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  1. #1
    scottnorm Guest

    Do I need to Scrap the 2 Pipe Chiller System?

    I am acquiring a 20 unit apartment/condo building with a 2 pipe heating and cooling system. There is a new boiler and a 10yr old cooling tower. Each unit has a 1950's vintage air handler/coil. it is located in the ceiling of the closets, which have been converted for washer/dryer use. the air handlers are getting clogged and are leaking due to condensation accumulation (i think?). Anyway, i've had it reviewed by an A/C contractor, and his recommendation is to rip out everything and replace with a DX system (insanely expensive). He says the DX system is more efficient and will save a lot of ongoing maintenance expense that I would have with the existing 2 pipe system. Plus, existing system is a two pipe system that limits individual control. My preference would be to avoid this huge expense and simply replace the air handlers such that they are easier to maintain, thereby avoiding the condensation issues. Please give me your thoughts on whether i should stick with existing system or consider a DX retrofit at some point (which appears almost impossible to afford). Thanks.

  2. #2
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
    Posts
    7,281
    DX units produce condensate as well

    Might want to consider though having a few opinions given from a few different contractors?

    Just because you have a new boiler and a 10 year old tower does not mean that the rest of the system is or is not falling apart, cant see it from here

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,179
    Changing out, you'd have power to run to the outdoor units, refrigerant lines to run, probably have to pull larger wire to each air handler for electric heat for the winter. Probably would make more sense to get rid of the relic air handlers and replace with modern, they aren't that pricey. Again as Chris said, depends upon the rest of the system. New boiler should be fine if put in right. How's the chiller?

  4. #4
    Join Date
    Jan 2011
    Location
    Central, PA
    Posts
    105
    the boiler is new and the chiller is not that old (depending on maintenance done) if the piping is in good shape i agree with bladloonie. you have to rip out the air handlers regardless of the option you choose. there are tons of companies out there that provide retrofit solutions for air handlers. it would be a lot less expensive

  5. #5
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    Depends on how good the pipe is

    If your basic pipe system is still good then look into a water source heat pump system with your 10 yeqr old cooling tower and boiler as an alternative
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  6. #6
    Join Date
    Jan 2003
    Location
    SE Pa
    Posts
    830
    What he said
    5 out of 4 people don't understand fractions

  7. #7
    Join Date
    Mar 2011
    Location
    GUYANA
    Posts
    34
    i agree with replacing the units but we had a similar problem and owner did not want to replace units.so we re-insulated the lines around the air handles as the insulation was very bad causing them to condense.

  8. #8
    Join Date
    Mar 2010
    Location
    Morgan Hill Ca.
    Posts
    1,219
    Quote Originally Posted by scottnorm View Post
    I am acquiring a 20 unit apartment/condo building with a 2 pipe heating and cooling system.
    How large (square feet) are the apartments?

    Quote Originally Posted by scottnorm View Post
    There is a new boiler and a 10yr old cooling tower. Each unit has a 1950's vintage air handler/coil. it is located in the ceiling of the closets, which have been converted for washer/dryer use. the air handlers are getting clogged and are leaking due to condensation accumulation (i think?).
    Clogged with what?

    Quote Originally Posted by scottnorm View Post
    Anyway, i've had it reviewed by an A/C contractor, and his recommendation is to rip out everything and replace with a DX system (insanely expensive).
    Way too expensive, not to mention intrusive.

    Quote Originally Posted by scottnorm View Post
    He says the DX system is more efficient and will save a lot of ongoing maintenance expense that I would have with the existing 2 pipe system.
    Bullsh

    Quote Originally Posted by scottnorm View Post
    Plus, existing system is a two pipe system that limits individual control. My preference would be to avoid this huge expense and simply replace the air handlers such that they are easier to maintain, thereby avoiding the condensation issues.
    Hmmm


    Quote Originally Posted by scottnorm View Post
    Please give me your thoughts on whether i should stick with existing system or consider a DX retrofit at some point (which appears almost impossible to afford). Thanks.
    My recommendation is to contact your local utility company to see if this building qualifies for any kind of rebate programs to bring it up to today's standards.

