The Forgotten Appliance

The water heater is one of the most forgotten appliances in a restaurant. As long as the restaurant has hot water there is no need to worry about the water heater. As we have all experienced, water heaters always seem to leak or fail after hours and/or on the weekend when a restaurant is the busiest. With the Health Department frequently visiting restaurants all day long, all restaurants are now closing their doors if they have no hot water and from what we have heard it can take up to 24 hours for the water heater to be back up and running. The only time we think about the water heater is when there is no hot water running out of the faucet or there is water flowing out of the water heater room. Preventative Maintenance is a critical key to the performance of a water heater and recommended by all water heater manufacturers. Lack of maintenance = high operating costs = less profit.

In restaurants the most common water heater failures are caused by lack of knowledge, lack of air, mixing/crossover, lack of maintenance, and negligence.

Lack of Knowledge

Most managers are afraid of the water heater in a restaurant due to the physical size, and therefore want nothing to do with the water heater. There are many different types of water heaters in today’s market ranging from a standing pilot water heater, to an electronic ignition water heater, to a boiler and storage tank, to a high efficiency heater with a hot surface ignition, to a tank-less water heater. Managers need to know the basics of their water heater: location of the water heater, model and serial number (where to find the info), gas or electric, and how to reset the water heater if needed.

Lack of Air

All gas/propane water heaters need the following to operate: air (oxygen), fuel (gas), source of ignition (spark), and water. If there’s a lack of fresh air, the water heater will not operate correctly. This can cause flame rollout, sooting, pilot outages, and fill the restaurant up with a gas smell.

Mixing/Crossover

Mixing/crossover is caused when cold water crosses over into the hot water supply line. This will cause a possible “no hot water” or “water not hot enough” situation. Mixing can occur at the following locations: mop sinks, pre-wash sinks, goose neck sinks, tempering valves, mixing valves, some bar sinks, kettle pot sinks, or at any sink where the cold water supply and hot water supply are left on and a third valve is controlling the water flow to the sink.

Lack of Maintenance

Like other equipment in a restaurant, the water heater needs to be serviced at least once a year. There are a lot of factors that can contribute to the life of a water heater.

The average life span of a commercial water heater is 3 to 7 years depending on the water quality, location and environment. Water heaters may last longer. This is only the average life span for commercial water heaters.

    •       Water Quality

            •           There are anode rods inside the water heater. The anode rod protects the glass lining from corrosion. Once the anode rods are deteriorated, the tank will start to corrode. Softened water is exceedingly corrosive because the process substitutes sodium ions for magnesium and calcium ions. The use of water softeners may decrease the life of a water heater tank.

            •           Sediment buildup in the tank will also decrease the life of a water heater tank. This is caused from hard water. The calcium ions fall out of the water and settle to the bottom of the tank as the water is being heated. Once the tank starts to get full of sediment, the water heater has to work harder and will cause the water heater components to fail prematurely. Most commercial-grade water heaters have a cleanout port to remove sediment.

    •       Environment

            •           All water heaters need to have makeup air so they can burn and vent properly. Contaminates in combustion air can lead to premature heater failure. Vapors from bleaches, soaps, salts, cleaners, paint, gas, etc. will contaminate the air. These items should not be stored next to the water heater. Flammable items should not be stored next to the water heater.

    •       Location

    •       When water heaters are located on the outside of the building or on the roof, they are susceptible to weather damage if not properly covered. If the location is at the beach, the air will always be contaminated. There is no getting around the salt in the air close to the ocean.

Preventative Maintenance

There are about 20 items that should be regularly checked on a water heater to maintain the efficiency and performance of the water heater.

    •       Burners                                    Combustion Chamber             Damper                                   De-lime As Necessary

            •           Gas Valve(s)               Gas Supply                              Gas Leaks                   High Limit Cut-off

            •           Ignition System                       Pressure Relief Valve(s)                      Venting                                   Recirculating Pump(s)

            •           Thermostat(s)              Anode Rods                            Wiring                         Electrical Component(s)

            •           Water Shut-off Valves            Heat Exchanger                                  Storage Tank(s)                       Water Heater(s)

If these items are serviced or replaced on a regular basis, the chance of the water heater failing after hours or on a weekend will be minimized. By having a Preventative Maintenance program for the water heater, not only will it eliminate the emergency (overtime) service calls, but it will give the managers and the facility managers an up-to-date status of their water heater (age, condition, recommendations) for future planning.

Negligence

Waters heaters can be dangerous appliances if taken for granted. Just this past March, at a California manufacturing plant, two people were killed and three others were injured due to a water heater explosion. When items such as boxes, paint cans, brooms, mops, gas cans, salt and any other flammable objects are stored in the water heater closet, you could potentially have a disaster on your hands. We have seen restaurants burn down from boxes full of receipts being too close to the burner. The water heater area should be kept clean, free from debris, and not used as a storage room.

Tommy Guerra is vice president of Orange, California-based Water Heater Man, Inc. He can be reached at whminctg@pacbell.net.

Temperature and Pressure Relief Valves and Expansion Tanks

All water heaters are equipped with safety devices from the manufacture.  One of the most common that almost everybody knows is a Temperature and Pressure relief valve.  A Temperature and Pressure (T&P)relief valve relieves water when the water in the tank reaches about 195 degrees, when the pressure in the tank reaches about 120psi, when there is thermal expansion, or when the valve is faulty.  Temperature and Pressure relief valves can be rated with different pressure ratings depending on the application.  They can range from 30psi (hydronic) – 150psi (domestic) for hot water systems.  Most State and local codes require the water pressure to be below 80psi.  When water pressure is above 80psi, there will normally be a pressure reducing valve installed to reduce the main water supply coming into the building. 

