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Old 12-27-2008, 09:59 PM   #31
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Furnace Filters


May have been caused by turbulance of the air meeting at the lower return grille.

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Old 01-14-2009, 10:23 AM   #32
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I have three bottom return grilles on the first floor and the one closest to the furnace on this floor was 1/2 way closed. This may be why there was a slight increase in static pressure on my last report as per message #28.
However, I'll explain something as to why my static pressure is higher then normal. Many years ago, when I replaced my gravity furnace to a blower model, there was no duct leading to the gravity furnace. All the return air dropped through wall and ceiling openings into the basement. When the blower furnace was installed by me, I also installed a 10 inch by 13-1/2 od drywall return duct in the finished basement where it goes into the next room and connected to a 8 inch by 20 inch metal return duct.
I used 2 inch by 3 inch wood framing for the drywall duct. I also have a return grille in the finished basement and one in the furnace room also.

Also there is another return coming to the furnace from the opposite side and is a 3-1/2 by 12 inch metal duct. This is the return air from the rear of the house, including second floor rear bedrooms.
Now I am wondering whether the drywall duct is of insufficient size or is the interior wood framing causing too much drag on the return air flow or both. Whats your opinion?
Now that furnace has been replaced with the latest model from Bryant and the installing dealer did not mention anything about the 10 inch by 13-1/2 inch drywall duct.

Also when I received my new Bryant 4 inch X 16 X 25 inch filters, I tested right away.
Static pressure on low heat was 0.23 from the previous 0.29. Rpm were 687 and cfm was 712.
Static pressure on high heat was 0.48 from the previous 0.58. Rpm were 989 and cfm was 1033.
I left the filter in because I want to see what the pressure is after 30 days because the other filter was in use for 30 days when I originally tested. What do you think? Do I need to improve the drywall duct by lining it on the interior with 1/8 or 1/4 inch smooth material or remove it altogether and make it bigger?

Last edited by rjordan392; 01-14-2009 at 10:42 AM.
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Old 04-13-2009, 07:00 AM   #33
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This is an update on my OEM Bryant 4 inch furnace filter.

After 3 months of use on the heating cycle, these are the results:

Static Pressure on low heat is 0.23
RPM is 680
CFM 712

Static Pressure on high heat is 0.47
RPM 984
CFM 1033

The filter also was checked and not much dirt was visable. The numbers are basically the same as when the filter was new. I do expect the SP to increase to perhaps to 0.60 on high speed before I turn on the cooling system sometime in June.
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Old 04-13-2009, 09:42 AM   #34
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I think your blower appreciates the OEM air filters.

After 3 months. They still have less PD then the other one did after 1 month.

With your low Static. I doubt you really need to do anything with your returns. Unless you see the static increase a lot in cooling mode.
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Old 04-13-2009, 09:58 AM   #35
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I suppose I could get a little more life out of these OEM's if I keep a eye on ther SP and wait for it to climb 0.60 to 0.70 before changing to a new one. I believe a while back you mentioned that the blower cost more to run when the SP reaches 0.80 on high heat or high cooling. Is that correct? I want to be economical but I do not want the blower to work too hard. What do you think?
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Old 04-13-2009, 10:24 AM   #36
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Quote:
Originally Posted by rjordan392 View Post
I suppose I could get a little more life out of these OEM's if I keep a eye on ther SP and wait for it to climb 0.60 to 0.70 before changing to a new one. I believe a while back you mentioned that the blower cost more to run when the SP reaches 0.80 on high heat or high cooling. Is that correct? I want to be economical but I do not want the blower to work too hard. What do you think?
I had similar questions about energy costs so I purchased a Kilo-watt meter that plugs into the wall outlet and the furnace plugs directly into the meter. It allow you to read wattage draw and amps easily so you can view the electrical impact on any change or adjustment you make.
For example: when I run in "fan-only" mode, my unit draws 92 watts (less than a 100 watt light bulb). When the heat is on the unit draws ~256 watts and when the AC is on the unit draws ~380 watts (not including the wattage draw from the outdoor unit). The wattage draw is directly proportional to the blower speeds which are 640 CFM for fan-only mode, 1000CFM for heat mode, and 1280 CFM for cooling mode.

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Old 04-13-2009, 10:37 AM   #37
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That's interesting Key1 but a bit extreme don't you think? There's not anything we can do to affect the costs of energy delivery but we can do something about our usage of it. As our equipment ages, I suppose the energy usage will also be affected and we cannot do anything about that except for yearly maintenance to keep the equipment running.
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Old 04-13-2009, 10:59 AM   #38
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Quote:
Originally Posted by rjordan392 View Post
That's interesting Key1 but a bit extreme don't you think? There's not anything we can do to affect the costs of energy delivery but we can do something about our usage of it. As our equipment ages, I suppose the energy usage will also be affected and we cannot do anything about that except for yearly maintenance to keep the equipment running.
Actually there is quite a bit you can do. When My static pressure was up around 1.1, my wattage draw was between 600 and 700 meaning it was costing me twice as much. I made some adjustments by adding a supply helper duct (Beentheres reccomendation) and a new return and now my home is more comfortable.

There is a direct relationship of airflow, static pressure, temp rise, and wattage draw (energy used).

...And yes........I am quite a bit extreme

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Old 04-13-2009, 11:10 AM   #39
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Oh, I see. You did have a high static pressure and your meter helped you solve that and your energy usage and also made your home more comfortable. I don't exect to need a kilowatt meter on my setup. My system gives me a digital readout on the thermostat on sp, rpm and cfm delivery. That's enough for me to determine when to change filters.
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Old 04-13-2009, 11:40 AM   #40
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Your Evolution ontrol will also tell you when you air filter is too restrictive. And needs changed.

Usually, it should be changed before the Evolution tells you though.

And yes, the lower the static, the less electric consumed by the blower.

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