    In all honesty (it was said above) converting the existing air handlers to water source heat pumps really wont cost that much more than what you are talking about doing with the fan coils, would make each apartment have it's own control, be quite efficient if done properly and increase property values ten fold....Not to mention the potential rebate programs in your area.

    The boiler may be a bit oversized, and the chiller will simply go away...The chiller can be replaced with a heat exchanger so you have very little worries when it comes to water treatment, utilizing the cooling tower as your heat rejector.

    Haven't seen the building or even know where it is geographically, but sure seems like a no brainer...

    GT
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  9. #9
    Join Date
    Mar 2011
    Location
    East Coast FL
    Posts
    1,058
    Nice post GT. I agree.







    (btw I took your advice on that pump and were having an industrial millwright type union shop come in to help us)


    sorry that wasnt related to this thread****

  10. #10
    Join Date
    Apr 2010
    Location
    Florida
    Posts
    14
    Condensation is probably due to clogged condensate pan drains. Algae that accumulates in the pan dries up when the heat runs and then when the cooling season rolls around again, the condensation won't flow thru the clogged pipe. It could also be due to improperly sized condensate traps.

    I agree also with the water source heat pumps. Condensation will still be an issue but the newere drain pans are better sloped and hopefully there will be fewer problems with that. I also agree with the heat exchanger. Typically, you would put in a closed cicuit cooling tower and maybe that's what is there and you don't need a heat exchanger. Anyway, because most towers are open systems, you don't want the dirt and crap flowing through your system so that is why you would want a eat exchanger.

    You might want to check the pipe size too. Most older chilled water systems will be sized at a 10 degree delta which means you would flow 2.4 gpm per ton. Typical water source heat pump systems will flow 3 gpm per ton. Your pipe diameter may be smaller now through poor water chemistry and flowing more water will require bigger pumps and more head.

    If you go with water source heat pump system you will need to utilize the boiler to maintain the water temperature at a minimum during the heating season. Again, make sure the water system is a closed one so you don't flow dirt and trash through your boiler. You will need to look at the efficiencies of the WSHP's to determine the water temperature in the heating mode. That is the temperature you want the boiler to maintain. The sequences are simple but you need someone who knows what they are doing to set it up right so you don't waste money.

    I don't recommend dx but if you must, go with heat pumps so you can avoid the cost of electric heat for each unit. You may have to add emergency heat anyway which would also drive the cost up. Utilize what you have in the boiler and tower. They have an expected life of 20-25 years if they are maintained properly.

  11. #11
    Join Date
    Mar 2011
    Location
    Texas
    Posts
    79
    Water source heat pumps will give you the most options. ( Independent control , re-use of boiler and tower, potential for energy credits) If you can get a replacement AHU at a substantial savings. Like 1/3 of a Heat Pump unit cost, then replacing like for like may look more apealing.
    Are you planning on flipping this property or in it for the long run?
    Is it a bills paid or do the tenants have there own meters?

  12. #12
    i'm planning on renting and then selling in the future. i'm told that the air handlers are filthy and old (1950's) and to rip out is a dirty and expensive job. I'm in Dallas area. Who can I talk to that will look at the project and give me an honest approach?

  13. #13
    Join Date
    Mar 2003
    Posts
    7,326
    If you want to add value to your project, the best move would be to convert to water source heatpumps. This option would give you indivdual control in shoulder season, so that some could be in heat, and some in cool if necessary. In cold climate, you might need the boiler to add heat to your loop, so it wouldnt be wasted. new equipment, unitary control, and water source will make your building more comfortable for al occupants, more sellable from an equipement standpoint, and possibly more efficient overall. it would cost you probably twnety percent more than straight up air handlers, but give you more flexibility. cooling tower asd it exsits should suffice.

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