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indirect heaters sizing

Matt_21
Matt_21 Member Posts: 140
in THE MAIN WALL
30 1 bedroom 1 bathroom apartment building. the owner is looking to replace the boilers and water heaters. the building currently has 2-76 gallon 199,000 btu bradford white water heaters. is 150 gallons enough to service all these apartments or is more needed? how do you calculate how much each apartment will on average need?

Comments

  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Fixture Units

    Get a hold of the ASPE guide (exact name, sorry not in my head now) and other recognized guides.

    Normally the usage is defined in fixture units and this is applied to what is known as "Hunter's Curve" which averages multiple usages to a probability at a given time.

    (e.g.: If a given apartment requires 3.8 GPM at any one time, ten such apartments might require 27.5 GPM, just discussion numbers.)

    More to it than that, and there are other application considerations but it is a place to start.
  • jackchips_2
    jackchips_2 Member Posts: 1,337
    Hi Matt,

    One of the first things you can do in an existing facility is ask the owner if there have been any complaints of lack of hot water.

    As for sizing, almost all water heater manufacturers have design manuals and most of their sales reps will work with you in sizing the type of system you are asking about.

    Through experience over the years I have noticed that they are quite conservative which isn't necessarily a bad thing when dealing with hot water. It's something people want when they want it.

    Good luck,

    Jack
  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
    30 - 1 bedroom apts

    There is a ton of things to take into considderation. Some of the most important:

    Do they run out now?
    How many people per apt.?
    Showerheads - energy efficient or not?
    Age of tenants?
    Common laundry -vs- private?
    Dishwashers?
    What condition is the old equipment in? Any condensation damage evident?

    Without these pieces of information I cannot say difinitively, however replacing the existing equipment with like SHOULD leave a comfortable margin - IMO.

    If they don't run out now, it would be foolish to make a cut in capacity. You can store alot of hot water efficiently nowadays.

    ((edit - forgot a biggie... do they have building recirculation for hot water? ))
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