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  1. #14
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    It seems pretty straight forward to use an anemometer to measure the air velocity from the grill and determine the ball park air cfm exiting the grill and had hoped someone had used this method before vice the expensive Air Flow hoods.. and would say.. heck yes i have used it a few times and it seems to be a very close ball park measure of the CFM... and have used it to set the initial setting of the dampers many time... before I waste good money on something that is horrifically wrong... but so far seems like no one has tried it...

    Example: You have a bathroom exhaust fan designed for 200 CFM. The system has an 8-in. exhaust duct. The area of an 8-in. duct is .35 sq. ft. You measure the velocity at a points in the duct and find the average velocity in the exhaust duct is 400 FPM. Multiply 400 Feet per Minute times the area of the duct, which is .35 square feet, to find 140 CFM exhaust fan airflow.

  2. #15
    Join Date
    Nov 2004
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    THE ART of
    _________ Balancing, Air distribution and It's Various Measurement Methods.

    1. Hot Wire Anemometer
    ….. a. Traverse - External
    ….. b. Averaging
    2. Static Pressure
    ……. a. Pitot Tube
    …….. b. Manometer
    …….. c. Traverse - Internal
    3. Orifice Plate
    4. Balometer [a.k.a. Flow Hood ]
    5.
    _________ _ _ _ ... ... _ _ _ ______

    NOT at all STRAIGHT FORWARD
    IF an Accurate, AVERAGE Velocity is not established.


    https://www.youtube.com/watch?v=TMgElmg_sbg

    DIFFUSERS
    __________ A.k = Effective Free Area
    __________ CFM = A.k * Velocity

    http://www.hartandcooley.com/files/a...5MS_A505OB.pdf

    http://www.hartandcooley.com/submitt...rformance-data
    Last edited by dan sw fl; 10-13-2019 at 12:53 PM.
    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

  3. #16
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    Nov 2004
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    SW FL
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    _ ___ OBD ( part AG-15) can be installed At each Diffuser

    https://www.titus-hvac.com/docs/lite...ction_mini.pdf
    Attached Images Attached Images   
    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

  4. #17
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    Thread Starter
    <quote>NOT at all STRAIGHT FORWARD
    IF an Accurate, AVERAGE Velocity is not established.</quote>

    Dan not sure I need all that grill analyzation.. but I do know how to get a ball park average just by measuring several places on the grill and calculate the average.. that should be straight forward... them multiply the entire 12x6 area of the grill (actually 11x5) times the average air velocity. Not sure i need exact average velocity as I am only looking for a ball park figure.. so what if it is 5-10 % off... that should be fine and the reason its called ball park.... anything will be more accurate that full wide open flow.

    BTW my grills are all 12x6 2 way actual air flow area is 11x5.

    I will just simply write a quickie program on my desktop that I will take say 5-6 quick anemometer velocity reading on the grill selecting similar locations on each grill and dump those velocity readings into the pgm to give avg of 6 then have the program add the grill sq in flow area that is in the program.. to quickly calculate the ball park airflow... as adjustments are made then measure the other grills to see how much it also affected them... but its seems like no one has ever done it this way and I sure don't plan to buy a hood.. though I have seen them as low as 300 bucks... but the anemometer is less than 30 bucks.

  5. #18
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    Nov 2004
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    Quote Originally Posted by govtom View Post
    <quote>NOT at all STRAIGHT FORWARD
    IF an Accurate, AVERAGE Velocity is not established.</quote>

    Dan not sure I need all that grill analyzation.. but I do know how to get a ball park average just by measuring several places on the grill and calculate the average..

    that should be straight forward... then multiply the entire 12x6 area of the grill (actually 11x5) times the average air velocity.

    Not sure i need exact average velocity as I am only looking for a ball park figure.. so what if it is 5-10 % off... that should be fine and the reason its called ball park.... anything will be more accurate that full wide open flow.

    BTW my grills are all 12x6 2 way actual air flow area is 11x5. << Mfg., model & Reference ?

