Saturday, December 09, 2006

The day we turned the generator off...

Wednesday, with 3 solar panels mounted to the roof, most of the circuits pulled into the main breaker box, and the inverter station wired to the breaker box, I realized that we could test out the entire power center for the house, if only I had the batteries on site and wired. I drove the backhoe to my workshop where the batteries were stored and brought them up to the house site. We wired them in a temporary location in the basement and ran the heavy 0000 ("four ot") gauge cables to the inverter panel. We had been backfeeding the breaker box with a honda generator, so we were careful to disconnect the generator from the "mains." Of course, our flourescent lighting went out as soon as we took the generator down. But then I threw the DC switch that connects the batteries to the "Master" inverter. LEDs flickered, Red, yellow, green, two greens, go! The inverter's cooling fan came on momentarily and then spun back down and everything seemed happy, so I threw the switch to the second "Slave" inverter. It performed exactly the same dance of lights and fan noises but settled into a blinking green LED state, because it was waiting in standby-mode for the power consuumption to warrant its active participation. Satisfied that everything was happy and dying of anticipation (sorry, I should clarify... the inverters were happy, and I was dying), I threw the switch that connects the inverters to the house's breaker box. The lights came back on! We were running on battery power! Not exactly solar power, but an important first step.

Quickly I ran outside and warmed up the crane. I thought I could temporarily wire the solar panels before it got dark... it wouldn't look pretty but it should work for testing purposes. My bro-in-law flew me up to the roof on the end of the crane and I wired 3 panels in series, made a make-shift strain-relief, and dropped the two leads back to the ground. When I got back to the ground, I shut the system back off and wired the solar leads to the MX-60 MPPT. (yes I know, there are supposed to be DC circuit breakers, lightning arrestors, conduit, and a chassis ground in this part of the story, but those will come soon, I promise) Satisfied that I had the polarity correct, I powered the inverters back up, and then turned on the MPPT. It woke up with a fancy display on its lcd screen, but then pronounced it was "snoozing". Snoozing?!?! At a time like this, how could it just sit there and snooze?! I looked outside and saw that the sun had set behind the hills... but surely there was enough light left to keep this thing from snoozing?! I started jumping through the menus on the MX60's display - aha there it was... a way to lower the current threshold so my MX60 wouldn't snooze in low light levels. But the system asked for my password and, defeated but not broken, I decided it was time to RTFM. There it was, on page B.26 the factory default password! By the time I got the password in the system and lower the cut-in threshold, the MX60 declared that it was now "Sleeping!" It was now dark outside... my window of opportunity had passed and I would have to wait one more day to "Go Solar."

Thursday started out cloudy, and then turned to snowy. With snow accumulating on the panels, it seemed like there was no hope of "going solar." Much to my surprise, the MX60 decided to wake up and started serving 5.... 10.... 15 watts of power to the batteries. Soon, it was reading 200 watts, even with snow on the panels. That did it, I pulled all of the generator wiring from the breaker box and decided that we were now "Solar!" Of course, I got little done that day - I couldn't take my eyes off of the status display on the MX 60. Every 5 minutes, I would run down to the basement and see how many watts we were producing and check our battery voltage. Before the end of the day, we registered a high of 400 watts from the 624 rated-watt panels. In fact, due to meager use of power tools and flourescent lighting, we finished the day with almost as much energy in our batteries as when we started!

Friday, the sky was clear for much of the day and we produced a whopping 1.7 Kwhrs by 2:00 pm - which was again enough to meet our power needs without ever turning on the generator. Bouyed by the success, and addicted to solar power, I decided to connect 3 more panels for a total of 6. (when in fact, what I really should be doing is working on the permanent installation of all of the panels, or the flashing for that slate roof.) We brought the second set of panels on-line at about 3:45pm - just in time to see 300+ watts from each set of 3 panels.


We didn't work today (Saturday), but I had to visit the house site and see how the panels were performing. Each set of panels was producing approximately 540 watts of power - almost 90% of their best case rating and the 48 volt batteries were at 54 volts! So, even though they're not permanently wired, these panels are permanently mounted. Eventually, I will cover the entire south roof with 48 solar panels, for a total electricity generating capacity of 10,000 watts in the noon sun. But for now I think we have enough electricity to run all of our tools.

Friday, September 08, 2006

Butt holes contributing to a self sufficient home


One of our goals with this house from the beginning has been to build a self-sufficient home. At the outset, I designed the largest continuous wall and roof plane of the house to face solar south. The south wall will have lots of windows for passive solar heat gain and the south roof will be covered in solar electric panels. Solar electricity is currently very expensive - it will take approximately 30 years for our solar panels to produce enough cumulative electricity to justify their initial purchase price (if energy prices remain constant). Given the high price of solar electricity (relative to the coal and gas fired electricity I could buy from the grid), it makes little sense to operate appliances like ovens, stoves, and clothes dryers with solar electricty. In fact, it's almost a prerequisite to operate these heat generating appliances from natural gas or propane if you're going to live off the grid and generate your own electricity. But, aye, there's the rub. Isn't it self-defeating to build an off-grid house that must also run on propane or natural gas? It seems to me like trading one devil for another. Unless...

One renewable source of natural gas that has intrigued me, ever since I started raising cattle on this farm, is the conversion of cow manure to methane. I've read about it on the internet and in some 1970's books on self-sufficient houses, but I was never sure how difficult it would be to do it myself. (just like timber framing!) The best way to learn is to try, so a few weeks ago I plumbed an old 55 gallon oil barrel, poured out some salt and minerals on the ground, called for my cattle to join me in the back yard, and waited for them to poop everywhere. I followed them around with a shovel and a 5 gallon bucket for about an hour. I filled the 55 gal drum with a slurry of cow poop and water and waited for several days. Would it work? Would the traces of old diesel fuel in the drum or the chlorine in the tap water prevent bacterial methane production?

