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01-10-2010, 09:24 PM   #46

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Its a pretty safe bet. your whole duct system was sized incorrectly. And was under sized.

01-10-2010, 10:02 PM   #47

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Quote:
 Originally Posted by Marty S. 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.

 01-10-2010, 10:23 PM #48 Member   Join Date: Dec 2008 Location: Dayton Ohio Area Posts: 671 Rewards Points: 502 Here is the thread from last year on the topic. HVAC - Airflow Issue __________________ -Andrew DIY hobbiest

 01-10-2010, 11:30 PM #49 Member   Join Date: Dec 2008 Location: Dayton Ohio Area Posts: 671 Rewards Points: 502 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. __________________ -Andrew DIY hobbiest Last edited by AndrewF; 01-10-2010 at 11:47 PM.
 01-11-2010, 04:14 AM #50 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,625 Rewards Points: 8,236 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.
 01-12-2010, 09:27 PM #51 Member   Join Date: Dec 2008 Location: Dayton Ohio Area Posts: 671 Rewards Points: 502 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. __________________ -Andrew DIY hobbiest Last edited by AndrewF; 01-12-2010 at 10:23 PM.
 01-12-2010, 10:20 PM #52 Member   Join Date: Dec 2008 Location: Dayton Ohio Area Posts: 671 Rewards Points: 502 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. __________________ -Andrew DIY hobbiest Last edited by AndrewF; 01-12-2010 at 10:39 PM.
 01-12-2010, 10:34 PM #53 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,625 Rewards Points: 8,236 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.
 01-12-2010, 10:37 PM #54 Member   Join Date: Dec 2008 Location: Dayton Ohio Area Posts: 671 Rewards Points: 502 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'? Attached Thumbnails     __________________ -Andrew DIY hobbiest Last edited by AndrewF; 01-12-2010 at 10:42 PM.
01-12-2010, 10:37 PM   #55

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Quote:
 Originally Posted by AndrewF 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.

01-12-2010, 10:41 PM   #56

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Quote:
 Originally Posted by AndrewF 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.

 01-12-2010, 10:46 PM #57 Member   Join Date: Dec 2008 Location: Dayton Ohio Area Posts: 671 Rewards Points: 502 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. __________________ -Andrew DIY hobbiest Last edited by AndrewF; 01-12-2010 at 10:50 PM.
 01-12-2010, 11:09 PM #58 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,625 Rewards Points: 8,236 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.
 01-13-2010, 08:13 PM #59 Member   Join Date: Dec 2008 Location: Dayton Ohio Area Posts: 671 Rewards Points: 502 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. __________________ -Andrew DIY hobbiest
01-13-2010, 08:30 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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