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Rather than ignoring the instructions, read them, avoid making assumptions and, when in doubt, do not hesitate to call a professional. With that said, the following highlights common water heater installation problems to be aware of.
Note: While not listed below, make sure you follow any local installation code requirements and obtain any necessary permits before beginning an install. Failure to do so may includes hefty fines, voiding your water heater warranty, or putting your home and family in danger.
Disconnection from Power Source Must be In-Sight or Lockable
For your safety, the first issue must be to deal with power. When working on an electric water heater, you must have a way to ensure the power remains off for the duration of the work being performed. When the breaker panel is in sight of the water heater, then using the water heater circuit breaker is sufficient to accomplish this.
However, if the panel is not in view, you need to have either a disconnect switch, a breaker or a pull-disconnect box installed near the unit. Outside of those options, you still can secure the power shut off by using a locking device that you can install right onto the water heater breaker switch located in the main panel.
Protect Electrical Cords in Conduit
As old-fashioned methods give way to modern tried-and-true practices, you do not often see a cord and plug to a nearby wall receptacle within sight of the water heater anymore. However, if this is how your unit is connected, be sure to protect your cord within the proper flexible electrical conduit.
For units that are installed in a separate compartment or an attic, this protection is not necessary.
Accessibility is Mandatory
Out of sight tends to keep things out of mind, and this is no less true when it comes to water heaters. The lifespan of a water heater is about 10 years, give or take. You should expect to need to access the unit at some point. Even tankless models need maintenance at some point.
So, if it is housed in the attic, there should be proper access in the form of a solid floor at least 24-inches wide that runs to a 30-inch square platform in front of the unit and no more than 20-feet from the opening hatch of the attic. At this opening, you should also have a power switch to the water heater along with a light source installed near the unit connected to a receptacle outlet.
With Gas, Location is Everything
Unless your gas water heater (see also ‘What To Do When A Water Heater Gets Frozen?‘) is housed inside a dedicated enclosure, it must never be enclosed. Housing a gas water heater in a storage room, bedroom, bathroom or their respective closets increases the risk of carbon monoxide poisoning.
Dedicated enclosures have solid weather stripping with a self-closing door and combustion air from an exterior source. One would assume certain things go without saying, but it is surprising how, with gas, it bears repeating that flammables need a minimum clearance. You need at least 6-inches from a single-wall metal vent or 1-inch for Type B double-wall.
Water Leaks are Extremely Rare with New Installations
Since you are dealing with connections at both the hot-water outlet and the cold-water inlet, these are the obvious culprits for water drips or leaks. Sometimes leaks are associated with the fitting around the Temperature and Pressure Relief Valve, or TPR, which can be tightened or repaired.
Incorrectly Installed TPR Valve and Drainpipe
The TPR is intended to release tank pressure, and while every water heater comes with a TPR valve, they do not come with drain pipe that is needed to direct the release of hot water downward to avoid scalding.
Configuring the discharge piping has to do with where the water heater is installed (see also ‘How To Install A Water Heater‘). It needs to be directed downward toward the ground or floor to within 6-inches specifically to guide the scalding hot water away from anyone who might be near the unit as this occurs.
The piping needs to be the same size or as big as the cold-water pipe but rated for hot water, which rules out PVC pipe. The piping cannot have any traps where water can be held but, instead, must be a direct downward pipe. There is a requirement that the end of the drainpipe must not be threaded to make it impossible to cap it off.
Take Your Time to Avoid Dry Fire
When it comes time to check if the unit is producing hot water, you need to wait until the unit is completely full of water before the electric power is restored and applied. This is important because you can easily burn out the upper heating element if you power it up too soon. This is a condition that is referred to as Dry Fire.
The best recommendation to prevent Dry Fire is to open a hot water faucet in the home allowing it to run fully open for at least three minutes before you power the water heater back on.
When you have reattached lines, air can get into them. Running the water will ensure that all the air is pushed out, water has reached the element and the lines are full before power is turned on.
However, if you have burned out the element, a replacement is both inexpensive to buy and widely available. Replacing the element is an easy task. If you have proceeded as recommended and there is still no hot water, you can first check to see if the unit is getting power, then you can check if the element has been burned out.
Checking the Power
A circuit tester and multimeter are useful if you need to check the electrical power. You must take care to turn off the breaker when you access the panel on the unit beneath the insulation and the plastic cover.
The supply wires are usually the top two wires but check your manual to be sure. Reconnect the breaker to check for voltage. Most residential water heaters run on 220/240 volts. If it is not getting the proper voltage, this could be an issue with your home’s wiring and a good time to consult with a qualified electrician.
These are not all of the issues that you must be careful of when installing a water heater. When installed improperly, there is potential for violent explosion, electrical shock due to flooding and the possibility of contaminated water.
Be prepared to get the required building permit and final municipal inspection after installing a new water heater in your home to meet current safety standards. There must be no short-cuts in the installation of a water heater.