in this recall are still in circulation.   Consumers are advised to contact Rheem if they have an appliance that should be replaced before a fire occurs.  A copy of the recall is shown below along with Rheem’s contact information.

 

Holiday Greetings

R.J. Hill Consulting would like to wish everyone a very

Happy Holiday Season!

 

How NOT to Install a Water Filter

We recently investigated the cause of failure of a water filtration unit that cracked and caused an extensive amount of water damage to residential dwelling.  During the course of the investigation, it was determined that a whole house water filter unit had been installed in a cabinet beneath the kitchen sink.  This location is perfectly acceptable as were the piping connections that were made to connect the unit to the cold water supply line.  However, when the upper and lower halves were assembled, the pieces were put together with pipe joint compound.  This is absolutely unnecessary and amounts to an improper installation.  The filtration unit comes with an O-ring that is intended to fit between the halves and seals any gaps while preventing water leakage.  Although the unit failed as a result of over pressurization,  the presence of pipe joint compound indicated that the filtration unit had been improperly maintained.  The failure of the unit is shown in the photographs below.

Continuing Education Update

We just completed a seminar on steam system design.  The course covered such topics as sizing steam valves, traps and pilot valve applications.  The course also covered piping distribution as well as load balancing.  Following accepted design practices is as important as correctly sizing the components that make up the system.  With more concern placed on the conservation of energy, the time when ignoring energy waste has come and gone.  More and more energy codes are being adopted by states in an effort to curtail energy waste.  Tennessee, for example, follows the International Energy Code.  As a result, architects and engineers can be held responsible for not following proper procedure as outlined in those energy codes.  More importantly, architects and engineers can be sued if their designs do not perform as building owners expect.  It then follows that insurance carriers that provide errors and omissions coverage for architects and engineers have to pay for designer’s mistakes.  Those of us that practice in forensic engineering will be looking for deviations from code requirements as well as accepted design practices.

 

 

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