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  1. #27
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    7,537
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    Quote Originally Posted by cuervo View Post
    Here's a question............
    If there's no way to pop a hole in the back of a residential furnace (walls or other restrictions) and evaporator coil is right above the furnace, is the limit hole (if centered) an option to take the TESP or is it still too much turbulence from the blower to get an accurate reading? I've never tried this myself.
    Yes, I have used the limit hole on more than one occasion. Testing at that location, although not ideal(due to possible airflow turbulence), is better than not testing at all.
    Instead of learning the tricks of the trade, learn the trade.

  2. #28
    Join Date
    Apr 2008
    Location
    Central CA
    Posts
    567
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    I recently stopped drilling and plugging holes in favor of using some cap tube in place of my static probes and just using the "factory installed holes" lol
    Iv tested the variances between the two and as long as you hold the cap tube 90* to airflow the measurements are correct.
    You can just remove a screw and place the cap tube in to take a measurement, easy peasy and no hole to plug.
    Much quicker and easier to use once you learn to trust the readings after doing alot of testing and becoming familiar with it.
    I use this for measuring SP on exhaust fans too since you cant drill type 1 hoods that carry grease through them.

  3. #29
    Join Date
    Jan 2007
    Location
    Stongsville Oh
    Posts
    1,171
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    Rundawg,I atempted to email you for your information on the topic but your email is shut off on this site. Am I doing some thing wrong?
    ckartson
    I didn't write the book I just read it!

  4. #30
    Join Date
    Jan 2007
    Location
    Stongsville Oh
    Posts
    1,171
    Post Likes
    Sory I found your email forget the last post
    ckartson
    I didn't write the book I just read it!

  5. #31
    Join Date
    Jul 2011
    Location
    Sacramento, CA
    Posts
    19
    Post Likes
    As long as it can measure tenths of inches of WC, you're good to go. I use the fieldpiece manometer head with a dwyer 303 tip and a 1/4" bit. It has a switch to change the scale for anything above 1"(gas valves), and below 1"(static)

  6. #32
    Join Date
    Sep 2012
    Posts
    2
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    Static Pressure

    It amazes me, reading all the seemingly accepted practices on measuring static pressure and the sizing of returns at a certain static or square inches and so on. These all lead to mediocrity.
    Velocity is where it's at. I just read one that says to read the return static before the filter. No. Given that the pressure drop across the filter should not exceed 20% of the design static, this means if you want 0.5" wc of total external static, the drop across the filter can only be 0.10" wc. If their rated pd is higher than that, you have to slow the air down. Return needs to hit the filters at what they are rated for or lower. Typically, 1" filters are rated at 300 fpm while 2", 4" & 6" are rated at 500 fpm. Another point, when the velocity is down to the level it should be. (Roughly 400 fpm) you'll find that larger returns (16", 18", 20") will have a resulting static as low as 0.01" wc or 0.02" wc Vs .05". wc. Size your returns at 400 fpm and stand back in amazement as to how the system performs.
    The information I shared here resulted in a $4 million decrease in compressor warranties over a 4 year period for this distributor. Hope this helps.

  7. Likes TBrazin liked this post
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