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  1. #14
    Join Date
    Dec 2004
    Location
    Tampa, FL
    Posts
    35
    Originally posted by swampfox
    I just did a very complex and costly Manual J last night on the computer in about 20 minutes
    I get your point. But one thing you pros haven't mentioned is who's going to pay for these calculations.... Manual J, D, and anything else that might be recommended? If you guys are willing to do them gratis, along with your free estimates, that's great. You can do all the free calculations you want. But I think that very few home owners--including me--would be willing to pay $ hundreds up front, just to determine A/C unit and duct size. ~rick

  2. #15
    Join Date
    Feb 2004
    Location
    Tucson AZ
    Posts
    55

    That's a shame

    Rick: you can pay now or pay later. If you don’t have the load calculations done the system will not work properly. Would you rather save a couple dollars now and not be happy with the system you install or spend the money up front for a system that does what it was DESIGNED to do. Find a contractor in your area that is willing to do the job correctly you will be happier in the long run. I agree that a Carrier factory authorized dealer would be a good starting point. This web site if full of people trying to solve problems that they could have avoided.

  3. #16
    Join Date
    Jan 2005
    Posts
    340
    Originally posted by rickintampa
    You can do all the free calculations you want.
    As you know, there is no such thing as a free lunch. The customer pays for everything, one way or the other. The only question is whether you want a quote from a competent, professional HVAC contractor, or not.

  4. #17
    Join Date
    Jul 2002
    Location
    Zelienople, Pa
    Posts
    2,965
    Originally posted by rickintampa
    Originally posted by swampfox
    I just did a very complex and costly Manual J last night on the computer in about 20 minutes
    I get your point. But one thing you pros haven't mentioned is who's going to pay for these calculations.... Manual J, D, and anything else that might be recommended? If you guys are willing to do them gratis, along with your free estimates, that's great. You can do all the free calculations you want. But I think that very few home owners--including me--would be willing to pay $ hundreds up front, just to determine A/C unit and duct size. ~rick
    Why not?
    Do you want it done right? You'll already be paying thousands to have it done, why not do it correctly?
    How tall are you Private???!!!!

  5. #18
    Join Date
    Jan 2005
    Posts
    340
    Here are other good reasons to do a formal heat gain / loss calculation:

    1) For your personal comfort and to insure that you get good humidity control, thus preventing cold, clammy A/C and the potential for mold growth.

    2) Many municipalities in Florida (I don't know about Hillsborough / Tampa) require it for permit issuance. Your contractor IS going to pull a permit, right?

    3) The manufacturer of the equipment (well, Trane, anyway) says it is required. If you don't install your system in accordance with the manufacturer's instructions, you may not get the installation approved by the permitting agency.

    4) If you are looking for an power company rebate, many utilities require it.

    5) The industry association says it is required.
    http://www.acca.org/tech/manualj/addenda/addendumA.pdf

    Prohibited Practices
    Do not use “rules-of-thumb.” The idea that the required equipment capacity equals the floor area divided by some magic number is absurd. Heat loss and heat gain depends on individual circumstances. Floor area to tonnage ratios for the U.S. housing stock can range from less than 500 ft2/ton to more than 1,200 ft2/ton. Efficient single family detached homes with a normal amount of well-distributed glass typically fall in the 700 to 1,200 ft2/ton range. Limited exposure dwellings with concentrated glass (that produces a time-of-day peak) may fall in the 500 to 800 ft2/ton range. Homes with exceptional features can be all over the map in this regard. Just rotating a home and changing its’ orientation exposure on the site can change the ratio by 100 to 400 ft2/ton.

    Comfort system performance is only as good as the accuracy of the heat-loss/heat-gain estimate. Efforts to “adjust the load” to provide a “safety factor” or to produce a solution that is compatible with the “I have been doing it this way for 30 years” syndrome are forbidden.

    When replacing equipment, do not use the existing equipment size as the criteria for the size of the replacement equipment. (There is a high probability that the existing equipment is oversized.)

    6) Professional contractors do it as a standard practice, to mitigate the risk of being sued by homeowners who are unhappy with their HVAC system.

  6. #19
    Join Date
    Dec 2004
    Location
    Tampa, FL
    Posts
    35
    Originally posted by sayco bob
    Rick: you can pay now or pay later. If you don’t have the load calculations done the system will not work properly. Would you rather save a couple dollars now and not be happy with the system you install or spend the money up front for a system that does what it was DESIGNED to do. Find a contractor in your area that is willing to do the job correctly you will be happier in the long run. I agree that a Carrier factory authorized dealer would be a good starting point. This web site if full of people trying to solve problems that they could have avoided.
    Bob,
    I understand what you're saying and appreciate the fact that you're kindly spending time and effort offering free advice to help the ignorant. But I doubt that many consumers will ever be willing to pay to do research before buying something; most people probably won't even take the time to thoroughly read a product brochure. It will be left up to those who sell and service goods (in this case, you guys) to tell us exactly what we need at exactly what price, and to give us those professional recommendations free-of-charge. That's why my method is to get many estimates and opinions as possible, then look for the most consistant information. By the way, one of the guys who came out was a Carrier dealer. I didn't care for him much. He came on too much like a salesman, and not surprisingly, his was the highest price by far. ~rick

  7. #20
    Join Date
    Jul 2003
    Posts
    51
    Rick,

    Finally talked the wife into a new system, eh?

    I'm in North Florida and had my heat pump replaced last year. While each of the contractors I called initially offered to replace my pump with a like sized system, I insisted they do a load calc before doing the job. As it turned out, my previous system was a half ton oversized, and my new system keeps the house much more comfortable for less money. Anyway, there's no reason you can't have the contractor do the calc after you make your decision - in other words, the quote should spec a load calc be performed and a system selected accordingly. The difference dollarwise between a 2 ton and 2.5 ton is minimal.

