An in-attic furnace duct system need not be the on-scene creation of an HVAC mechanic, done unhappily in darkness and danger, then defying inspection and service, perhaps never competently reviewed. The found system examined in this post, helter-skelter thoughtless, contributed to inaccessibility of the attic, and to the darkness and danger.
A fire wall defying access and good work in a "main attic" had no redeeming value, where it was necessarily violated. Someone finally threw a heavy wood door off its hinges. Two passes through the wall by a 12" flexible duct would readily have propagated fire.
The better way to block a garage fire is to complete a ceiling to required fire rating. Here an unblocked access hole and several slots through ceiling drywall were patched with superior Densarmor drywall. Safer, better access to the attic is via a one-hour fire rated Calvert ladder. New Calvert models in 2013 include fire rating at $70 average added cost.
Four fat ducts and an exhaust B-vent crossed over the main attic, chest high or lower, like the last one in this view. Tying everything to roof joists is stupid.
Half of the attic had been accessible only in a remodel, before new drywall ceilings were installed. All new drywall was left uninsulated. Who could ever know?
It is radical to think of destroying the fire wall, and taking down all ducts, as the work of a weatherization contractor. Almost none would have the courage. There is need to convince a home owner that all will be put back together, better.
Think of the promised outcome as a circuit diagram. A map is detailed in the end by measurements vs. the regular system of decking. The beginning was a sketch upon satellite photos. Symbols are invented for the duct elements. Red for warm air ducts. Blue for return ducts. Wyes and reducers quite evident as diameter products. Take-offs I imagined but did not invent, as groups needing some consensus, here only in 12" flex ducts, as diameters leaving one or two cone saddles. Everything connects to ceiling registers, identified by diameter of serving flex ducts. The furnace is evident with its plena.
Please read on in a captioned web photo album.
The pleasing outcome is noted in these photos:
This portion of the attic, before inaccessible, was completed first. Access is via a Fakro LWS-P 25/47 attic ladder. As with the garage fire-rated ladder, the limit arm pivots were custom-set to have ladder deployment at a 60° angle. At that angle, one may carefully ascend the ladder with both arms encumbered. The many trips for proper work easily justify the modest cost of the ladder. Such a ladder, beautiful, strong, well insulated and gasketed, adds $1000 to the value of a home. One use, avoiding a fall, is worth a lot more. One moves more easily and a lot safer upon the raised floor, than upon trampled insulation hiding floor joists. Composite beam construction of decking supports efficiently aligns and levels the plywood flooring.
Please note the wonderfully-formed warm and return headers here, lined, not needing exterior insulation and not contributing to cycling thermal mass. These are not "D-boxes" crudely hacked-in by an installer on-the-job. They were fabricated by a very competent sheet metal business. For me, in Portland, Oregon, that fabricator is Vinje & Son. If you don't have such convenience in your town, Vinje & Son will serve you anywhere. Please see a subsequent post where I describe a similar installation in a crawl space . We must no longer permit thoughtless D-boxes that may be impossible of airtight sealing, robbing air flow and adding to operating cost, through high flow resistance.
I will do better with the warm header the next time a 180° return is needed. The header (next photo) was formed as two pieces, where a one-piece unit with turning vanes would not have cost more and would have served the customer much better. I was still somewhat accepting of rectangular shapes. I did at least insert a round far wall of the second 90° turn. Even without the turning vanes this is a big improvement upon an octopus D-box.
The label Skylight Insulation is added, as innovation with a skylight is reported in another album for this job, Dosch Attic. Innovation is in finding a use for old flex ducts now scrap. Scrap included about twelve feet of 12" duct ruined by crawl-upon. As a determined recycler, I separated the twisted liner wire for my bin of steel scrap. Remnant very long R8 fiberglass insulation 24" wide is useful in filling irregular spaces on skylight drywall, between on-flat 2x4s. The tough R8 fiberglass is superior to flimsy R11 commonly found, in filling 1 1/2" pockets between on-flat 2x4s.
Here is an exercise in use of Brightness Numbers to compare point source bulbs with LED downlights.
This post was originally offered on 8/25/2013, for comment about a bulb newly fussed-about "60 W" bulb from CREE. I bought one of these at Home Depot, for $12.97, in May, 2013. My findings damn the product and impugn the judgement of those praising it. I have felt OK about keeping mum, for a few months.
