Ebo David

+ Follow
since Feb 17, 2018
Washington DC area
Apples and Likes
Apples
Total received
4
In last 30 days
0
Total given
0
Likes
Total received
10
Received in last 30 days
0
Total given
7
Given in last 30 days
0
Forums and Threads
Scavenger Hunt
expand First Scavenger Hunt

Recent posts by Ebo David

Looking into this a little more, "R-value per ASHRAE 90.1-2016 Section A9.4.2. Airspaces less than ½” thick shall have no R-value. The Rvalue for airspaces between 3.5” and 12” thick shall use 3.5” thickness as basis."  So a 30" air gap would give you something around R-8.5 if you can trap the air.  Anyway, this is an interesting idea.  I am just concerned about its effects on the soil in case of a leek.
2 months ago
ok... a bit more awake now...  It looks like there are working examples been running for 17+ years now, so the low temp behavior is not an issue.  They build a trench that recaptures the bubble solution.  What little I have read does not look into the soil/tox issue at all.  Have you seen any discussion on what soaps work in this application and have been tested to not harm soil organisms or pollinators?
2 months ago
@C Letellier, the soap bubble system looks interesting but there are a number of things that I would want to see worked though before I would consider it, and also cautionary tales I would suggest --

* the type of soap is crucial.  May soaps contain anti-bacterial additives, and that could really mess up the soil organisms.  So could just regular soap itself if it gets on the soil at all.  I do not know if you know, but one anti-mosquito trick if you have open non-potable water sources like a smithy quench tub, is to put a couple of drops of soap on it -- it changes the surface tension on the water and the mosquitoes drown.  I would be seriously concerned about all the beneficial insects, detritivores, and bacteria.  This would completely mess up the soil organisms unless you could recapture basically all of the soap, and you have to plan for dealing with the consequences of the inevitable tear or leak.

* working out how it behaves after the temperature drops below freezing.  Do you know at what temperatures the materials in the bubbles freeze and become a frozen shell?  How sharp would those shells be in a storm when the wind pushes against the exterior surface of the glazing and they break and rub against the plastic.  It is possible that they might remain flexible throughout, but this would have to be tested.  That said, if this was set up as an emergency measure to save a winter crop, it might be worth the cost to re-glaze if you saved enough produce to cover the cost of re-glazing.  This would be a cost benefit analysis.

Hmmm... I just realized that I might have come down as a nay-sayer/downer.  Not my intent.  If you could work through the issues of recapture, potential toxicity to soil and pollinators, and mechanical strength, this could be a simple solution to a really nasty problem.  If you could find a way that would pass organic certification I would definitely go for it.  Maybe there is someone at one of the ag extension research universities that could help you work through these issues.

There are likely other issues as well, but I bumped into this at 2:45 in the morning after waking up, and I have not had my first cup of tea and not all of the 8 cylinders are firing -- feels more like the old single cylinder hit-and-miss <https://www.youtube.com/watch?v=euIMiSaYPX0>...
2 months ago
punched send to quick...

re: SS vents.  Take a look at stove pipe and I have seen commercial SS ducting advertised around.  
2 months ago
@Mike, Here is an updated (version 2.0) of the calculator http://www.ecosystems-design.com/uploads/2/5/1/9/25191018/climatebatterycalculator2.0.xlsx  Apparently they did not take into account the displacement of the hoses and some other things.  I am not sure what the difference is between 1.2 and 2.0, but maybe since you have the numbers handy you can rerun them.  Yes you are correct with the Citrus in the Snow using air outside.  For some reason I thought that it also circulated air and brought it back in, but you might be right.  Also to think of, and probably not experimentalable is something I was taught back in New Mexico working with adobe -- the thickness of the walls are not random, but chosen because of the temperature lag as it migrates through the material.  It has been 40+ years since I was told this and I could have the information wrong, but... at 9" thick walls, the heat will migrate through the adobe in 12 hours.  So the max heat of the day will actually migrate through into the interior by the middle of the night, and the cool of the night will might through to the heat of the day.  The thick walls (I forget if they were 24" or 26", but that would migrate through in 1.5 days.  All that said, the head does not travel in one direction, but all, so you would get this attenuated fluctuation due to the thermal mass.  I always loved living in adobe homes, but you *must* make sure you have a good roof and a good foundation -- everything in between is negotiable.
2 months ago
Also forgot to say, this is one cool build Mike.  I wish you the best of success with it!
2 months ago
@Mike, if you know of any good engineering books/materials going over the earth battery, please post here.  I have not seen any.  All I have seen is very rough numbers from the Citrus in the Snow guy, and soil temperature profile normals.  The Citrus in the Snow guy uses something like 4 to 8 pipes running something like 200' to get the temp to stabilize.  I would use plastic underground, and try to use stainless above.  I have read people using perforated pipe underground so that any condensation will leak out.

Derating the estimated 100A @90C capacity of 2-2-4 aluminum SER wire is a very good idea.  Also use niloc (or whatever it is called -- which keeps the connections from oxidizing).  Your electrician shoud do that, but know that if you are in a place that will allow you to do your own wiring to read through the code books and comply with at least the residential standards, if not the commercial ones.  Like I tell people "every sentence of the code book represents someone being injured, maimed, or killed".  Following the code is not just the law, it is a VERY good idea.  Also, run another separate ground wire (unless the 2-2-4 is shielded).   Also, go ahead and wire up the an extra outlet circuit (or a special outlet near the door for 240V and 120V).  You never know when you need to run an extra fan, emergency heater, water pumps, welder, etc.  It is easy to wire up when you are starting, and a pain later.  Also, make sure that the ground and commons are *not* tied together in the breakout panel, but *are* in the main panel where you took the power from -- tying both can create a ground-loop.  Oh yea, and this is likely very important also, use GFI's where it makes sense, but know you should not use them on circuits with GFI's...

Before putting in a inflation fan (that will const constantly), try just installing a wax-filled vent piston (see: https://www.amazon.com/Univent-Automatic-Solar-Vent-Opener/dp/B0083IZG0A for a good one that would work close to the ground, but I would look for one that can be set to open near 90 or so for a vent near the apex).  Once you know what can be done with passive means, you know what you have to operate actively.

I probably forgot a dozen things off the top of my head, but this should be a decent start.  Hope this is a good start.
2 months ago
Well... looks like you have your priorities about right ;-) meaning do what you need and you know first...  I have the embedded electronics and similar stuff sitting in my room to poke at when I wake up and have a moment to play.  BTW, it looks like the house part of my renovation will *finally* get done in a week or three...
3 months ago
@Mike, do you have any of the temp probes up and plotible?  I forget your background, but if you need help setting up some code to generate plots (and maybe also display details from local weather forecast, etc.) let me know and I will try to break away some time.  Actually I have plans for doing the same for myself...
3 months ago
Mike!  Good to be back.  Lots on my end, but that is for another discussion.

I agree with Cristo.  I remember reading about a rare high elevation plant that daily survives freezing temperatures at night, and very hot during the day.   Very few plants can withstand that, much less food crops.  Realistically we need to help you keep the temp range down.
4 months ago