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Filter Box On Top Of Coil

 
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Old 10-31-2008, 10:45 PM   #1
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Filter Box On Top Of Coil


Some folks may say,"Flash, what kind of malarky are you talking about now?" Well, while installing a filter rack, I thought, why don't we....

So here it is: Down flow application, furnace in the garage or closet.
Why not install the furnace say 12" from the ceiling, and install the filter rack on the supply side.

Something I noticed, is that filter boxes are not "old folk" friendly a lot of times. In other words, One needs a ladder to get to the filter or, a filter does not easily slide in. I think installing the filter rack on top of the coil box would be nifty. That would have the filter rack at roughly 22" off the floor.

It's just a thought I don't intend on acting on this, just thought it might be worth discussing?
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Old 11-01-2008, 09:26 AM   #2
 
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Re: Filter Box On Top Of Coil


Quote:
Originally Posted by flashheatingand View Post
Some folks may say,"Flash, what kind of malarky are you talking about now?" Well, while installing a filter rack, I thought, why don't we....

So here it is: Down flow application, furnace in the garage or closet.
Why not install the furnace say 12" from the ceiling, and install the filter rack on the supply side.

Something I noticed, is that filter boxes are not "old folk" friendly a lot of times. In other words, One needs a ladder to get to the filter or, a filter does not easily slide in. I think installing the filter rack on top of the coil box would be nifty. That would have the filter rack at roughly 22" off the floor.

It's just a thought I don't intend on acting on this, just thought it might be worth discussing?
that is the craziest thought possible. why would anyone want all of that filth to go through the blower along with heat exchanger and coil? the equipment would be ruined within a few years. the way i would do it is by putting filter grilles inside the home.

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Last edited by studog; 11-01-2008 at 09:29 AM.
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Old 11-01-2008, 03:54 PM   #3
 
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Re: Filter Box On Top Of Coil


I'm not sure you realize the primary responsibility of the filter is to prevent dirt and dust from collecting in the equipment. It isn't met to clean the house air. There are pre-filters in front of EAC's and other add ons and these filters prevent a large percentage of dirt from building on the grids.
You might think you are doing the HO a favor but you are really doing a dis-service to those people. Their equipment will suffer and probally fail prematurely. The a/c coils will become blocked with dirt. The heat exchangers will fill with dust and the first couple of times the furnace is used it will burn that dust causing a nasty oder and maybe even setting off the smoke alarms. The heat exchanger might even burn thru.
You, as the contractor, are supposed to be the expert and you should realize that you could be held accountable for an improper installation, causing equipment failure.

Last edited by Pegleg Smith; 11-01-2008 at 04:02 PM.
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Old 11-01-2008, 05:21 PM   #4
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Re: Filter Box On Top Of Coil


Granted, it is a little out of the ordinary. And, I haven't actually acted on this thought, it was just something worth discussing with other heater dogs.
As for protecting the equipment from filth, a filter before the furnace will "help" prevent dust from forming on the blower motor and wheel. But, I have never heard of a heat exchanger cracking due to dust build-up. I can accept that one risks losing the blower motor prematurely if one does not pull the motor and clean the furnace every year or two. But otherwise, I do not see how you are hurting the equipment. I have seen many nasty furnaces w/out a filter installed. Never have I seen a heat exchanger coated with dust buildup as you are suggesting. I believe I stated that one would put the filterbox on top of the coil. So, you are still protecting the coil from excess dirt. Hey, even with filters installed upstream of the furnace, we still deal with the burned dust smell upon the first firing of the season.

Filter grills are great. But a drawback is that sometimes one needs a ladder to get to the grills. Also, 14x14 filters (or any filter that isn't standard sized) can be costly. I know, one can install a filter grill that is 14-20, 16-20...etc. But that isn't always the best option.

