I'm a homeowner. I've seen some kind of an inexpensive "meter" for sale for about $15 that you place in the return air stream/system that you 'zero' when you place a new filter(s).When the resistance/negative air pressure increases to a certain spot on the meter, It lets you 'know' it's time to change the filter(s) for your central hvac system...Are these bunk or are these worth fooling with? I'm trying to use the thicker pleated filters that last longer rather than the cheap monthly filters.
Thanks in advance, Mike
I'm not sure this is helpful as I'm not familiar with that particular device. But in general, anything that helps remind a homeowner to change the filter in a meaningfull way would be good. We all tend to forget the maintenance required for the things we own inluding our bodies.
Some Thermostat systems have such a device built in such as the Honeywell Perfect Climate control system.
How that unit works is it keeps track of the actual time the blower is on and therefore the filter is used.
This is in contrast to the time honored tradition of marking the date of a filter change on the furnace and changing it at a certain time interval. The problem with the traditional method is that it does not keep track of actual use and doesnt compensate for vactions or hot or cold spells.
The device appears to use pressure drop. Pressure drop could be another way, but though the concept is problaby the best engineering wise, there could be a number if areas where the detailed implementatin of the concept causes problems. My beleif is that a well desinged pressure drop system is expensive and may not get you much more than an "ON time" indicator.
How much is the unit?
I'd also want to understand the installation issues in
Maybe someone else is familiar with the details
[Edited by hoffa on 03-09-2005 at 01:22 PM]
You can just pull the filter out and see if it's dirty once a month and replace when needed. That doesn't cost anything and would probably be more effective.
So does going down stairs to look at the meter that will probably be located in the r/a drop
There is an area in the central part of my home (a partitioned off back of a colset) about 1 1/2' X 4 1/2' which houses the 20 X 25 filters ( X 2 filters) and has duct work in the top of this space that goes to the return plenum to the horizontal hvac unit in my attic. I considered puting this 'change filter meter thing' in this area where the filters are housed. Mike
Agree - so the question is which takes less time, removing and inspecting the filter or looking at the meter.
The other option is the on-time alerts built into the Thermostats. There a red indicator comes on - no isntepction required.
You probably should still change the filter monthly.
Good ones have smaller holes, and will restrict airflow quicker than the cheap ones.
I haven't seen the device you are talking about, but it certainly should work.
Large commercial systems use something similar.
Some window units have a little "tattle-tale".
Both of these are visual indicators.
A better device would shut the system down, if the filter gets dirty, or sound an alarm.
What is the name & model of this little gadget?
Where did you see it?
RSES Certificate Member Specialist
Southwest Regional Association of RSES Secretary, 2017
probably talking about the "whistler"
round disk you stick to the filter when you change it, filter gets dirty and causes this to annoy you
most people put them on their dryer after the first change
I think bwal is on to something. The reason pros use a pressure drop system is that at that price point of commercial units, adding a quality pressure drop system is attractive.
My concern remains whether a quality after market pressure drop system can be done. And if it can be done is this such a unit.
Interval replacement does not necessarily relate to useage - but it is the most common residential method.
The way I see it
If you just change filters on a fixed number of days, you have to pick a number based on worst case conditions. If your thermostat measures the hours the central fan runs, that will certainly be more in proportion to how much life the filter has left.
It is my understanding that commercial systems often use a manometer permanently connected, to tell when the pressure drop gets higher (i.e. when the filter loads up and should be changed). The following link is a cheapie meter that will do that:
This link has a clearer picture:
To actually say a homeowner can "look at" the filter and know when it needs changing... how is that not inferior to having a meter to actually measure pressure drop? How can it be easier to expose the filter, than to look at a wall mounted meter? I am simply not understanding how a measurement is anything but the best answer.
Unless it is a Carrier Infinity system which both measures and interprets the data, i.e. tells the homeowner how much filter life is left. Great if you have it, but of course the Infinity will cost somewhat more than $15.
Hope this helps -- P.Student
P. Student posted links to the exact "gauge" I was asking about.
It definately looks simple