A coil's postion in chilled water system
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  1. #1
    Join Date
    Sep 2008
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    8

    A coil's postion in chilled water system

    Hi!

    We own a 800sq.ft condo in a small complex(44 units) with chilled water cooling.
    We'd like to replace the 15 year old electric furnace with gas furnace. It's an up-flow system and the A coil is below the blower. Is that right or it should be mounted on top of the furnace?
    Also there's a Little Giant VCMA-20ULS Automatic Condensate Removal Pump (not connected to a power source). Do i need a pump with the new gas furnace?
    I'm sure the zone valve actuator needs to be installed on the new system, to turn off the cold water flow to the A coil in the heating season.

    You'll have a nice day!

  2. #2
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,279
    You should first find out if your condo owner's association allows the switch from electric heat to gas heat.

    If it does, the chilled water coil should be located on top of the gas furnace, not the bottom. Chances are, your current unit may be an all-in-one system, containing the electric heat strips and the chilled water cooling coil. A gas furnace does not come this way. You will need a new chilled water coil installed. Your contractor should know these things.
    • 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.

  3. #3
    Join Date
    Sep 2008
    Posts
    8

    Ours is the only one with electric heat

    Thanks for your help Shophound.
    Everyone else has gas heat in the complex.
    Last year I've called at least 20 companies to replace the furnace and coil. Only 4 of them were working on chilled water systems, 3 of them gave us an estimate and none of them came back to do the job

    Only one of the contractors noticed that the valve actuator is not wired. In the cold season we were heating and cooling in the same time. Called the complex's contractor who is maintaining the chiller to wire the actuator. They came out twice, charged over $100 each time and still not working properly.
    Switching the thermostat from heat to cool, or cool to heat doesn't activate the actuator. I have to do it manually.

  4. #4
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,279
    Sounds like either the actuator is jammed, or it is not wired correctly. Typically a residential chilled water coil is an on or off configuration, not modulating, so there's not much complexity to it. Call for cooling, the actuator opens. Call for cooling satisfied, the actuator closes, and stays closed until the next cooling call. The actuator does not care about the heating cycle; it should only respond for a call for cooling.

    Seems like there would be at least one of your neighbors in your condo who has received satisfactory service from a contractor for his/her system, since everyone else already has what you want...gas heat with chilled water cooling. I would ask around.

    Also, is there a meter on your condo for amount of chilled water being used? I've seen some buildings like this...it's how the condo association figures its charges for owners using water from the chiller plant. If you're having to manually open and close the actuator, you're possibly leaving it open until you switch the heat on. If that water use is metered, you're paying for a lot of chilled water you're not getting benefit from.
    • 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.

  5. #5
    Join Date
    Sep 2008
    Posts
    8
    The condos are charge for the water and gas by ownership percentage.The electricity is charged by submeter+ownership percentage.
    I'll make sure the actuator will be wired correctly with the new furnace.
    Does a gas furnace needs a pump too?


    In 2005-2006 the complex paid $60,000 for chiller repair. Last year I've proposed the owners at the annual meeting to switch from chilled water to individual units. They have rejected the idea It would have cost $250,000 + electrical work.

  6. #6
    Join Date
    Sep 2002
    Posts
    2,715
    Why are they not heating the water in the winter instead of furnas in each space

  7. #7
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,513
    Quote Originally Posted by andchill View Post
    The condos are charge for the water and gas by ownership percentage.The electricity is charged by submeter+ownership percentage.
    I'll make sure the actuator will be wired correctly with the new furnace.
    Does a gas furnace needs a pump too?


    In 2005-2006 the complex paid $60,000 for chiller repair. Last year I've proposed the owners at the annual meeting to switch from chilled water to individual units. They have rejected the idea It would have cost $250,000 + electrical work.
    I'm not meaning to pick on you. HVAC systems are often the most overlooked but most important part of a home or condo or whatever you live in when a person purchases whatever they live in. If people would pay more attention to what heats and cools their homes before buying something, a lot of problems would be avoided. Instead they focus on the shiny refrigerator or granite countertops, but they have a POS heating/cooling system or a co-op style chiller system like you have and are at the mercy of a dumbarse maintenance person that the complex hires and whatever they will allow you to do to your home, which is yours and you bought. But you have to do what they want you do to. Now you are screwed. I get this a lot, where people buy a home that has been completely remodeled with everything shiny and snazzy, but they have a 25 year old Rheem a/c system with strip heats to heat and freak out when they get their first electric bill, not too mention some room is way too hot, the ductwork is the old gray flex that is falling apart and it smells like piss when the unit runs. But the wood floors sure look great.

  8. #8
    Join Date
    Dec 2003
    Posts
    709
    Could you be removed from there chiller arrangement and just put your own heating and cooling unit in? This might require a lawyer but sounds like what I would want because you are at the mercy of how efficient their chiller is and what the maintenance cost will be, and with chillers you could expect that 60k every year as it gets older.

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,694
    Quote Originally Posted by hivacer View Post
    Could you be removed from there chiller arrangement and just put your own heating and cooling unit in? This might require a lawyer but sounds like what I would want because you are at the mercy of how efficient their chiller is and what the maintenance cost will be, and with chillers you could expect that 60k every year as it gets older.
    Might be cost prohibitive. For one unit to do it. With all the electrical work that would need to be done.
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  10. #10
    Join Date
    Dec 2003
    Posts
    709
    I see your point if there electrical service isnt big enough which is very likely. But if it is big enough to add on a dx condensing unit then the cost would only be running a new circuit.

    Also if there electrical service is too small she may be able to switch an electric water heater/stove or dryer over to gas to make room.

  11. #11
    Join Date
    Sep 2008
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    8
    Quote Originally Posted by coolperfect View Post
    Why are they not heating the water in the winter instead of furnas in each space

    What is need to replace the furnaces with heated water?

    I'd like an energy efficient system in the complex, but it's hard to change people's mindset. It's an old electric(?) Carrier chilled water system, old water pipes running on the flat roof and individual furnace with coil in outdoor or indoor closets.

  12. #12
    Join Date
    Sep 2008
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    8
    Quote Originally Posted by hivacer View Post
    Could you be removed from there chiller arrangement and just put your own heating and cooling unit in? This might require a lawyer but sounds like what I would want because you are at the mercy of how efficient their chiller is and what the maintenance cost will be, and with chillers you could expect that 60k every year as it gets older.
    Yes, I could do that. I've asked the board of directors for approval, they denied it. I've found a company to replace the whole chiller system w/ 44 individual units - the board and most of the owners voted against it.

    So we've put our condo on the market.

    For one year I was a board member, couldn't help much. When four are against you, can't do much. They are waisting money with bad decisions.

  13. #13
    Join Date
    Sep 2008
    Posts
    8
    [QUOTE=bmathews;1989542]I'm not meaning to pick on you. HVAC systems are often the most overlooked but most important part of a home or condo or whatever you live in when a person purchases whatever they live in.

    The place wasn't remodeled. I put some work and money in the kitchen and bathroom, and now is time to replace the furnace with the A coil.

    The palce is on the market, hope we'll sell it fast.

    I wouldn't buy another one without individual cooling/heating system.

    We're planning to buy a house, I'd prefer to build a passive solar ICF (insulated concrete form) house, well insulated with energy efficient windows/doors. And w/ hurricane shutters - I don't like to run when Ike or his brothers and sisters are coming to town

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