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Old 01-09-2012, 07:05 PM   #16
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Lennox ML193 with a Filtrete


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Originally Posted by beenthere View Post
Try testing some. Go to the box store and buy some, and then buy Honeywell OEMs. And test them. You'll find some big differences.

Why? its all ready been done......how do you think the filter industry came up with the MERV rating system? they didn't pull it out of a cereal box one morning...........

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Old 01-09-2012, 08:33 PM   #17
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Lennox ML193 with a Filtrete


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Why? its all ready been done......how do you think the filter industry came up with the MERV rating system? they didn't pull it out of a cereal box one morning...........

Do you ever measure PD?

Its been discussed over at HT a hundred times already. Go read the threads about it.
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Old 01-09-2012, 11:58 PM   #18
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Lennox ML193 with a Filtrete


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Originally Posted by beenthere View Post
Do you ever measure PD?

Its been discussed over at HT a hundred times already. Go read the threads about it.
Yes, when its needed for trouble shooting............across a coil.....not a friggen clean filter............if its dirty you change it. Read whats left of my signature.......if you still dont get it, maybe YOU should be the one doing some reading? Have a nice day.
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Old 01-10-2012, 04:36 AM   #19
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Lennox ML193 with a Filtrete


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Originally Posted by harleyrider View Post
Yes, when its needed for trouble shooting............across a coil.....not a friggen clean filter............if its dirty you change it. Read whats left of my signature.......if you still dont get it, maybe YOU should be the one doing some reading? Have a nice day.
Try checking the PD of different MERV filters, and of different brand filters of the same MERV. You find they have different pressure drops.

PD is also used to determine when a filter needs to be changed.

Measuring an air filters PD is not rocket science. But many shy away from doing it like it is rocket science.
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Old 01-15-2012, 01:12 PM   #20
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Lennox ML193 with a Filtrete


Hi!

Thank you all for the responses, and I hope nobody got upset after responding to the thread.

I wanted to post some results I took. I finally got off my butt and did a "temperature rise" check. I measured the supply and return from the HVAC system. The return was measured about 42" from top of filter (61" from bottom of filter), and the supply was measured about 3" from the top of the A-coil, and about 32" from the bottom of the A-Coil, and to the top of the furnace.

I used a Craftsman Autoranging Multimeter #82028 with the temperature probe inserted into a 1/4" hole, about 1 to 2" inside of the ductwork.

Thermostat set to 70 (temporary set to 75 to run tests), and it's about 27 degrees outside today.

With a 3 month old 16x25x5 Honeywell (MERV11 or 12) filter, I read 160 in the supply, and 78 in the return (diff of 82).

With a new Filtrete 1550 16x25x4 filter, I was reading about 158 in the supply, and 78 in the return (diff of 80).

With no filter and the filter box closed, I was getting about 138 in the supply and 78 in the return (diff of 60).

The stick on the furnace says the following...

INPUT (BTUH) - 110000
OUTPUT (BTUH) - 102000
Manifold Pressure (IN W.C.) - 3.5
Gas Supply Line Press - 10.5/4.5
Maximum Outlet Air Temperature - 180
Temperature Rise - 40-70
MFR Recommended Orifice Size - .063
Max Static Pressure (IN WC) - 0.5

Model Number: Lennox ML193UH110P60C-01



Sooooo....... with all of this data, you can see that the Filtrete filter does run the furnace above the temp rise, but the Honeywell one does as well. I ordered two Lennox 16x25x5 filters for it online and see if maybe it will bring the temperature down a little too.

Is a 10 degree difference that huge? Is there a 4 or 5" filter that is a little better? The only ones I've seen are MERV10 (and higher).

Thanks!

EDIT: A note... I was looking in the manual, and apparently, I read the supply temperature in the wrong location. The manual says to measure it on a horizontal run in the supply, closest to the furnace. I measured mine vertically, right above the furnace. I might go back and check it, and I would assume that it would be lower, since I'm farther from the furnace.

