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How much A/C do we need?

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  • How much A/C do we need?

    I really need some expert advice. My church has been getting some quotes for an air conditioner installation in our main sanctuary and the quotes range from 35,000 BTU to 60,000 BTU. The room is 30 x 65 ft with a 13 foot ceiling. How many BTU's or tonnes do we need for such a room that can fit 100 people? The climate here is Ottawa can get very hot and humid so a summer day of 90 degF is not unusual.

  • #2
    Re: How much A/C do we need?

    You need to get a "manual n" done to calculate the btu load. I would call in a local AC company to handle this.
    Buy cheap, buy twice.


    • #3
      Re: How much A/C do we need?

      Cooling the room is useless if the system does not account for the load of the occupants. We have a commercial building here that has 10 tons of cooling which is enough for the room itself. They forgot to figure the room holds 350 people. Everytime there is a wedding or large function in the summer, atleast 1 person seems to pass out from the heat.

      A person at rest produces 700BTU. That same person up moving around or dancing is about 900BTU. Just in occupant heat alone you have 70,000 BTU of heat. Now figure the building requirements. Are you at an altitude that requires deration of the equipment is another factor.

      If the church does not want to look at more than 5 tons then there you go. I don't see anyway of going less than 5 tons.


      • #4
        Re: How much A/C do we need?

        I'm thinking a 10ton package unit with 2 stage cooling.



        • #5
          Re: How much A/C do we need?

          i say you need to ask the people you got a quote from how they came up wit there size
          if they say its off the top of there head say good bye
          if they ask you haw many windows ,people ,lights and insulation there is in the room then they will put it in a computer program and it will tell them what you need

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