Blog About Stuff That's In Your Home | Appliances and Stuff

21 Jul 10 HVAC BTU and Ton

I show how to calculate the tonnage raging based on the BTU information on a data label.
Video Rating: 4 / 5

This is the first troubleshooting video.
Video Rating: 4 / 5

Tags: HVAC

Reader's Comments

  1. |

    @apnaconstruction You should put about 2 pounds of refrigerant per ton of air before starting the system for a weigh-in charge or for superheat and subcooling charge.

  2. |

    so how many lbs r22 i need to put in 3 ton unit
    there is any calculator for that ??
    how to calculated freon to put in unit ??
    Dr z

  3. |

    @blissJesus1 You could get a ductulator from a HVAC parts house. Just line up your duct size and cfms to get your friction rate. Friction rate is the amount of drag there is on the air flow.

  4. |

    dr. Z,
    I am trying to wrap my mind around friction rates, with length of duct by size; for example’ A duct is 40 ft. long, and is 6 in. by 9 in.. The quantity of air to be delivered is 400 cfm. What is the friction rate?. Is there a simple way to understand how to figure this out?, and thank you Dr. Z, your the best HVAC/ YOU TUBER.

  5. |

    @Aussie50 The refrigeration “ton” comes from ice. It takes 144 BTU to melt 1 lb of ice. A ton 2000lbs in the US would absorb 288,000 BTU in melting. The scale is based on it melting in a 24hr period which would be 288,000/24=12,000
    So the ton of ice as it melts in one day’s time would absorb 12000 BTU per hour

  6. |

    @whyms1 Yep, Usually you can call the manufacturer and ask how much more refrigerant needs to be added per foot of line set.

  7. |

    @DrZarkloff Does the lenght of the line set effect the amount of gas needed to charge a HVAC system Mike Key West, Fl

  8. |

    @whyms1 the refrigerant charge should always be weighed in with packaged systems. Split systems, with the exception of mini split systems, should be charged by superheat or subcooling.

  9. |

    how do you calculate the amount of refreg gas to put in a system when rechargeing a hvac system

  10. |

    @yantur52 Thanks for watching.

  11. |

    You r the best teacher that I see at this time for real thanks to be here.

  12. |

    @uchemp I live in High Springs, Florida. I was born in Ohio, raised in Arizona and I’ve lived in Florida nearly all of my adult life.

  13. |

    Here are you from?

  14. |

    @DrZarkloff ill have to see how its done at a few of our customer’s buildings… and come back to you on that. there rough. even our experienced tech who can handle em, hates them to hell and back lol.

  15. |

    @death2opposeme All of the zoning controls that I work on are by computer. Alerton is the most common.

  16. |

    zone control systems just flat out dont work. they cant keep up in the summer time.

  17. |

    say Dr. Z you got anything on zone controls?? or 24v communication boards?? or anything like water towers, chillers, boilers, larger package units with rtrm or upc boards in them. ice machines or drink machines?? i do a little of everything. im lucky starting out on the large equip.

  18. |

    Hi dr zarloff just want to say you are doing a wonderful job in helping us young A/C techicians. im a A/C and refrigeration technician from Jamaica. a good topic would be types of compressor and how they work. respect, nuff luv seeen yeh man

  19. |

    I’m sure that it can be done. I all depends on the type of compressor. Be it scroll, reciprocating, centrifugal, screw, rotary, etc.

  20. |

    DR Z can you figure the btu.s by measureing current readings ? If so can you make a short video to prove the point thanks very much for your videos Pete from Newyork city electrician

  21. |

    1 ton = 12,000 BTU. BTU/HR: means British Thermal Units per hour. One BTU is the amount of energy that it take to raise one pound of water one degree F.

  22. |

    Just a question… I thought 1 ton = 12,000 BTU/hr. BTU is unit of energy, where BTU/hr is a unit of power? What am i doing wrong?

  23. |

    Thanks for watching.

  24. |

    thanks a lot man that really helps… i am a pretty ignorant person when it comes to things like this… i learned something thanks to you..

  25. |

    that’s right!!

  26. |

    @DrZarkloff too werid for me

  27. |

    big girl

  28. |

    @deyenak1 If you think that she is nutty in this video, you need to check out her channel DearestBecky.

  29. |

    your wife is nutty on this video

  30. |


  31. |

    @cruz47144 Thanks for watching.

  32. |

    Thanks for posting your videos. I’m a electrician by trade but have always been fascinated by HVAC. I use to listen to cooltalk online before discovering your videos. Installed my own complete system and I got certified on refrigerants. Saved a ton of money. I’m grateful for learning more. I service my families systems.

  33. |

    @mxdunksdad You really should replace the bad high pressure switch. You might want to clean the coil in your out door unit. It’s easy to do. Just turn off the power to the unit and use a hose to clean the coil. Coil cleaner isn’t always a necessity unless the coil is really a mess. It is possible for a dirty coil to be why your condensing unit is shutting down on high pressure.

  34. |

    HI DrZ, I have looked at all your videos to try and fix my outside unit a 3.5 ton Ducane split AC. The condenser stopped running ( heat pump ) it was not heating the AC guy came out and snipped the two HIGH pressure wires and tied them together the only way it would come on connect it and the little spring switch wont engage. The problem is the High pressure now overheats and stops cooling I have had three guys out and they cant tell me what to do any advice ? i ran the heat and temp drops to

  35. |

    @vector00234 when checking the HP switch and LP switch, do you have to disconect both wires or only one?

  36. |

    @jrm1559 Thanks for watching.

  37. |

    Dr. Z is a great HVAC/R. The problem I had with this video is that it jumped/skipped. I was trying to very closely follow but the video seemed to jump and I may have missed something critical to know. I appreciate Dr. Z.

  38. |

    I was just told by my Instructor to always put the gauges on and check the pressure.

  39. |

    @Tyrone7994 Thanks for watching.

  40. |

    Good points. I agree that you should not automatically put the guages on a system that is not running. Great video. I’m a hvac student with 3 months to go until I complete the hvac program at my college. I just got my universal and I’m looking to learn as much a possible. Keep the videos coming.

  41. |

    oming out the high and low dude you need to disconnect from the board as this will return false readings

  42. |

    oming out the high and low dude you need to disconnect from the board as this will return false readings

  43. |

    have to admit im guilty of that one. im quick to pull out the gauges

  44. |

    @DCGamer92 Thanks for watching.

  45. |

    Dr. Z Truly a good video on how to troubleshoot a heat pump/air handler. im in the HVAC program at my schools vocational school this really helps me catch up to the shops standards troubleshooting is a big part of it so thanks for the help!

  46. |

    @mike111777 Thanks.

  47. |

    @handyman0587 Thanks for watching.

  48. |

    great video keep them coming i learn more from you then i do from my apt supervisors and my school

  49. |

    You are the man Dr Z. Fist bump.

  50. |

    your the best