The goal is to make things easy for the homeowner. Too frequently, I run into installations in which the filter is a pain to access. Once again, its only a thought.
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Old 11-01-2008, 05:46 PM   #5
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Re: Filter Box On Top Of Coil


I did forget to factor the secondary heat exchanger involved (90+) furnaces. You don't want to have to clean that up. I guess I'll have to put that in my pipe to smoke.
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Old 11-02-2008, 08:30 PM   #6
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Re: Filter Box On Top Of Coil


Hey Flash,
Have to say that you are a little off base here. I'm pretty sure that I would have to fire myself if I tried that one out.
Depending on the environment ( and older people usually have pretty clean environments ) a 4 1/2" media filter should last about one year. Most of the racks are easy to install and even easier to change the filter in. A&H sells some common sizes that are pretty slick, sturdy and locally manufactured.
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Old 11-02-2008, 09:52 PM   #7
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Re: Filter Box On Top Of Coil


Yeah, it was a bad idea. It sounded like a good one at the time. But, it doesn't sound too bright anymore. Thanks for the input.
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Old 11-05-2008, 09:51 AM   #8
 
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Re: Filter Box On Top Of Coil


Hey Flash

The filter in the supply ducts are going to destroy the static pressure of the system. The return ducts and evap coil will become dirty. However
I did work on a 20 ton system in a medical building that had 4-24"x24"x12" thick hepa filters in the supply duct. The system required a high static evap motor. It worked fine. Good luck

Greg
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Old 11-05-2008, 07:07 PM   #9
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Re: Filter Box On Top Of Coil


The thought was to put the filter upstream of the coil. The reason...a lot of times, changing the filter can be awkward because a vent pipe is in the way or some other obstruction. I had to install a filter rack pretty high one day, and a ladder is necessary to change the filter. It's ok, I was just thinking about people who can't easily get on a ladder. I never actually installed a filter on the supply side. I just wondered what other people in the trade thought about doing it. It was a silly idea. Unfortunately, it's not the dumbest thing I have thought of or even did.

Thanks for the input.
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Old 11-11-2008, 03:18 PM   #10
 
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Re: Filter Box On Top Of Coil


ha ha ha did i also understand you were installing the coil on the return side or are we speaking of an a.h.u pretty sure the coil supposed to be onthe supply unless of course its an a/h ok reread and at least you know where the coil goes

Last edited by [email protected]; 11-11-2008 at 03:22 PM.
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Old 11-11-2008, 06:46 PM   #11
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Re: Filter Box On Top Of Coil


Quote:
Originally Posted by flashheatingand View Post
Granted, it is a little out of the ordinary. And, I haven't actually acted on this thought, it was just something worth discussing with other heater dogs.
As for protecting the equipment from filth, a filter before the furnace will "help" prevent dust from forming on the blower motor and wheel. But, I have never heard of a heat exchanger cracking due to dust build-up. I can accept that one risks losing the blower motor prematurely if one does not pull the motor and clean the furnace every year or two. But otherwise, I do not see how you are hurting the equipment. I have seen many nasty furnaces w/out a filter installed. Never have I seen a heat exchanger coated with dust buildup as you are suggesting. I believe I stated that one would put the filterbox on top of the coil. So, you are still protecting the coil from excess dirt. Hey, even with filters installed upstream of the furnace, we still deal with the burned dust smell upon the first firing of the season.

Filter grills are great. But a drawback is that sometimes one needs a ladder to get to the grills. Also, 14x14 filters (or any filter that isn't standard sized) can be costly. I know, one can install a filter grill that is 14-20, 16-20...etc. But that isn't always the best option.

The goal is to make things easy for the homeowner. Too frequently, I run into installations in which the filter is a pain to access. Once again, its only a thought.

I have seen many a store in a strip mall that hasn't had a filter in the system for a while when I was there for a heat start up. You smell the dust in the heat exchanger burning and I have even seen them so clogged that the dust ends up in flames, granted those units had holes in the heat exchangers (I wonder why?). There are many reasons that you draw through the filter, in the supply stream your airflow would be turbulent at best trying to pass through a filter, even a fiberglass rock catcher, causing a huge loss due to restriction ad freezing up your coil. As others have said the filter is there to trap dust and debris before it gets into the system, this is even more important with 90 plus units that have secondary heat exchangers. Let's keep the filter in the return and the freon in the system.

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