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Thread: Replacing HVAC

  1. #1
    Join Date
    Mar 2005
    Posts
    28
    Yesterday, I had a Trane dealer come by to give me a price quote for replacing my two furnaces and a/c units - He did inspect the units and the duct work in my attic and crawlspace and then provided his recommendations equipment and as well as a recommendation to upgrade my existing duct work etc. He also gave me a price quote without first doing a calculation load. When I asked him about the cal load, he stated that this was a start and if I was really interested in company that he would come back to do the cal load and then firm up prices for the furnace and a/c units.

    I plan on getting a couple other quotes but shouldn't he have done the cal load first? His procedure seems ass backwards to me. I've talked to some people in my area and this seems to be standard practice.

    Would appreciate some feedback.

    Thanks in advance

  2. #2
    Join Date
    Mar 2004
    Location
    SE Michigan
    Posts
    17,598
    I always do a manual j load calc and submit it with my proposal and equipment literature. Not sure why this individual would make a second trip out to your home to do a load calc. Sounds a bit strange to me.
    "The road to Hell is paved with progressive policies."

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    Measuring the house ,windows ,etc. ,plus the load calc.,is time consuming,as long as he does a proper calc,it doesn't matter is he does it later.

    Many members on this board,have stated that's the way the do it.

  4. #4
    Join Date
    Dec 2004
    Location
    Derby City
    Posts
    3,955
    Doesn't sound strange when you consider he is probably hoping to get some type of preliminary committment from you before taking the time to do the load calc. Sounds like he provided you with 'budget' numbers. If it was a hard number with model numbers of equipment and size, then I am concerned that he did not run a load. The load calculation is for his benefit as well as for yours. I have always maintained that a load calc. is part of the process, and it should be performed. If in fact, he is going to run one, it does sound like it is just going to cost him a trip back. I would be curious if he is wanting you to committ BEFORE he comes back to do the load. If other than the load, it all seems in order, then I would make sure that his price did not change AFTER performing the load calc. I would also want to see the load calc so that it corresponded with the capacities he proposed. Which one of these contractors normally does your work. In all fairness, if he is the one you usually deal with, he has a better feel for the system than anyone, and in an isolated case like that, he may be comfortable doing the load calc. as a subsequent step in the process. Bottom line, I would not make the type of investment you are getting ready to make with anyone who did not perform a load calc on the home. He's trying to pre-qualify you on price before going further, sounds like.

  5. #5
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    I take the same approach as your contractor. I would give you a price based on what is seen and what I as a professional feel best suits your needs. If there is any question regarding proper sizing I would return to perform a load study before deciding on final equipment sizing, but only AFTER I was awarded the job. You should pick a contractor you feel comfortable with. And remember, hvac equipment sizes do not move in micro increments. We look at these systems on a daily basis and have a very good feel for making preliminary suggestions. Trust the expert.
    There is nothing more frightful than ignorance in action....Mark Twain

  6. #6
    Join Date
    Mar 2005
    Posts
    28
    Thanks everyone for your input. The contractor did actually quote me for specific furnaces, a/c unit and coil model numbers.

    Upstairs Furnace 90 Two stage variable Upflow
    TUY060R9V3W 40 17.5 28 37,000 56,000 93.0

    Downstairs Furnace 90 Two stage variable Downflow
    TDY060R9V3W 40 17.5 28 37,000 56,000 92.0

    Upstairs Air Conditioner
    XL14i AIR CONDITIONER (R410A Refrigerant)
    4TTX4024A 2.0 40 33 30
    Two ton unit

    Downstairs Air Conditioner
    XL14i AIR CONDITIONER (R410A Refrigerant
    4TTX4030A 2.5 40 33 30



  7. #7
    Join Date
    Mar 2005
    Posts
    28
    Another question guys

    He stated that he was going to replace the flex ducting to the existing registers from the current 5" to 6". He also stated that he would replace the supply and return ducting but did not say what size. His quote included two Trane XV90 two-stage gas furnace and two XL14i air conditioners. Can he determine the size of the ducting without doing what you call a manual d for duct design that I have been reading the on posts.

    Thanks

  8. #8
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    Manual D,or equivalent is required to get perfect.However he may have enough "experience to get in close,without it.Pluss with VS ,as long as the static is within the limits of the fan ,total cfm is assured.


    Room by room air flow,and temperature differences is another thing.

    Are the ducts being increased from 5 to 6',because the rooms ,were too cool/warm??

  9. #9
    Join Date
    Mar 2005
    Posts
    28
    He stated that they were required to be changed from 5" to 6" because they were not large enough for cooling. He also stated that I should have had 6" when the house was built and this was one of the reasons I could not cool my house to a comfort level.

  10. #10
    Join Date
    Dec 2004
    Location
    Derby City
    Posts
    3,955
    you almost double the amount of cfm going from 5" to 6". As long as the outlet (register AND register boot) can accomodate the added air, this should result in a substantial increase in airflow throughout the system and added comfort. Be sure to inquire as to whether he has made accomodations for the increase airflow on the return side of the system as well.

  11. #11
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    Originally posted by gemmint
    He stated that they were required to be changed from 5" to 6" because they were not large enough for cooling. He also stated that I should have had 6" when the house was built and this was one of the reasons I could not cool my house to a comfort level.

    Is this for all or most all the branch ducts?If just a few,were those rooms to cool in the winter and too warm in the summer?

  12. #12
    Join Date
    Mar 2005
    Posts
    28
    dash

    I have had a problem since I moved into this house with both cooling and heating of the first floor. I have never have been able to cool any of the rooms during the summer months 85 - 100 degress (I live near VA Beach, VA) below lets say 78 degrees without the a/c running almost the entire time. The existing a/c units are both 2 tons. The house is now 19year old. In the winter I have had similar problems with heating and the furnaces on both floors cycle on and off constantly. In fact, I have had to supplement my heating with a wood stove to stay comfortable. I haven't had much trouble with cooling the upstairs, which doesn't make sense to me.
    My upstairs is about 1000 sg feet and the 1st floor is about 1400 sg feet.

    The contractor stated that he was going to change all of the flex duct to all registers on the 1st floor from 5" to 6". I have a very open floor plan with almost 1/2 of the house open with 16" ceilings. He also stated that he was going to change both the supply and return ducting but was not specific to the size or the reason other than saying the Trane furnaces he recommended required different sizing.

    I wish I could ask him meaniful questions. He seemed like he knew what he was talking about and stated that I could call him any time with any questions. I believe he does not want to do the cal load until he feels that I am really serious with him doing the job. I can understand that but having it done would make me feel better.

    I am finally in a better position to spend the dollars so the family can be feel comfortable but not knowing much just causes me concern. Some times I wished I never found this forum.

    I am a consulant by trade for the Navy and the biggest part is doing research but the HVAC world seems some what judgemental after reading all of these posts. I suppose there are many ways to get to your HVAC comfort level.

    I appreciate your input.

  13. #13
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    6" branch ducts should be the minimum with the possible exception of course to half baths or other very small areas. I would probably even run them to those areas, with volume dampers of course. In fact I would recommend volume dampers on every branch runout.
    There is nothing more frightful than ignorance in action....Mark Twain

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