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  1. #1
    Join Date
    Jul 2013
    Location
    Putnam Co, NY
    Posts
    3

    Confused trying to complete an effecient HVAC system, and need cooling advice

    Good day Ladies and Gentlemen,

    I would like to start this post by thanking the owner for granting me membership so that I can make use of the site and thank you all in advance for you considered responses. I know that this topic has been posted before but want to make sure I am doing the best I can for my home investment and my family.

    Now to the particulars, I have purchased a newly constructed home from a developer that ran into some trouble and could not finish the building beyond rough-in condition. The home was built in 2010 and from what I can see was built with high efficiency in mind. The home is 1100 Sq. Ft per level with the first and second floors being finished and the basement level unfinished. From the design documents I can see that the HVAC system was calculated to be 1.5 tons per zone I want to use as much American manufactured equipment as I can. So far I have installed what I believe is called a hydronic heating system. In other words I have installed an Energy Kinetics "system 2000" approx. 130,000 BTU boiler and connected it to two air handlers (one per floor) manufactured by Firstco (model # 18HBXB-HW) along with a 60 gallon Hot water storage tank. They are fueled by a 1000 gal underground propane tank and controlled by a Venstar soft touch 5600 thermostat. So far the system has exceeded my expectations. Also, you should know that the house was built as a "closed" system, I can see that there is no ridge or soffit venting and the entire building envelope is spray foam insulation. I do notice that the second floor is always warmer than the first floor by at least 2 degrees F.

    My reason for this post is that I am now looking to install central Air Conditioning and while doing a great deal of research and reading I have come to the conclusion that American Standard seems to have the best service record with the least amount of documented repair issues. But, in trying to keep with my higher efficiency mandate, I have run into the problem that AS does not produce a 1.5 ton compressor/condenser unit with two stage scroll compressors. or at least not that I can find. the smallest two stage compressor they produce is a 2 ton unit (model #4a7a6024) and I wanted to know if I should connect the larger tonnage unit and If I do, will I see the peak performance I am looking for, or should I sacrifice the higher seer rating for the single stage compressor of the gold unit (model #4a7a5018) and match the 1.5 ton rating? If I have left out any pertinent information please don't hesitate to ask me for any additional information you may require.

    Thanks,

    Spanky M

  2. #2
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,292
    130,000 BTU for a 2200 square foot foam insulated house? How was that number arrived at for your boiler?

    I would not trust load calculations from a builder that couldn't finish a house, personally. I would run new calcs for the a/c - someone who understands foam insulated homes should run the calcs. If the calcs are run with the usual thinking - ducts in attic and batt insulation in walls and on attic floor - your a/c tonnage will typically come out way oversized for the foam house. From your post above I assume your roof deck is foam insulated, meaning any ducts in the attic are actually "in conditioned space", meaning they're not technically outdoors like they would be in a ventilated attic.
    • 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
    Jul 2013
    Location
    Putnam Co, NY
    Posts
    3
    as far as the BTU rating for the boiler, I nay be wrong about the BTU rating, could be 120.000 btu it was calculated by a licensed HVAC contractor here in the Hudson Valley and the system has performed very well. As stated, it is fueled by Propane, and from Oct 2012 to May of 2013 it burned less than 500 gallons to keep the house at 70 degrees F round the clock as well as hot water for showers. dishes, and gas for cooking. much less than my 80 year old former 800 sq. ft home burned the prior year. Also, the 1.5 ton design was produced by a licensed Mechanical engineer that I happen to know. You are correct about the ductwork in the attic and please keep in mind that all ducting is well wrapped and all joints are cemented not taped together, so from what I can tell, there are no leaks in the ductwork.

  4. #4
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,292
    Well, your challenge now is to find a competent contractor to install the system. Installation quality outweighs brand selection in many respects...there are units out there that drive service techs crazy...but even those will perform well if they are installed with care, and do not have outright defects from the factory.

    If your mechanical engineer acquaintance provided you with a load calc report, I would also ask him to spec the equipment for your house. You can then obtain your bids against that spec so you have a consistent comparison against the various bids. This is hardly ever done in a residential setting, which is why homeowners can often become overwhelmed by how much variance there may be between bids in what is offered in terms of equipment and price.
    • 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
    Nov 2004
    Location
    SW FL
    Posts
    6,242
    Two 2 ton High HSPF heat pumps will get you to close-to-zero (i.e. << 50 gallon for Heating ) propane use.
    lower speed capacity for GREENSPEED heat pump = 40% * 2 tons = 0.8 ton = 9,600 BTU/HR

    http://www.carrier.com/homecomfort/e...umps---25vna0/

    http://www.climate-zone.com/climate/...ut/bridgeport/
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  6. #6
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,263
    Quote Originally Posted by spankyM View Post
    G
    Now to the particulars, I have purchased a newly constructed home from a developer that ran into some trouble and could not finish the building beyond rough-in condition. The home was built in 2010 and from what I can see was built with high efficiency in mind. The home is 1100 Sq. Ft per level with the first and second floors being finished and the basement level unfinished. From the design documents I can see that the HVAC system was calculated to be 1.5 tons per zone I want to use as much American manufactured equipment as I can. So far I have installed what I believe is called a hydronic heating system. In other words I have installed an Energy Kinetics "system 2000" approx. 130,000 BTU boiler and connected it to two air handlers (one per floor) manufactured by Firstco (model # 18HBXB-HW) along with a 60 gallon Hot water storage tank. They are fueled by a 1000 gal underground propane tank and controlled by a Venstar soft touch 5600 thermostat. So far the system has exceeded my expectations. Also, you should know that the house was built as a "closed" system, I can see that there is no ridge or soffit venting and the entire building envelope is spray foam insulation. I do notice that the second floor is always warmer than the first floor by at least 2 degrees F.

