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  1. #14
    I agree with shophound,the daikin systems are excellent systems very energy efficient but pretty costly,or you could go with a fujitsu mini split system their condensers can carry up to 4 heads.both of these systems have 410A refrigerant so be sure installer is aware of the different operating pressure and oil.

  2. #15
    Join Date
    Jan 2004
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    Lancaster PA
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    67,903
    Quote Originally Posted by bartmanbartman9 View Post
    Typically set it for about 75F. Best it usaully does is 77F (even if we set it lower).

    B
    How much of teh existing structure will be covered by the addition.
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  3. #16
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    6,361
    What is the summer dew point inside the home? You need <50%RH or the cool surfaces will be damp and grow mold. Supplemental dehumidification is a must with radient cooling. Indoor dew points must be 10^F below surface temperatures. Suggest units like Ultra-Aire for fresh air and <50%RH. Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  4. #17
    Join Date
    Feb 2008
    Location
    Charlottesville, VA
    Posts
    15
    So I did get a quote for both a conventional forced air heatpump and for a split system (Mitsu.) and both seem reasonable. However, I would like to get the AC/cooling system in the rest of the house working effectively. I certainly understand that by efficiently cooling the addition the rest of the house may be more comfortable.

    So I was wondering if anyone had a recommendation for a contractor that would be willing to work on my entire system? I unfortunately do not live in a large metropolitan area, though Washington D.C. is about 2 hrs away (I live in Charlottesville VA). I have contacted a few of the local HVAC companies and they are willing to work with the addition, but don't want to touch the existing system. I can be contacted off-line if you like(email address in Profile).

    To address some of the prior postings.

    Coverage of the addition: The house is more or less a rectangle of 28x40. The addition will be an 18x18 box taking up the West side (long side) of the rectangle.

    Relative humidity: Don't know for sure. I think the Spacepak reduces humidity enough. Never had any condensation or moist floors.

    Thanks,

    BN

  5. #18
    Join Date
    Jan 2004
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    Lancaster PA
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    You could be reducing your existing structures load by 10&#37;.
    Atempting to address it before the addition is completed and you see what effect it has on the existing, is putting the cart before the horse.

    You choice to do that if you want.

    The chiller still has to be matched to the load you want it to handle.

    Click on the HVAC CALC link, pay the fee, and do your own load calc on it. So you know the load with the addition.


    Click on the link in my sig. You may find someone from this board in your area.
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  6. #19
    Join Date
    Feb 2008
    Location
    Charlottesville, VA
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    15
    Quote Originally Posted by beenthere View Post
    You could be reducing your existing structures load by 10&#37;.
    Atempting to address it before the addition is completed and you see what effect it has on the existing, is putting the cart before the horse.

    You choice to do that if you want.
    I don't necessarily want to upgrade the existing system first, I just wanted to see if there was someone in the area who could consider my whole system. OTOH, I asked for opinions and so I value yours. I'll look into doing the load calcs myself. Thanks.

    BN
    Last edited by bartmanbartman9; 03-01-2008 at 08:17 AM. Reason: added sentence

  7. #20
    Join Date
    Feb 2008
    Location
    Charlottesville, VA
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    15

    Update to thread

    So we had one of the local residential contractors come out and look at our system and provide options.

    Basically, based on his load calculation, our current system is under powered by about 0.5 tons (we have a 2 ton system and he calculated a need for a 2.5ton). He's calculating a total of 4.5 tons needed for the existing structure and the addition. His suggestion, put in a conventional heat pump into the addition (2.5ton) and try to duct some into the existing structure. Sounds like the cost is going to be prohibitive to upgrade the chiller and the Spacepak.

    Thoughts?

    B
    Quote Originally Posted by bartmanbartman9 View Post
    Hi,

    This is somewhat of a complex (and long question). Sorry.

    I am a Homeowner. We live in central Virginia. We have a 2000sqft home that is well insulated. We have hydronic RFH. For cooling we have a slightly unusual system. We have a 2 ton chiller (Aquaproducts)which feeds cooled fluid to a 2 ton Spacepak high velocity system and small diameter/high velocity ductwork. The chiller also cools water that is circulated in the radiant system for some degree of radiant cooling. The system is just barely adequate. I think that the fault is that the chiller is too small, as the fluid temperature into the Spacepak system can be as high as 55F. Because of this the chiller runs continuously during the summer. The house is just barely OK except for runs of several days over 95F when it can get pretty warm inside.

