Recent Topics
WEN 2800 power washer oil question
by z71offroader83
08/15/18 05:12 AM
A lot of bubbles in oil?
by FordCapriDriver
08/15/18 02:58 AM
Does oil go bad?
by TallerTrucker
08/14/18 11:43 PM
OBDII Scanner
by JeffKeryk
08/14/18 11:08 PM
Automatic headlights not working after replacing bulbs
by mclasser
08/14/18 08:34 PM
Fluid Film Rustproofing Video
by Warstud
08/14/18 08:33 PM
Cloyes timing sets any good?
by FastLane
08/14/18 08:08 PM
Free AMC Movie Theatre Beverage
by Recalculating
08/14/18 07:53 PM
ABS Problem... 2001 Honda Odyssey
by DeafBrad
08/14/18 07:05 PM
6 qt of 5w2- Penzoil platinum for $12
by danez_yoda
08/14/18 06:43 PM
Tire Plug Experts Advice
by jrvn
08/14/18 06:41 PM
What insurance do you need to drive for Lyft/Uber?
by JimmyJohns
08/14/18 06:18 PM
Name a good alternative to Kendal GT1
by Vern_in_IL
08/14/18 05:23 PM
Any other car audio nuts here?
by cwilliamsws6
08/14/18 04:14 PM
Quaker State Advanced Durability Rollback at Wal Mart (CDN)
by irv
08/14/18 03:49 PM
Digital Valve Actuation
by Sluggo0018
08/14/18 02:31 PM
:::Why Ford Made An INCREDIBLE Blunder (RE 2019 Ford Ranger)
by NDL
08/14/18 02:29 PM
2 Minute EASY Headlight Restoration
by NHHEMI
08/14/18 01:57 PM
Is this wear on new rotors and pads normal?
by JimmyJohns
08/14/18 01:45 PM
Barn Find
by Snagglefoot
08/14/18 01:32 PM
Newest Members
dumasarok, amribakri, JimFisher, aerowill, bpp
65711 Registered Users
Who's Online
34 registered (Astro_Guy, bradepb, berlyn, 2015_PSD, Bambam, 4 invisible), 874 Guests and 38 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
65711 Members
67 Forums
288698 Topics
4815708 Posts

Max Online: 3590 @ 01/24/17 08:07 PM
Donate to BITOG
Topic Options
#4665733 - 02/14/18 11:41 AM When to Change my 4 Inch Furnace Filter?
Gebo Offline


Registered: 09/18/02
Posts: 2168
Loc: VA
I just installed one of those 5 inch furnace filters. I attached one of those vacuum differential devices as well. When furnace blower runs in propane mode is shows .20 inches of water. When furnace runs in HP mode is shows .30 inches of water. Reason being the fan runs slower in the Propane mode.

My question is how high does the resistance need to go before I replace the filter?


_________________________
'98 LEX LS400 280K
'00 LEX GS300 195K
'02 4Runner 225K
'05 Lex LS430 85K
'06 Toyota Highlander 145K
'09 Lex IS350 85K


Top
#4665743 - 02/14/18 11:48 AM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
SVTCobra Offline


Registered: 12/11/09
Posts: 726
Loc: Battle Creek, MI
First thing I would do is make sure the Magnehelic is level and vertical, otherwise the readings won't be accurate.

Can't help answering your question though.
_________________________
If marriage was outlawed only outlaws would have in-laws.

Top
#4665758 - 02/14/18 12:04 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
oldoak2000 Offline


Registered: 07/23/14
Posts: 119
Loc: North TEXAS
Originally Posted By: Gebo
I just installed one of those 5 inch furnace filters. I attached one of those vacuum differential devices as well. When furnace blower runs in propane mode is shows .20 inches of water. When furnace runs in HP mode is shows .30 inches of water. Reason being the fan runs slower in the Propane mode.
My question is how high does the resistance need to go before I replace the filter?
..


Interesting, I woulda thought the CFM should be higher for the propane furnace?
how many btu is the furnace, and how many btu is the heatpump ??

