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  1. #1
    Join Date
    Aug 2007
    Posts
    339

    Confused Load Calculations

    Just wanted to know when is it a good time to give a load cal to a customer? It seem like everytime I go to a customer house and do a load cal and give it to the customer they use it to get another companies bid and they get the job! Should I wait until they agree on my qoute before I do a load cal?

    Thanks

  2. #2
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    I give them the calc. after I get a signed contract. I also write incomplete model numbers on the quote.

    I had the same problem you have. They will give a copy to everyone that bids the system. There is just to much time involved to let that happen.
    Its a good Life!

  3. #3
    Join Date
    Aug 2007
    Posts
    339
    Quote Originally Posted by m kilgore View Post
    I give them the calc. after I get a signed contract. I also write incomplete model numbers on the quote.

    I had the same problem you have. They will give a copy to everyone that bids the system. There is just to much time involved to let that happen.
    So you just show them and take it with you? And by incomplete model numbers you mean the type of epuipment you have to offer them?

  4. #4
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    I doon't give them the manual J results while I am there. I write on the proposal that it will be a properly sized system per manual J calcs. If you give them the size of equipment that you came up with then its the same as giving them the calc. that you just did.
    Its a good Life!

  5. #5
    Join Date
    Aug 2007
    Posts
    339
    Quote Originally Posted by m kilgore View Post
    I doon't give them the manual J results while I am there. I write on the proposal that it will be a properly sized system per manual J calcs. If you give them the size of equipment that you came up with then its the same as giving them the calc. that you just did.
    Thanks for the info hopfully I will start making a profit now!!!

  6. #6
    Join Date
    Dec 2007
    Location
    East central Indiana
    Posts
    477
    Quote Originally Posted by m kilgore View Post
    I doon't give them the manual J results while I am there. I write on the proposal that it will be a properly sized system per manual J calcs. If you give them the size of equipment that you came up with then its the same as giving them the calc. that you just did.
    So, in other words, if your load calculation indicated they need 3 tons and 100,000btus, you would write the equipment as ABA***NI4R and 2AC13***-2, instead of ABA100NI4R and 2AC13036-2?

    What if they pushed the issue and asked you what the ***'s stood for?

  7. #7
    Join Date
    Nov 2004
    Posts
    977
    I would tell them they could have the detailed results of my labor intensive load calculation for $ 500.00, with that amount taken off of the quoted price if they elect to go with me.

    I don't even list anything near a model number. M Kilgore has it right about quoting a "properly sized unit".

  8. #8
    Join Date
    Oct 2004
    Posts
    37
    I'm looking at the LACK of ability to compare bids as a homeowner from the other side of the fence.

    Because I have a scientific and math background, I always want numbers to back up a proposal that is not in my area of expertise.

    What has happened with my home geothermal proposal is that I got three estimates, all for different tonnage.

    As a result I am inclined not to choose ANY contractor unless they can show me that they have justfication for sizing. This is especially important for geothermal.

    So what matters most to my selection is (1) backup information and (2) backup references that I can actually call.

    Without either of those things, no contractor is going to win my job.

    Sorry, but I just won't go out and drop tens of thousands on speculation and blind trust, the way some people buy a used car. I don't believe the final answer merely because a contractor says, "I have XX years experience and I did the calculations." When the numbers don't match between bids as to sizing, that proves to me that NOT ALL CONTRACTORS CAN BE CLOSE TO BEING RIGHT.

    Anyways, sorry you are having problems with people taking your results and picking someone else. However, I view this as the consumer has a right to know whether the decision they are making is based on good data.

  9. #9
    Join Date
    Dec 2007
    Location
    East central Indiana
    Posts
    477
    Quote Originally Posted by rru2s View Post
    ...I have a scientific and math background...Sorry, but I just won't go out and drop tens of thousands on speculation and blind trust, the way some people buy a used car. I don't believe the final answer merely because a contractor says, "I have XX years experience and I did the calculations." When the numbers don't match between bids as to sizing, that proves to me that NOT ALL CONTRACTORS CAN BE CLOSE TO BEING RIGHT
    Keep in mind, it's highly unlikely that any of your contractors successfully completed algebra. After all, building trades schools are usually not the top choices for people who aced the SAT.

    Since you, however, have a strong background in science and math, you should be more capable than those people of doing the research and making the correct calculations.

    But also be advised, your contractors may have something in their favor that outweighs a strong math/science backgroung: experience in selecting HVAC equipment.

    So my recommendation to you would be to do your own research, and then weigh the results against the opinion of the contractor whom your natural instincts deem to be the most experienced.

