Saving Money on Water Heater

The Tank Saving Money on Water Heater

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    Hello@! I currently have 2 40 gallon natural gas water heaters in series. My house is about 3600 sq feet with 4 bathrooms and a whirlpool tub and 3 kids. The current water heaters American General (junk) need to be replaced. I am leaning towards the AO Smith 40 gallon Pro Max Series. Not looking for anything fancy but my question is around energy efficiency. Is it cheaper to operate 2 40 gallon nat gas units (.59 EF)? or one larger 75 gallon unit? Just wandering if I need to buy 2 units or just one larger. The estimated energy costs for each unit is $309/year but I am sure that it’s not as simple as just adding $309 + $309. Not sure how much a 75 gallon costs to run/operate?

    To Summarize
    1. Cheaper to operate 2 units or one larger? Is it true that if one of the units fail that both need to be replaced?
    2. Based on info above what gallon size would be appropriate?
    3. Should I buy one large unit or 2 small units?
    4. Any recommendations on specific models?


    AO Smith makes good heater. Air intake/ flammable vapor screen located on bottom, so stand 3-legged water heater on bricks so screen can be more easily inspected and cleaned.
    Modern water heaters require ample amounts of fresh clean air. Make sure venting is not obstructed.
    One water heater has less surface area that two heaters, so expected energy loss would be better with one heater.
    If you have two heaters, one can be set at lower temperature especially during summer months when incoming water is warmer and water heater does not have to raise temperature of each gallon as much as when incoming water is cold.
    If you have two tanks, and one goes bad, then you replace the one bad tank… no need to replace both.
    Don’t turn on hot side faucet when using water… since cold water immediately enters tank, even if hot never arrives at faucet.
    AO Smith posts service manuals on their website, and product amnual includes required maintenance. Read manual to ensure correct installation.
    All water heater warranties are about the same, with 1 year full parts and labor, and then parts and tank after 1 year.
    AO Smith uses generic anode rod that can be inspected and replaced so tank does not rust out.
    Others probably have different opinions.

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