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  1. #1
    Join Date
    May 2005
    Posts
    13
    I have a 30 year old colonial (about 2500 sq ft)in NJ with forced air heating and cooling. I want to accomplish 3 things by upgrading the system.
    1) zone the house
    2) cool a family room extension (facing south and has many windows).
    3) lower costs

    I have 2 quotes ...

    How to zone the house into at least 3 zones basement, main floor, and upstairs is conflicting in the quotes ...
    One says use arzel (quieter, non mechanical won't break etc...) easier to work with existing ductwork ... the other says Zone a Trol and replace some duct work ... which he says is too big for the furnace anyhow. I have read elsewhere that zone a trol (an older technology) is mechanical and therefore can be nosier and dampers break.
    What do you suggest in terms of zoning technology and why.

    Both quotes suggest a ductless AC for the extension .. OK that's consistent ... they said it would not make sense to just make that room a zone ... it's about 16 x 12 ... and furthermore it does not have ductwork and would be costly. what do you think of ductless AC?

    Both quoted a furnace replacement ... one a trane variable speed xv90 100k btu and other other a trane tud140c960 140k btu. One says the variable will save $ and make the overall temp in the house more consistent. the other says you don't need it? What do you think of the variable speed furnance.

    Both also suggest Trane AC unit one a 5 ton 13 seer and the other a trane 4 ton 13 seer.

    I really want to move forward but find it difficult to figure what is the best solution. This is a costly investment and we want to make the right choice. thanks

  2. #2
    Join Date
    Feb 2004
    Location
    Wadsworth, OH
    Posts
    316
    Larger ducts lend themselves nicely to zoning...I would not change ducts unless this is grossly oversized.
    Regarding equipment size...100k w/ 4tons cooling is probably more than you need for a 2500sq ft colonial in NJ.
    Our contractors do many additions with existing equipment by adding zoning. What about heating the addition?
    Variable speed is a plus with zoning.

  3. #3
    Join Date
    May 2005
    Posts
    13
    Thanks for the response. The addition is heated with a separate baseboard boiler heater. not sure why previous owner did not address cooling this room?
    How to tell if main duct is oversized for the house size?
    Is there a rule of thumb?
    as far as equipment size ... when you say 100 k do you mean furnace and 4 ton do you mean AC?

    if so it sounds like the trane xv90 100k btu and the
    trane 4 ton 13 seer would do the trick?
    i still need to understand the zoning options better?




  4. #4
    Join Date
    Feb 2004
    Location
    Wadsworth, OH
    Posts
    316
    ...How to tell if main duct is oversized for the house size?
    Is there a rule of thumb?
    20 to 30 sg in of main duct area per each 6" branch run that it feeds.

    ...as far as equipment size ... when you say 100 k do you mean
    furnace and 4 ton do you mean AC?
    correct

    ...if so it sounds like the trane xv90 100k btu and the
    trane 4 ton 13 seer would do the trick?
    Unless you have a very poorly insulated house with old, leaky windows the smaller equipment is still on the heavy end of the scale. I have an old, two story home, (NE Ohio) 3 zones, 80k furnace, 2 ton a/c. No Problem down to -10deg and up to 90deg!

    ...i still need to understand the zoning options better?
    My guess is that the fellow quoting the Zone a Trol (electro-mechanical) system has to change the main trunk duct (add a second trunk) in order to utilize motorized trunk dampers. a much more intrusive installation
    The Arzel dampers are insertable into the branch ducts as is. You end up with more dampers but much less labor involvment. Dividing into 3 or 4 zones is much easier with branch dampering. All parts are covered by a Five Year parts and labor warranty

  5. #5
    Join Date
    May 2005
    Posts
    13

    Question

    It turns out the sq footage is 3100 counting the basement.
    2 proposals say a 3 ton AC and variable speed 100k btu furnance (although they did not count the basement) , the other proposal says NO WAY (he icluded the basement)!. He suggests a 5 ton AC and 140k btu non variable furnance 80% afu furnance. He says there is no way to heat with a 100k btu? ALL 3 said they did manual j calcs. I don't want to under or over buy - what is the best way for me to get the correct solution?

  6. #6
    Join Date
    May 2003
    Location
    Sarasota. Fl
    Posts
    1,246
    Originally posted by gregam
    It turns out the sq footage is 3100 counting the basement.
    2 proposals say a 3 ton AC and variable speed 100k btu furnance (although they did not count the basement) , the other proposal says NO WAY (he icluded the basement)!. He suggests a 5 ton AC and 140k btu non variable furnance 80% afu furnance. He says there is no way to heat with a 100k btu? ALL 3 said they did manual j calcs. I don't want to under or over buy - what is the best way for me to get the correct solution?

    Ask for copies of the manual j calculations.
    It is the job of thinking people not to be on the side of the executioners.

    ~Albert Camus

  7. #7
    Join Date
    May 2005
    Posts
    13
    i did see 1 manual j calc ... it was done assuming 2400 sq ft ... not that sq ft is all the matters. This dealer concluded 3 ton and 100k btus. It's hard me to imagine that
    i would need another 2 tons and 40k btus for about 600-700 sq feet in the basement ... assuming the other tons & btus numbers are correct for the 1st and 2nd floor.

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