    I will just simply write a quickie program on my desktop that I will take say 5-6 quick anemometer velocity reading on the grill selecting similar locations on each grill and dump those velocity readings into the pgm to give avg of 6 then have the program add the grill sq in flow area that is in the program.. to quickly calculate the ball park airflow... as adjustments are made then measure the other grills to see how much it also affected them... but its seems like no one has ever done it this way and I sure don't plan to buy a hood.. though I have seen them as low as 300 bucks... but the anemometer is less than 30 bucks.

    ____________ DEFINITELY NOT AT ALL STRAIGHT FORWARD


    ___ CFM = A.k * Velocity

    https://www.titus-hvac.com/file/4181...w%20Factor.pdf


    https://installerstoreblog.com/2012/...-vs-free-area/
    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. #19
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    Dec 2005
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    Cincinnati, Oh
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    What does IAW mean?

    I donít expect anyone to do anything. I expect them to pay for the services I render. If you donít purchase the service, itís not rendered.

    Itís kinda crazy. I put trash out to the street the other day that the trash company wouldnít take. Itís took large to fit in their truck. How do they expect me to get rid of it? Doesnít really matter, because I donít pay for their bulk service, I didnít receive it.

    I wouldnít recommend anyone who is uncomfortable crawling in their attic to do it.

    Again, your assuming everyone would need to adjust their dampers to get precise airflow room by room.

    Sounds to me like you asked them to do a Test and balance and they said no, and now your looking for ammo to go after them.

    Everything youíve said about your install is on the negative.
    Since your not happy, and itís too hard for you to get in the attic, hire a test and balance company.

  7. #20
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    May 2017
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    [QUOTE=hvacvegas;25794157]What does IAW mean?

    Everything you’ve said about your install is on the negative.</quote>

    IAW = In accordance with....

    Large trash items: I am surprised your area has no call in for pickup of large items.. we get 12 pu per year all included in the water bill...

    The reason I am negative about the install is that almost everything was done horribly..

    But now I realize its fairly normal for the hvac teams out there install something they don't adjust it.. they say it you want my stuff that you paid me for adjusted call someone else... not my job. And as long as you make sure the customer knows that you do not make adjustments to your duct installations then that is fine. They were warned..

    And i would be much happier had I known they would not even make ball park adjustments I would have said NEXT.
    But now that I find out they know nothing about the adjustments they did not do them which is fine as I would rather have the ducts not adjusted vice adjusted wrong.

    Most of my complaints were something that a normal homeowner would never have known... here is one or two of 324 major discrepancies with the install.

    1. Two stage system installed with thermostats that had no 2nd stage capability. homeowner would never know that.. till they tried to sell the home and the home inspector alerted them. both upstairs unit and downstairs unit.

    2. No PT1 and PT2 ports installed so that geo water flow could be set... they did not know how to set it.. so really what would they do with PT1 and PT2 ports. homeowner would never know as it still cooled decently with water valves full open

    3. Install a double Ptrap in the condensate line of the 1st floor which shut me down for the entire weekend.

    4. Install huge 3 ton Trane Geo sidewise since the door would not close otherwise. Works great but when you try to sell your home the home inspector would require replacement due to unserviceable. Homeowner would never know its sidewise.

    Yes there is 324-4=320 more major gripes that i had to find for them so they could fix them...
    So yes I am negative..

    Thanks for your input.. I appreciate all the inputs.. and it helps me understand that this is complicated and way more complicated than my contractor could handle.. so at this point I don't even want him to do it as I plan to hire a balancing company and hope that they will be better than the contractor I have... certainly cannot do any worse..

  8. #21
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    Sep 2008
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    VA
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    I’ve personally spent over $6k in air flow and duct testing tools, and I can tell you using each one of these tools on a single measurement can provide very skewed results. Depending on what you’re measuring certain tools work better than others.
    So, can you use an el cheapo eBay anemometer? Sure, but if you’re not getting any accurate measurements what’s the point?

    Isn’t comfort the ultimate goal? The ducting should be designed close to a proper balance without the dampers. Dampers are for individual comfort. If you have occupants in one room that prefer cooler air adjustments can be made. If you have a room you decide to install an elaborate media center in, adjustments can be made.

