RF (Antenna) plumbing

How did you do that? A giant "cold air SPDT relay"?

One company makes ceiling vents for that. Forgot the brand but they open into the attic when pressure from the cooler builds but close through a temp fuse when there is a fire. Not sure how well they hold up in winter.

Hmm, but don't we have some moral obligations for after when we leave this earth? Paying for assisted living would also require fetching a pretty penny for the house. Unless you'be been a state employee with a super-fat pension plan. It'll be tough to sell if the installation is deemed "weird". If the home inspector doesn't understand or doesn't approve of it people usually nix the deal.

Probably when he sells and the buyer comes in with a smart home inspector. Not sure about the law but I assume they'd have to report an unsafe structure, and then all hell would break loose.

Hi Joerg,

The supply ducts are located high in the rooms. So, it is convenient for a roof mounted, downdraft cooler to push chilled air *down* into the ducts. Barometric dampers are located below the cooler (yet above the ducts) and above the A-coil (yet below the ducts) acting as one way valves, of a sort.

But, these leak. So, when I *know* the heating/cooling season is over, I install baffles below/above the ducts alongside the dampers for a tighter seal.

I wanted to just install motorized skylights -- and vent them when the cooler needed to run. This would have the added benefit of bringing light into rooms. (we like *lots* of daylight in the house)

You will note that I said *remove* the kit when leaving the house! (in an earlier post) That's the reason that I'm going to the effort of installing more conventional infrastructure (regular telco wiring, CATV drops, etc.).

No doubt! If not sometime *before* that! ("Bob, why is the living room ceiling sagging?")

I thought I had understood it but this throws me off guard. That kind of damper is usually mounted under where a rood-mounted the evap cooler pushes it's cool air inside, isn't it? Also, doesn't code require a fire-shutoff function?

Yeah, the leaks is what I am concerned about. Usually manufacturers do not understand this and homeowners are on their won, and must kludge. Took me a couple of hours to make a decent looking cover box for the evap cooler inlet. SWMBO wanted one that blends into the textured wall.

And brings wasps and other nice guests inside :-)

That I never do. I want it to be so that I can essentially drop the keys and move out. Of course, it'll never be that way but I try to strive for that.

I wonder when the first homes with "engineered beams" show such problems. Probably all it takes is a leaky toilet or bathtub.

Hi Joerg,

One is located "above the roofline" (to be accessible AND above the ductwork) but *below* the cooler (to place it in the outlet air flow). This is what make it troublesome to "baffle", manually (i.e., you have to climb onto the roof)

The other is located in the outlet duct of the furnace -- just above the A-coil (thereby blocking airflow BACK into the furnace from the cooler).

AFAICT, they are identical devices.

Of course, the one in the furnace is very readily accessed.

Apparently not. Note that it (rooftop) only opens when air wants to be blown DOWN through it. As soon as the cooler shuts off, it snaps closed (annoying to hear the louvers slap shut).

Oh, I'm *sure* they "understand it"... they just don't *care*! :>

Coolers are often covered (weatherized) in the winter so someone is up there to cover the cooler -- and can insert the baffle.

The biggest appeal to the dampers is NOT the heating vs. cooling switch but, rather, the ACbrrr vs. swamp cooler switch. Previously, we would use the cooler for most of the Summer (hot, dry) and just resort to the ACbrrr during Monsoon. The automatic dampers made this really easy (though switching to AC from cooler has to be done with a bit of care as the moisture content of the air -- from the cooler plus the fact that RH is rising, in general, when we want to make that switch -- can be a chore for the AC to address).

No, you put a screen on the window.

We are debating a 46" square skylight for the kitchen (anything larger starts to present significant structural challenges). But, are worried about the thermal load it will place on the cooling system.

(It's amazing how hard it is to get concrete data that you can *relate* to for things like this!)

I'm not willing to live with what "normal" folks would consider acceptable! :> E.g., most folk see nothing wrong with lots of "equipment" (hifi, dvd, cd, tv, etc) cluttering up the place. I don't want to see *any* of that, here! So, the burden falls on me to come up with ways of *hiding* it.

The bigger worry is, "what happens if some ill befalls *me*!" :>

Yeah, each time I look at that stuff, I (intellectually) understand how it works. But, it doesn't leave me with a warm, fuzzy feeling thinking something as "flimsy" as that might be keeping the roof up over my head!

Ah, so you made yourself a "poor man's SPDT switch for air flow".

I do not believe that passes muster WRT the code.

Ever since I discovered a major boo-boo in the design (!) of our pellet stove and I as an EE had to tell those MEs how to do it right, my confidence in the "understanding" part has been shaken.

Oh, and when the cooler arrived and was unpacked, guess who had to balance the squirrel cage?

For our small one they don't even make a jacket. Plus those jackets can be a perfect recipe for mold because warm moist air from inside hits a very cold surface.

On our roof that wouldn't last a long time. Some of the birds out here have several feet of wing span and corrspondingly powerful beeks. Sometimes you'd think a roofing contractor was up there.

Why? It's basically just a window, and I am sure you can get automatic shutters for it to avoid being pelted by a scorching sun.

Exactly. And that can happen faster than we think.