    Anyway, we want to build an addition. It will be 3 stories, with each floor being about 320 sqft (a little over 1000sq which includes a finished basement room). We have now gotten 2 proposals for cooling the addition and helping the rest of the house. I am also wondering about other options.

    Proposal #1: Increase the size of the chiller (5 tons)Unico and add an additional 1.5 ton Unico fan coil/distributor. Cool the addition with high velocity ductwork. The estimate for this is expensive.

    Proposal #2. Increase the size of the chiller to 4 tons (Multiaqua). Use some of the chilled fluid to a) feed the current Spacepak, b) feed chilled water to 2 Multiaqua air handlers in the addition situated in such a way as to primarily cool and condition the Addition as well as help the rest of the house and c) supply cooled water for the radiant system. I have gotten a quote for this and it is expensive.

    Other ideas (mine):

    1) 2-3 zone Mini-split system to cool and condition the Addition (and some of the house). This would hopefully take some of the load off of the current system.

    2) Install a small conventional heatpump/AC with conventional ductwork in the addition which would hopefully also take some of the load off the house. Right now the plans do not take into consideration conventionally sized ductwork, but I imagine we can change that.

    I do not know if anyone has done a Manual J calculation (but will be asking)

    Thanks for letting me ramble.

    Bart

  8. #21
    Join Date
    Mar 2003
    Posts
    7,321
    I think some sort of split system would be okay. The suggestion was made to consider a mitsubishi or Daikin multisplit with a single condenser. This might be a good option for a couple of reasons. The inverter type technology will allow you to oversize a bit, without causing other problems. While this might seem wastefull, consider the other side of the dwelling. You are slighlty short on required capacity, you seem to run warmer water than necessary for good dehumidification, and you use readiant cooling to some extent. The warm water temps dont allow for good moisture removal, a minisplit can do this well at almost any load. Slightly oversizing will help reduce capacity on the other system to SOME extent, Zoning will give you very good overall control, and noise is pretty much a non-issue. While the equipment seems pricey to some contractors, the relatively simple install makes them competetive.

  9. #22
    Join Date
    Feb 2008
    Location
    Charlottesville, VA
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    15
    Actually, same contractor also proposed a Mitsu split system. He is more favorably inclined towards the conventional system, however. Part of the equation is that we want to finish the existing basement. It will need some level of cooling, but mostly dehumidification. Contractor felt he could take care of this + addition more economically with a conventional system.

    I plead some ignorance here with this question, but does a 2 ton high velocity system have the same cooling capacity as a 2 ton conventionally ducted system? In other words, if his load calc. suggested we needed 2.5 tons, is the same whether we use either system?

    B

    Quote Originally Posted by flange View Post
    I think some sort of split system would be okay. The suggestion was made to consider a mitsubishi or Daikin multisplit with a single condenser. This might be a good option for a couple of reasons. The inverter type technology will allow you to oversize a bit, without causing other problems. While this might seem wastefull, consider the other side of the dwelling. You are slighlty short on required capacity, you seem to run warmer water than necessary for good dehumidification, and you use readiant cooling to some extent. The warm water temps dont allow for good moisture removal, a minisplit can do this well at almost any load. Slightly oversizing will help reduce capacity on the other system to SOME extent, Zoning will give you very good overall control, and noise is pretty much a non-issue. While the equipment seems pricey to some contractors, the relatively simple install makes them competetive.
    Last edited by bartmanbartman9; 03-18-2008 at 03:01 PM. Reason: added paragraph

  10. #23
    Join Date
    Jan 2001
    Location
    Pamnyra VA.
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    710
    nobody near hooville have any idea about high velocity.

  11. #24
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    Feb 2008
    Location
    Charlottesville, VA
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    15
    We just got the GC's HVAC guy to come out and look at the system. Figured this was a good a first step as any. Other than just calling around, is there some other way of finding out who has experience with HV systems?

    Quote Originally Posted by skibme View Post
    nobody near hooville have any idea about high velocity.

  12. #25
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,903
    The manufacturers web site.
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    How-to-apply-for-Professional

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

  13. #26
    Join Date
    Feb 2008
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    Charlottesville, VA
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    Quote Originally Posted by beenthere View Post
    The manufacturers web site.
    beenthere: Been there. I filled out their form and it gave me the phone number of the local supplier. I haven't had a chance to call the supplier to see if there was anyone they wold recommend. Thanks for the heads up.

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