If you have the heatpump model, there should be a chart on in the specs that show performace at specific cfm's (your ultimate answer can be calculated from that).
However, IF you have ECM/variable blower motor, it can automatically compensate for filter loading to maintain ideal performance (assuming a perfect/near-perfect install).

5" media filters are the LEAST likely to get 'loaded up' prior to the 6-month swap time; too much older than that you'll get mite population munching the dead skin cells buildup (dust) right ON the filter (releasing THEIR allergens into the flow) frown

Top
#4665844 - 02/14/18 01:31 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
Nick1994 Offline


Registered: 02/19/13
Posts: 10442
Loc: Phoenix, AZ
Slip a new one in and see what the pressures are for a new filter. If it's the same or close and it looks ok put the old one back in.
_________________________
2015 Hyundai Sonata 2.4L 82k Mobil 1 AFE 0w30 & OEM
2000 Toyota Camry 2.2L 229k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 146k Mobil 1 HM 10w40 & Fram Ultra

Top
#4665873 - 02/14/18 01:55 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Nick1994]
Gebo Offline


Registered: 09/18/02
Posts: 2168
Loc: VA
Originally Posted By: Nick1994
Slip a new one in and see what the pressures are for a new filter. If it's the same or close and it looks ok put the old one back in.


The above readings are with the new filter. I was wondering if we had some super-duper HVAC genius's here on BITOG. I'm sure we do.

IF .2 and .3 are my starting points, at what pressure differential is my filter getting too restrictive?
_________________________
'98 LEX LS400 280K
'00 LEX GS300 195K
'02 4Runner 225K
'05 Lex LS430 85K
'06 Toyota Highlander 145K
'09 Lex IS350 85K


Top
#4665920 - 02/14/18 02:44 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
road_rascal Offline


Registered: 12/09/02
Posts: 836
Loc: Stillwater, MN
The old house we owned before we moved had a 20x20x5 Air Boss filter. I changed it every 6 months. This was based on several HVAC people I know.
_________________________
2012 Toyota Rav4 V6 4WD (66,000 mi)
2018 Chevy Equinox 1.5T (4000mi)

Top
#4665970 - 02/14/18 03:37 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
Yah-Tah-Hey Offline


Registered: 05/26/14
Posts: 3572
Loc: Columbus,Nebraska
Ask Lennox

Top
#4666104 - 02/14/18 06:11 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
Rand Offline


Registered: 08/20/03
Posts: 12804
Loc: NE,Ohio
usually 2x a year

unless it runs a ton a few extra months esp the spring or fall when it wont run as much wont hurt.

ie if you are feeling cheap you can stretch it to 8months easy enough but maybe not 1 year.

And the highest usage months are summer and winter usually in our climate.
_________________________
2019 Jeep Cherokee Trailhawk 2.0T

Top
#4666120 - 02/14/18 06:35 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
MasterSolenoid Offline


Registered: 09/26/17
Posts: 197
Loc: One Step Beyond
Same gage I installed on my furnace.
I'm only a home owner, not a contractor.
This is just my 2 cents.

You want to find the maximum static pressure of your furnace.
Don't make the mistake of guessing.
The info should be on a label inside your furnace.
If you can not find it, call the manufacturer.

My furnace is max static pressure of .50" of water column.
My filters are one inch thick.
New filter reading .32"
After one year ... reading of .44
So, I could go longer, but change at one year.

Like other poster said, mount the gage as it was designed to be.



I also noticed, when the fan runs higher RPM, the gage will give a higher reading.
I only have natural gas, but my furnace fan is two speeds.
My fan only goes to higher RPM after 10 minutes of running. Which is hardly ever.




Edited by MasterSolenoid (02/14/18 06:42 PM)

Top
#4666173 - 02/14/18 07:45 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
WiskyBadger Offline


Registered: 01/14/13
Posts: 1664
Loc: Wisconsin
I change mine at a year, based on a couple hvac fellas.
_________________________
14 Buick Verano “Blanche” 61k Castrol Edge & Delco filter
01 Ford Ranger “Rick” 165k MS5K & Fram OCOD
78 Chevy Stepside
11 Chevy Traverse 114k Carquest 5w30 and Carquest filter

Top
#4666195 - 02/14/18 08:02 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
Srt20 Offline


Registered: 07/14/14
Posts: 514
Loc: Wisconsin
I forgot about mine this fall. It had been in about a year, maybe a little less. It was so plugged, it burned up my fan motor. $150, and it was an easy replacement, but filters are alot cheaper and alot easier to replace.