  10. #10
    Join Date
    May 2007
    Location
    Naples, Fl
    Posts
    889
    Quote Originally Posted by ECIndHVAC View Post
    Keep in mind, it's highly unlikely that any of your contractors successfully completed algebra. After all, building trades schools are usually not the top choices for people who aced the SAT.

    Since you, however, have a strong background in science and math, you should be more capable than those people of doing the research and making the correct calculations.

    But also be advised, your contractors may have something in their favor that outweighs a strong math/science backgroung: experience in selecting HVAC equipment.

    So my recommendation to you would be to do your own research, and then weigh the results against the opinion of the contractor whom your natural instincts deem to be the most experienced.
    Dave Thomas was a foster child and on his own at 15 years of age do you think he even took an SAT and how many A and B IQs do you think he employed?

    The fact that some people are nothing more than petty opportunist has nothing to do with the OP's or anyone else's algebraic abilities, sorry.

    Familiarity breeds contempt and children.

  11. #11
    Join Date
    Dec 2007
    Location
    East central Indiana
    Posts
    477
    Quote Originally Posted by adrianf View Post
    Dave Thomas was a foster child and on his own at 15 years of age do you think he even took an SAT and how many A and B IQs do you think he employed?

    The fact that some people are nothing more than petty opportunist has nothing to do with the OP's or anyone else's algebraic abilities, sorry.
    Look at rru2s's post. Three different contractors, three different tonnages. Clearly, at least two of these men were wrong.

    Now, I'll admit that there are some VERY VERY VERY intelligent contractors. This website proves that. But if you were to pick three contractors at random and ask them to solve an algebraic equation, chances are VERY VERY VERY good that you would get three different answers. And chances are still VERY VERY good that none of them would be right. So, why should we expect anything different in the case of manual J calculations?

    So, I stand by my assertion that, if rru2s really does have a science and math background, then he should, at least partially, trust his own judgement, provided that the appropriate research is done.

  12. #12
    Join Date
    May 2007
    Location
    Naples, Fl
    Posts
    889
    Quote Originally Posted by rru2s View Post
    I'm looking at the LACK of ability to compare bids as a homeowner from the other side of the fence.

    Because I have a scientific and math background, I always want numbers to back up a proposal that is not in my area of expertise.

    What has happened with my home geothermal proposal is that I got three estimates, all for different tonnage.

    As a result I am inclined not to choose ANY contractor unless they can show me that they have justfication for sizing. This is especially important for geothermal.

    So what matters most to my selection is (1) backup information and (2) backup references that I can actually call.

    Without either of those things, no contractor is going to win my job.

    Sorry, but I just won't go out and drop tens of thousands on speculation and blind trust, the way some people buy a used car. I don't believe the final answer merely because a contractor says, "I have XX years experience and I did the calculations." When the numbers don't match between bids as to sizing, that proves to me that NOT ALL CONTRACTORS CAN BE CLOSE TO BEING RIGHT.

    Anyways, sorry you are having problems with people taking your results and picking someone else. However, I view this as the consumer has a right to know whether the decision they are making is based on good data.
    So hire a mechanical engineer to do the design work and then solicit bids based upon the design that you and the engineer come up with.

    Or demonstrate that you can be trusted not to just shop one contractor's heatload. Considering that less that 20 percent of contractors even perform heatloads I bet with your strong math and science background you can see why the ones that do tend to be a little guarded.

  13. #13
    Join Date
    May 2007
    Location
    Naples, Fl
    Posts
    889
    Quote Originally Posted by ECIndHVAC View Post
    Look at rru2s's post. Three different contractors, three different tonnages. Clearly, at least two of these men were wrong.

    Now, I'll admit that there are some VERY VERY VERY intelligent contractors. This website proves that. But if you were to pick three contractors at random and ask them to solve an algebraic equation, chances are VERY VERY VERY good that you would get three different answers. And chances are still VERY VERY good that none of them would be right. So, why should we expect anything different in the case of manual J calculations?

    So, I stand by my assertion that, if rru2s really does have a science and math background, then he should, at least partially, trust his own judgement, provided that the appropriate research is done.
    And there in lies the problem with the reference to tonnage due to the fact that actual capacities of the equipment vary. One manufacturer's 3 ton unit may be 33,000 btuhs and another's maybe 37,000 btuhs. Then there is the SHR and capacity correction for design conditions that are different than the ARI capacities.

    All this is academic without the heatloads and the data used to compile them and whether proper equipment selection protocol was applied.

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