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  1. #1

    Old HVAC system-help needed

    We have problems with the coils, the blower, the refrigerant, ducts.

    The coils continously get dirty.
    Our technician informed us that the blower was bad. No further information was given.
    The refrigerant constantly leaks.
    The ducts open and close by themselves, causing rooms to not be properly heated and cooled.
    The biggest problem we have with the system regards cooling.
    Our building has 7 large rooftop units, an 2 smaller york units. The large units are 20+ years old and has surpassed its lifespan. Thermostats currently serve at least 2 areas, sometimes up to 5. A budget of $80 000 has been allocated for this project. Any and all suggestions would be greatly appreciated.

  2. #2
    Join Date
    Feb 2006
    Posts
    224
    pretty open ended question, you need to get a few bids by reputable companies. remember the lowest bid is only the lowest bid , not the best price.you might need to look at return duct cleaning, or at least inspect it to see if very dirty.new units need minimum 2" pleated filters of a reasonably high efficency ie. 70% or >. they need to fit well in the filter racks with no bypass. as far as 20 year old units leaking freon, most will at that age. but are they in a corrosive enviroment near kitchen exhausts. move them.(the new ones) dampers willy nilly moving, what controls them, pnuematic, electronic, or 1 expensive centrally located tstat.? dont know, but you need some on site investigation. word of mouth, from reliable source, on a good one stop shop, mechanical, electrical, ventilation and controls. that way their is no finger pointing about my bits wrong because his bit is wrong!!

  3. #3
    Join Date
    Dec 2001
    Location
    Southern Tier, NY
    Posts
    6,066
    not enuff money in these parts

  4. #4
    Join Date
    Jun 2001
    Location
    San Diego, CA
    Posts
    1,149
    Yep, 80k doesnt make a dent in that project of yours.

    Need more info as requested above.

    Type of control system
    Detailed description of the larger units
    Some idea of the design of the air distribution system (ex: perimeter reheats, VAV's??) What do you have there?

    That's a place to start.

    Look for ways to save money through economizing, scheduling, occupancy sensing, as a way to justify a bigger budget.

  5. #5
    Join Date
    Sep 2005
    Location
    Boston
    Posts
    66

    Think Big

    With out having the specifics of the problems, this is my way of analyzing problems:

    (1) Look at the total picture of the building's HVAC
    (2) What's wrong with the currrent system , and why did it fail?
    (3) Verify all expensive diagnosis
    (4) Refrigerant leaks are a no no, and will only cost $ for compressor repairs
    (5) If cooling is a problem, the outside air may not have been maintained properly. Fix all dampers and install good operators (they didn't move that's why they failed)
    (6) Although expensive, consider a DDC automation system for unooccupied shut, maintain temp, and open outside air for cooling etc
    (7) Consider combining roof-top systems and ducts
    (8) Replace all high voltage disconnects on units to be repaired




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