Posted by Harold Kestenholz - Hydronic Network on March 10, 2001 at 13:09:26:

In Reply to: What size Hot Water Heater do I need? posted by Scott L on March 10, 2001 at 10:30:00:

This is a common problem. It requires different approaches depending upon the family situation. If everyone agrees to shower in sequence, take the number of people who can take a shower before the water runs out, see how many other people must take a shower one-after-another. Add them all together. Divide the number who successfully took a shower into the total who shower. Multiply this number times the number of gallons in the existing water heater. This will indicate the total storage volume needed to shower everybody in the family once every other two hours.

Another approach is to find out the recovery rate of the water heater as you now do. If one person can take a shower with one tank full of water, find out how long it will take to reheat the tank of water so the next person can shower. Then have each person shower at a designated interval so they can have a warm shower. This might take one hour for an oil-fired heater, three hours to get everyone showered if the heater is gas fueled or six hours if the heater is a 52-gallon electric heater.

Water heating must be tailored to the family negotiation customs.