The 55 gal drum is of course a scaled down prototype of what I would use for my house gas generation. I think I will need about a 1,000 gallon tank (already bought it at a farm auction for $50) and the manure of 7 confined cattle. My cattle are free-ranging, but I have 40 head, and I think that if I place a concrete pad in a central location where my cattle come to get their water and minerals, I can capture the equivalent manure of 7 confined cattle in this loafing area. I'd use a hose to wash the pad off occasionally (when it wasn't raining frequently enough) into a drain that would gravity feed to the methane digester. That's the big plan... now back to the small plan...

Within a few days, I had bubbles coming out the water trap of my methane digester. I didn't get too excited because I surmised these bubbles would be CO2 - the result of "aerobic" microbes. I hadn't purged the drum of oxygen, so based on what I've read, it is normal to expect aerobic digestion to occur for several days as a precursor to anaerobic digestion. Each day, there were more bubbles... venting to the atmosphere, because I had resolved not to waste my time with building the gas-storage stage of the methane digester until it actually produced methane gas. Seemed like a good idea at the time - but I soon found that my logic was flawed. You see, at night, the temperature (and therefore pressure) of the digester dropped low enough that it sucked the feed pipe of my digester empty, allowing oxygen to enter the digester every night. I would need a gas storage aparatus... if for no other reason than to accomodate the 24 hour rhythmic pressure differences in the digester. But what to use?

I told my wife... I need one of those mylar balloons. My 2 year old daughter overheard me. She had watched the older kids help me build and fill the digester, but now she saw her chance to contribute. Quickly she volunteered... "I have berry cake balloon. You can use it." She went in the house and came out with a balloon that still held helium. I tried to explain the irreversible consequences of her intended donation, and she nodded her head that it would be fine, but I was certain she couldn't fathom it. The moral dilema was gut wrenching for me... would I actually empty my daughter's perfectly bouyant helium-filled Strawberry Shortcake balloon and fill it with artificial cow flatulence? Of course I would! I rationalized that methane (CH4) is lighter than air, and although the helium release would be permanent, her balloon might actually float again with swamp gas in it.

I painted the drum black (except for the wonderfully ironic Quaker State logo on the side), to help with solar heat absorption. (Methane generation works best at some temperature range that I think is close to internal body temperature.) The balloon soon filled and then the overflow realease mechanism (a msaon jar with water) vented bubbles into the atmosphere. At night, the balloon got saggy, but allowed no new oxygen to enter the digester. Surely this could be working now! But I got busy with the house - really busy. I watched the balloon inflate and bubbles release every day... and weeks passed. Was I really generating methane? How much? When would the first charge of manure run out? I needed to conclude the experiment soon, before daily temperatures dropped too low for my uninsulated methane digester to be viable.

Finally, yesterday, I got up my courage to try and light some of the gas in the balloon. At first I couldn't really get anything to light. But I didn't have a proper aparatus for burning gas - I was simply trying to squeeze gas out of the balloon (through clear U-shaped hose with a water trap in the bottom for safety). Every time I got gas flowing out of the pipe, water would spurt out with it and extinguish my pilot light. The gas didn't seem explosive, so I dispensed with the water trap and started squeezing the gas out of the balloon straight on to a pilot flame. Eureaka. Although I couldn't develop a self-sustaining flame (because I lacked a proper burner), I could squeeze gas directly on to a flame (with the balloon under my arm and actuating it like bagpipe bellows) and get a much hotter, bigger, bluer flame than the pilot flame itself. My next step will be to find a proper burner/orfice and see if the gas is pure enough to provide a self-sustaining flame. In the mean time, I think my digester is making some Berry Sweet gas! [Kids, and litigious adults, please don't try this at home!]

Monday, November 20, 2006

Our home's power station has arrived!

One of our goals in life is to be as self-sufficient as possible. Long before we decided that our house would be a timberframe, we decided that it would be an off-grid home. In other words, we do not intend to connect our house to public utilities. Our house will be powered by solar electricity. I think we can do this, but my wife remains a healthy skeptic. (maybe I shouldn't have spent so much time on the calculator when she asked if solar panels would be able to provide enough energy for air conditioning)

This is a picture of what I call our home's power station. We ordered it from Nathan (he's "good people"!) at Affordable-Solar. This power station takes DC electricity from solar panels (they will sit atop our roof - sorry no pictures of those yet!), charges a 48 volt DC battery bank, and converts that DC power to 120/240 V AC power for use by normal household appliances (I'll let you know if it'll run my MIG welder, because you can bet I"m gonna try it!). From right to left: The two tall rectangles on the right are called Max Power Point Trackers, and they will take power from the solar cells and charge our batteries. The biggest green rectangle houses all of the DC circuit breakers and connections. The two short&wide black rectangles are inverters that convert DC electricity to AC electricty. (there is room for two more inverters above them - I plan to expand soon!) And finally, the green rectangle on the left houses the AC circuit breakers and connections. The output of this panel will feed into a regular "gray" household breaker box. All of the components in this system were manufactured by a company called Outback and then integrated by contract engineers working for Affordable Solar. The Outback manuals are well written and the components seem to be extremely well made. Feels good to buy something made in the USA that creates clean energy.

Here is a picture of the Rolls-Surette battery bank. There are 12 lead acid batteries, each of which produces 4 volts of electricity, giving us a total of 48 volts DC. (and 1000 Amp hours, for 48,000 Watt-Hours of energy storage). Whereas the solar panels are waranteed for 25 years and are expected to last much longer, these batteries (the best you can buy I am told) are warranteed for only 10 years, and aren't expected to last much longer. Batteries are the weakest link in an off grid home power system... or in an electric car, or in a hybrid car, or, well, you name it... battery technology is stuck 100 years in the past! My strategy was to somewhat undersize our battery system (it could provide for 2 or 3 days of bad weather at most), plan on having a backup generator, and hope that battery technology improves by the time these need replaced. BTW, after waving the American flag for Outback, I should admit that these admirable batteries were made in Canada.

Saturday, October 03, 2009

moh powah

We've been operating with 5Kw of solar panels on the roof, while 2.5Kw sat in the basement... waiting for me to get up the gumption to put them on the roof. I used my 1974 Grove crane to put the first 5Kw of panels on the roof, but this time I thought I would try it w/o the crane... thereby freeing up the crane operator (my wife!) to do other tasks around the house.

My panels are attached to the standing seam roof using S5! clamps. These clamps have kept my solar panels in place for two years through high winds and adverse weather, so I decided to literally go out on a limb, and used them in conjunction with 2x4's to build a chicken ladder on my roof. After reaching the peak of my roof, I was able to attach a rope to my (almost finished) chimney, thereby providing a higher degree of safety. I attached myself to the rope using a lanyard and a rope grab with a ratcheting action, allowing me to scramble up and down the roof fairly easily.

Then I started at the peak, removing the 2x4's one at a time and attaching the solar panels as I worked my way back down the roof. These 208 watt panels are heavy, bulky, and sharp on the corners... so even though my safety was assured, I had a hard time wrangling these panels onto the roof without scratching the painted roof. (I kept a bottle of automobile touch-up paint in my pocket) There were a few times I was genuinely afraid I would drop the panels to the ground. But somehow I managed.

The wires for my solar panels pass through a hole in my roof near the eaves. From the roof surface to the breaker box under the eaves, I used solid metal conduit. Anywhere wires from roof mounted solar panels pass through a habitable structure, metal conduit should be used. (fire safety) I wired my panels so that three panels are in series. In the breaker box, four of these "sets of three" are wired in parallel. Then two wires are required for 12 panels to get power to the basement where my MPPT battery chargers reside. (I know, I know, I need a schematic to explain this.)

As of this writing, I have six new panels (approx. 1250 watts) on the roof and wired into our system! The rope remains on my chimney so I can add the other six panels this week, which will bring out solar capacity up to 7500 watts.

Sunday, February 15, 2009

Off grid energy storage - practical hydrogen?

I usually post only original material on my blog, but I came across a video so incredible, I wanted to share it. (This man is incredible as well.) Like my house, this guy's house has geothermal and solar power. He has a utility line run to his house (it was his original power source and still functions as a backup), but for some reason, he's chosen not to sell power back to the grid.

I'm not selling my power back either (I don't even have an umbilical from the grid here), so the question becomes... how to save the extra energy in the sunny months so one can use it in the cloudy months? Lead acid batteries can only do so much. His solution... split water to create hydrogen, store it in LP tanks, then use a fuel cell to convert the hydrogen to electricity in the winter. Brilliant! I looked into something like that, but I couldn't get the economics to work out for me. Heck, I couldn't even locate a fuel cell for less than 6 digits. Because I live 150 feet up on a hill (with another 150 feet to the ridge), some day I'd like to implement pumped-water-storage-hydro to bank my seasonal electricity peaks. But this guy has me thinking about hydrogen for storage again...



By the way, I've been using a 15 amp, 120 volt floor sander for the past 24 hours using nothing but my off-grid power system. (While I was sleeping, the neighbor kid ran the sander!) My point is not that I'm cheap and trying to milk the 24 hour rental for all it's worth (although that much is true). The point is, if I hear someone in the media or government say that solar power isn't practical, one more time, I'm going to lose it! Solar power is absolutely practical. It's also expensive, but it is not prohibitively expensive... even in Kentucky where the available solar resource is 70% of what it might be in California. On an inflation adjusted basis, off grid solar power is the same price as grid electricity was in the 1940's. Was fossil-fuel grid power practical in the 40's? Of course it was, so how could anyone say that solar power is not practical now? OK, energy storage problems not withstanding, but we can solve that too! Please check out the video if you have 7 minutes to kill. I love the twangy banjo sound track!

Monday, December 08, 2008

Off Grid Geothermal Cooling and Heating

This week marks the 2 year anniversary of our Off Grid electrical system. Two years ago I turned off the generator and commissioned the solar panels and we haven't looked back since. In fact, we haven't so much as run a backup generator at the house site in those two years. (In the interest of full disclosure: I did run my welder from a tractor PTO generator, independent of the house system. But that's it - I promise!)

Currently, we have two computers, a refrigerator, lots of lights, a 220 air compressor, random power tools, a small window air conditioner, and a deep freezer running flawlessly on the system. (We have expanded the solar array from 1250 Watts to 5000 Watts as we've added appliances.) At present, our inverters can produce 7200 watts, but soon I'll be expanding the inverter system's capacity to 14,400 watts to accommodate the most ambitious off-grid appliance yet... but first some background.

When my wife and I were just in the planning stages for our new house, I was insistent that it should be off grid. I wanted to produce all of our own power and not rely on public utilities. I realized that once you convert the biggest electrical pigs in the household (furnaces, electric ranges, water heaters, and clothes dryers) to gas or wood, then the electrical requirements for most homes can be met with an array of solar panels equivalent in price to a new SUV. I conveniently left air conditioning out of the equation, but my wife started asking about air conditioning, so I thought I had better look into it.

One wild, but no so practical, idea I had was to buy a tractor-trailer refrigeration unit on ebay and run home grown soybean oil in it (in place of diesel) to cool the house. Hmmmm. I got bogged down at the "squeeze/press the soybeans and filter the oil" stage. I'm an eternal optimist, but that idea was starting to look doubtful even to me. So I continued to dodge and dismiss the air conditioning question for as long as I could. This only aroused my wife's suspicions that I had no viable solution.

I know, I know... why not just suck it up and live without air conditioning? I thought the same thing too, and I was just about there, but then my wife said in no uncertain terms that if I wanted to live without air conditioning, then I was going to be living without her. In other words, she wasn't at all against my dream of living off the grid... it just had to mesh with her dream. You see, the 900 sq foot mobile home we've been living in for 5 years has air conditioning... and it's hard to go back once you've lived the good life. ;)

The solution, I realized, was to compromise on some other aspect of the house (sorry kids, there went the pool!), increase the eventual size of the solar array to 10,000 Watts, and find the most efficient geothermal heat pump in existence. I decided to go with the two speed Envision series from Water Furnace. An on-the-grid friend of ours had two Water Furnace systems installed in his timber frame ten years ago and he loves them. (I think his are single speed models.) He introduced us to his installer (a man who has put in several hundred of these systems) and we hit it off. I don't just trust he can do the job - I like the way he thinks.

The systems have a COP (coefficient of performance) that can approach 5 under ideal conditions. In other words, for every 1 unit of electricity they consume, they can add or remove 5 units of heat. For instance, 2 Kw of electricity could yield 10 Kw of heat (equivalent to 34,000 BTU/hr). Our house will have two, 2 ton units. Under full power, these units will consume a combined total of 4 Kilowatts of electricity, which is within the capability of our solar array when the sun is shining. On cloudy days we can run at least one of the units at the low power setting so long as we have 1200 watts of available sun power. In fact, one of the units (the one dedicated to the bedrooms), can run for 8 hours at night and use only 25% of the KwHrs that our batteries can store.

I doubt I'll be able to keep the house at 68 degrees when its 105 degrees outside, but I'm confident that we'll be able to keep the house in the low to mid seventies in the summer. More importantly, these units will reduce the extreme humidity we see here in Kentucky. Make no mistake, the primary purpose of installing these geothermal heat pumps in our house is to provide air conditioning, but we can and will use them to provide heat for the house when the sun is shining and our batteries are full (like today!!). I won't count on them for heat, but when it is available, it'll be that much less wood I'll have to burn!

Fifteen years ago, our installer put these systems in exclusively with ground loops buried in trenches (that he dug with his own back hoe). He has since become convinced that drilled well systems are superior, and installs almost all of his systems in wells now (he farms out the drilling process). He convinced me that wells are superior (especially for our clay soil), so we're having ours installed in four wells, similar to this picture from Water Furnace's web site. If we can hit the ground water table, the system will work much better, so he recommended that we go to 200 feet instead of 150 feet, due to our location on a hill. Regardless of whether we hit water, the extra loop length can only improve the efficiency of the system.

I'll be updating the blog with pictures of the installation. I also plan to develop some automated way to turn the ground source heat pumps on and off, depending on the availability of sun and the temperature of the house. For instance, if the sun is shining and the batteries are charged, the system could go ahead and lower the thermostat from 74 to 70 (in air conditioning mode) in order to bank some of the solar energy. When I get that working, I'll describe it on the blog. But first, I must go add two inverters to the system, so I'll have more than enough current to start the compressors in the heat pumps when they're installed.

Friday, August 29, 2008

Passive Solar Heat Gain

One key element of passive solar design is to provide lots of roof overhang on south facing windows. Because the sun is higher in the sky in the summer, the overhang (if designed properly) prevents direct sunlight from impinging on the windows in the hottest months of the year. In the winter the sun is lower in the sky, so the overhang will not impede the sun from striking the windows and providing welcomed solar heat gain.

All summer, no direct sunlight has entered our great room through the large south facing windows. Recently, it has been cloudy and rainy in Kentucky, so the sun's rays haven't even reached the house. Today was sunny though and I was pleasantly surprised when I looked into the great room and saw a sliver of light beaming in on the floor. By December, this sliver of light will grow and move across the room, such that the entire north wall of the great room will be illuminated by direct sunlight passing through the south facing windows. I love it when the math works out!

It's still warm here in Kentucky, so ideally the sun wouldn't start peaking through for another month, but the warmest month (July) does not coincide with the sun's highest point in the sky, which occurs in June. Nor does the coldest month of January coincide with the sun's lowest point in the sky, which occurs in December. Therefore it was necessary to allow a little sun in the house in early September so that the benefits of passive solar heat gain could still be realized in late March. Life's a compromise.

I dug around and found this picture of the south side of the house that was taken at around Halloween 2007. As you can see, the sun (due to its annual journey to a lower position in the sky) is already fully illuminating the upper windows in spite of the overhang. Yep, that's how it's supposed to work!

The west side of the house has very few windows, because the sun always sets in the west, no matter what time of the year it is. It is hard to control unwanted solar heat gain through west facing windows on summer afternoons so we simply kept the size and number of those windows to a minimum.

Thursday, September 07, 2006

Materials have arrived!

Last week, our standing seam metal and Structural Insulated Panels (SIPs) both arrived!

The entire south roof of our house will eventually be covered in photovoltaic solar electric panels. It didn't make any sense to roof that portion of the house in slate and then cover it up with solar panels. Plus, I couldn't figure out an easy and leak-proof method of attaching the solar panels to a slate roof. I did however find some nifty extruded aluminum clamps from Unirac that allow you to attach solar panels to a standing seam roof without making any penetrations through the roof. So, I decided to roof the southern portion of our house with gray standing seam metal. A local supplier was able to order it for me and the metal was custom manufactured, cut to exact lengths, crated, and delivered in less than 2 weeks!

Procuring our SIPs was not nearly as easy. Over 5 months after we sent in our 50% deposit to Thermocore, they were finally able to manufacture our SIPs. I'll have a lot more to write about the SIPs later... In the mean time, here's a picture of nearly all of the walls for our house... on one truck!

Thursday, April 06, 2006

Sunroom (breakfast area) added

Yesterday we added the sunroom, and this morning we pegged it together. The long wall of this room faces "solar" south, and will be 90% windows. The rafters (and roof) overhang the south wall considerably, to keep the direct sun from hitting the windows in the summer and baking us. (The summer sun is higher in the sky than the winter sun.)

Before digging our foundation, I oriented our house exactly in line with the sun at high noon. To do this, I went on to weatherchannel.com and found the sunrise and sunset for our zip code. (you can do the same with a GPS unit that gives sunrise and sunset). I then divided the difference by 2, and added that to the sunrise. That gave me the exact minute that "noon" happens at our location. I put a very long pole in the ground, careful to keep it vertical, waited for exact noon to happen at our location, and recorded the shadow line cast by the vertical pole. I then aligned everything in the foundation, according to the shadow that was cast on the ground at high noon. This was very important to us, because we plan to have solar panels on the roof of our house, and will use the windows on the south side of the house to gain some heat in the winter from "passive solar gain". (BTW, most windows nowadays are glazed so as to limit solar heat gain, so we had to order special windows for the south side of our house - but that's another article).

There are no diagonal (wind) braces in the exterior walls of this room. The main reason that I left them out is that they interfered with the windows and and french doors. My wife especially hates pictures of timberframe houses with braces in front of otherwise unobstructed windows. (I have to agree with her - seems like poor planning). But won't the room be shaky or flimsy? Well, partly I'm relying on the fact that this relatively small room is tied to a very stout structure, and partly I'm relying on the SIPs that will enclose this room to add stiffness.

In the picture, you can see that we we are flying the last rafter in to place. About 2 hours before this picture, we were scratching our heads because the rafters were not fitting at all. I had forgotten to notch the top plate to accomodate the rafters. The top plate was already in place, so we had to notch it in right there while standing on the scaffolding you see in the picture. Whoops!

Thursday, January 01, 2009

Solar Geothermal - Part II

The day after Christmas, the geothermal installer called me (waking me up) and told me the well drillers were on the way. I began to protest, but then reconsidered since I had been waiting for months to get them on site. Actually I had feared that with the onset of mud season, our window of opportunity might have passed. The road was in terrible shape, but if the drillers were rarin' and ready to give it a try, so was I... I thought the road might just be in good enough shape to push and pull a well drilling rig to the top of the hill. I was ready for some fun.

Miraculously, the top heavy 60,000lb drilling rig teetered slowly up the dirt road to the top of the hill on its own power without going wheels up, but then it got mired in the mud at the top. I used my backhoe to pull him free, but the last 20 yards proved to be even tougher. The clay on top of our hill is slicker than fish snot, and it was starting to rain. The backhoe was not up to the task, so I got the bulldozer and shoved him up the bank into the front yard. I'll have to say that the driver of the well rig (the owner's nephew - 25 years old?) had a fine sense of adventure. After he was in position, he called it a day and rode home with his helper in their Ford truck.

A few days later, they showed back up ready to drill holes. I loaned them some timber cut-offs to stack under their front outrigger because the hydraulic outrigger didn't have enough extension to level the drilling rig on the hill side. It all looked a bit precarious, but the young drill operator was un-fazed. In the picture to the right, you can see one of the carousels holding the rusty drill extensions. I believe they had twelve of these 25 foot drill extensions, which enabled them to drill to 300 feet if need be. Our geothermal contractor usually bores to 150 feet, but he suggested we go another 50 feet in each well on our job to compensate for the height of the hill. His goal was to strike water, because if your geothermal wells are wet, the heat transfer to the surrounding soil is more effective.

Our whole family watched with great anticipation from a second floor window as they drilled the first hole. They began with a 6" bit for drilling dirt, and as soon as they hit the first layer of rock, they extracted that bit and replaced it with a 4" rock bit. The kids and I documented the color of the cuttings that were blown from the hole, as the drill progressed downward. Every 25 feet, the men operating the rig had to add another extension to the drill in the ground, so we could estimate the depth of the drill at any time. Red, brown, yellow, gray, blue-gray... and then from 50 feet and beyond, our notes recorded only varying shades of gray. We saw dark gray and wondered hopefully if that meant water.

After the drill reached 200 feet, the operators began extracting the 25 foot segments one at a time. The first three segments to emerge from the hole were no longer rusty - but instead shiny gray steel. The last five segments to come out had mud stuck to them - the operator confirmed that we had hit water at around 100 feet! After removing the drill from the hole, the operators inserted a 200 foot long loop of 3/4" black PE pipe all the way to the bottom. The loop was actually two pipes with a u-fitting fused to the bottom, so the total length of pipe in each hole is 400 feet.

The next three holes went exactly as the first had. The kids lost interest after the first hole, but I was captivated until the end. When completed, this geothermal system (aka ground source heat pump) will effectively multiply the energy of our solar panels by a factor of at least four - how could I not be excited about that?!

Rather than backfill with grout, the well drillers filled the holes back up with the cuttings from the boring process. I have my doubts about the thermal transfer efficiency of the cuttings (only about 30% of them went back into the hole!), but I speculate that the cuttings never went all the way down the hole and that the bottom of the hole is immersed in water. I think it will work just fine. I tried pouring some water into the holes after the drillers left, and the fine powdery cuttings in the top 5 feet of the hole turned to clay and would let no more water flow in. With the tops of the holes sealed so well, I doubt there is any chance of contaminating ground water with surface runoff - which I believe is the main reason some installers use grout.

A few weeks earlier, I had begun upgrading our inverter system, so it would have the wattage necessary to start the heat pumps. Unfortunately, one of the two new Outback inverters was dead - right out of the box. Not usually a problem since these have a two year warranty, but I had bought these inverters over two years ago and had left them sitting in the box since I didn't yet need the extra capacity. Slightly concerned about how they would treat the warranty situation, I called Outback, and they agreed to send me new boards for the bad inverter - free of charge. This is a class A company. Due to the aborted upgrade, our inverter system looked like the picture on the left while I waited for the boards to show up. Mind you - it was still functioning the whole time!

The boards showed up and I installed them in the inverter. The directions for installing the boards, written for professional installers not home owners (I consider myself somewhere in between), were nonetheless some of the most amusing technical writings I have ever read. One passage read... "Before getting into the unit you need to make sure you do not have a static charge built up on you or your clothes. The safest way to accomplish this is to stand naked in a mud puddle while disassembling the inverter. Another method would be to...(goes on to describe more conventional ways to avoid static discharge)" . I like a company that takes their customers seriously, while maintaining a sense of humor! With the help of the well written instructions, I successfully completed the inverter surgery without disrobing. Here's a picture of the upgraded system with four functioning inverters - capable of providing 14.4 Kilowatts of continuous power!

Incidentally, the heat pumps will collectively consume less than 4 Kw while running at full power (less than 30% of the inverter system's capacity). I upgraded our system to ensure that the lock rotor amps (startup current) of the heat pump compressors will not exceed the peak capability of the inverters. As an added safety margin, the geothermal contractor tells me that Waterfurnace (the brand of geothermal heat pumps we will be using) are supportive of this unique installation and will provide some special soft-start electronics for the compressor motors.

With all of these preparations, I am confident that these inverters will be able to start and run the two 2 ton units. Some day, running geothermal systems with off grid solar power may be common place. In the mean time, I'm happy to be the guinea pig.

Tuesday, February 10, 2009

Wood Gasification Boiler

Whew, for over a month, I've been immersed in the "theory and practice of modern hydronic heating." My task was to install our wood gasification boiler, build a heat distribution manifold (the circulatory system of our house), and get our radiant heat floors going. I'm happy to report that I have accomplished my mission - it's a balmy 66 degrees inside the house now!

The heart of our hydronic heating system is a "Tarm Solo Plus 40" wood gasification boiler. This unit is made in Denmark and distributed by BioHeat USA (formerly known as Tarm USA). Unlike the outdoor wood boilers that are gaining popularity (and unfortunately notoriety in some areas) in the United States, this boiler is made to work indoors, and burns with little or no smoke. By cooking the wood and drawing gas off the wood to burn in a separate ceramic chamber (at nearly 2000 degrees!), the boiler is able to extract more than 80% of the BTU's available in the wood. By comparison, most outdoor boilers and fireplace inserts do well to achieve 50% efficiency. Less wood to cut - sounds good to me - where do I sign up? The other benefit of the super high combustion temperatures is that very few unburnt byproducts are released into the air. It's odd to see steam coming out of my chimney, but that's what's going on as I type this!

There simply aren't many tradespeople familiar with radiant heat and wood boilers in eastern Kentucky, so I decided to install the unit myself. It turned out to be a lot more complicated than I first imagined, but fortunately, I found a vast resource of friendly people and information on an internet forum devoted to wood boilers at hearth.com. The Tarm boiler comes with instructions, but every installation is so unique that the instructions are more or less "general guidelines." Furthermore, the instructions already assume that your radiant heat manifolds (or air handlers, or baseboard radiators) are already installed and hooked to an existing fuel oil (or natural gas) boiler. I had to start from scratch.

I began by plumbing the accessories that go directly on the back of the boiler. This is fairly standard, so the Tarm manual was helpful here. In this picture, the four copper lines pointed in the air are (from left to right), the supply line, the emergency return line, the emergency supply line, and the return line. The emergency loop is for dissipating the heat in the boiler if your power should fail (and your circulator pump stops) while a fire is in the boiler. A valve on the emergency loop opens when the power fails, and hot water can thermosiphon through the emergency loop if it is designed properly.

The red item is a Grundfos 60 watt circulator pump, and the brass "T" shaped item with red arrows is what they refer to as a "tempering valve." Its purpose is to temper the cold(er) water returning to the boiler, by mixing in the appropriate amount of hot supply water. This keeps the boiler running at the proper temperature regardless of the heating loads. After I finished plumbing all of this, I pressure tested my threaded fittings and sweat joints and everything looked good to go, so I rolled the unit into its permanent location. (Spatially, it is in the basement, directly under my fireplace but it uses a dedicated flue in the chimney.)

*** warning - skip this paragraph if you're not fascinated by pipe thread trivia ***

I'm leaving out a lot of the _really_ boring details, but one detail that deserves mentioning is the pipe-sealant that comes with this European boiler. Whereas in the U.S., we use tapered threads (aka NPT) that get snug after a certain number of turns, the Europeans use straight threads that never get tight no matter how many times you turn one pipe within a fitting. (please, someone from the EU correct me if I'm wrong!) The systems are otherwise similar in that the threads have the same pitch and diameter on both continents. Fittings and pipes will interchange. In the US, we commonly apply teflon tape and sometimes pipe dope to help seal the tapered threads. And this is where it gets interesting (if it ever does)... The boiler manufacturer sees fit to include a unique pipe sealant better suited to the straight threads on their boiler taps. With their system, you wrap the pipe threads with long dry fibers that smell like wet dogs stewed in sour milk (hemp? horse hair?) , and then apply a generous portion of some squishy substance which is partially composed of "animal lipids," before twisting the pipe into the fitting. It was so delightfully archaic that I used their system on all of the fittings I could until I ran out of the stuff. My wife and I were cracking up at this stuff. (if I could have over-ridden my gag reflex, I might have tricked her into smelling those fibers too). Was it a joke on stupid Americans, or would it work? The joints performed fabulously during the pressure test and subsequent operation - no leaks whatsoever. Now I know what to use for pipe sealant in a post-apocolyptic, non-industrialized society should I ever find myself in such a scenario.
*** end pipe thread trivia warning ***

*** warning, veering off topic, gratuitous Appalachian scenery ***
Midway through my installation, we were hit with an ice storm here in Kentucky (reminiscent of the 2003 ice storm that felled all of the trees that became our house). The miserable weather just provided me with more incentive to get the heat functioning in the house! I took this picture from a second floor window, looking south. Fortunately, very few trees fell in this latest ice storm.

*** end warning, back on topic ***

With the boiler plumbed, I focused my attention on the heat distribution manifolds. Some day, I'll make a proper diagram of the whole system and post it here (my wife insists I make one some time before I die), but for now, I'll just point out some of the highlights that might be interesting to someone designing their own hydronic heating system.

First, the architecture is "primary-secondary." In hydronic-speak, this means there is a single primary loop that circulates the heat in the system, with several secondary loops tying in at various points along the way in order to extract heat for various functions in the house. With ths architecture, the pressure and flow in each of the secondary loops is isolated from the primary loop (and therefore from each other). One of my secondary loops is the radiant heat loop. Another of my secondary loops is my indirect domestic hot water heater. I may add other secondary loops in the future (e.g. a huge hot water tank to store heat, a solar hot water collector, a clothes dryer that uses hot water for heat, etc.) . It's very easy to add on to this architecture and that's one of the reasons I chose it. The more widely used alternative is to have one giant supply manifold and one giant return manifold, but that architecture has drawacks that I won't go into now.

Another important aspect of this design (and virtually all hydronic radiant heat designs) is how to obtain the proper temperature for the radiant heat zones. Specifically, the boiler heats water to 180 degrees whereas water somewhere between 110 and 150 degrees is appropriate for radiant heat floors. There are several sophisticated ways to achieve the temperature drop, but I chose the rather simple method of a three way thermostatic mixing valve. In this picture, 180 degree water from the primary loop enters the top port of the mixing valve, cooler water returning from the floors enters the left port of the mixing valve, and 130 degree water magically exits the bottom port of the mixing valve. The valve is entirely mechanical (no electrical components), and presumably fairly reliable. This one is made to be taken apart and cleaned, should that ever be necessary. Incidentally, the copper T in the upperleftmost of the same photograph is where the rest of the return water from the floors is injected back into the primary loop.

At least one more aspect of the system deserves mentioning... Because the entire heating system is using off-grid solar/battery power, I was very critical of the power consumption of the circulators (pumps), zone valves, and the boiler fan. My concern was heightened by the fact that the heating system is most in demand when my solar resources are at a triple minimum... (1) during the winter... (2) during cloudy days, and (3) at night. The boiler requires only a small circulator because it does nothing but circulate water through the relatively short primary loop. I chose a Grundfos 15-58, which consumes only 60 watts. It has a low speed setting that I might get by with that uses only 48 watts. The fan on the Tarm boiler only uses about 50 watts. These are manageable, but not insignificant numbers (50 watts + 60 watts). With these components pretty much "fixed," I focussed my attention (i.e. budget!) on the large circulator that pushes water through almost one mile of 1/2" pex pipe in the floors of the house. For this task, I found a German (they are more energy conscious than us Americans) made WILO Stratos pump that is super efficient. In fact, it has a microprocessor that will vary the pump speed based on how many zones are calling for heat. (The technology to control the pump speed is called ECM for "electronically commutated motor.") The motor draws between 9 and 130 watts, and in my application, I think it will usually be drawing about 80 watts based on my measurements. A conventional circulator pump for this application would probably draw at least 150 watts constantly.

Well - that's it for now. I could go on about how to check for leaks, sweat joints, choose a pex manifold, store heat, bleed lines, etc., but most of that stuff is already on the internet. I've included just enough detail here to bore most folks to tears, while not enough detail to reproduce my results and avoid my mistakes. If you have questions about this system, or questions about a system you are designing or modifying, I am glad to offer what little knowledge I have picked up while building this system. I'm still tinkering and will post updates later on. For now, the house is warm and I can work in my T-shirt! On to other unfinished, inside projects...

Wednesday, October 07, 2009

Finally up to 7.5 Kw of solar


In spite of wind, rain, and visiting friends, I finally finished our solar panel installation. We now have 36 panels on the roof. Each of them is rated for 208 watts, so the total production capacity of the array under ideal conditions is 7488 watts. Today, when the sun appeared between the clouds, I saw the system reach its theoretical maximum of 7.5Kw! The best number I could capture today after getting my camera out was 7.2Kw.

Speaking of clouds, it is possible (and I saw it happen when I had fewer panels on the roof), for the array to put out even more than its theoretical maximum when the sun is peeking around the edge of a cloud. I won't pretend to understand the optics, but the edge of the cloud focuses the sun on the array. The extra power is trivial since the condition only occurs for a brief period of time (clouds move!). But it is important to consider this "peaking" effect when sizing fuses, wires, and battery chargers.

Here's a picture of the cloud obstructed sun earlier today, trying to shine through the timbers and our as-yet-untrimmed windows on the south side of the house.

Saturday, November 03, 2007

More Solar Power!

Throughout the project, we've usually had one or two people helping us ("inlaws and outlaws"), but we've slowed down a bit and now it's just my wife and I working on the house most days. (plus the dry-wall finisher) My wife has been running the crane, with me on the end of it (talk about excitement!), in order for us to mount more of our solar panels. Since December '06, we had been operating the house site with just 6 panels. Now we have 24 panels on the roof. On a bright day, we receive 5,000 watts of power from these 24 panels!

Of course we don't use much power up there, so our batteries have been staying full. Because we're not connected to the grid, there's nothing to do with the excess power. So as not to feel wasteful, we go around turning ON lights in the house when the sun is shining! (it produces a small amount of free heat which is useful this time of the year) To use our power more effectively, we bought the most energy efficient upright freezer we could find (527Kwhr/yr. for 20.6 cu ft., manual defrost) and moved it into the pantry yesterday. This will let us unplug a not-so-energy-efficient deep freeze that we had connected to the grid elsewhere on the farm.

We haven't moved into the house yet, but some of our frozen food has - that's a milestone. :)
Posted by Picasa

Tuesday, January 01, 2002

Massie House Blog Posts Indexed by Category

Masonry, Stonework, and Foundation

the rumford fireplace/brick oven/cook stove structure
Pizza Oven Hearth (Part VI)
Pizza Oven Base (Part V)
Rumford (Part IV)
Stone Arches Without Mortar (Part III)
Starting the Stonework (Part II)
Building a Rumford (Part I)
Concrete is Always Exciting
foundation
Stainless Steel Termite Flashing
Pouring the Basement Slab
exterior stonework
Still in the Stone Ages
Stone on the Little Tower
Custom Stone Lintols
Stone Age the mixup
How to Babysit Boys
Dawn of the Stone Age
Stonemason terminology
quarrying stone
Rubble Rousers


Slate Roofing

learning about slate roofing
Slate Book Review
Slate Conference in Pennsylvania
the eyebrow dormer
Eyebrow Dormer is Finished
Nine Courses of the Eyebrow Dormer
Five Courses of the Eyebrow Dormer
Begining the Eyebrow Dormer
Eyebrow Dormer is Framed
Inside the Eyebrow Dormer
West Side Story (Eyebrow Dormer Framing)
copper, stainless, and terne coated stainless flashing for slate
Flashing for Slate
Copper Shingles Are On
Stealth Airplane or Cricket
Copper Flashing for South Dormer
Installing and Flashing Slate Hips
Back on the Roof
other slate roof topics
DOT Approved Finial
Tower Half Done (lots of lightning rod comments on this post)
Quick Roof Update
Slate slate and more slate
Slating the North Hip Roof in the Rain
First Doghouse Dormer Slated
Head Scratching at the top of the Tower
The Little House (hexagonal slates)
The slate is here!
slate flooring
Recycling Slate Roofing for Flooring



Offgrid Living and Alternative Energy

Our Wood Cook Stove
Adding More Solar Panels
Cooling The House
Recessed Compact Flourescent Lighting
Going Solar for the First Time
An Experiment to Produce Methane from Cow Manure
Our Home Electric Power Station (Inverters, Balance of System)
Making Maple Syrup in the Kitchen

**Uggh... I am still adding pages to this category archive... manually**

Tuesday, August 28, 2007

Climate control....

This summer has been exceptionally hot and dry in Kentucky. To keep the heat down at the house site, we've been opening a few first floor windows at night and placing an exhaust fan in one of the windows on the third floor. If the outside temperature is in the high 90's in the day and mids 60's at night, I can keep the temperature in the house between 72 and 80 degrees with the fan alone.

Even though I've only mounted 6 of 36 solar electric panels on our roof so far (1200 of 7200 watts), we've had a surplus of solar electricity all summer. So I went out and bought a small 8000 btu window air conditioning unit (less than $150) in order to do something with the extra electricity when the batteries were full. (we are not connected to the utility grid, so we don't have the option of selling back the excess energy capacity.) The sticker on the 8,000 btu unit said it would consume about 1000 watts, but in reality I think it consumes 700 or 800 watts (based on our inverter display readings). Somewhere in the 700 to 1000 watt range is just right for using up the average daytime electricity from the 1200 watt array on our roof, without dipping into the batteries too much when a cloud passes over.

Our SIP panel walls are R-24 and our ceilings are R-50, and we have a fairly tight house, so the little 8000 btu unit actually does make a difference. No, it won't change the temperature of the whole house by more than a couple of degrees during the course of a day, but it can drop the relative humidity by at least 10%. When we get the rest of the panels on the roof, there is no doubt in my mind that they will be able to run an air conditioner of sufficient size to cool our house during the hottest months of the year (July and August). I'm also hoping (confirming?) that for 6 months out of the year, all we'll need is a fan and opportunistic window openings/closings in order to keep the house at a comfortable temperature. That's good news!

Thursday, June 25, 2009

A Windy Tale

Last weekend, our daughter's softball game was interrupted due to a tornado warning. Rather than book it back to our mobile home, we decided to weather this one out at our house site. Our brick pizza oven was still warm from the night before, so we heated up leftovers and listened to the radio for weather updates.

In spite of strong winds and driving rain, things were calm and cozy inside our timberframe. Our peace and quiet was interrupted though when giant hail started slamming the steel garage doors on the north side of our house. We soon retreated to the basement !

While studying a clumpy ball of hail about the size of my fist (and pondering the condition of our solar panels), I watched a 100 plus foot oak tree slam into the stone pile in our front yard. Four more trees of that size fell within seconds, but I didn't get to see them, because I was herding our family away from the windows and into the storm room that adjoins our basement.

Torrential rain accompanied the winds, such that all of the runoff from the roof (we don't have gutters yet) was blown against the house walls and ran down behind the unfinished stonework and into the basement. When the greatest danger passed, we emerged from the storm room to place buckets where water was running past the sill plate. And as soon as the rain subsided we walked upstairs and looked out our windows to find 80 to 100 year old oak trees laying in our front yard and across our driveway.

Fortunately, the tree damage was limited to the vicinity of our house -- very few trees fell elsewhere on our farm this time. Still though, the uprooted trees were eerily reminiscent of those that came down in the 2003 ice storm and supplied all of the timbers for our house. By comparison, this week's storm was insignificant... providing only 17 loader buckets of firewood and 12 large logs (for our porch timbers perhaps?).

We were lucky that no trees hit the house, because I now realize that some of the remaining standing trees are within range of the house if they were to fall. I believe I'll do some heavy pruning when I get caught up on some of my other projects. I have no desire to splice a timber frame back together or repair a slate roof. (Incidentally, the solar panels were just fine - the somewhat slushy hail came from the north whereas the panels face south.)