IME, if I don't have a warm and fuzzy about something it is mostly indeed junk over the long term :-)

Hi Joerg,

Moe like a "diode switch" :>

It is apparently accepted practice, here. I.e., *we* didn't do it, the HVAC installer did. The previous system used removable baffles (present on *every* house that has a swamp cooler). I.e., anyone with a swamp cooler has an *opening* through the roof that is "open" throughout the cooling season (i.e., the damper *closes* ours when the cooler is not blowing air)

I suspect the covers are effectively "decoration". Hard to imagine they do much/anything to improve thermal efficiency.

One of my pending improvements is to install a spiral staircase to make it easier to get onto the roof (think: getting OLDer! :> ) so I can just stuff the cooler with a thermal block/insulation in the heating season. I've already replaced the fasteners for the access doors so that they can be removed without tools...

The window "looks up", not "out". And, the vent position usually only "cracks" the skylight. So, it's a relatively small target -- and, "uninteresting". E.g., we've never had any problems with the Harris' Hawks, etc. in the neighborhood. OTOH, the little "critters" can't say likewise! :>

But we *want* it unshuttered during the daylight hours. Shutters/blinds would actually only be useful at night to trap the heat in the winter.

I've heard horror stories that the space under these can be significantly warmer. And, seeing that this would be the meal prep area (i.e., where we spend a fair amount of time), increasing light at the expense of added *heat* isn't appealing (I'd rather just add more light fixtures).

Yup. But, then again, it wouldn't be *my* problem! :>

Well, I don't get that feeling from "metal studs". Yet, I have grown accustomed to using them liberally! OTOH, I don't use them for the same sort of structural support that I might use dimensioned lumber.

Amazing that the code allows that in your area. Out here the fire marshall would probably have a hissy fit.

That is what neighbors thought, too. Until the day when they heard a commotion in the kitchen and a racoon was duking it out with their cats, over who gets to eat the stuff in the bowls and who does not. He had made a hole in the screen and was rather unimpressed by our neighbor showing up in the kitchen.

I think they make modern IR-repelling glass or something like that. It ain't grampa's old skylight no more.

Not guaranteed either. My wife and I visit Alzheimer's places as volunteers. Some people live there for years or decades. Some permanently in wheelchairs.

I would _much_ prefer metal over wood. Not this flimsy coke can strength stuff but real posts and such. Unfortunately those are unobtanium in the US and importing costs too much in freight. So we'll be forever forced to fix rot on decks and such.

Hi Joerg,

Never saw a racoon, here. Bobcats and bears, yes. Racoons, no.

But you can't *relate* to the number on a spec sheet! Just like you (meaning some *real* person) can't quantify how much warmer you feel standing in the sunlight than in the shade.

I can look up the specs for a window (skylight) but can't, from that number, decide how comfortable/uncomfortable it would be to stand under it for any length of time.

If *I'm* in that state, then it's still "not my problem" :>

You can buy steel buildings, etc. It's just too expensive to be practical. (A house I had in Illinois used a steel I-beam as the main carrying beam)

The metal studs are more convenient than dimensioned lumber for non-load-bearing framing -- it is *really* nice to be able to trim things with a pair of tin snips instead of a saw (electric or hand). But, I wouldn't count on such framing to support anything (perhaps other than a simple drywall partition).

Is it that far to the wine shop? ;-)

Further than that on Long Island, though Martin Riddle defined it as "down the block" ;-) ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

Are you forgetting that most of this stuff is low end Asian designs? Whay would they want it to lst very long?

All of the units I repaired only had a single transistor. Maybe BFR96?

I think I'll order a few, just in case I run out of repaired TV amps.

Most of those so called 'Bullet' amplifers that I've tested were around 10 dB.

The supply that came with mine was: +15 VDC, center positive, 400 mA but I would think 9 to 12 V would ork OK.

They are junk, IMHO. Once during an EMC debug job I had trouble getting a panel off a large machine. So I pulled some more, then even more ...

The panel suddenly gave up and I flew backwards into a wall. My shoulder made a major hole in a wall and bent some of those coke can strength "studs". The guys from production (on the other side of this wall) came running out to see if I was ok. I did not feel any pain whatsoever, the wall just went like that, as if if was cardboard.

On the bright side: You worked up a thirst, walking that far. :)

Much of it was US-engineered and US-manufactured. More industrial stuff, not low end gear. Some European ones, too.

I think the BRF92 and BFR93 are at the core of most designs. Almost impossible to beat in price.

The only marked transistors were all BFR96, so I bought them 10 or 25 at a time for about 35 cents each.

That must have been back in the days of the Pilgrims :-)

It's a really old TO-50 can and nobody carries it these days. Well, Arrow lists them but there is no stock.

Hi Joerg,

They won't "support" anything. And, rely on other "members" for their strength -- e.g., the drywall spanning the gaps between the studs. In commercial environments, *all* of the associated framing is usually of a like kind (I've found tying them *to* a lumber framework greatly enhances their utility as the lumber doesn't have the same sort of give/flex that a purely metal framework does).

They are also a PITA when it comes to stringing wire as any unprotected edges (i.e., cutouts) will shred insulation in short order.

We had some metal 2x2's (!) that were well designed. A heavier gauge of metal, "curled" ("rounded under") edges, longitudinally ribbed, etc. Coupled with their smaller dimensions, they proved to be excellent to work with (as I said, relying on tin snips to trim things to size instead of running back and forth to the chop saw!)

Unfortunately, I've not been able to locate a source for these, locally. :<