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  1. #1
    Sorry to rehash this point, but I've spoken to over a dozen HVAC installers (some on the phone, some actual bids). They've all been in business a long time -- some since the 1960's. Only one of them considers a Manual-J important -- and that company costs $4K more than the others. The others all say they go by square footage; that with a house built in 1948, the Manual-J doesn't apply anyway. Since the one company that did the calc came up with 3.5 ton -- what's wrong with asking for that size system from another company and getting the job done for less $?


  2. #2
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    and get what you pay for. if you are looking for a rebate most ultility companies require a manual J

  3. #3
    Join Date
    Feb 2004
    Location
    southern illinois
    Posts
    5,522
    yeah,that figures the guy that is doing it right gets to do load calc. and then gets undercut and the other guys get the job and the load done for free for them,......just because they have been in business along time doesn't mean that they are doing things right.In my opinion it is alot harder nowadays to be going in to this business than it was 20 years ago because of all the changes that we are dealing with.............

  4. #4
    Join Date
    Jan 2005
    Location
    Crooksville, Ohio
    Posts
    77
    To properly size any equipment, it is necessary to do a heat load calc. From what I have seen, most older homes have over sized equipment. IMO, any contractor telling you that a heat load calc. is not necessary because he can use square footage is wrong. Room sizes, windows, doors, fireplaces, insulation, is important information to correctly size your home. Now taking the information from the one contractor that did do a heat load calc. and getting your equipment from someone that did not do one is wrong! That contractor took the time to do it right.
    All Seasons Heating & Cooling

  5. #5
    Join Date
    Jul 2004
    Location
    midwest
    Posts
    2,868
    There is some truth to the statement that since it was built in 1948 it does not apply. Manual J is only accurate if you use actual data in the calculations. With a home built in 1948 you are going to be guessing on some of the important data unless you have gutted the house and basically started over. Some will not agree but experience plays a large roll in selecting the right equipment in some homes.

  6. #6
    Join Date
    Feb 2004
    Location
    southern illinois
    Posts
    5,522
    1948 or not,a load still needs to be run on it.You can still figure windows,insulation,etc.,.....JMO.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,913
    Manual J is an educated semi guess on most exsisting construction.

    But it still applies to older homes, it has the r, and u values. Withj out a blower door test, infiltrtion is a guess.

    If the other companies are going to guess at the size equipment needed, then they're going to guess at the size of duct work also.

    So if you get one of them, and it does cool the rooms evenly, and its loud, just think of all the money you saved.

    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Nov 2003
    Location
    northern mass
    Posts
    411
    jacquelynn.....from reading your post.....it read like a school book.

    It sounded funny enough that I had to reply...no offense please.

    You talked to one respectable company, and a bunch of idiots.

    It is very typical of alot of companies from around my neck of the woods as well. Those guys that have been in buisness since the 60's are still in the 60's. And the rest are just as bad.

    The answer is simple. Yes it is important and nesasary.

    The problem is lack of education. I have a good friend who owns his own HVAC company and has so for years. He took it over from his father who probably did it for 30 years or so. He says Man J is stupid, and there is no need for such things.

    He is a perfect example. He has no proper training in his own field. He doesn't even realize just how un-educated he is !


    Here is a perfect example........Take two houses that are exactly the same except for a couple of things. Let one house have spray foam insulation and real good windows, and let the other house have regular fiberglass bats and cheap windows.

    Now send in the clown that doesn't like Man J and have him do both houses. After he gets done with his tape measure and pocket calculater, he'll come to the conclusion that both homes have the same needs.

    Now what happens a year later when both house wives are out walking the dog and start talking about their climate conditions ?? I'll tell you....the contractor's phone will be ringing and he won't be happy !

  9. #9
    Originally posted by jacquelynn
    what's wrong with asking for that size system from another company and getting the job done for less $?
    Besides being wrong, think about this...

    If the other company is cutting this VERY IMPORTANT procedure from his job, what else is he taking short cuts on?

    Doing things right takes time and material... neither of which are CHEAP or FREE!

    Do it right, or do it twice... you choose, but doing it the correct way FIRST is cheaper and will cause you less headaches.

    Load Calc Here

  10. #10
    Thanks everyone for your responses.


    The calc. I received from the one company is one page only and it's titled "Right-J Short Form," Manual J: 7th Ed. Right-Suite: V4.1.10. The contractor said it took about two hours to do.

    Is this the real thing, or did they use a short-cut version?

    Thanks so much.

  11. #11
    Thanks everyone for your responses. I'm sure you're right (tho I hate to resign myself to paying the highest-priced bid of all). I hadn't thought about the ethics in using someone else's figures, and I agree with you that it's not right.

    Trane: I'm not sure how thoroughly this contractor did the calc, or if he asked me all the right questions.

    The calc. I received from the one company is one page only and it's titled "Right-J Short Form," Manual J: 7th Ed. Right-Suite: V4.1.10. The contractor said it took about two hours to do.

    Is this the real thing, or did they use a short-cut version?

    Thanks so much.

  12. #12
    It's the real deal... and NOT a cheap one either!

  13. #13
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    If they measured the walls,windows etc.,plus they know the r-values of the insulation,there's a good chance they did it right.

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