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  1. #1
    Join Date
    Dec 2004
    Posts
    61
    I have an American Standard high efficiency gas AUY060 furnace (60,000 BTU heating and variable speed DC motor).
    I believe this is the same as the Trane TUY080.

    I don't have any external filter box, and until now have been using the OEM washable filter inside the furnace. I just tried the 3M Filtrete "Micro Allegen" filter, which looks like it will clean the air a lot better.

    Unfortunately 3M doesn't make the 17x25x1 size that this filter requires, but they do make a 16x25x1 which fortunately fits fine, thanks to the spring loaded filter holder.

    Are these 3M filters too restrictive for the variable speed furnaces in the long term? I will be sure to keep up with inspecting/changing the filter once a month. What should I look for to ensure that the filter isn't making the blower work too hard?

    I would consider an external filter, but due to the furnace location and the side/upflow configuration, the return duct would have to be rerouted and angled funny away from the furnace so that there would be room for an external box, and that isn't feasible in my case.

    Also are there any better 1" filters than 3M Filtrete (more air flow for the filtering, better value, etc.

    Thanks for any advice!

  2. #2
    Join Date
    Apr 2003
    Posts
    5
    I wouldn't waste my money on a filter like that, if you want to clean the air in your house you're better off installing an air cleaner.
    Semper Fi

  3. #3
    Join Date
    Mar 2002
    Location
    Northeastern Illinois
    Posts
    611
    By all means use the better filter in your furnace. It will help with the dust in the house and protect your motor from dirt build up. With the VS furnace if it notices a restriction it will step up the speed until it is satisfied. I have seen them rip a filter to shreds when they get to dirty. Check and change them often,every 2 weeks or once a month. The 3m is one of the better ones but, there are cheaper alternative brands.
    If it ain't broke don't fix it!!

  4. #4
    Join Date
    Apr 2002
    Location
    Texas
    Posts
    165
    Actually as a American Standard Dealer, if you broach that question to AS, they'll tell you that a filter that restrictive will void your warranty.

    Don't do it.
    Frank
    No good deed goes unpunished.

  5. #5
    Join Date
    Dec 2004
    Posts
    61
    Originally posted by Frank_G
    Actually as a American Standard Dealer, if you broach that question to AS, they'll tell you that a filter that restrictive will void your warranty.

    Don't do it.
    Frank
    Now I'm curious: How restrictive a filter will void the warranty for American Standard furnaces? Some manufacturers, like 3M, supply pressure drop values for their filters. 3Ms vary between .14 and .20. I sure don't want to hurt my equipment, although I remember reading in the service facts or somewhere that the furnace can sense excessive pressure or negative pressure in the ductwork and can compensate or shut down to protect itself, is this true?

    Thanks!

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    3M's are very restrictive,load up with stuff in days to become even more restrictive.


    Test your system for air flow.Feel the air at the supply farthest from the frurnace ,with a regular filter installed ,then with the 3M to fel the difference.If it's not much,which is unlikely,feel it after two weeks of operation.

    It would be best to have a Pro check the static difference of the 3M,and advise what duct modifications are needed to use a Better filter.

    Even if your variable speed blower can overcome the 3M filter,understand that the extra resistance, may be increasing the cost to run the fan by 50%.



  7. #7
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    Your air handler is not the only thing to consider. The duct system is a highly important variable. The amount of filter area will affect the air speed at the face of the filter, and if your speed is different from the 3M test conditions then your pressure drop will be different. Like Dash says, if you get a pro to measure the system's static pressure then you can either 1) use it with confidence, or 2) know that it should not be used.

    Your air handler is a close relative of mine and there aren't many which can handle the 3M better. But you still need to be wary of what pressures will exist after a few weeks' use. Although I am a homeowner, I have installed a manometer to continuously watch external static pressure, if it tells me something out of bounds then I know to find a problem.

    The simple answer is to call a pro, have him take some measurements with that Filtrete in YOUR system, and then advise you. Personally I would shun a pro who attempts to answer the question without taking measurements.

    Hope this helps -- Pstu

  8. #8
    Join Date
    Apr 2004
    Posts
    7,680
    If that filter is in the bottom of the furnace, it may or may not be ok. It really depends on how well sized your ducts are. As has been mentioned, they will increase the static (or work) on your blower motor. Since you have a VS motor, it will likley ramp up and overcome the restriction but at a cost. The costs will be a louder duct system and increased energy use.

    If you really like the filter, then maybe he can fabricate a proper filter rack for one that is more appropriately sized. If you are going to go that far, you might as well have a real air cleaner installed. Besides I am always leary of a disposable filter being installed in the unit. Too much dirt can get around the perimeter and ultimately let just as much dust by, especially once it gets loaded.

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