    Dampers in residential design are more for personal comfort adjustments. They provide an “opportunity” for comfort adjustments should the occupants deem it necessary.
    "The only true wisdom is in knowing you know nothing" Socrates

  9. #22
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    Quote Originally Posted by mgenius33 View Post

    Isnít comfort the ultimate goal?

    The ducting should be designed close to a proper balance without the dampers.

    Dampers in residential design are more for personal comfort adjustments.
    Thanks for your input..

    OMG! Design for balance.. no design was ever done...
    As you can see above 324 major discrepancies include No Manual J, S, or D... so what I got was a mess.. and now am stuck with balancing with dampers due to the lack of Manual D design....

    Course what I am seeing is very few do the J,S,D trick many because they do not know how and basically tell you if you want one of those thing-a-ma-jigges you will have to purchase that from someone who knows how... and same with duct setting...

    I was really just looking to setting the rough airflow and then using temp measuring to tweak the rooms each for winter and summer so it will be easy in hte future. So I can do it with the tweaking each room based on temp but would be much faster if they were initially set to close to what Manual D expects.. but with no load values from the Manual J.. just going to initially distribute the air based on what each bedroom needs in my opinion splitting the 800 cfm of air from a normal 2 ton unit.

  10. #23
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    Mar 2018
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    Chico, Ca #StateofJefferson
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    I'm sorry, I was laughing so hard at the inspector will do this and do that, I woke up the baby and dogs! I've met hundreds of "inspectors" and only 1 would ever go farther than turning the tstat and make sure hot or cold air came out so unlikely it will come up. About as useful as a football bat. Maybe a member on this sites contractor locator map is near you,

  11. #24
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    Quote Originally Posted by Makeitcold View Post
    I'm sorry, I was laughing so hard at the inspector will do this and do that, I woke up the baby and dogs! I've met hundreds of "inspectors" and only 1 would ever go farther than turning the tstat and make sure hot or cold air came out so unlikely it will come up. About as useful as a football bat. Maybe a member on this sites contractor locator map is near you,
    NOPE no contractors on the locator map in my neck of the woods... the only one in the Hampton Roads area is Wholesaler not a serviceman...At least that is what he said when I contacted him for help.. Don't mind paying for good help when i can find it but so far have been batting a low score on good ones.
    Even those who come for a quote depress me.. for example one quoter wanted to send his ace tech to make sure all is well when he quoted duck upgrade.. and I thought to my self how nice.. even though he wanted 89 bucks for the look see and had no problem with that till I noticed the tech measure the water temp on my PT! and PT2 water inlet and outlet.. and sez... you need more water flow call your well man... My response is "How so.. do you see the water valve there in the return line half way closed... I suspect when the factory rep himself came over and set my water he had too much so he throttled it into half... if you need more water for the test why not just open the water valve some... He continued water is low trust me.. I asked "How did you determine that I only saw you use a thermometer.. He asks if I have the manual on hand.. so I gave it to him and he showed me that for such and such water.. you should have such and such temp split.
    I said fine... but look here in the same manual written by TRANE... it says "NEVER EVER use temp split for adjusting use it only as a ref for troubleshooting... its way to inaccuracte ... TRANE demands the use of PRESSURE DROP across PT1 and PT2 and in my case a 2 psi drop mean 6 gpm. on the chart... HE continued with well just for good measure have the well man check it out...
    So he wants me to pay a well man to check out something when my manual just showed him his test was worthless...
    And worse yes is another contractor asked me to have a new well return dug at 2 grand due to a 36psi.. back pressure in the return line to the well.. Boy was he embarrassed when I connected a water hose to the return and dumped it in my yard directly... with no back pressure in my yard... but still wanted me to have the well man verify it was all ok... Too many folks just wild ass guess what the problem is vice testing to determine. But poor homeowners would have to blindly do what they say as they are the experts.. and to what expense.

    So it should be easy to see why I have become a little less positive not about just my contractor but many of the others that I am exposed to.. That is why I seek advice here as I know many of the contractors have more knowledge than the avg contractor in the field... and so I try to glean as much as I can here with this gang.... Maybe not all here are top of the line but I am sure many of you are... and I get to here more than just one idea from my contractor who i have learned is not the sharpest cookie in Hampton Roads.

