primitives discuss coils in furnaces

[franksolich]

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=287x9356

Oh my.

Hassin Bin Sober  (1000+ posts)      Thu Aug-04-11 12:19 AM
Original message
 
I cleaned the "A coil or evaporator coil" on my furnace and, boy, did it make a difference.

I thought I would pass along my experience.

This is a fairly easy project for a moderately skilled do-it-yourself-er.

I consider myself a fairly skilled carpenter but I have never done much with HVAC. I've always paid to have my system checked/repaired - I guess that's what pisses me off the most. I've had people in to do the "routine cleaning" every year but no one ever mentioned the A coil so I didn't think much about it....

Until last year when my neighbor had hers replaced. We use the same service and the HVAC company refused to clean hers when the coil was diagnosed as very dirty. The airflow had become too restricted and caused over-temp shut-downs last winter resulting in the service call. Their policy is to replace, not repair/clean. I guess that explains why mine was never cleaned.

This got me to thinkin' about mine. So I figured I would tackle mine this summer. And I"m glad I did.

The A coil/evaporator coil is located (in my furnace) above the furnace in the plenum. See below:

after which an image of the interior guts of a furnace

The process was fairly simple.

I used my Dremel wheel-cutter to cut an access hole in the side of the plenum. I cut one "test" hole in the side to see how the coil was oriented. The second hole was cut in the right place so I was able to get my hand all the way in under the "A" portion.

I pulled 15 years worth of gunk from the coil. It was like a layer of felt on the coils. Yikes. Now my AC blows like a wind tunnel compared to the flow I had before. Also, the heat will blow better because, even in winter, the warm air blows over the coil when the coil is not in use.

The hole was patched back up with a piece of sheet metal and some self tapping screws purchased at Home Depot. The seams were taped up with the foil backed tape from HD also - as was the rest of the furnace. Don't use "duct tape" - it's crap. I re-taped the entire furnace seams. That made a difference also (I assume). The closet where the furnace is kept is no longer ice cold.

Note: The evaporator coil in the furnace is sometimes referred to as an "A coil" due to its A shape - some are slant coils on 45 degree angle. Your may vary.

Note: sheet metal is sharp and can easily cut you. Wear gloves and eye protection when handling or cutting.

Note: Be gentle on the coil "fins" so you don't bend them and further restrict airflow. Come to find out, there is a commercially available coil cleaner that I will be looking for for a more extensive cleaning now that I have fairly easy access to the coil.

Stinky The Clown  (1000+ posts)        Thu Aug-04-11 12:42 PM
Response to Original message
 
1. The HVAC company we use put in a removable access panel when they installed our new system.

They replaced all the ductwork from above the A-coil to the furnace. The replacement has this access panel with screws and a gasket. Take out the screws and you get to the A-coil.

By the way, they clean the A-coil as part of their standard annual service.

Well, one surely hopes they carry a union card.

Hassin Bin Sober  (1000+ posts)      Thu Aug-04-11 01:11 PM
Response to Reply #1
 
2. "part of their standard annual service"

Smart outfit. That's why they left an access panel, I suppose. Well now I have one too.

It's funny. You talk to different people and you get different answers.

My partner's dad is the person who kinda walked me through the process when we were considering cleaning the neighbor's (she bought a new system). He's a retired commercial pilot but he dabbled in HVAC with one of his pilot buddies. He says they cleaned them all the time by either cutting the access hole... or sometimes they would remove the unit all together and hose the coils off.

I talked to my ACE hardware guy and he looked at me like I had a screw loose. He says you should NEVER have to clean the coil if the furnace is properly filtered. But that doesn't make sense considering 5, 10, or 15 years is a long time for residual junk to get past the filter.

You don't realize how clogged something is till you clean it out. Last year, I was at my wits end. We couldn't keep the condo below 80 degrees on hot days. We resorted to using a small window unit in the bedroom to sleep. Now we are living it up at 76,77 in the day and 73 at night - and the system actually shuts off.

Other things we have done is blown in cellulose in the attic/crawl-space thanks to rebates from the gas company. Reflective coating applied to our west facing front windows. And a temporary cover for the skylight- it's landscape fabric bungeed to the skylight until I find a suitable commercial product..

This is a good year for conservation.

sammytko  (1000+ posts)     Sat Sep-03-11 12:37 AM
Response to Reply #2
 
3. We had ours thoroughly cleaned this summer and it's only 2 years old - filthy!

We change the filters becausevwe live in an old drafty house and it seems we pull in all kinds of lint and fur balls from somewhere. Oh yeah, we have 5 dogs and 4 cats! He did find that the installation crew left the manual inside and it was blocking air flow. It would freeze up because it was working too hard to cool. It took him a couple of hours to check it out.

I have it checked winter and summer.

The bug-eyed caretaker checks and cleans the furnace here once a year; I dunno what he does.

But the furnace works fine, and no service call charges.

[BlueStateSaint]

He probably changes the filter, among other things.  Our complex changes the filters twice a year.  Good thing, too, because our central air was freezing up on us, from a clogged filter.

[franksolich]

He probably changes the filter, among other things.  Our complex changes the filters twice a year.  Good thing, too, because our central air was freezing up on us, from a clogged filter.

