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Wednesday, May 29, 2013

How It Works: Solar Hot Water

System Purpose.  Maximize sun as heat source for hot water.

How It Works Summary.  Like a fancy solar camp shower, solar hot water panels convert sunlight into heat which is stored in hot water tank until used.  Gas-powered tankless backup.

System Cost.  $9,000 including installation.  Also received large tax credit.    Long system life reduces major future replacement cost.    LP gas for backup estimated at $20 annually. 

System Components

Pump circulates a few liters of glycol through solar hot water panels and---when the glycol is warm enough---through a heat exchange coil in the hot water tank, thereby heating the tank’s water without contaminating it with glycol.  Glycol prevents freeze-up during our long winter.    An in-line expansion tank prevents explosion from boiling glycol, a frequent occurrence on sunny, hot days.  

3 Solar Hot Water  Panels, interconnected by tubes filled with circulating glycol, warm the glycol with sunlight, much like a sun-penetrated windshield warms the inside of a vehicle.   Amount of heat generated depends upon amount of sunlight which is a function of solar veiling (trees, structures, clouds, fog, snow, rain, ice..) and solar angle.  No trees and structures veil our panels.  Angle impact changes throughout the day, peaking at noon and falling to zero  between sunrise and sunset.   Angle impact changes throughout the year,  maximized on summer solstice and minimized on winter solstice.   Unlike solar electric, the actual heat delivered to the hot water tank is significantly less than the amount generated due to thermal losses (conduction, convection, radiation).  Though the circulating pipes are well-insulated, the heat loss is substantial on cold days and (sadly) becomes larger as the panels produce more heat.   Unlike the “instant-on” of solar electric, the pump will not turn on---and thereby heat the tank--- until the glycol in the solar hot water panels is significantly warmer than the water in the tank.    

Hot Water Tank capable of storing 80 gallons of water.  The well-insulated tank is fed by cold water (from our rainwater harvest cistern).  This cold water is then heated, via a heat exchange coil, by the circulating hot glycol.  Sunny days heat the tank well over 130F, as high as 160F or more.  The programmable maximum temperature is kept at 170F in winter and 130F in summer.    The lower summer temperature prevents the tank from heating the basement via thermal loss.  Tank temperature drops after each usage (shower, dish-washing…), since incoming water is cold.

Backup gas water heater provides a boost  if the water temperature in tank drops below 100F, else the backup remains off, allowing a “solar-only” hot water experience.   Our backup, the in-famous Bosch LP tankless, is one the few on the market which accept pre-heated water, essential for our solar hot water application.  In reality, all hot water passes through the backup.  What varies is whether the backup heats the water and by how much.  The lower the incoming water temperature the greater the boost required.  

System Maintenance.  Change maximum hot water tank temperature (when both summer and winter begin).    Replace glycol in loop (every 5 years).  Scrape snow off solar panels (as needed). 

Report Card.   Warm Season = A.   Cold Season =  B-.    (See blog post for details).

 Biggest Challenge.  The inability of the Bosch tankless heater to preheat water above 100F causes cold-shower when tank temperature is between 100F and 105F.  (See blog post for details).

Biggest success factor.  Right-sizing of hot water tank versus number of solar panels.  Tank too big will not achieve desired heat.  Tank too small will achieve maximum temperature too quickly.   Either way, backup is used too much.  For 3 solar panels, our 80 gallon tank seems just right.  A bigger system requires both a bigger tank and more solar panels.

The Connection.    Behaving like our ponds, solar panels make transparent the amazing power of the sun.  Like the Land, off-grid  solar hot water follows the seasonal cycle of scarcity and abundance, requiring extra sources of heat in winter and avoiding the excess heat in summer. 

Tuesday, May 21, 2013

The Garden of Eden AND Eating

“Are you going to plant a garden?” Toni asked.

“In 2004, the very year we acquired the Land, we seeded our ½ acre test-plot prairie,” I replied.  “Then in 2007 we seeded our 40 acre high-diversity prairie, which is now coming into its own.  You should have seen it burn this year.”

Toni looked at me dumbfounded.  Yet I played on, refusing to submit to the intent of his question.  “Last week we planted 39 native trees and shrubs in a permaculture-inspired terrace I grubbed out of an eroded hillside.   Such a miracle that Linda’s new bionic hips could endure that grueling day on hands and knees.”  

I knew I wasn’t answering the question, but I couldn’t help myself.  “And today I dug in a sand-bed to plant a dry prairie garden.” 

At wits end now, Toni blurts out, “Aren’t you planting tomatoes or anything?”  Of course, I knew all along what Toni wanted to know:  Will we grow our own food?  Understandably, it's the official question you ask someone who moves to the country.   I must confess there is no Toni.  Or better put, I’ve met dozens of Toni’s who want to know if we’re planting a garden.   The answer I finally give goes something like this.

