Description
The term "commercial" in regards to water heaters simply means it has one or more of the following features which are different from residential water heaters. Commercial heaters put out a minimum of 75,000 british thermal units. They also have a clean-out port on the side of the water heater (residential water heaters have to be cleaned out with special equipment and the drain valve). Commercial gas water heaters also have multiple gas flues and automatic ventilators. Commercial electric water heaters may have an ignition feature. Cold water also enters from a cold water inlet near the bottom instead of the top; cold water entering the bottom is definitely the better way. Commercial water heaters may be found in residences as well as commercial businesses. The commercial water heater will also cost thousands of dollars more than a residential heater.
Side Port
Only after the water heater is emptied, can the side port be removed. It is bolted to the tank with one or more bolts. To remove it, loosen all the bolts and tap the side port piece with a hammer from the outside. It will fall into the empty tank. Pick it up and turn it on its end in order to pull it through the opening. The side port is often an oval shape. Now the inside can be vaccuumed using a shopvac, but you'll need an extension piece for the shopvac's hose. NOTE: Household vaccuums and hand-vaccuums do not generate enough power and usually do not have a long enough hose to clean the side port.
Clean the the opening of the side port of debris and, if possible, replace the gasket. The gasket must be put back on correctly and be undamaged in order to get a water tight seal.
Gas Heaters and Flues
Multiple flues inside the tank add to the surface area inside the tank and heats more water faster than residential heaters. Commercial heaters have multiple flues running upward through the tank. Cleaning around them is difficult but can be accomplished with a special 3 foot nozzle you can attach to the end of a rubber yard hose. Do not chisel or strike the surface of the flue to remove any sediment. This could damage the thin metal. Lye can be used to dissolve sediment inside the tank and on the flues, but only use it if you know what you're doing. Call a professional if needed.
Impressed-Current Anode Rods
These anodes found in commercial heaters work via electrical energy supplied from an electrical outlet or other source. If impressed-current anodes are installed in your tank, it will be stated on the wiring diagram found near the instructions on the front of the tank. If you have drained the water heater and opened the side port, you can observe if there is any rusting on the interior surface. If rusting appears, call the manufacturer, a plumber, or install sacrificial anode rods instead.
Removing Sediment
To clean sediment from a commercial heater, first shut off the gas or electricity and the recirculating pump if there is one. Next drain the tank of all the water using a rubber garden hose attached to the drain valve found at the bottom of the tank. The drain valve looks like an outdoor hose bibb similar to those found on the outside of a house. Close the valve on the hot water outlet, cold water inlet, and recirculation lines. Open the T&P valve to speed up the draining process. If there is so much sediment that no water will exit via the drain valve, remove the drain valve and use an ice pick or screwdriver to break up the sediment through the opening where the drain valve was. It will be messy so be prepared. Now you can unbolt the side port, rinse down, and use a shop vac on the inside. Do not strike or chisel the inside surface of the tank. Hire a plumber if needed to chemically dissolve the harder sediment inside the tank. Plumbers have special tools for this process. Don't forget to replace the gasket on the side port after you reinstall it.