Whoa.

Wait.

What?

I change the filters myself.

As they're only 96 cents apiece, I put a new one in every month September through April, and then twice during the summer.

I thought that's what one's supposed to do.

[DumbAss Tanker]

What the idiot is actually talking about is the AC's heat exchanger, which is in line with the furnace in a central air HVAC installation and usually directly above it and 'Downstream' in terms of airflow.  It will accumulate dust and fiber over the years, particularly if one runs the system for an extended period with a broken filter or no filter.  Avoiding having to disassemble the ductwork around the heat exchanger (Everywhere I've lived, it was accessible by removing screws and tape without cutting metal) is the primary reason to check and change your filters every so often.

The normal way the grunge causes HVAC failure is by holding water condensed from the air against the cooling fins, where it freezes into a solid sheet of ice in maximum AC season, preventing any air at all from going through.  If it was actually nasty enough to prevent HOT air from going through, it was three times worse than any I've ever seen and it would have also been a fire hazard.

[Skul]

I wish mine were under six bucks a pop.
They get changed about once every two months. (got two filters)
Plain old common sense.
What I save in energy costs is about what it costs for the filters.
Break even, and I'm GREEN!!
Can you DUmpmonkeys say the same?

[BlueStateSaint]

Whoa.

Wait.

What?

I change the filters myself.

As they're only 96 cents apiece, I put a new one in every month September through April, and then twice during the summer.

I thought that's what one's supposed to do.

Maybe he doesn't do that, Coach.  If we were in our own house, you can bet I'd be doing that twice a year, at the least.  Your region may differ from mine in those filter-changing requirements.

DAT, you're not referring to me as "the idiot," right?  (Though it could probably fit here.)

[longview]

I change my funace's filters monthly, too, during the months it runs.  I'd sure like to hear that it is only necessary to go into the spider and bug infested hole once a year. 

Yeah, I bug bomb it first, but even dead bugs creep me out.

[NHSparky]

Central air?  No such animal for me.

Most of the time, any A/C is provided by opening a window.  We had our window units in between late May and mid-August when Scoobie pulled the upstairs unit out.  In that 2 1/2 month period I think we used it a total of 6-7 days, and the downstairs unit only the few days with truly oppressive heat.

And in winter, my burner is oil-fired to a hot water baseboard system.  Annual maintenance is provided by the same folks who sell me my heating oil.  $90 for maintenance, including replacing the jets and cleaning the system, checking the efficiency/exhaust gases, etc.

[GOBUCKS]

I change filters the first week of every month, year round.

[I_B_Perky]

I used my Dremel wheel-cutter to cut an access hole in the side of the plenum. I cut one "test" hole in the side to see how the coil was oriented. The second hole was cut in the right place so I was able to get my hand all the way in under the "A" portion.

OK I am confused. First of all... why in hades do you have to cut a hole or two? Second.... did he really cut a hole in the plenum (heat exchanger) or the access panel? If it's the plenum... oh that's real smart!!! Dummy will die of carbon monoxide poisoning this winter. If it is the access panel... well that is stupid too. Undo the bolts or screws that hold it on you stupid idiot!!!

Man alive these people are freaking stupid!!!

[DumbAss Tanker]

DAT, you're not referring to me as "the idiot," right?  (Though it could probably fit here.)

Never, my young friend.  You aren't lacking anything that simple experience won't fix.

[Skul]

The info that DAT posted a few up there is correct.
No, BSS, he wasn't messin' with you.
Even automobiles need the "coils" cleaned now and then.
Dirt and grunge on the cooling fins reduce how well the unit works.

[DumbAss Tanker]

Perky, for the love of God do not screw with the heater plenum chamber, the DUmmie's actually talking about the AC components, not the actual heater.

[GOBUCKS]

OK I am confused. First of all... why in hades do you have to cut a hole or two? Second.... did he really cut a hole in the plenum (heat exchanger) or the access panel? If it's the plenum... oh that's real smart!!! Dummy will die of carbon monoxide poisoning this winter. If it is the access panel... well that is stupid too. Undo the bolts or screws that hold it on you stupid idiot!!!  

He's saying the plenum, the big first section of galvanized ductwork, is where the A-frame is located. You have to have an access panel in the plenum to reach the A-frame. If there isn't already one there, you have to cut a hole in the plenum, and then replace the piece you cut out to reseal the duct. The plenum isn't the heat exchanger, it's like a manifold that the ducts branch off from. I did that many years ago when I installed central air in my house up north. He described exactly what I did, except I did seal things up with duct tape after screwing a cover on the access hole. It was still working like new when I left 15 years later.

[Skul]

He's saying the plenum, the big first section of galvanized ductwork, is where the A-frame is located. You have to have an access panel in the plenum to reach the A-frame. If there isn't already one there, you have to cut a hole in the plenum, and then replace the piece you cut out to reseal the duct. The plenum isn't the heat exchanger, it's like a manifold that the ducts branch off from. I did that many years ago when I installed central air in my house up north. He described exactly what I did, except I did seal things up with duct tape after screwing a cover on the access hole. It was still working like new when I left 15 years later.

That's because you changed the damn filters on a regular basis. THAT's why.
You took care fo your shit, and it worked. No other reason.