A 60 watt equivalent bulb already existed, and was the subject of the initial L-Prize. The prize-winning Philips bulb presently costs more, perhaps $38 vs. $13, with poorer efficiency, drawing 12.5 watts vs, the new CREE at 9.5 watts, 65 lumens per watt, and with same claim of durability, life more than 25,000 hours. The CREE at reported 800 lumens, is 84 lumens per watt, but I doubt that high number, where 65 lumens per watt seems ordinary current manufacturing technology.
A 22 watt similar Philips is reported 1780 lumens, 81 lumens per watt, and costs $69 each at Amazon right now.
The new CREE bulb is progress, for residential decorative illumination. It is not progress in residential task lighting, where Glimpse or Sylvania projecting planar LEDs serve best. I offer side-by side comparison of illumination, including statement of Brightness Numbers, where a CFL or LED bulb is accepted as an illumination match with a stated-equivalent incandescent bulb. May, 2013 observations here don't include yet-to-be offered Sylvania 70732, 900 Lumens, too bright for sight comparison.
I don't really accept that the Cree 60W LED bulb has brightness 2.4. The 4" Glimpse, dimmed to B2.4, would give 270 lumens. If a 100 watt incandescent gives 1490 lumens, a 60 watt equivalent point source is about 900 lumens. I think the Cree product is advantaged for some reason, by at least 10%. B2.4 times 800/900, is B2.1, and that is still not a credible number. Way too high.
Here try comparisons at same color temperature, full power. Imagine the 4" Glimpse dimmed to B2.2 at 60 watt equivalence. The Cree 60W LED would surely still be less bright. B2, or whatever, the Cree 60W LED is not useful illumination.
Within 24 hours of purchase, this CREE 60 watt LED was broken. My test stand thudded to the floor in a 6" rotation, and the glass globe separated from its base. What a pitiful light. Perhaps carelessness came from poor attitude. But, now I get to look inside.
The broken CREE 60 watt LED bulb is a pretty toy for a moment. Then comes sadness. An LED light should live for very many years.
Posted photos are from this captioned web album.
At November 2013, this post is edited to employ phrase "projecting planar LED." With the notion no light should be recessed, seek an antonym, and coin that phrase. Do you like it? The aim is to define lighting that may be retrofit with future organic LED lighting, OLED. Surely OLED will never be tricked to act as a point source. Where OLEDs are best buy, we will increasingly throw out our dear bulb fixtures.
The original post used phrase "plate LED," intended as a brief statement that the luminaire is fully revealed upon the ceiling surface and may be wired directly into a junction box. That phrase is confused with license plate lighting, and is not accepted elsewhere.
At end-October 2013 I edited in phrase "surface mount LED," in some of my posts. Then I realized that even an incandescent bulb on a porcelain holder, is surface-mounted.
Projecting Planar LED lighting is not recessed for foolish styling reasons, to look like a can-mount downlight. Can-mount downlights were a consumer adaptation of theater downlighting, where upon a black ceiling, there is nothing bright to divert attention from a stage. In any circumstance other than a stage center, there has never been a bit of virtue in recess setting of a light. It has been quite disastrous in our waste of the Earth's ready fuels, that many have loaded their can lights with bulbs that are simple point sources, with no reflector bouncing to usefulness, the light that otherwise does not beam downward; all such light and heat energy, totally wasted.
The money to be made with LED lighting will go far more to the users, than to the sellers. Versus doing nothing, the money to be made depends only on how soon you are bold enough to act. You. Every ordinary person who only is obliged to accomplish things otherwise in darkness. You will be spending the money not saved if you do nothing with such opportunity, Don't fail to act.
This post is aimed at family which recently let me install fourteen Sylvania 70732 LED Disk Lights, $35 each on sale and emptying the inventories of two Lowe's stores in Denver. $490 there. I also spent $100 for involved dimmers, needed where before darkness was suffered. Now there is light to spare sometimes. I told these "investors" they would get their money back in a year. Showing this is not simple. It's a lot of money. I couldn't show them supporting argument from powers that be. A 7.5% sales tax added to the cost. A needless luxury? Denver, like Portland, still offers no rebates for residential LED lighting. No one cares what you do, or how you do it.
Before getting to the math, create a summary of involved Brightness Numbers. Our needs are for useful task illumination, whether just reading a book, keeping out of danger, or guiding a tool. Light intensity upon a task is not measured in lumens. A Brightness Number with standard definition yet to be established, expresses the task light intensity, integrated lumens in a unit work space. I define B4 as the useful task illumination from a 100 watt point-source bulb, and find that fully-presented directional light from a 4" Glimpse light, 300°K, 450 lumens, is matched to the task illumination of assorted "100 watt" point-source bulbs. The Brightness Number for any other fully-presented LED light will be proportional to its measured lumens, whatever the task and location/ size definitions.
