Load-Calc????
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Thread: Load-Calc????

  1. #1
    Join Date
    Sep 2001
    Location
    Long Island NY
    Posts
    63

    Confused

    I received a faxed copy of my load calc from one of my contractors, what should I look for? It states "Total sensible heat Gain = 30,406 and Total Latent Heat Gain= 5338 and Total Sensible and Latent Heat Gain= 35744" How do you calculate for tonnage, heating?? Is there suppose to be a Total Heat Loss calculation also? where would that be?

  2. #2
    Are you doing ac and heat? if so you should get a heat loss and a heat gain. So they only sent you gain (a/c) 35744 gain is a perfect 3 ton a/c or 36000.btu Where do you live?

  3. #3
    Join Date
    Sep 2001
    Location
    Long Island NY
    Posts
    63
    I live in Long Island NY, I got quoted for heat & A/C. So I am missing part of it right I need the Heat Loss as well. He says even though its a perfect 3 Ton he would recommend a 3.5 ton due to the R5-R6 Insulation downstairs.

  4. #4
    Join Date
    Jul 2000
    Location
    Ottawa, Ont. Canada
    Posts
    1,729
    Pete, relax. If the contractor was good enough to do a load calculation for you, I would suggest you give him a chance to explain it to you. The fact that he did the calc is a good sign, he may be the one to do the best job for you. It is Friday night, relax until Monday and get in touch with him then. I am sure he can explain it all to you then, after all, he took the time and effort to do a load calculation for you, I'm sure he would be pleased to explain it also.

    I think you have found yourself a good contractor, you are 95% there to a great system. Enjoy your weekend.

    don
    don sleeth - HVAC-Talk Founder
    HVAC Computer Systems
    Heat Load Calculation Software

  5. #5
    Join Date
    Sep 2001
    Location
    Long Island NY
    Posts
    63
    Don, I am relaxed the fact that he only gave me a partial load calc is what upsets me. I asked him for the load calc on what he quoted me, he stated he would fax it to me when I spoke with him over the phone. If he knew that he was only going to fax the A/C part only he should of told me that in the first place during our phone conversation.

    Just be straight forward and do what you say your going to do, I've never seen a load calc before so thats why I was curious. I gave him the benefit of the doubt and when I finally get a chance to look it over its incomplete.

    Maybe I'm over reacting but thats just the way I feel. I already called and left him a message regarding the rest of it. I was polite and respectful just mentioned that if he was aware that it was incomplete to check the fax in case some pages did not come through and hope to see the rest of it soon.

    He is the only one out of 3 contractors to give me at least a partial load-calc, so thats good. Hopefully I will get the rest and he could do the job for me.

    [Edited by Pete924 on 10-27-2001 at 02:26 AM]

  6. #6
    Join Date
    Apr 2001
    Posts
    621
    Originally posted by Pete924
    I live in Long Island NY, I got quoted for heat & A/C. So I am missing part of it right I need the Heat Loss as well. He says even though its a perfect 3 Ton he would recommend a 3.5 ton due to the R5-R6 Insulation downstairs.
    Ask for the heat loss calcs for the furnace sizing.

    A correct load calc takes insulation R-values into account and the A/C should be sized as closely to the calcs as possible. Since your heat gain is just under 36,000 BTUs or 3 tons, you should insist on a 3-ton unit. This will give you better humidity control.

    http://homeenergy.org/archive/hem.di...96/960907.html


  7. #7
    with tonge like that your not relaxing like don asked.get some better insulation for the climate seems has code vialation or is there no min. up there.spend a little now or pay for ever.

  8. #8
    Join Date
    Jun 2000
    Posts
    60
    Axraw hit the nail on the head. Those basement r values should already have been accounted for.

  9. #9
    Join Date
    Jun 2000
    Posts
    60
    Sorry arxaw, I previonsly spelled ya axraw.

  10. #10
    Join Date
    Apr 2001
    Posts
    621
    Originally posted by E-Man
    Sorry arxaw, I previonsly spelled ya axraw.
    heheh, I've been called much worse... :-)

  11. #11
    Join Date
    Sep 2001
    Location
    Long Island NY
    Posts
    63
    "with tonge like that your not relaxing like don asked.get some better insulation for the climate seems has code vialation or is there no min. up there.spend a little now or pay for ever." Quote DSWAir

    House was built in 1962, Dormer is 16 yrs old. I guess R5-6 was the norm in NY back then? I cant reinsulate the whole downstairs again.

  12. #12
    Join Date
    May 2000
    Location
    Clarksville, TN USA
    Posts
    608
    Hey Pete, maybe he doesn't want to do all the other guys' work for them.

    I don't know how many times I've done a load calc, and sometimes even a duct layout, only to have the homeowner give them to my competition, and then give them the job because they priced it less (maybe because I did the legwork for them!).

  13. #13
    Join Date
    Oct 2001
    Location
    New Orleans, LA
    Posts
    23
    Several have said that the Pete should install a 3 ton system as a result of the 35744 BTUH total heat gain result that one of his contractors sent him. Assuming that the sensible and latent loads were correct, wouldn't he be better off basing the sizing of his A/C on the sensible capacity of the equipment that his contracor is proposing. From the numbers that he gave, his sensible gain is 85% of the total. If the equipment that is being proposed has a sensible ratio of less than 85%, and the numbers are correct, he could be undersizing the system. Don has the best advise, talk to the contractor. Find out how he did his calculation. Did he take notes when he visited the job regarding window sizes and numbers? Did he measure the walls? Or did he just ask about the square footage? Most of the contractors I've talked to sized by converting square feet to tons. One who claimed to do a heat load calc didn't even visit the house. He basically converted square feet to BTU's. Not very much difference. So do what Don suggested and talk to your contractor on Monday. If you have time and want even more piece of mind, download the homeowner version of HVAC-Calc for less than $40 and do a heat load calc for yourself. You can even download a demo for free, with fixed weather data, to see how easy the progam is to use.

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