1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How do I calculate BTU?

  1. Aug 5, 2010 #1
    I have a gas water heater that has an exhaust of 475 degrees Fahrenheit. I would like to know, what formula can I use to determine the amount of BTU's that the water heater produces (or wastes) per hour of use. I only have the temperature of the exhaust (475 Deg. F) and the diameter of the flue which is 3". I would appreciate any help or guidance. Thank you.
     
  2. jcsd
  3. Aug 8, 2010 #2

    russ_watters

    User Avatar

    Staff: Mentor

    You can't calculate it from the exhaust temp. But You can read your gas meter a couple of times when it us running. Or read it off the nameplate...
     
    Last edited: Aug 8, 2010
  4. Aug 13, 2010 #3
    You could do an experiment . A BTU is the amount of heat needed to raise one pound of water one degree F . You could place a glass jug of water near the exhaust and measure the temp increase . And of course measure the amount of water . Or you could
    do it in calories , then convert to joules and then divide by the amount of time it took so this will give you power .
    At least this would give a crude approximation .
     
  5. Aug 18, 2010 #4
    @ cragar: it is a great method to estimate the heater's power within three orders of magnitude.

    @attitudeworks: it is impossible to tell using only this information. Can't you contact the company?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook