Page 6 of 7 FirstFirst 1234567 LastLast
Results 66 to 78 of 79
  1. #66
    Join Date
    Jul 2009
    Location
    gods country maui
    Posts
    16
    Quote Originally Posted by rojacman View Post
    put a tip jar on your toolbox???????????....Jack
    No but I never turn one down

  2. #67
    Join Date
    Jun 2008
    Location
    NW Florida
    Posts
    707
    Tip? What is that? In florida the tips you do get are from retired yankees. Local people very rarily tip.

  3. #68
    Join Date
    Jul 2008
    Location
    Nova-Scotia, Canada
    Posts
    271
    I thought the first reply was in good humor. Jeese guys....

  4. #69
    Join Date
    Sep 2008
    Location
    Western N.C
    Posts
    15
    Quote Originally Posted by meoberry View Post
    Tip? What is that? In florida the tips you do get are from retired yankees. Local people very rarily tip.
    The tips u get here in the mts. r the good kind like( dont eat yellow snow) or the rare jar of homemade honey or something fresh from the garden lol

  5. #70
    Join Date
    Jul 2007
    Location
    Chicago IL
    Posts
    167
    a salon gave me a bottle of shampoo the other day...
    i think they were trying to tell me something.

  6. #71
    Join Date
    Nov 2004
    Location
    NJ
    Posts
    1,203
    Quote Originally Posted by skizot View Post
    Reading this again, I have a question. What about the increased face velocity across the coil with higher air flow? The velocity increases when you increase the CFM. The higher the face velocity, the higher the coil bypass factor. The higher the coil bypass factor, the less efficient the coil is. This seems somewhat contradictory to what you've stated.
    What leads you to believe that?

    You have made several statements in this thread as if they were facts based on what you have learned and they have been incorrect.

    I make my statements based on what I have learned and use product application data and field measurements to be sure I am correct.

    Going back to the bolded statement in the quote above, show me something that backs it up, I'd be interested in reading it.

    In the mean time go to york.com or goodman.com (I like these manufacturers because they will allow access via the net where as some you need to be a dealer to access equipment info) and find some application data. Pick a system, any system and see what happens to capacity, efficiency and sensible heat ratio when the airflow is increased or decreased.

    We can pick it up from there .
    Ed J

  7. #72
    Join Date
    Jan 2009
    Posts
    386
    Quote Originally Posted by Ed Janowiak View Post
    What leads you to believe that?

    You have made several statements in this thread as if they were facts based on what you have learned and they have been incorrect.

    I make my statements based on what I have learned and use product application data and field measurements to be sure I am correct.

    Going back to the bolded statement in the quote above, show me something that backs it up, I'd be interested in reading it.

    In the mean time go to york.com or goodman.com (I like these manufacturers because they will allow access via the net where as some you need to be a dealer to access equipment info) and find some application data. Pick a system, any system and see what happens to capacity, efficiency and sensible heat ratio when the airflow is increased or decreased.

    We can pick it up from there .
    This is the article I read:

    http://www.iaqdirect.com/Main/Produc...r/Humidity.htm

    It could be completely inaccurate.

    I stated in a later post that I think I understand what you're saying now though. I didn't go look at either site, yet. I did come across this formula that I've seen before on here:

    Delta T * CFM * 1.08 = BTU/h

    That's for sensible heat removal, right? My question on that is the Delta T does not remain constant when you increase airflow though, right?

    I'm pretty sure I understand the SHR in regards to airflow now though. The lower the fan, the more latent heat you'll be removing, dropping the humidity, but not as much temperature. Higher fan will remove less latent heat, and more sensible heat, therefor increasing the SHR. The 530 CFM you stated possibly being correct just seemed a little high (basing that on what I've read here). The VS blowers out there have a comfort mode (350 CFM / ton) and another mode of 400 CFM / ton, right? Do some have a setting for more than 400 CFM / ton?

  8. #73
    Join Date
    Nov 2004
    Location
    NJ
    Posts
    1,203
    Everything you just wrote is correct.

    I'll add: more air more efficiency, but to a point. I don;t think it's realistic to continue to move more air across a coil after the units capacity is 100% sensible.

    ACCA's Manual S has the formulas for determining CFM based on space gain system capicity and SHR, thats accurate. The 350 a ton or 400 a ton values are starting points or nominal numbers, that's ball park.

    I'm gonna go read the link.
    Ed J

  9. #74
    Join Date
    Jan 2009
    Posts
    386
    Here is another link I found on the coil bypass factor. It states something similar to that first link:

    Marks' Standard Handbook for Mechanical Engineers

  10. #75
    Join Date
    Nov 2004
    Location
    NJ
    Posts
    1,203
    I know what bypass factor is, but I see why you though along the lines you did. I read the first one and as soon as the author stated taking about using a good motor and slowing the fan down I was expecting to see an add for fan handler, I scrolled down and what did I see? .

    To an extent your correct with regards to higher velocity lowering efficiency, but I can't think of why you would run a system outside the typical operating parameters of what the systems are made to perform under. If you stay within the velocity's in the application data it becomes a non issue.

    Bad duct designs have to be really bad designs to get water to start blowing off the coil, these are the kinds of velocity's you're going to need to see capacities (or efficiencies) affected.
    Ed J

  11. #76
    Join Date
    Jan 2009
    Posts
    386
    Quote Originally Posted by Ed Janowiak View Post
    I know what bypass factor is, but I see why you though along the lines you did. I read the first one and as soon as the author stated taking about using a good motor and slowing the fan down I was expecting to see an add for fan handler, I scrolled down and what did I see? .
    LOL.

    Quote Originally Posted by Ed Janowiak View Post
    To an extent your correct with regards to higher velocity lowering efficiency, but I can't think of why you would run a system outside the typical operating parameters of what the systems are made to perform under. If you stay within the velocity's in the application data it becomes a non issue.
    Yeah, but the system needs to be engineered by someone who understands airflow. Unfortunately, I don't think the company who designed the system in my house understood that. The velocity in the return drop right by my air handler is 955 FPM (1592 CFM / ((20" * 12") / 144)). The blower compartment has larger dimensions, as does the coil compartment, so I'm sure the air slows down some, but probably not a whole lot. Is 300-400 FPM across the coil what you should be shooting for? What type of velocities are we talking about that would affect coil efficiency?

  12. #77
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally Posted by skizot
    Here is the URL for the technical data sheet for the furnace: Furnace Spec Sheet

    Model Number: G1N80BU100D20C-2A

    The speed was Medium. Supply was 0.19" return was 0.20". Those were both taken by the auditor at the air handler as well. The return was measured before the filter, and by the looks of his diagram, the supply was measured at the coil.




    Quote Originally Posted by dash View Post
    Between the coil and furnace or exiting the coil?

    Thought you stated the ESP was .8 in wc.

    If the filter is .35 the return would be more then .20,unless that's the filter in the furnace,as it's included in the fan data.


    Sounding like you may not be getting the cfms you think you are.


    One test of .8 static on a certain speed ,does not mean you use .8 for the other speeds to determine cfms,change the speed you must retest.

  13. #78
    Join Date
    Jan 2009
    Posts
    386
    Quote Originally Posted by dash View Post
    One test of .8 static on a certain speed ,does not mean you use .8 for the other speeds to determine cfms,change the speed you must retest.
    I know, I need to retest the static on Med/Hi, but I don't own my own manometer. I assume the static will probably be higher on a higher speed, so the 1592 CFM on Med/Hi for 0.8" is probably not 1592, but less. How much less I'm not sure of until I have it measured again, but I'm sure I'll still be over 800 FPM, easily. 800 FPM is 1333 CFM (given my dimensions), which is less than what I get on Medium with a measured static pressure of 0.8.

    BTW, the ESP is definitely 0.8" W.C. on Medium. The tech that was out the other day verified this.
    Last edited by skizot; 07-10-2009 at 03:40 PM. Reason: added ()

Page 6 of 7 FirstFirst 1234567 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event