Top
#4666240 - 02/14/18 08:42 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Srt20]
MasterSolenoid Offline


Registered: 09/26/17
Posts: 197
Loc: One Step Beyond
Originally Posted By: Srt20
I forgot about mine this fall. It had been in about a year, maybe a little less. It was so plugged, it burned up my fan motor. $150, and it was an easy replacement, but filters are alot cheaper and alot easier to replace.

I wonder what the static pressure was ?
That would be the difference in pressure before and after the filter.
Every Home and Furnace is different, that's why the filter Co. says to change every 3 Months.

But I like using the differential pressure gages.
I change it a little sooner than need be, but also know that I'm not changing them too soon or too late.

Another good thing with using the pressure gage is: there are cheap filters (spun glass) and there are
the best filter (HEPA) and several (pleated) in between.

Depending on the furnace and duct work, some people may use a (new) HEPA filter and be close to the maximum static pressure.
Then you have to use the next least restrictive filter.

Just my 2 cents.
I'm not a Contractor.

Top
#4666291 - 02/14/18 09:46 PM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
Gebo Offline


Registered: 09/18/02
Posts: 2168
Loc: VA
Mastersolenoid, thank you! I found the info on a tag in my furnace. .50 inches water pressure maximum. Thank you for your help! Most excellent.
_________________________
'98 LEX LS400 280K
'00 LEX GS300 195K
'02 4Runner 225K
'05 Lex LS430 85K
'06 Toyota Highlander 145K
'09 Lex IS350 85K


Top
#4666303 - 02/14/18 09:54 PM Re: When to Change my 4 Inch Furnace Filter? [Re: MasterSolenoid]
Srt20 Offline


Registered: 07/14/14
Posts: 514
Loc: Wisconsin
Originally Posted By: MasterSolenoid
Originally Posted By: Srt20
I forgot about mine this fall. It had been in about a year, maybe a little less. It was so plugged, it burned up my fan motor. $150, and it was an easy replacement, but filters are alot cheaper and alot easier to replace.

I wonder what the static pressure was ?
That would be the difference in pressure before and after the filter.
Every Home and Furnace is different, that's why the filter Co. says to change every 3 Months.

But I like using the differential pressure gages.
I change it a little sooner than need be, but also know that I'm not changing them too soon or too late.

Another good thing with using the pressure gage is: there are cheap filters (spun glass) and there are
the best filter (HEPA) and several (pleated) in between.

Depending on the furnace and duct work, some people may use a (new) HEPA filter and be close to the maximum static pressure.
Then you have to use the next least restrictive filter.

Just my 2 cents.
I'm not a Contractor.






































IDK I dont have gauges, but it was enough to fold the filter over. The blower motor had to be working hard.

Top
#4666459 - 02/15/18 06:55 AM Re: When to Change my 4 Inch Furnace Filter? [Re: Gebo]
dnewton3 Offline



Registered: 05/14/07
Posts: 7440
Loc: Indianapolis, IN
Typical filter dP should be no more than a few tenths of water column from baseline.
Example, if a "new" filter offers WC of .3", then by the time it gets to .6", it's time to change.


Anyone with minimal skills can build their own manometer at home. Just get some clear flexible plastic tubing, create a "U" shape, fill part-way with water, hang it vertically on a piece of cardboard and measure off inches above/below a baseline at atmospheric pressure. Put a couple of small port holes in the duct upstream and downstream of the filter; connect tubes. Viloa!



Edited by dnewton3 (02/15/18 06:58 AM)
_________________________
The act of preventative maintenance, in and of itself, is FAR MORE important than brand/grade/base choices among lubes and filters.
- under maintaining something is akin to abuse/neglect; that can kill equipment by shortening the lifespan
- over maintaining something has never been proven to be anything but a waste of time and money

Top