I'm wondering how often to change this filter. It's huge and very
expensive. I'd hate to change it more often than necessary. The
installer said every six months.
I sent an email to Carrier and they told me once a month. That sounded
ridiculous to me. The documentation says to look at it at least every
six months and change it at least once a year.
Can I just look at it and know when it needs changing?
As you an tell I'm a novice at this so help would be appreciated.
Changing filter is like changing oil in the car. Depends on how much you
drive, where, etc.
If your furnace runs very little, you have no pets (or children), floors are
hardwood, etc. - you're filter will pickup very little dirt. And after all
that's what it's for. You can afford to change it less often.
Additionally, you can often vacuum the dirt off or blow it off with
compressed air. All messy, but practical. If you can distinguish clean
from dirty - by all means look at it and decide.
What kind of filter, how wide is it. I change a 4" April Air media once
a year and its still very clean, my furnace runs little. In my friends
house their april air is dirty after a summer of continous AC.
You must have not read the post very carefuly - the question was not posted
by a tech, but a homeowner. This person may not even understand what static
pressure is - who are you trying to impress, besides yourself.
So can evil eye, if it's applied hard enough :-)
A manometer is the best way but one doesn't usually have one around the
house. One thing that you might have around is a barometer. There are all
kinds of these instruments for the house--I guess you would put it in your
duct or furnace near the discharge side of the furnace filter. What you
weren't told is what reading or pressure drop across the filter is
acceptable or unacceptable. For the pressure drop use the difference
between the measured pressures from both sides of the filter.
pressure guages are widely available and come at widely varying price
points. Used ones on ebay for $10, to new ones direct from mfg on
Internet for $200 or more.
The inlet to the pressure gauge is hte plenum leading to the fan, i.e.
behind the filter.
We are looking for a pressure differential of a few psi. a 0-10psi
guage would work, but 0-30psi is more common. You will need to
calibrate by installing a el-cheapo fiberglass filter, and note the
reading. Then install a new filter of the type you intend to use and
note the reading. When the pressure reading increases ??50%??
??100%?? its time to change the filter.
Nick, you amaze me at time. Irritate me VERY very often.
It is a very low pressure differential we are attempting to measure, to
be certain. We don't need a 0-25 psi gage, a 0-1 to 0-2 is all we
need. Several models in the Dwyer Instrument catalog will do the job.
Access to the specs for the filters is not easy to come by, so I am
asking 3M about the Filtrete line of filters.
High efficiency filters 4 inch 5 inch and 6 inches deep often get a
differential pressure gage installed to alert homeowners when the filter
needs to be changed. Dwyer shows illustrations of such a setup and even
includes models with switches builtin to trigger air handler actions
when the filters load up.
Our ONLY consideration here is to get a gage what will register the
range of pressures we are talking about. The gages you pointed us to
will cost us about $70 each unless we can buy them in a secondary market
from a distributor.
Perhaps because you are wrong so often :-)
Both is preferable to neither; but naturally both both and neither is
preferable to neither both nor neither; but naturally both both both and
neither and neither both nor neither is preferable to neither both both
and neither nor neither both nor neither; but--naturally--both both both
both and neither and neither both nor neither and neither both both and
neither nor neither both nor neither is preferable to neither both both
both and neither and neither both nor neither nor neither both both and
neither nor neither both nor neither.
from Hare Brain/Tortoise Mind--How Intelligence Increases
When You Think Less, by Guy Claxton.
Magnehelic is a BRAND name, like referring to a refigerator as a Kelvinator.
Ok, here is one answer.
3M Filtrete filters when new have a pressure drop across them of about
0.20 inches of water. This value will change over the life of the
filter. And it changes very very slightly with specific filter model
of the 1" filters.
So a Dwyer Inst Series 2000 Model 2000-0 0-0.5 inches water will work
as will Model 2001 0-1.0
For some folks, this is not the limiting item, dust and mold spore
buildup over time will trigger allergic reactions, and dictate a more
frequent filter change interval that max pressure drop across the filter.
3M indicated that my question was a bit novel to them and that it would
be forwarded to the laboratory for further research. I suspect that
they think I am asking THEM to provide such an instrument. to dte, they
have not published any figures on what a fully loaded, end of life
Filtrete's pressure drop is.
These high performance pleated media filters, particularly the 4 inch
and deeper models say that they work BETTER, trapping more dust and
pollen as they pick up stuff. Also, one useful tip is to always run the
HVAC, fan at least, when vacuuming, dusting, or moving furniture so that
the filter has a better chance to pickup the dust out of the air as we
engage in these activities.
Again, Nick has a really irritating way of saying WRONG.
That's 0.2/12/144x62.33 = 0.00721 psi, and you suggested measuring this
with a 0-25 psi meter? :-) If the pointer moved 3" full scale, it would
move less than 0.001" across this filter, so once again, your suggestion
is utterly useless.
We needed a calibration point and you IGNORED the rest of what I said in
the message concerning the Filtrete filter. Yes the pressure drop is
far less than what a 0-25psi gage will show. OK, we need a 0-1.0 inch
water pressure gage.
However, for $14.99, you can get inexpensive gages that will hang up to
10 feet away witha large red arrow that moves as the pressure drop
increases. These are sold at the many of the same places that sell the
4" to 6: deep filters. Filters-Now.com is one such place. $15 vs $70
for the Dwyer Inst gage. We don't need high accuracy, just a reliable
indicator of end of life.
|> I'm wondering how often to change this filter. It's huge and very|> expensive. I'd hate to change it more often than necessary. The|> installer said every six months.|> |> I sent an email to Carrier and they told me once a month. That sounded|> ridiculous to me. The documentation says to look at it at least every|> six months and change it at least once a year.|> |> Can I just look at it and know when it needs changing?|> |> As you an tell I'm a novice at this so help would be appreciated.
I have a Carrier Infinity 96.
What type of thermostat do you have? Is it an Infinity controller?
If so, it should tell you on the screen when the filter needs
to be changed.
My first filter lasted about a year before I got the message.
This alert is a function of a 'reminder' system/program preset in the chip,
rather than any kind of sensor.
Look at it monthly..If its a cheap fiberglass type, replace it. For under $
50.00 you can get a reusable electrostatic one that you wash off and
Yes I have an Infinity Control but the reminder is based on timing and
not on whether it senses the filter is dirty or not.
How much do you pay for your filters? This filter is SO much bigger
than the ones in our old furnace that we are worried about cost.
The filter is an aftermarket item. The furnace itself does nto come
with a filter, so the dealer has a choice when installing the furnace,
what filter to install.
Many dealers will go with a 4" pleated filter as they make an extra
$100-$200 profit in selling this filter.
Replacement filters cost between $35 and $60 depending on the source and
the size of the filter. Filters-Now.com sells all sizes and shapes, 3M
and many other brands!!
You will need to look on the case that houses the filter to determine
brand of the filter, then slide it out to get the size and part number
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