    My reason for this post is that I am now looking to install central Air Conditioning and while doing a great deal of research and reading I have come to the conclusion that American Standard seems to have the best service record with the least amount of documented repair issues. But, in trying to keep with my higher efficiency mandate, I have run into the problem that AS does not produce a 1.5 ton compressor/condenser unit with two stage scroll compressors. or at least not that I can find. the smallest two stage compressor they produce is a 2 ton unit (model #4a7a6024) and I wanted to know if I should connect the larger tonnage unit and If I do, will I see the peak performance I am looking for, or should I sacrifice the higher seer rating for the single stage compressor of the gold unit (model #4a7a5018) and match the 1.5 ton rating? If I have left out any pertinent information please don't hesitate to ask me for any additional information you may require.

    Thanks,

    Spanky M
    What kind of fresh air ventilation do use on this air tight home? In your climate, with the short a/c season and small cooling load, go for the simplest a/c possible. Your total cooling cost will be less than $100 per year. Saving 30% will be $30 per year. The idea of two speed or VS a/c will complicate your like without any payback. More important is get a adequate fresh filtered air change to purge indoor pollutants and renew oxygen. An filtered fresh air change in 4-5 hours while maintaining ,50%RH is a more critical long term health issue.
    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"

  7. #7
    Join Date
    Jul 2013
    Location
    Putnam Co, NY
    Posts
    3
    TB, I can not answer your question regarding fresh air, I went down and surveyed the entire duct system, and it does indeed seem to be a closed loop. I can not find a fresh air inlet. my only notion is that the air handler itself takes in fresh air from the basement. as far as fresh air for combustion on the boiler, The EK 1 F has a fresh air induction fan and direct duct to a sealed burner for ignition. lastly for this post, thanks to all for your learned advice, I have found in my twenty some odd years in the construction industry that the installers usually know a bit more about real world scenarios than the theoretical engineers of which I am one. structural, not mechanical. I will continue to read any new posts to this thread for a while as I am still saving up to buy the outdoor units, and always like to learn. please continue to post as you all see fit.

  8. #8
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,292
    Engineers create mistakes, technicians fix them.

    A moment of opining; please indulge me:

    Do engineers ever go beyond designing something and actually participate deeply in field testing? Were I a mechanical engineer I would not be happy with any design that wasn't subsequently run ragged with tests to see how well it held up, what worked well, and what did not. And...for the service tech in me and others here: how easy is it to work on? Is it a knuckle-buster or can parts be repaired or replaced with relative ease?

    How often do mechanical engineers participate in field commissioning of HVAC installs?

    Opining over...
    • 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.

  9. #9
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,242
    Quote Originally Posted by Shophound View Post

    Engineers create mistakes, technicians fix them.

    A moment of opining; please indulge me:

    Do engineers ever go beyond designing something and actually participate deeply in field testing?
    Were I a mechanical engineer I would not be happy with any design that wasn't subsequently run ragged with tests to see how well it held up,
    what worked well, and what did not. And...for the service tech in me and others here: how easy is it to work on?
    Is it a knuckle-buster or can parts be repaired or replaced with relative ease?

    How often do mechanical engineers participate in field commissioning of HVAC installs?

    Opining over...
    Mechanical Engineer will never participate in commissioning unless its his design.
    How many HVAC residential designs have you seen being performed by Mechanical Engineers?

    All firms need to develop a COMPLETE Process, like ...
    http://www.energywisestructures.com/

    One will be forced to emulate a superior design/build/commissioning process
    where required to meet HIGH Efficiency standards.
    For example,
    http://www.energycodes.gov/resource-...oulder-co-2008

    You'll probably never see Real Commissioning in the Residential HVAC arena
    unless the homeowner writes specific requirements
    into the contract with the builder.

    . HOUSE SEALING
    . DUCT SEALING
    . OVERALL AIR FLOW AND ROOM CFM
    ___ ought to be in all state building codes
    http://www.acca.org/Files/?id=739

    Homeowner’s responsibilities: The homeowner is ultimately responsible for the HVAC
    equipment’s required maintenance. They should use appropriately licensed and certified
    HVAC contractor to either perform inspection tasks or implement a maintenance
    program.
    The homeowner must understand which corrective actions are included and
    which corrective actions require their authorization to perform.

    Commercial and retail HVAC work is definitely a much different arena
    where Commissioning IS REQUIRED.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,741
    You won't get much if any benefit from a 2 ton 2 stage if you only need a 1.5 ton.

    Are those Firt company air handlers VS blowers? if not, just stick with a single stage.
    Contractor locator map

    How-to-apply-for-Professional

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

  11. #11
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,907
    If the air handlers aren't variable speed, don't bother with high SEER, you won't get it. Probably won't get it since you won't be on a matched coil. Stay 13 SEER.

    Friend had a 1600 sq ft foamed house, not counting basement that she never turned heat on to. 1st stage of a furnace heated it to below zero. That was 33,000 BTU output.

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