If a T&P relief valve leaks, it indicates there is a potential problem with the water heater.  When a T&P leaks it must be repaired correctly.  It is important that the cause of the relief valve leaking be determined by a qualified plumber or water heater specialist.  If not, the water heater can become a very dangerous appliance.  If a T&P is left leaking, eventually it will corrode shut and the device will no longer act as a safety feature on the water heater.  We have all seen people plug or cap off the T&P.  This is a BIG safety concern.   If a T&P is corroded shut, plugged, or capped off, your water heater now has the potential of becoming a rocket.  If thermal expansion is present and no water is being run in the restaurant, the pressure in the tank can increase upwards of 250psi and if the there are other faulty parts, your water heater can explode.   Water heaters have exploded in restaurants and after the investigation it has been ruled that a faulty T&P was to blame for the explosion.  In some cases, deaths have occurred from these explosions.  Weather is was due to lack of maintenance, negligence, or faulty parts, it is imperative to check out the operation of your water heater.     T&P’s have to be sized properly if and when they are replaced or installed.  A T&P has to be able to release the same amount of water per hour the water heater can heat up.  Example: if a water heater can heat up 240 gallons of hot water then the T&P must be able to discharge 240 gallons of water within one hour.  Incorrectly sized T&P’s can cause nuisances service calls. 

As discussed in the beginning the T&P can leak from Thermal Expansion.  What is Thermal Expansion?  When water is heated it expands.  Water cannot be compressed.  If there is nowhere for the excessive pressure to go, the T&P will start to discharge some water from the system so it can relive pressure in the tank.  It like boiling a pot of water on stove with a lid, the longer the water is heated eventually the water will over flow and spill out all over the stove.  The longer you heat the water, the more expansion occurs.  Equipment in a restaurant can assist in creating thermal expansion.

In almost all restaurants there is either one or multiple of the following: water softener, back flow preventer, water pressure reducing valve, and check valve.  When hot water is used, cold water has to refill the tank.  When the water heater turns on to re- heat the water, the water in the tank will start to expand.  If the water system has one of these devices, the expanded water will have nowhere to go unless a hot water faucet is open.  When the expanded pressure in the tank rises and gets to about 115psi the T&P will start to weep.  The T&P starts to drip and has the pressure increase the drip turns into a stream until the pressure in the tank is relieved.  If somebody in the restaurant opens faucet on the hot water line the pressure in the tank is relieved and the cycle starts all over when the heater heats up another tank of hot water.  When any of these devices are installed on the system, it creates a closed system.  A closed system means there is nowhere for the excessive pressure to go unless a faucet is open.  Unlike an open system, when the water heater heats up the water, the excessive pressure will have the cities potable water supply to absorb the excessive pressure.  Open systems do not have one of these devices.

Water softeners and pressure reducing valves may have a built in check valve.  A check valve is a device that only allows water to flow in one direction.  A back flow preventer has the same concept.  It stops contaminated water from going into the main water system.  When a water heater is installed and a plumber installs a check valve on the cold water line, the system has just been closed.  An expansion tank should be installed between the check valve and the water heater.   Some State and local codes may require the installation of an expansion tank on the water heater system.   

An expansion tank is secondary tank that gets installed on the water heater system.  It is imperative to make sure that the expansion tank is installed after a check valve, water softener, water pressure reducing valve, and back flow preventer.  Most expansion tanks will be plumbed in on the cold water line.  They can be installed on the hot water line, but it is not recommended.  All expansion tanks will have a temperature rating of the water that can fill the tank.  When expansion tanks are installed they can be installed anywhere.  If the water heater room is tight and an expansion tank is won’t fit in the same room, it can be installed somewhere else as long as the water feed to the expansion tank is between the water heater and the device mentioned above. 

How does an expansion tank work?  Expansion tanks are made of steel with a rubber diaphragm in the middle.  They have two sides in side of them.  Half the tank is filled with air and the other half is filled with water.  The side of the expansion tanks that is filled air will need to have the same air pressure as the water pressure going into the building.  Example: if the water pressure for the building is 75psi then the air pressure in the expansion tank should be 75psi.  Because air is compressible, this will allow the expanded pressure on the water side to push the diaphragm into the side of the expansion tank that has been filled with air to absorb the excessive pressure.  When someone opens up a hot water faucet the excessive air in the expansion tank is released.   The expansion tank will absorb the excessive pressure in the water heater system.  This relieves some of the expansion and contraction from the water heater.  Expansion tanks much like T&P’s have to be sized properly for the system.  Expansion tanks can prevent your water heater from failing prematurely.  Expansion tanks are relatively inexpensive and very easy to install.  Expansion tanks should also be checked for proper operation.  If the rubber diaphragm gets a hole in it or malfunctions the expansion tank will fill up with water and there will be nothing absorbing the excessive pressure except for your water heater, pipes, fittings, T&P leaking, or faucets. 

All water heater manufacturers recommend expansion tanks.  Not only will they relieve the hour to hour stress on the steel tank (expansion and contraction) every time the water heater turns on, but is will also help protect the piping, fittings, joints, and faucets.    If a water heater is septible to thermal expansion and the problem is not corrected the manufacturer’s warranty may be voided.    Please check with your water heater manufacturer for warranties. 

Be sure to check with your local building department for code requirements on expansion tanks, T&P’s, water pressure reducing valves, and back flow preventers.  You Tube has some great examples of water heater explosions.