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Old 01-10-2010, 10:24 PM   #46
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Its a pretty safe bet. your whole duct system was sized incorrectly. And was under sized.
Including your supply branches.

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Old 01-10-2010, 11:02 PM   #47
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Quote:
Originally Posted by Marty S. View Post
Just by count you have plenty of suppies for a 5 ton system but are lacking on returns. Add your one in the kitchen hall and two 6x30's in the basement.
Other then about 540CFM to the second floor. And 4 unknown size supplies to the basement.

What makes you think he has enough supply.
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Old 01-10-2010, 11:23 PM   #48
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Here is the thread from last year on the topic.

HVAC - Airflow Issue
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Old 01-11-2010, 12:30 AM   #49
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Hmmh, I cant seem to get the online forumulas to work for me.

All E-heat engergized, I pull 88.5 amps per 240 leg.
VAC: 238
1KW = 3413 BTUs

Convert Amps to Watts: 88.5 amps * 238 volts = 21,063 Watts
Convert Watts to Kw: 21063/1000 =21.06 KW
Convert KW to BTUs: 21.06KW * 3413 = 71,888 BTUs.

Is that right?

As for my WC test.

If I take out the 20x25x4" filter, There is about a pencil mark difference in the water level on my homemande manometer.

If I leave the filter in, I have approximately 1/8 - 1/4" per side, so 1/4 to 1/2" WC.

As for temperature rise (to calcuate CFM)

Input: 66
Output: 105
Temp Rise: 39
Corrected: 42.12

My CFM is around: 1706 with no air filter
and is around 1584 with the filter.

I still have 2 more turning vanes to install on the supply side, and 5 on the return.
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Old 01-11-2010, 05:14 AM   #50
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Static on the supply side should be read also.
Your math is correct on BTU.

1706 CFM is still too low for a 5 ton heat pump. Weather in heat or cool mode.

Adding the hydro coil to the return would lower your air flow even more.
2 over sized coils on the supply, won't lower the air flow as much. And if you have a sheet metal shop make the fitting as a radius Tee. It will help improve/increase air flow.


From your other thread, you have 27-6" supplies. At 1706CFM total from the air handler, that would make them have an average of 63CFM.
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Old 01-12-2010, 10:27 PM   #51
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I put the remaining turning vanes in tonight and opened up another return.

71,888 BTU
Temp rise corrected: 37.8

CFM = 1901

This is with no filter.

I dont think I can get it much better than that based on what I have to work with.

The WC measurements coming up next.
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Old 01-12-2010, 11:20 PM   #52
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I get less than 1/16" of an inch of WC change on my supply side.

On the return, I get 1/16" of an inch with no filter installed (one sie of manometer)

I get a little over 1/8 (so likely 3/16") with my 20x25x4 filter.

Return no filter 1/8" WC .125
Return with filter 1/4" WC .25

These are based on the fan speed of high.

If there is a decent tool online that will give me digital readings on this, I'll buy one if being that accurate is critical.
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Old 01-12-2010, 11:34 PM   #53
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Digiatal manometers
A303 static probe kit for manometers

The last link also sells manometers. But, I don't think you'll like the price of them.

The static probes, make it easier to get a accurate reading.
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Old 01-12-2010, 11:37 PM   #54
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SO which is more accurate for a CFM reading. The temperature rise method or the WC numbers based on the manufacture chart?

If temperature rise, won't it be off some based on the fact that depending which direction of my supply plenum, results in different temperature readings? Also, if I am say, 5' from the turn, is that less accurate than being at say, 1'?
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Old 01-12-2010, 11:37 PM   #55
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Quote:
Originally Posted by AndrewF View Post
I get less than 1/16" of an inch of WC change on my supply side.

On the return, I get 1/16" of an inch with no filter installed (one side of manometer)

I get a little over 1/8 (so likely 3/16") with my 20x25x4 filter.

Return no filter 1/8" WC .125
Return with filter 1/4" WC .25

If there is a decent tool online that will give me digital readings on this, I'll buy one if being that accurate is critical.
If thats 1/8 on one side, and 1/4 on one side.
Then your total static is .75" with air filter.
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Old 01-12-2010, 11:41 PM   #56
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Quote:
Originally Posted by AndrewF View Post
SO which is more accurate for a CFM reading. The temperature rise method or the WC numbers based on the manufacture chart?

If temperature rise, won't it be off some based on the fact that depending which direction of my supply plenum, results in different temperature readings? Also, if I am say, 5' from the turn, is that less accurate than being at say, 1'?
If you use static probes and a digital, or inclined manometer. The wc.

What blower speed is it set for with those readings.

Since amp readings can vary with how you hold the amp probe.

But, you see that you CFM is not on the chart, with your Static pressure.

Temp reading should be 1 to 3 foot from plenum to be uneffected by radiant heat.
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Old 01-12-2010, 11:46 PM   #57
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If supply is less than 1/16th of an inch per side of manometer, and we assume it is 1/16 total, that would be .0625.

Add the .25 for the return side with filter, and then subtract the manufacture specs for the 20kw heat tape.

.0625 + .25 -.02 = .2925

I could be wrong here...hence why I might scour ebay for a cheap digital manometer.
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Old 01-13-2010, 12:09 AM   #58
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See post 53 for links.

Never assume with a water tube.

If your going to get a digital manometer, and the static probes I posted links to. You be able to get much more accurate readings.

Was your return 1/4 one side. Or both sides added together.
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Old 01-13-2010, 09:13 PM   #59
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At this point, I am not sure what else I can change to tweak the system anymore than I have...so I dont think spending $70-80 is worth it.

What I might do is wait until Spring and have the system refrigerant levels checked and at the same time have them do the test.

I suspect my system might be overcharged a little.
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Old 01-13-2010, 09:30 PM   #60
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You may have a hard time finding a company that knows how to check static pressure.

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