There was a post here in the RAIN the other day that recommended replacing your own electric water heater.
I would like to caution anyone from taking on this project unless you really know what you are doing. Improperly installed water heaters can result in dangerous conditions and merely copying the old installation will almost guarantee that the new one will be installed improperly.
In the spirit of the other post I will stick to discussing the installation of electric water heaters. Here is a list of a few of the things you need to know about installing your water heater. If you do not know the answer to these questions, or do not know what some of the words mean, then you most likely are not qualified to tackle the project yourself. The answers to some of the questions is further complicated by there being different answers depending on your jurisdictional requirements as well as where in the house the heater is located.
Very first question: Will my installation conform to IRC or UPC?
Will you need a permit to change the heater?
Will your new heater need seismic strapping?
Will your new water heater need a water collection pan under it?
Will your new heater need a foam pad under it?
Does your water heater need heat-traps?
Will your heater need an expansion tank?
Can I use a flexible connector on my TPRV drain?
Can I use PVC on my TPRV drain?
What happens if you empty the old water heater and don't turn the power off?
Does my water heater need a Vacuum Relief valve?
What size water heater do I need for the number of fixtures in the house?
Does the wiring have a proper connector to the heater?
Will you utilize a lock-out device while working on the heater?
Can the TPRV drain slope upward?
Can the end of the TPRV drain be threaded?
How many 90 degree elbows can be used in the TPRV drain?
Can the TPRV drain terminate in a pan under the heater?
Can the TPRV drain terminate at a laundry sink?
Does the TPRV drain need an air gap?
What is the maximum temperature that the water heater should be set at?
If you think that none of these questions are really important, if you go to sell your home and the water heater during its life span, the home inspector that inspects your home will be looking for these things--and more.
Charles Buell, Real Estate Inspections in Seattle.
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WA State, Home Inspector Advisory Licensing Board