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  1. #1
    So I was talking to my Parents and they told me they we having central AC put in. Their house is a tri-level house. For those who dont know this style, it is basically a Y turned sideways with the bedrooms on the upperlever with a full finished basement below, and the main floor as the stem on the Y with a 3.5 foot enclosed crawl space with dirt floor below it.

    Right now it has a warm air furnace (located in the crawl space) with large vents in the finished basement and smaller vents on the mail and bedroom level.

    Because this is warm air only, none of the ducts were insulated.

    This house is in Massachusetts

    So here is what was proposed.

    Install a 3.5 Ton 10SEER Armstrong condesor with an A coil in the return. Also a condensate pump. Thats it

    So I told my parents this does not sound right

    I told him to ask if a load calc was done.

    What about condensate on the duct work??? Mold??

    How will they balance airflow so that the temp will be relatively even.

    The hvac guy mentioned that he could put in a dehumidifyer in the basement to control the ductwork sweating


    Thanks


  2. #2
    Join Date
    Apr 2005
    Location
    Richmond, Virginia
    Posts
    365
    Not knowing the sqft of the house it's hard to say if 3.5 tons in the right size or not.

    Also, what is the size and configuration of the AHU? Horizontal I assume since it's in a crawl space. It's good practice on a retro fit like this to put the coil in the supply after the heat exchanger there is the risk that moisture will blow off the coil onto the heat exchanger and rust it. Are the ducts in the crawl space insulated? If not they should be. Since the ductwork in the basement is in conditioned space you really don't need insulation. It's similar to exposed duct you see in large grocery stores.

    Do the supply registers have dampers in them or are there dampers at the branch ducts? That's how you balance the system.
    Sean Cantrell

  3. #3
    You are correct this is a horizontal unit. The hvac co is planning on putting the coil in the return size. Also the registers are able to be closed. However there are no zone zone dampners anywhere in the branch or trunk lines

    the house is about 2300 sq feet. Build in 1970 with all brand new windows.

    Also, the crawl space although it is enclosed it is not conditioned. And like I mentioned before it has a dirt floor


  4. #4
    Join Date
    Sep 2004
    Posts
    172
    Duct in all unconditioned areas will need insulation, it will be hard to keep the duct from sweating and still receive adequate cooling. Controls can be added to read dew points that can control the air temp inside the duct (add outside air or shut the compressor down) but there will be times when the vent temps will be very high and very little cooling since the compressor will be shut down or a large amount of outside air is being added, and this will happen when you most need cooling. Are the duct lines not acessible so that insulation could be added? If left to shoot cold air thru the uninsulated duct at will, this AC unit (if charged correctly and under moderate to high temp/humidity conditions) will sweat the metal ductwork a whole bunch in the unconditioned areas, you are right to be concerned.

    [Edited by dnt on 05-16-2005 at 11:36 AM]
    When you give a lesson in meanness to a critter or a person, don't be surprised if they learn their lesson.

  5. #5
    Join Date
    Nov 2000
    Location
    Waco, Texas, USA
    Posts
    6,153
    dave the problem here is you are looking for skilled design work for free. If you want something designed to work right then you need to pay for it. 99% of the time there is no design and the customer gets screwed by buying something that is doomed from the start because of their own cheapskate behaviors.
    "And remember my sentimental friend......that a heart is not judged by how much you love, but by how much you are loved by others" - Wizard of Oz.

  6. #6
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,350
    A few items of concern:

    Definitely get a Manual J heat load done. Rules of thumb based upon square footage are not the way to go for best results.

    Present air handler/furnace may not have enough CFM capacity to move sufficient air across cooling coil. Also, if age of furnace is advanced, it would be better to replace at same time cooling equipment is being installed.

    Any ductwork that will move cooled air should be insulated. Even possible for ductwork passing through chases in house to reach upper floors to sweat if conditions are right.

    Cooling coil should not go on return side of furnace.

    Ductwork should be assessed to determine if it has sufficient capacity to move higher CFM's of more dense, colder air. If it was sized for heating only, it may be undersized for cooling requirements.

    Get more than one bid!
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  7. #7
    Originally posted by Steve Wiggins
    dave the problem here is you are looking for skilled design work for free. If you want something designed to work right then you need to pay for it. 99% of the time there is no design and the customer gets screwed by buying something that is doomed from the start because of their own cheapskate behaviors.





    Don't you think that's a little harsh Steve?
    An uninformed customer is different from a "cheapskate".
    Dave wants advice and seems willing to do what is needed to correct any problems.
    Why the cheapskate label?

    Dave;
    Insulated ductwork is needed.
    A load calculation is also needed.
    Correct duct sizing should be verified and equipment can be sized after load considerations.


  8. #8
    Join Date
    Nov 2000
    Location
    Waco, Texas, USA
    Posts
    6,153
    I am taking all my past frustrations out on dave. I think he can handle it, he seems pretty level headed.
    "And remember my sentimental friend......that a heart is not judged by how much you love, but by how much you are loved by others" - Wizard of Oz.

  9. #9
    Back off Steve !!!!! Nah just kidding :-)

    You have to understand I was at my Parents Saturday and this is what my mother showed me. She does not know any thing about this. Well the HVAC guy should know what he is doing right? Is what I was told.
    To make matters worse she also payed this guy his 50% down. I just want to make sure they get the best systems without having problems very quickly down the road.

    DAve


  10. #10
    Get that money back now. Step up to the plate and do this for your mom. Paying 50% up front is always a red flag in my book. Any good company will only ask for payment after the install is finished and all is working. Do get more bids. Good luck.

  11. #11
    Join Date
    Dec 2002
    Location
    Toledo, Ohio, United States
    Posts
    12,911
    Originally posted by thunderglass
    Get that money back now. Step up to the plate and do this for your mom. Paying 50% up front is always a red flag in my book. Any good company will only ask for payment after the install is finished and all is working. Do get more bids. Good luck.
    We often ask for a down payment, even 50%, you have to trust the customer to pay you, why can't they trust you to do the job?

    Also cuts down on buyers remorse. Keeps you from putting them on your schedule and ordering special equipment and getting out to their home and finding out they changed their mind.

    Down payment doesn't equal dishonesty.
    No Heat No Cool You need Action Fast

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,174
    we always get a down before we start, some times the day we start, some times when we close the sale.

    I thought it was standard procedure.
    Contractor locator map

    How-to-apply-for-Professional

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

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,174
    Oh, and what chilly said.
    Contractor locator map

    How-to-apply-for-Professional

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

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