    The cheapest time to fix duct and sizing issues is at the time of install. If you're going to do it, do it right.

  8. #21
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Rick,

    1.The code on returns is for new construction,at least interpeted that way in your are and mine.But Travis is correct ,it should be addressed,they don't have to be ducted back ti the unit ,can be "passthru" type.If you rooms are small and there is 1" between the door and floor./carpet,that may enough already.

    Test:With the system running feel the air flow close to the vent,have the wife shut the door,how much if any does it "slow Down"??


    2.Call companies and ask for a load calculation as part of the estimate,I think you will find many that are willing to do that.Ask when you call not when they arrive.

    Problem :Get three and one will be 1/2 ton more or less.

    How's the 2.5 ton been doing in the heat of the summer,likely lacking with the addition,may have been fine before.3.5 tons sounds like to much,IMHO.

    3. Assuming the original home is a pitched roof,it should be relatively easy to move the run(s),from where they are tapped in ,back to the plenum.I'd ask about it.

  9. #22
    Join Date
    Feb 2004
    Location
    Tucson AZ
    Posts
    55

    Carrier Dealer

    Rick: was this a Factory Authorized Dealer? There are different requirements for becoming Factory Authorized. If so I am sorry to hear this. You certainly do not need to go thru Carrier to replace the system. I think you could probably make some phone calls to the local Registrar of contractors or the local utilities to find out who they recommend. You can possibly talk to the sales reps on the phone and eliminate any that are not willing to do a load calculation. I personally will give potential customer a rough price if they like before I run load calculations. I also don’t like to waste my time when the only thing the consumer is considering is price. The toughest thing to overcome for sales reps to overcome is price when the consumer does not understand the differences in a quality job. Check the wall of shame pics to see some low bid work. You don’t want to do this twice.

  10. #23
    Join Date
    Dec 2004
    Location
    Tampa, FL
    Posts
    35
    Originally posted by jmas65
    Rick,

    Finally talked the wife into a new system, eh?

    I'm in North Florida and had my heat pump replaced last year. While each of the contractors I called initially offered to replace my pump with a like sized system, I insisted they do a load calc before doing the job. As it turned out, my previous system was a half ton oversized, and my new system keeps the house much more comfortable for less money. Anyway, there's no reason you can't have the contractor do the calc after you make your decision - in other words, the quote should spec a load calc be performed and a system selected accordingly. The difference dollarwise between a 2 ton and 2.5 ton is minimal.

    The cheapest time to fix duct and sizing issues is at the time of install. If you're going to do it, do it right.
    Indeed I did. Thanks for remembering me. Okay, you guys have all convinced me...I have to get a load calc before getting a new system. Since the existing 2 1/2 ton system was put in by the developer when the house was new in '87, and a 400 sq. ft. room has since been added, probably not likely that it's oversized, but who knows. I do know that the system is now barely adequate for cooling the addition, even when the two glass doors connecting to the rest of the house are open. Anyway, I'm going to start with an electric company energy audit/duct inspection and go from there. Thanks for your advice. ~rick

  11. #24
    Join Date
    Dec 2004
    Location
    Tampa, FL
    Posts
    35
    Originally posted by dash
    Rick,

    1.The code on returns is for new construction,at least interpeted that way in your are and mine.But Travis is correct ,it should be addressed,they don't have to be ducted back ti the unit ,can be "passthru" type.If you rooms are small and there is 1" between the door and floor./carpet,that may enough already.

    Test:With the system running feel the air flow close to the vent,have the wife shut the door,how much if any does it "slow Down"??


    2.Call companies and ask for a load calculation as part of the estimate,I think you will find many that are willing to do that.Ask when you call not when they arrive.

    Problem :Get three and one will be 1/2 ton more or less.

    How's the 2.5 ton been doing in the heat of the summer,likely lacking with the addition,may have been fine before.3.5 tons sounds like to much,IMHO.

    3. Assuming the original home is a pitched roof,it should be relatively easy to move the run(s),from where they are tapped in ,back to the plenum.I'd ask about it.

  12. #25
    Join Date
    Jun 2003
    Location
    Hell Hole Swamp
    Posts
    4,180
    Originally posted by rickintampa
    I'm going to start with an electric company energy audit/duct inspection and go from there. Thanks for your advice. ~rick [/B]
    Good idea, I cant speak for your electric company obviously, but ours here in SC will do a Manual J for you as part of the energy audit (no charge), you might ask if they will do the same for you.

  13. #26
    Join Date
    Dec 2004
    Location
    Tampa, FL
    Posts
    35
    Originally posted by dash
    Rick,

    1.The code on returns is for new construction,at least interpeted that way in your are and mine.But Travis is correct ,it should be addressed,they don't have to be ducted back ti the unit ,can be "passthru" type.If you rooms are small and there is 1" between the door and floor./carpet,that may enough already.

    Test:With the system running feel the air flow close to the vent,have the wife shut the door,how much if any does it "slow Down"??


    2.Call companies and ask for a load calculation as part of the estimate,I think you will find many that are willing to do that.Ask when you call not when they arrive.

    Problem :Get three and one will be 1/2 ton more or less.

    How's the 2.5 ton been doing in the heat of the summer,likely lacking with the addition,may have been fine before.3.5 tons sounds like to much,IMHO.

    3. Assuming the original home is a pitched roof,it should be relatively easy to move the run(s),from where they are tapped in ,back to the plenum.I'd ask about it.
    Thanks for your good points. The existing system may have been sufficient before the sunroom was added, but now the cooling to the addition is minimal. In the summer, the electic use is 4 to 5 times what it is this time of year. I'll research these issues thoroughly and get a load calc before buying a new unit. ~rick

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