Photo of propane tanks (uploaded to Wikimedia Commons by J.Smith)

QUEUE modified BEATLES LYRIC:

“I read the news today—oh, boy   About a selfish species which failed the grade…

BigCarbon WANTS you to believe that propane is utterly safe and friendly — that it’s not a “greenhouse gas” — that it’s good for the planet.  BUNK !   We’re choking ourselves to death by burning and leaking hydrocarbons — methane, propane, butane, insane.  I was in my backyard up north when I heard a huge explosion 20 miles away which killed seven people and leveled a four-story building, demolishing a four block area in downtown Buffalo NY, 37 seconds after the firemen arrived (and died). Yep, an employee tried to move a propane tank with a forklift, dropped it, cracked it.  Soon — BOOM.  Propane explosions are not rare, as can be readily noticed by searching.

So I was not happy when a supplier exchanged an empty tank for full, of propane for our home.  What they delivered was so badly rusted that it leaked away in less than a week.  In spite of the evidence, they said I had a leaky gas line, blaming me.  And they refused to replace the lost propane, abandoning the tank (which I still have).  They sent me a bomb, which didn’t detonate.  Well, I cancelled my account and bought my own tank, and began traveling to a local depot where it could be refilled.  But I also began to research a plan to heat hot water with the sun.  It’s crazy not to do this when you consider that we live in a hot zone that never freezes.  The lowest temperature I’ve ever experienced in Merida was in the lower 50º’s F (10ºC).   Yet few people in this zone (which includes much of Florida, Texas and the Gulf Coast) ever experience a hard freeze. So we get free solar energy year-round!  But why do we still heat water with such a risky source?  It’s time for change.  A solar thermosiphon can do the job.  And you can make your own.

Yeah, there are turnkey systems which are, in my view, often over-engineered.  I’ve learned much about water over the years on the farm, and in business.  Minerals complicate plumbing, and this certainly applies here in Yucatan, where pumps and plumbing systems often fail due to mineralization — so I didn’t want a system that relies on a pump. I wanted a passive system, using convection, as there is less to go wrong.  I enjoy plumbing (supply-side only) and have maintained four wells, and plumbed a large-format commercial photo lab.  (But I’m still a rookie, always eager to learn.)

Below is a photo of a 3/4″ plastic fitting, the flow of which has been reduced by ~50% due to “hardening of the arteries”, discovered when I modified our propane water heater for this project, which device had failed after only two years of low use — adapting it to its new role as a storage tank for my DIY solar collector.  (The tube had accumulated minerals over a longer period.)

Replacing tanks and pumps and pipes can’t be avoided, but it can be reduced.  And harvesting energy for free directly from the sun makes it more fun.  Note: I spent about $6000 pesos ($300 usd) on parts and materials to build my device.  It would have cost almost that much to replace the water heater, foregoing the cost of fuel, which I expect now to harvest for free.   “Here comes the sun, deedle-doo-dah — here it comes.”

Before I show you my low-tech design, I will share a bad design that failed, at a place we rented in 2013.  The unit had burst because of poor design, and poor maintenance.  The glass tubes appear to be vulnerable to hail and hurricane damage, since they are exposed.  And they lose heat to the breeze.

Apparently the storage tank required frequent “blow-down” to reduce minerals, which had not been done, resulting in a failure-to-open, of the pressure-relief valve. So the tank burst along a seam, below. Oooops.  Bad investment.  (Maybe designs have improved since then.)

My design uses (strong) blue, inch-and-a-half cpvc tubing, as a collector, and is then covered with clear .125-inch polycarbonate as a “concentrator”, which also shields the collector tubing from airborne trash during windstorms, and prevents heat loss by housing the tubing inside an insulated “sandwich”.  Polycarb’ is a clear plastic used in banks as “bulletproof”, but thicker.  (I would have used wider diameter blue tubing, if I could have found it, but inch-and-a-half was the max available here.)

If you venture forth to build your own, be sure to use tubing that is rated for hot water!  If you can’t find blue, you could use “yellow”/beige/normal cpvc tubing, painting it black; but the blue probably absorbs more heat due to its darker color throughout.  (Paint might flake off.)  Don’t use hydraulic pvc, as it transmits light which will grow algae.  And don’t use thin “sanitary” drainpipe, as it will melt and collapse.  Be sure to use cpvc cement on all fittings, first “cleaning them” with cpvc solvent before applying cement, to soften the plastic before bonding, installing parts with a twist to make a good adhesive seal.  This should prevent leaks at joints, which are frustrating, especially when there are so many bonds in such a manifold.  Don’t build a “sprinkler system”!  And be sure that there is always water above the manifold (the collector tubes) in the supply tank.  If your tank is drawn down below the manifold, you will collect no energy, as convection will cease to recirculate the water, due to lack of “head pressure”.  (Adjusting the fill-level of a rooftop tank is easily done simply by sliding out the cord of the float valve, shortening it to maximize the fill level.)  I’ve adjusted mine never to fall below the shoulder of the tinaco, our 1100-liter rooftop tank.  Also, avoid dead-ends when designing your manifold.  Convection moves in one direction only, with help from gravity; it doesn’t have a “reverse”.  Circulation wants to be circular.  Think like water.  Also, dry-fit your manifold before gluing, to study this flow.  Avoid sharp turns by using 45º (codetes) fittings instead of right-angle 90º turns (codos), as this enhances flow.  Chamfer the interior of all tubing edges, removing burrs that could slow the flow.

For much of the year the water stored in the rooftop tank / tinaco flows by gravity into the home at about 82ºF (28ºC).   Without any heating system that’s tolerable for a refreshing rinse on hot days, or even for a cold shower — but if much colder, as in January, when hot showers are preferred, it would not be pleasant.  This system will not deliver scalding-hot showers. However, reasonably hot showers can be had without burning hydrocarbons, getting by with a little help from our friend, The Sun. . .  Here it comes.

UPDATE (29FEB,2024):  As December/January are cold, I’ve installed a supplemental propane heater, made by Bosch, with a six liter water tank, supported by a very small propane tank.  I’ve added bypass valves to allow me to redirect the solar hotwater during warmer months, shutting down the appliance, and shutting off the propane.  This allows me to bypass the 6-liter tank which includes a sacrificial anode intended to reduce mineralization inside the tank.  The anode is replaceable, but why let it dissolve while doing nothing?

CONCLUSION:  heating water year-round with propane is wasteful, dangerous, stooopid.  Tempering it with sunshine, is smart, practical, affordable.  Be a good Scout – let’s try to leave the campsite better than we found it.  It’s been said that people in hell want ice water.  Hot showers from flaming devices are surely contributing to bringing hell on Earth.  Please consider a solar hotwater approach.  (Note:  At our house we still use propane as a cooking fuel on the stovetop, which lasts and lasts; but we close the tank valve at night.)

One of the principles of successful living, established by the Stanford Marshmallow Test, is “delayed gratification”.  Those who “gotta have it now” are more likely to have a failed experience in life: unhappiness.  Do you really want a hot shower right now, at any price, even if it means humankind will soon choke itself out of existence ?  (May your grandchildren survive to wonder why we’ve been  so careless.)

NOTE :  My design, as configured, does not promise a hot shower, but rather a lukewarm shower, very suitable for the subtropics.  (In part, this is due to a long copper line inside a concrete wall, which I can’t insulate, dissipating heat.)  I will be collecting data and observations gleaned from operating it over the next several months, which I will share here.  I may modify the orientation after January, re-tilting it northwards to capture more energy from the northern track of the sun, if it isn’t enough  during January.  Presently the system boosts the hot side of the shower stream by ~10º, from 80 to 90ºF  by 10:30 a.m. — adequate for our needs.

Friend Jim Conrad over at BackyardNature cooks eggs with a passive solar cooker which he designed.  He starts ’em in the morning, and they’re ready by dinner. (He is also developing a solar sourdough bread.)  I admire his example.  For a guy with a size 14 shoe, he has the smallest carbon footprint of anyone I’ve ever met. But my wife and I like to cook, so we’ll continue to use some gas.

BELOW is a slide-show of my project to help you imagine your own.  (Ask a friend to help each other if you don’t have the handyman skills to do this.  Two heads can git’er’done !

Red roof above our 2nd floor bathroom is the chosen location.

Constructing piers and frame. Diagonal corners should be the highest point of delivery, and the lowest of supply. The concrete blocks are filled to add weight, preventing liftoff during high winds.  I’ve also tethered the frame to the home.

A solar manifold baffles the slow moving water during convection, collecting heat radiated by the sun onto more than 50 feet of tubing. I added one length of blonde 2-inch cpvc (which I plan to paint black) for delivery to the old heater, to increase volume.

Chamfer all interior edges, removing burrs to improve flow.  (Note: in reusing the old hotwater appliance as a storage device, I decided to fill the fire chamber with sand and gravel, displacing air which would have invited cooling, to store heat in thermal mass for quicker recovery.)

The installed system prior to painting 2-inch download tubing. (Fat tube is a roof drain.)

Also, be sure to add a breather tube extending above the elevation of the tinaco, for proper drainage, preventing glug-glug-glug when the home calls for water.  I’ve also added two beer-maker thermometers to monitor the system across high-low points ($15 each/Amazon), for learning purposes.  My design has increased the volume of available hot water from 40-liters to maybe 60.  (I’ve included a drain valve, and several threaded unions / tuercas uniónes, so I can disconnect the system if I want to modify or service it.)  Plastic valves often fail in intense sun.  Bronze ball valves are better.

Plumbing is a language about parts and relationships.  If we want our relationship with Mother Nature to remain friendly, we need to respect her.  Farting carbon pollution into her living space is not nice.  Think globally. Act locally.  Do it yourself!  (Don’t wait for politicians to solve this – they’re too busy getting re-elected.) Act before it’s too late. Form a solar-collector club, even. Help each other to save this precious planet. We can do this.

NOTE: for those living in freeze zones, turnkey solar hotwater systems exist which use antifreeze and a heat exchanger (like your car’s radiator).  In this era of Russian gas turmoil such a system might be wise and economic.  “Pay now, or pay more later.”

ROBOTICS.  Do you remember that scene from Sorcerer’s Apprentice where Mickey teaches the broom to carry water, but fails to teach when to stop?   Well, that just happened here.  There was so much mineral on the float valve that it changed the balance, and overflowed the tinaco.  It’s only water, and flowed into the downspout, like rain.  But glad we were home to halt the waste.

Minerals changed the flotation balance and caused overflow of the tinaco.

UPDATED!

Polluting the commons is disgusting and deadly.  Having recently weaned myself off propane for heating water, I’m bummed to learn that the gas industry is daily dumping massive amounts of methane into the atmosphere.  Intentionally!  This is beyond rude. The stench of death will soon be overwhelming.

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