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Water heater sizing & idle operating costs

jserr68594 | Posted in General Questions on


I have a vacation condo that I am looking to install a hot water heater into. The condo has a kitchen sink, bathroom sink, and 1 shower. I am wanting to make sure that I have enough water to shower 2 people in a row. I have a 2.5 GPM shower head. What size water heater would be best?

I am also trying to figure out a rough idea of the idle costs of water heaters when they are just keeping the water warm and not being actively used. I was originally planning on going tank less, but I do not have the electrical capacity to do so. I am assuming I will need a 20-40 gallon water heater. If the idle costs are very similar, I am thinking the larger water heater is the way to go.

Any input is appreciated! Thank you!

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  1. GBA Editor
    Martin Holladay | | #1

    The correct way to size a tank-style water heater is by its first hour rating, not its capacity. Here are links to two documents to help you:

    Sizing a New Water Heater

    What size of water heater do you need?

    I'm guessing that a 30-gallon electric resistance water heater will work in your case.

    Standby losses depend on the R-value of the insulation around the tank. If you want a unit with minimal standby losses, look for a unit with a high EF (energy factor).

  2. jserr68594 | | #2

    Thanks Martin!

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