    That makes it even worse if we cannot depend on the home inspector to find faults.. that means a crooked contractor can get away with even more as most home owners have any idea what they are doing so they will never catch a contractor shorting them.... So most home owners would have to wait till the house is sold and the new homeowner signs up with his old hvac maintenance guys and when they come out to change the blower motor they say to the poor dumb home owner "Mr. New owner... we have two options on this... I can remove all the trim from the door of the under stairwell and try to get your HVAC unit out that way so we can open the box and change the fan motor... and while we have it out we can give you a really good price on a new Bosch that will fit right in there w/o even removing the trim.. Or once we change that blower motor we can poke it right back in the hole side wise and un-serviceable (you would think the city inspector would have noticed that many of them are worse than any home inspector i have ever seen... rarely do they go under the house.).. if you do not want the expense of a replacement... but I prefer to change it out since it makes my company look bad years from now and who ever buys it next might call it out and if we have been servicing it.. makes us all look bad... your choice as you have been with us many years and we can still knock an extra 20% of the motor change since its gonna be a whopper especially with all the trim to be removed and reinstalled each time we need to do any major work in the future.

    (course that will not happen with me since I had already caught it and they ate that one and replaced it with the only thing we could find to fit.. a 3 ton bosch)

    OR since you have only owned this rats nest a year.. we can write it up as a huge negligence on the owners part who sold it for not disclosing this bag of worms... then you can go to court and get all your damages back and most likely the old owner can sue the contractor and get all his money back with court costs.... most likely the fear of the court the old home owner will just pay us to replace the unit.. which may be best for all.... court costs and lawyers are very high..

    In response to your comment "home inspector don't do much:"
    I have been in real estate sales for 30 years and have had more than one home inspector come in with the IR cameras looking for moisture in the wall and more than one ask the seller to produce the permit for a replacement hvac system that should have had a permit and does not.. for example you may be able to get away with no permit for replacement but not when the compressor (in my case) that was under the stairwell had to be moved to the garage... required both mechanical and electrical permit why was never pulled until i demanded it.

    And my guess is any home inspector no matter how dumb or lazy would have caught the side wise (un-servicable) 3 ton trane when looking for the age of equipment.. and has to put his head all the way in a hole on the left to even get a glimpse of the panel which is normally right out front in your face.. I have never seen any inspector not search the equipment for date clues including the roof, hot water, hvac and all else.. Many inspectors feel that if they find something that makes the deal fall thru they have done their job... and I guess it makes sense if they do find something so bad the deal falls thru they may have saved the day... as long as it serious like a side wise unit and not something piddly..

  12. #25
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    Mar 2018
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    Chico, Ca #StateofJefferson
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    My experience is that the inspector is there to protect the bank, who is providing the loan. My wife made us get a home inspector for our first home, she was so disappointed when I showed her the contract and pointed out the part that says he cant be held liable for not finding stuff or not knowing it was against code, basically you cant sue because he sucks at his job or is incompetent. Nice. I've found so many units that were unserviceable it's not even funny but the installers dont care, they arent ever coming back. As far as inspections go, best bet is to call all the trades, have a roofer inspect the roof, a pool company inspect the pool and an hvac company inspect the hvac, etc. No one person can have all the knowledge of all the trades, and if they did you couldn't afford them!

  13. #26
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    Quote Originally Posted by Makeitcold View Post
    My experience is that the inspector is there to protect the bank, who is providing the loan. My wife made us get a home inspector for our first home, she was so disappointed when I showed her the contract and pointed out the part that says he cant be held liable for not finding stuff or not knowing it was against code, basically you cant sue because he sucks at his job or is incompetent. Nice. I've found so many units that were serviceable it's not even funny but the installers dont care, they arent ever coming back. As far as inspections go, best bet is to call all the trades, have a roofer inspect the roof, a pool company inspect the pool and an hvac company inspect the hvac, etc. No one person can have all the knowledge of all the trades, and if they did you couldn't afford them!
    100% on required by the bank.

    Home inspector are lower then HVAC Techs!

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