https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/ Building science knowledge, HVAC design, & fun Tue, 17 Oct 2023 13:56:44 +0000 hourly 1 https://wordpress.org/?v=6.6.2 https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4545 Mon, 20 May 2013 14:44:09 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4545 Hey hi..
Hey hi.. hahahahahahahhahahahahaha nice work.

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4544 Thu, 06 Sep 2012 01:59:46 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4544 Does the “sludge”
Does the “sludge” look green because it’s avocado flavored, because it’s trying to give the airflow a green light, because long green will be required to fix it, or because one gets LEED points if one’s crud is the same color as Kermit the Frog? Inquiring minds want to know.

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4543 Sat, 25 Aug 2012 17:07:16 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4543 M. MacFarland
M. MacFarland: I forgot to mention that I added a caution statement to the article right after the duct sealing advice.

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4542 Sat, 25 Aug 2012 17:05:44 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4542 Bob: True.
Bob: True. I don’t know the actual story here but it’s likely the furnace had problems, too. Regarding ducts in conditioned space, I’ve written about that here in the blog: 
 
Case Closed: Get Those Air Conditioning Ducts out of the Attic 
 
Tapani Talo: It almost sounds like you didn’t even read the article.  
 
Thomas B: I didn’t mean to give the impression that I don’t like filters at the return grille. I do, for ease of changing them. You just have to make sure that the duct system is designed, installed, and sealed properly. 
 
M. Johnson: Maybe it only works with the R-40 walls and R-60 attic that Tapani mentioned. But you’re right — Tapani’s comment seems completely unrelated to the article. I guess he/she thinks they’re getting some benefit from having the link there, even though they’re not. 
 
M. MacFarland: Thanks for the reminder. I do usually mention the proper air flow when I talk about duct sealing because I’m like you — articles about duct sealing without mention of proper air flow kind of drive me crazy. It all goes together. I’m sure a lot of people who read this blog would love to know how you get all your customers to afford and agree to a complete duct system change-out. 
 
David B.: Thanks for your contributions, again.

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4541 Tue, 21 Aug 2012 18:01:53 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4541 @David Butler,  &lt
@David Butler, 
 
I agree sealing the return side and locating filter at the return register can be ideal. In new construction it is not hard to do. In the existing homes, it can be a challenge. In the low-income homes that I work on (with a limited budget), it’s often difficult. It can also be tough in homes with multiple return registers.

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4540 Tue, 21 Aug 2012 05:13:08 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4540 @MacFarland: I agree with
@MacFarland: I agree with most of what you said. It’s true that duct sealing can cause more problems than it solves. However, your suggested advice is hardly appropriate. 
 
As you stated, high static (and low airflow) is often the result of an undersized return side. But this usually is the easiest to fix without having to resort to complete duct system replacement. 
 
If client doesn’t want to fix the duct system, then it may be reasonable to refuse to seal the ducts, but that should never be the recommended course of action after a whole house assessment.  
 
@Thomas B wrote: 
> locating the filter at the return register is not ideal 
 
Actually, it often is ideal. You just have to make sure the return side is tight. Not hard to do, actually.

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4539 Tue, 21 Aug 2012 02:07:54 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4539 If you REALLY want to save
If you REALLY want to save money bring the ductwork into conditioned space. Will make a bigger difference than throwing a ton of insulation in the attic/wall.

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4538 Mon, 20 Aug 2012 18:28:24 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4538 The duct leakage may be the
The duct leakage may be the very thing keeping the system, and the clients, happy, alive, and kicking (especially on the return side, in the case of distribution systems located outside of conditioned space). My personal suggestion is to change the second sentence of the middle bullet point to “Only seal the leakage if the results of the whole house assessment indicate it makes sense to do so, and then have your house re-evaluated for combustion safety.”  
 
We see on almost all of the homes we test, nearly 100% of the available total external static pressure, which the manufacturer planned to be placed against the fan, has been used up by the poor design of the return side. And this despite very low airflow across the coil. This is because nearly every system we test is in the 40-50% range of having the proper amount of grille area (target=2 SF per AC ton), and the FPM across the filter face is too high (target=keep below 250 FPM), and they are using high efficiency filtration in a system designed for 30 day filters (that’s being nice, it was never designed at all) and then not changing them regularly as mentioned.  
 
Sealing up leaks is great when that is the problem. Because of the issues above (just on the return side, I haven’t even started on the supply), we’ve never found a system that could be saved by sealing the leaks. Distribution systems are much happier when they are completelty removed, and taken on a permanent vacation.

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4537 Mon, 20 Aug 2012 17:23:09 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4537 So Talo, having geothermal
So Talo, having geothermal technology keeps the coils clean???

]]> https://www.energyvanguard.com/blog/the-sludge-that-kills-post-mortem-of-an-air-conditioner/#comment-4536 Mon, 20 Aug 2012 16:38:39 +0000 http://energyvanguard.flywheelsites.com/?blog_post=the-sludge-that-kills-post-mortem-of-an-air-conditioner#comment-4536 We see dirty coils in
We see dirty coils in weatherization, but more commonly we see filters that look like these coils because they haven’t been changed in years. I agree that locating the filter at the return register is not ideal. However, we sometimes recommend filters at the register for elderly, disabled, or clients who otherwise cannot or will not go into the creepy attic or crawl space to change filters.  
 
Good read!

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