Page 1 of 2 12 LastLast
Results 1 to 13 of 16

Thread: Cfm

  1. #1
    Join Date
    Mar 2012
    Location
    Kentucky
    Posts
    21

    Cfm

    I'm using an anemometer to measure cfm. How do I I find out how much air flow I need and how much needs to be put out?

  2. #2
    Join Date
    Jun 2012
    Location
    Texas Hill Country
    Posts
    53
    Are you asking how to figure it in general? Or are you asking how to get your specific anemometer to tell you the cfm?

    I only ask because it sounds like you've never used an anemometer.

  3. #3
    Join Date
    Mar 2012
    Location
    Kentucky
    Posts
    21
    I have never used one. I'm wanting to know how to figure out if I'm getting good airflow.

  4. #4
    Join Date
    Jun 2012
    Location
    Texas Hill Country
    Posts
    53
    I saw from your post history that you're using a Fieldpiece with an anemometer attachment. It turns out that attachment has a useful how-to page about how to roughly figure CFM:

    http://www.fieldpiece.com/accessory-heads/aav3

    You're going to need more data to be able to figure it, with or without the equipment. Go over that page, and I'll help you out with the calculations if you need it.

  5. #5
    Join Date
    Mar 2012
    Location
    Kentucky
    Posts
    21
    How do I figure how much airflow I need at return and supply to make sure the air flow is good. I do apartment maintenance and some residents complain that the upstairs never gets cool. I'm going to check the supply but not sure what I would need as far as cfm. I know how to figure cfm, free area of the vent x air velocity = cfm

  6. #6
    Join Date
    Jun 2012
    Location
    Texas Hill Country
    Posts
    53
    What made you focus on cfm for that problem? There are about a billion other things to check before even considering how much air you're moving.

  7. #7
    Join Date
    Dec 2002
    Location
    Arizona
    Posts
    4,412
    Quote Originally Posted by schr8er View Post
    What made you focus on cfm for that problem? There are about a billion other things to check before even considering how much air you're moving.
    Really?
    Make your expertise uniquely valuable.

    Make your influence uniquely far-reaching.

  8. #8
    Join Date
    Jun 2012
    Location
    Texas Hill Country
    Posts
    53
    Well, no, obviously. Just that there are other factors to consider before worrying about CFM in an apartment.

  9. #9
    Join Date
    Mar 2012
    Location
    Kentucky
    Posts
    21
    Inside and outside coils clean. Pressures are right and superheat is correct. I've noticed that the squirrel cages are very dirty. Figured airflow could be a problem. Now that I have anemometer I'm going to clean the squirrel cage and check before and after. This was just something that I wanted to check out. I've been keeping a clean blower with me and changing them out on all my ac calls. So far no one has called and said it isn't any better. What else could be the problem? I'm still new to the trade.

  10. #10
    Join Date
    Dec 2002
    Location
    Arizona
    Posts
    4,412
    Quote Originally Posted by Kymike View Post
    Inside and outside coils clean. Pressures are right and superheat is correct. I've noticed that the squirrel cages are very dirty. Figured airflow could be a problem. Now that I have anemometer I'm going to clean the squirrel cage and check before and after. This was just something that I wanted to check out. I've been keeping a clean blower with me and changing them out on all my ac calls. So far no one has called and said it isn't any better. What else could be the problem? I'm still new to the trade.
    Hard to know if pressures are rite if ya don't know if air flows are rite!
    Make your expertise uniquely valuable.

    Make your influence uniquely far-reaching.

  11. #11
    Join Date
    Jun 2012
    Location
    Texas Hill Country
    Posts
    53
    What size HVAC units are we talking about here? I had a similar problem with some new townhouses not long ago, where the downstairs would cool off just fine, while the upstairs roasted. It turned out the units were undersized for the cooling load, because contractors around here are cheap-asses.

  12. #12
    Join Date
    Mar 2012
    Location
    Kentucky
    Posts
    21
    I know if the airflow is completely obstructed that you can't get the correct pressures. I was taught if you feel it coming out its good. With coils being clean. I already check more than what they want me to.

  13. #13
    Join Date
    Mar 2012
    Location
    Kentucky
    Posts
    21
    1 1/2 ton for about 1000sq ft. Trane units inside and out.

Page 1 of 2 12 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