Hello everyone and Happy Holidays!

Attic ductwork is ubiquitous in extant, single floor, single family housing and we are all too aware of the numerous shortcomings. A number of years ago, I decided to address the issue of a single, central ceiling return in my 1750 sq. ft,, 2002 home (10' ceilings) and the subsequent problems with cold hardwood floors and interminable recovery from setback.

I won't review my crawl space encapsulation or the fact that I have limited setback to just one degree (it makes my wife happy to "force" heating upon our typical wake-up time), both of which have improved comfort at no measurable difference in heating cost. After reading Dr. Bailes recent tretis on HDD, I suspect savings would be difficult to estimate anyway. The home has been blower door tested (precise numbers escape me, but were excellent) and insulation heavied in the attic.

Back to that single, central ceiling return.

Being a rocket surgeon in my spare time, it occurred to me that pulling cooler air from floor level in the heating season could only help the previously described problems and I found a place in the corner of a hall closet, very near the central ceiling return, where I could install an 8" flex duct. Much larger, and the duct took more space than my wife would approve. At the bottom of the duct, I installed a 90* adapter with a section of 5" X 14" filter media.

In the closet ceiling, a suitably sized, very tight clearance hole permitted entrance of the flex into the attic, where the duct is connected to an adapter on the single, enormous flex duct that leads back to the furnace.

An appropriately sized grill on each side of the bottom of the closet door ensured air movement.

I appreciate overall return air has not increased, but my calibrated, wet finger indicates considerable air flow. Also, the added duct is closed during the cooling season.

My questions to the group are, what unintended consequences may I have introduced into my system and does anyone have any thoughts on potential cost savings? My DIY efforts came in at around $50 and two band-aids.

All the best.

Views: 213

Replies to This Discussion

Why use insulated flex if the return duct is in conditioned space? You could have used a 10" hard pipe, but you would have been limited by the 5x14 return anyway.

My house is similar, 10' ceilings, 1999 construction, 150sqft less, slab instead of crawl space. The house came with (2) 20x20 ceiling returns in the hallways which have 8' ceilings. Here's what I've done:
1: Replaced the standard 4 way residential registers with fully adjustable commercial registers. Helped tremendously as supply air can now be directed to the floor w/o blowing directly on us. Well worth the $20/ea they cost.

2: Downsized HVAC system. House came with 88k furnace and 3ton AC. Replaced with 44k furnace/2 ton AC. The long run cycles help a lot with better air mixing. With the old oversized furnace setting the blower speed on high helped with air mixing, but still wasn't as comfortable as downsizing the furnace.

RSS

Discussion Forum

HVAC integration – the past, the present, and the future

Started by Igor Mitbarg. Last reply by Lucifer Prescott Apr 11. 1 Reply

Target superheat formula

Started by Miguel Orduno. Last reply by John Proctor Feb 18, 2015. 6 Replies

Now for Something Different

Started by John Porterfield. Last reply by John Porterfield Jan 12, 2015. 2 Replies

Latest Activity

John Nicholas replied to Brent Shapiro's discussion Investigating 3257KWH monthly usage issue.
"Check out the DHW unit.  What temperature is the water entering and leaving the unit?…"
2 hours ago
Brent Shapiro replied to Brent Shapiro's discussion Investigating 3257KWH monthly usage issue.
"With regard to the outside lighting - zero outside lighting, in fact the lighting in the basement…"
4 hours ago
Green ID posted blog posts
5 hours ago
Rob Buchanan posted a discussion

Building envelope and mechanical interactive effects

Good afternoon everyone,I was reviewing some of the old BPI newsletters and noticed a…See More
9 hours ago

Photos

Loading…
  • Add Photos
  • View All

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service