The manual also says that the blower speed can be increased or decreased to reduce (or raise) temperature, if the firing rate is acceptable. I'm assuming the firing rate is acceptable because the heater does turn on and heat. If one wanted to change the blower speed, how would you accomplish this? Here is the except from the manual....

B−Temperature Rise
Temperature rise depends on unit input, blower speed,
blower horsepower and static pressure as marked on the
unit rating plate. The blower speed must be set for unit operation within the range of TEMP. RISE F" listed on the
unit rating plate.
To Measure Temperature Rise:
1 − Place plenum thermometers in the supply and return air
plenums. Locate supply air thermometer in the first horizontal run of the plenum where it will not pick up radiant
heat from the heat exchanger.
2 − Set thermostat for heat call.
3 − After plenum thermometers have reached their highest and steadiest readings, subtract the two readings.
The difference should be in the range listed on the unit
rating plate. If the temperature is too low, decrease
blower speed. If temperature is too high, first check the
firing rate. Provided the firing rate is acceptable, increase blower speed to reduce temperature.
To change existing heat tap, turn off power then switch out
speed tap with tap connected to "PARK" . See unit diagram
for blower motor tap colors for each speed.

Thanks!

Last edited by wiz561; 01-15-2012 at 01:35 PM. Reason: edited fix for temp reading and manual insert.
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Old 01-15-2012, 01:43 PM   #21
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Lennox ML193 with a Filtrete


Duct wok is probably under sized as most are. And the furna is probably a bit over sized.

At a 60 degree rise, it was moving 1574 CFM, at 70 it was moving 1349, at 80 it was moving 1180 CFM.

Get that temp rise back in spec, or it will probably have a short life span.

may need to add return, or increase return size.
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Old 01-15-2012, 01:44 PM   #22
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Lennox ML193 with a Filtrete


PS: try a 4" MERV 8.
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Old 01-15-2012, 01:46 PM   #23
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Lennox ML193 with a Filtrete


Thanks for the response...

There was a 16" x about 16" vent on the return that I covered up because the basement door would slam shut if it was open because of the pressure difference. For kicks, I untaped it and tested it, and there was zero temperature changes.

Would you suggest increasing the blower motor speed? There's a brown wire on the 'heat' terminal, and a 'red' and 'yellow' on the park. From what I've read, you just change the wires.

Thanks.
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Old 01-15-2012, 01:53 PM   #24
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Lennox ML193 with a Filtrete


yep. you can also use the black wire for heat and brown for cooling as long as you get the AC checked and freon pressures/temps/superheat checked. not all ACs need the highest speed and some work better/dehumidify better with a lower speed. I would use a merv 8. need to check the supply temp 1 foot downstream from where the plenum attaches to the main duct. your ac coil may be dirty underneath and need cleaning also and could be part of the problem.
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Old 01-15-2012, 03:20 PM   #25
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Lennox ML193 with a Filtrete


That's good to hear about checking the temperature downstream.

I rechecked the temperature about 6" to 1' from where the vertical supply connects to the main trunk, and it read 143, which is in the range for the furnace.

I'll keep an eye on this and not mess with the blower speeds....but it's also good to hear I can change them if needed. With the colors of the wires, what does the brown/red/yellow represent, as far has hi/med/low goes? On the board, the black is connected to Cool, Brown to Heat, red and yellow to park.

Thanks all for the great information. Slowly, I'm starting to feel better knowing that things may not be as bad as I originally suspected!
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Old 01-15-2012, 03:32 PM   #26
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black = high, brown =med high, yellow = med, red = low usually. I would have to look it up on the Lennox site to be sure but that info should be on the wiring diagram or in the manual. You just have to ask the right questions from the right people and give the right info to get the right results, Right??
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Last edited by yuri; 01-15-2012 at 03:37 PM.
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Old 01-15-2012, 04:01 PM   #27
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Lennox ML193 with a Filtrete


Everyone is forgetting gas pressure............what is the gas pressure at the manifold?

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