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Old 05-23-2009, 10:41 AM   #16
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


any links to a "cheap" water/utube manometer? i am guessing homedepot or lowes wouldnt have them. i dont want to buy the wrong one. thanks again

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Old 05-23-2009, 10:44 AM   #17
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


No, I got my u tube from a wholesale supplier.
And the rest of manometers are digital, starting at 150 bucks, on up.
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Old 05-23-2009, 10:53 AM   #18
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


i dont know if links can be posted, but would something like this be ok?
http://www.dwyer-inst.com.au/htdocs/...3Price.cfm#CRA
http://www.dwyer-inst.com/PDF_files/1221_cat.pdf

Last edited by Yamvmax; 05-23-2009 at 10:55 AM.
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Old 05-23-2009, 11:09 AM   #19
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


You can use one of them.
they are hard to read at times though.

When you use it. And the level changes by say .1" on one side. Double that, and that is the actual reading.
Because the level actually changed on both sides.
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Old 05-23-2009, 01:57 PM   #20
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


Quote:
Originally Posted by Yamvmax View Post
i do have my manual, and have the graph. How do i figure out esp? i need to take readings before the filter, and after the coil, correct? What do i need to measure that? Thanks
I have attached a video link to a site that may provide you some insight on testing ESP.
Watch the "Shawn on ESP" Video.

http://www.bacharach-training.com/ESP100.wmv

Also, I have attached a link to the dwyer magnehelic guage that I use to check ESP (in the amazon.com link) below

http://www.amazon.com/Dwyer-1-0-Wc-M...3100291&sr=1-2

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Old 05-23-2009, 02:23 PM   #21
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


Quote:
Originally Posted by key1cc View Post
I have attached a video link to a site that may provide you some insight on testing ESP.
Watch the "Shawn on ESP" Video.

http://www.bacharach-training.com/

Also, I have attached a link to the dwyer magnehelic guage that I use to check ESP (in the amazon.com link) below

http://www.amazon.com/Dwyer-1-0-Wc-M...3100291&sr=1-2

Key1

Thanks. for some reason the video wont open. when i click on the link on the website, media player opens, but nothing happens.
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Old 05-23-2009, 02:44 PM   #22
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


Quote:
Originally Posted by Yamvmax View Post
Thanks. for some reason the video wont open. when i click on the link on the website, media player opens, but nothing happens.
I edited the link
Now try it.

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Old 05-23-2009, 02:56 PM   #23
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


well, 2 different computers no luck. Thanks anyway
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Old 05-23-2009, 03:06 PM   #24
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


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Originally Posted by Yamvmax View Post
well, 2 different computers no luck. Thanks anyway
I am sure this will work.
Go to post number 44 in the attached link and try it again..

Key1

http://hvac-talk.com/vbb/showthread....ighlight=video
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Old 05-23-2009, 04:52 PM   #25
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


ok, got it. media player was screwed up. thats a great video. thanks. so i guess i will need probes also? Damn. this is getting expensive. Is there a fairly cheap way to do this?

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Old 05-23-2009, 05:52 PM   #26
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


Quote:
Originally Posted by Yamvmax View Post
ok, got it. media player was screwed up. thats a great video. thanks. so i guess i will need probes also? Damn. this is getting expensive. Is there a fairly cheap way to do this?
You really only need 1 probe. Link attached. You can measure the positive and negative seperately. You do not need to measure them at the same time.

http://www.amazon.com/Dwyer-303-Port...3114950&sr=8-2

Personally I feel that static pressure is one of the most important things you can know about your system. That way, when you make changes you will understand if the impact is potentially positive or negative for your system. You will also be able to measure the "back pressure" caused by your filter or stated as the pro's say "the pressure drop across your filter". It will give you insight if you want to move to a better filter. It will also provide insight if one area of your home is less comfortable and you need to close dampers or register grills to get a more even temp. Essentially being able to measure static pressure is kinda like having xray vision to the changes you make on your system.
Have fun.

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Old 05-23-2009, 06:58 PM   #27
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


thats great. i really appreciate all the advice. i didnt realize how complex a HA system is.
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Old 06-01-2009, 05:58 PM   #28
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


Update guys. I got my magnehlic gauge. My esp is .55. I am guessing this is very good. Now back to my orig question. Based on the furnace stats, i am pushing 775 CFM at the fan speed i am using for the AC. I have a 2 ton unit, so i fairly close to the 400 per ton. If i were to lower the speed I would be at 536 CFM, which would be too low. If i increased the speed, I would be at 1025 CFM, which is slightly too high. So i should leave it exactly where i am, correct? Thanks for any input. BTW my ducts are 50 yr old galvanized. i am reading .40 just after the filter, and .15 right before the acoil. Do these sound like good numbers? I disassembled and thoroughly cleaned the insides, and sealed them back up with mastic. What do you guys think?
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Old 06-01-2009, 06:20 PM   #29
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


Must have big supply duct to have that low of a supply static with a wet coil.

One thing you may have made a mistake on though.

When you look at your blower cahart to see what CFM you would be moving if you lower the blower speed.
You don't use the .55" ESP.
When you slow the blower down. Since its moving less CFM, your static pressure decreases.

So you may have to look at .3" or .4" on the fan data chart.

EG"
At 775 CFM and .55" TESP. When only moving 536 CFM, the TESP would drop to .26".

Since you don't have a VS blower that controls RPM to regulate CFM.

Switch it to the lower blower speed, and see what Static you have in your ducts. And then compared that to your fan data chart.
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Old 06-01-2009, 06:34 PM   #30
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Can I reduce my AC CFM/ton to under 300 to lower static pressure?


Quote:
Originally Posted by beenthere View Post
Must have big supply duct to have that low of a supply static with a wet coil.

One thing you may have made a mistake on though.

When you look at your blower cahart to see what CFM you would be moving if you lower the blower speed.
You don't use the .55" ESP.
When you slow the blower down. Since its moving less CFM, your static pressure decreases.

So you may have to look at .3" or .4" on the fan data chart.

EG"
At 775 CFM and .55" TESP. When only moving 536 CFM, the TESP would drop to .26".

Since you don't have a VS blower that controls RPM to regulate CFM.

Switch it to the lower blower speed, and see what Static you have in your ducts. And then compared that to your fan data chart.
I do have a large return. It is only a 2 bed 1000 sq ft house, but has a return in main living area, and one in each bedroom. SO you are saying take an ESP at each blower speed? Then look at the chart?

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