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Old 11-18-2011, 03:06 PM   #1
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Dirty or moldy plenum?


These are pictures of my main supply plenum and air handler.

Should I be concerned about this and replace them or is it merely dirty because it's over 30 years old?

It looks like it's just a lot of dirt and hopefully not mold.
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Old 11-18-2011, 03:58 PM   #2
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Dirty or moldy plenum?


Change it out immediately and have an hvac company diagnose and remedy the humidity issue which is causing the problem.

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Old 11-18-2011, 04:23 PM   #3
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Dirty or moldy plenum?


Quote:
Originally Posted by Doc Holliday View Post
Change it out immediately and have an hvac company diagnose and remedy the humidity issue which is causing the problem.
Oh wow. That bad eh?

It's a heat pump that's at least 10 years old.
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Old 11-18-2011, 04:29 PM   #4
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Dirty or moldy plenum?


12 years in the trade and yours is the worst I have ever seen. I would not have myself or my family in that house.

Some of my enemies I would.
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Old 11-18-2011, 04:53 PM   #5
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Dirty or moldy plenum?


Bud, the fact is that there should not be any dirt or mold anywhere in there and a properly balanced, properly charged and sealed system that has proper air flow due to proper duct design will not have that happen. Not in one day, not in ten years, not in thirty.

It's the air you breath. With yours it's like sticking your head in the dirt (near or in a land fill) and inhaling.

I'm not trying to be rude but I am trying to scare you as you should be concerned. I can not stress enough how bad that is.
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Old 11-18-2011, 05:23 PM   #6
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Dirty or moldy plenum?


I definitely appreciate the advice and agree with the urgency.

Since we've moved here (three years ago) I've found all sorts of surprises like this!

I suppose only reason I mentioned the heat pump age was that it might have contributed to the cause and we will also examine replacing it at the same time.

I'm sure the ducts are not sized properly and the system never worked well anyway.
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Old 11-18-2011, 05:31 PM   #7
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Dirty or moldy plenum?


The good thing is once it's all said and done you'll be pleasantly surprised with the comfort of your home, not to mention your much lower electricity bill.

It's not going to be cheap to have it done properly so be prepared. It can cost near as much as a new car.

This will entail having a heat load analysis done (to verify the proper size system for your home) know as a Manual J and then a Manual D for proper duct work. Then comes the equipment and the install.

But this is your home so it's very well worth it in the short and long run, the best return on any investment you will ever see.

Let us know what you do.
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Old 11-22-2011, 10:59 PM   #8
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Dirty or moldy plenum?


I had somebody look at it today. Another different person will look at it Friday.

This guy was very thorough. We went through a few scenarios of what to do with the dirty ducting and whether or not to zone the system. He also gave me contact info for two people that I could call to look at the dirty ducts and see if they could be salvaged at all.

I really don't think there's any cleaning/sealing process that could be successful -- he wasn't aware of one either -- but I don't mind getting someone else to look at it to be sure and to confirm the seriousness of it.

He's doing a quote for a system replacement. He measured every room and window. Inspected insulation. Went into attics, etc.


As for what caused this? Not really sure unfortunately. It seems to have happened prior to us moving in three years ago.

We know the previous owners corrected serious drainage issues with the house and rerouted the gutters well away from the house.

I suppose our oversized, poorly sealed, improperly balanced, 14 year old, undercharged, inefficient heat pump just couldn't keep up with humidity?
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Old 11-22-2011, 11:38 PM   #9
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Dirty or moldy plenum?


Oversized a/c system (regardlesss of heat pump, no need to think that a heat pump has anything to do with it outside of size) usually satisfy desired set point sooner rather than latter, meaning less run time. less run time equals less dehumidification. Less dehumidification equals moldy situations such as your plenums.

Oversized system and possibly undersized duct work is like trying to stick a square into a triangle, you're really screwed then.

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