We might plant some tomatoes.  But our neighbors, Lonny and Sandy Dietz, operate an organic vegetable farm.  We get almost everything we need from them.   They grow better veggies, and far more varieties, than we could ever dream of growing.  AND we believe more in community-reliance than self-reliance.  It’s fun and engaging to go over to Lonny and Sandy’s.    And why not support my neighbor?  We look forward to planting apples, cherries, plums, hazelnuts and a number of edibles they don’t sell.  

So that’s the answer Toni finally gets out of me.  But, I’m embarrassed to admit, it’s not the “real” answer.  And today I want to apologize for holding out on you, for not confessing the deeper reason I’m not focusing on growing food.  And I need to say “I” here and not “we”.  While Linda may agree with me, she probably wouldn’t explain things as I do.    It was so challenging---and compelling---for me to understand, that I devoted 9 years of novel-writing discovery .    So rather than explain it, I offer this set of highly connected thoughts. I use “we” if I’m pretty sure Linda would say it this way.

We heal ourselves by healing the Land

I believe that the 10,000 year effort to feed humanity destroys humanity by destroying the earth we need.

I believe that as humanity moves from “humanity-focused” to “humanity AND earth-focused” it will feel like moving from adolescence to adulthood.

We plant our “garden” not just for us, but for us AND the Land.

If we feed us AND the Land, the Land will feed itself AND us.

I believe a MUCH better world is coming SOON.

The better world will be a revolution in Community-reliance, relying---for the first time in history---on both human communities AND earth communities.

Humanity can never return to its childhood, to the Garden of Eden.  I believe it is time to leave our adolescence, the Garden of Eating, and move into our adulthood, the Garden of Eden AND Eating.

By now, both you and Toni are probably wishing I’d stayed with the half-truth.  Can’t blame you.  This may be my craziest blog yet.  Or at least the blog where I shout out my craziness.  But I figured I better start coming out of the closet.  After all my novel, The Corridor, releases in 3 weeks on Amazon.  

Then you’ll discover how truly crazy Mike is!  Can I blame it on that stinging nettles frittata?

Tuesday, May 7, 2013

How It Works: Rainwater Harvest

How it Works:  Rainwater Harvest

System Purpose.  Provide all water with no well or tie to water grid.

How It Works Summary.  Roof and gutter collects and directs rainwater to cistern where water is available on demand via a pump.  Several filters assure safety.   1” of rain = 1000 gallons for us.

System Cost.  $10,000 including installation.  Compare to $30,000 for well system.   Does not include cost of roof.   No water bill.  Minimal replacement costs (pump / filters).


System Components

Steel Roof collects up to 1000 gallons per inch of rain.  Steel roof minimizes particulate / organic build up and washes clean. 

Gutter and downspout directs water to first flush diverters.  Any standard gutter will suffice. 

First flush diverter “washes roof” by directing first 50 gallons into yard, then allows rainwater to pass on into cistern via buried PVC pipe.   This is the most important filter since the roof and gutter are always “dirty” (smoke, pigeon pooh, dust, leaves…).      Not effective on snowmelt, so we do not harvest during the long Minnesota winter. 

Cistern.   Stores and protects water.   Our 5400 gallon buried concrete cistern contains two manholes for maintenance and for adding emergency water.   Overflow pipe directs water downhill when cistern fills. Spring through fall, overflow is the “normal” state. 

Pump.  Provides high pressure water to house (faucets, shower) on demand.   

Filters.  All water is filtered 3 times.  A screen on the first flush diverter filters very large objects (leaves, bugs, seeds…).   First flush diverter “washes away” worst of “dirt”.  Cistern pump draws water through a floating 5 micron filter.  By floating 1 foot below surface, we get the cleanest water (sludge sinks, pollen floats).   Water for drinking is poured into Big Berkeyfilter and stored in Red Wing crock.   Big Berkey removes 100% of “bugs” and many others impurities, including Atrazine. 


System Maintenance.  Supply Red Wing crock drinking water with filtered water from Big Berkey.  Turn on / off first flush diverter (as needed).   Clean gutters and diverter screens.   Clean cistern every few years.  Fill cistern with water from milk truck in emergency.  Note:  it would be cheaper to get all our water from the milk truck than to drill a well.  Crazy huh???

Report Card.   Warm Season = A-.  Cold Season =  B+   (See blog post for details).

Biggest Challenge.  Not knowing how much water remains in cistern.  (See blog post for details).

Biggest success factor.  Composting toilet minimizes water usage.  Even low flow toilets leak.  (See blog post for details).    Irrigation water harvested off shed roof and stored in above ground tank.

The Connection.    Rain is a delight, especially the first rains after the long drought of winter, or any drought for that matter.    Like the plants on The Land, we thrive in the abundance of water, yet harvest no more water than is available by rain.