How To Clean and Remove Sediment from a Commercial Water Heater

Commercial water heaters have several features that differ from residential water heaters. To begin with, commercial heaters produce a minimum of 75,000 British thermal units whereas residential heaters residential water heaters produce anything less than 75,000 British thermal units.

Also, commercial heaters have a clean-out port on the side of the water heater; residential heaters must utilize the drain valve and require specialized equipment in order to clean them. With commercial gas water heaters, there is more than one gas flue and automatic ventilator, and with commercial electric heaters, there is often an ignition feature.

One other difference is that on a commercial water heater, the cold water inlet is at the bottom of the tank instead of the top. This allows cold water to enter the tank at the bottom—a definite improvement over residential heaters.

Commercial water heaters are, of course, used for commercial businesses, but they may also be used in residences. However, commercial heaters do cost thousands of dollars more than residential heaters.

Once you've decided on a commercial water heater, you'll need to know how to care for it.

1. Removing Sediment. Before cleaning and removing sediment build-up from your commercial water heater you must first turn off the gas or the electricity, as well as the re-circulating pump (if there is one), and then drain the tank.

   To drain the water tank you will need to attach a garden hose to the drain valve at the bottom of the tank. The drain valve looks similar to an outdoor hose bib like those found on the outside of any house. You will need to close the valve on the hot water outlet, cold water inlet, and recirculation lines; then open the T&P valve in order drain the water from the tank.

   If no water comes out because of sediment blockage, remove the drain valve entirely and use an ice pick or screwdriver to break up the sediment in the drain valve opening. WARNING: Do NOT strike or chisel the inside surface of the tank. Now unbolt the side port (see Side Port), thoroughly rinse out the tank, and use a shopvac on the inside of the tank. This will be messy, so be prepared.

   Note: Household vacuums and hand-vacuums do not generate enough power, and usually do not have long enough hoses to clean the side port.

   When you are finished, remember to replace the gasket on the side port after you reinstall it.

   Plumbers have specialized tools to chemically dissolve the harder sediment inside the tank, so if you have pervasive sediment build-up, hire a plumber rather than risk damaging the tank by chiseling it away yourself.

2. Side Port. The side port is bolted to the tank with one or more bolts, and you can only remove the side port after the water has been drained from the tank. Once drained (see Removing Sediment), loosen all the bolts and then gently tap the side port piece with a hammer from the outside until it falls into the empty tank. The side port is often an oval shape so once loose, you will need to turn the side port piece on its end in order to pull it through the opening.

   Now you can vacuum the inside with a shopvac, using an extension piece for the shopvac hose. Make sure you also clean the opening of the side port as well. If possible, replace the old gasket with a new one; a damaged gasket will not be able to prevent leaks. Be careful to reinstall the gasket properly in order to create a water tight seal.

3. Gas Heaters and Flues. Commercial water heaters have multiple flues running up through the tank. This creates more surface area inside the tank which allows more water to be heated faster than residential heaters. Cleaning around these flues can be difficult; however, you can accomplish this with a special 3-foot nozzle attached to the end of a rubber garden hose.

   When removing sediment, do NOT chisel or strike any sediment on the surface of the flue because this could easily damage the thin metal. Sediment on the flue must be dissolved chemically. Lye can do this, but only use it if you know what you are doing. Most likely you will need to call a professional plumber.

4. Electric Heaters and Impressed-Current Anode Rods. Impressed-current anode rods used only in commercial water heaters require electricity from an electrical outlet or other source. If your electric heater is installed with impressed-current rods, the wiring diagram found near the instructions on the front of the tank will state this.

   After draining the water and opening the side port, check to see if there is any rusting on the interior surface of the tank. If rusting is present, call the manufacturer, a professional plumber, or replace the impressed-current rods with sacrificial anode rods instead (see Anode Rods).