We must become fully aware of a roughly times two advantage that directional light has, in illuminating a task, vs. that old point-source candle. We used point-source light, only when that was all we had. Down lights were a step in the direction of lighting efficiency, if point light really received concentration in a well-directed reflector. The ideal light now is in the natural directionality of a glowing plate, usually left to just beam away without guidance.
Times-two efficiency vs. point sources is yet to be emphasized in product marketing, but I have one public acknowledgement to share. I think a number like this is inferred in "efficiency" numbers, at page 3 in this Lithonia document. The Lithonia numbers acknowledge that CFL point sources are inferior to incandescent, CFLs beaming very little where needed.
Brightness Numbers appear in the following table of information and math operations.
I replaced a mix of bulbs in the fourteen can lights, mostly foolishly-employed CFL bulbs shining out very little of their light. The change of house cheerfulness is dramatic, especially in bathrooms.
Differences in the column, Savings vs. Reference are directly usable to infer time until investment is recovered. Forget the dimmers investment for now and think only of the bulbs hauled out. Each Sylvania plate LED will save at least $150 in 35,000 hours, more than was saved by just moving on from incandescent bulbs. How long does it take to save just the $35 luminaire cost? Not more than about 8000 hours. That's 2.7 years at 8 hours per day. Some lights will run eight hours a day. Payback time isn't the year I had promised. Maybe I said two years? There were incandescent bulbs replaced. Payback for them, is in less than a year, if operated five hours a day.
In hours, Payback in replacement of any incandescent bulb with the Sylvania luminaire is as:
Payback/35,000 = 19/396. Payback = 1679 hours
If used five hours per day, Payback = 0.9 year.
Whatever, and if someone can offer helpful correction of my thinking, payback is better than anyone should expect from money in any other investment, including almost all other forms of "weatherization."
Money back on the dimmers? If a dimmer works only one light, longer payback of the larger investment will bother.
Oh, about that Costco Luminus LED light at bottom in the table? It's OK. Lots of brightness probably to be dimmed. Same savings. Same 65 lumens per watt technology as the Sylvania 70732. Tight against the ceiling it may be a better block of a leaky can light than the Sylvania 70732. I think the can retrofit is easier with the Sylvania 70732, which does not demand that the can have clips to engage springs. I still want to eliminate attic floor cans, know how to do so in all cases, and want to replace cans with junction boxes. I hope the Costco offering doesn't encourage anyone to newly install a light can. Use a junction box!
Please see all posts on blog subject LED Plate Lights.
Early Adoption Is Good:
At 7/29/2014, add comment on "early adoption." You will not save money by waiting for an improved version of an acceptable product. I have customers still happy with Version One of Sylvania 70732 lights and with 6" Glimpse , both now superseded by better lights. Where a customer is not happy with imperfect dimming or with the mild buzzing of Glimpse lights, I will take them back, credit half the material cost I and they paid, install the improved light at my cost of the light, and will give the returned light with disclosure to another customer.This is good for everyone. I hope other installers will follow my example.
I will not give the less-perfect light to charity, where the deficiency would not be disclosed. I imagine efficient-lighting informed charities, where I might donate even live CFL bulbs and fixtures now unwanted. Where a light might last forever, individuals too will look for means to move on to new products.
Know that where an energy-saving investment survives for twenty years, or sixty, there are important returns because energy costs grow much faster than inflation. Please help me to imagine the more-complete payback math where there is accounting of inflation and present value in energy conservation, of a perpetual return on investment, Perpetuity Math .
I have had the important pleasure of nearly two weeks with the two generations that follow mine, striking out in adventures from metro Denver. On one, we ventured through Balcony House, at Mesa Verde National Park, with a Native American NPS guide.
Our guide explained seven generations in a way I had not known. Seven generations as a time interval of 140 years or more, is a span we ordinarily experience in our lives. We are born to the living knowledge of three preceding generations, parents, grandparents and great grandparents. In old age we touch three following generations, if we have the good fortune to be followed by children, grandchildren, and great grandchildren.
Seven generations is a very finite span of responsibility.
Living with disregard of those who follow in fewer than the seven generations a great grandchild might touch, is monstrous.
