Utilizing Passive Solar to Reduce Oil Consumption

[Chad300tdt]

In addition to installing a wood-burning fireplace insert with blower as a supplement/alternative to OIL, I am building some passive solar window box heaters. I'm building 5 of them that can be removed during the warmer months. They are inexpensive and VERY effective/efficient. I still have an oil burner for home heat and hot water, but hope these changes will reduce my costs. I will also be switching over to an electric water heater tank (super insulated) with solar preheater as time and money allow.

Here are some links with diagrams:
http://www.jrwhipple.com/sr/solheater.html

http://www.homeconstructionimprovement.com/2007/12/solar-box-window-heater.html

http://www.cd3wd.com/CD3WD_40/JF/JF_VE/SMALL/23-564.pdf

Here's a link with a video showing how effective even a small temporary solar box can be ... although this style would never be approved by my wife.
http://www.savingadvice.com/blog/2007/11/16/101901_build-your-own-solar-window-heater-for-10-save-45-a-month.html

Here's a link with other cool DIY'able passive and active solar solutions:
http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

[Mistel]

I am right in the middle of installing a solar hot water heater on my house. I will get about a %20 rebate from various levels of government here in Canada.

I am using http://www.thermomax.com/

[Chad300tdt]

That's very cool. Thanks for posting the link, I bookmarked that site for more in depth reading. I'd like to know how it turns out when you're finished, and how long it ends up taking for complete installation.

[Chad300tdt]

Originally Posted by Mistel

I am right in the middle of installing a solar hot water heater on my house. I will get about a %20 rebate from various levels of government here in Canada.

I am using http://www.thermomax.com/

Which system are you using? That site has a bunch of options. I thought you were doing a pre-heater system with a storage tank that would keep the water up to temp, but I'm thinking I may be mistaken based on your "soft copper" thread.

[raymr]

Look into a Beckett Heat Manager. Its a gizmo that wires into the burner and thermostat to delay burner firings until absolutely necessary. They claim 10%+ in fuel savings.

[A264172]

Unless I misunderstand his profession, I think Tom W. could give you a good idea of the function of those devices.

If you could seal their entry to the house with a smaller square foot of higher R-insulation when the sun wasn't shinning, I would bet that you would get a net better effect.

Which direction will the five of them be pointing?

[Chad300tdt]

I'll have 3 on the south facing side of the house and one each on east and west.

That's a good idea about sealing them off. I can build a little door on hinges lined with celotex like I plan to line the box itself with. In the morning I can open the door and let it hang (like the glove box in your car), and close it at night.

Some of the plans I've looked at have sliding doors to close the box off in summer so you can leave them in the windows year round without unwanted heat entering the home, but I'm sure it would work in the way you mentioned too.

[A264172]

If you did that, you could close the east one in the afternoon and keep the west one closed in morning when possible.

It seems like the wider ones would have a chance to collect some more serious heat.

What kind of btu's do you think you might get out of them?

[Chad300tdt]

Originally Posted by A264172

If you did that, you could close the east one in the afternoon and keep the west one closed in morning when possible.

It seems like the wider ones would have a chance to collect some more serious heat.

What kind of btu's do you think you might get out of them?

I was planning to make them 3' x 5' so I'd have 15 sq.ft. of collecting area.

I've read that standard glazed windows get 1,300 btu/sq.ft. Using that figure I would expect at least 19,500 btu per unit, maybe more since it will be black inside and insulated. I've read that a well insulated box can deliver a stream of 120˚ air as long as the sun is shining on it.

I have a 2000 sq.ft. of living area needing heat and at 166.67 btu needed per sq. ft. I need to have 333,340 btu to heat the house. I believe I should be able to get 78,000 btu from the 5 units considering that 2 won't be as effective in their placement. That's 23% of the heat I need.

I'm not an expert so these are my amateur figures. Once I build the boxes and test them this winter, I'll have actual data to report.

[Botnst]

Wood is a greater source of air pollution that anthracite coal, IIRC. I think even lignite is better than wood in terms of pollution.

B

[Chad300tdt]

Originally Posted by Botnst

Wood is a greater source of air pollution that anthracite coal, IIRC. I think even lignite is better than wood in terms of pollution.

B

LOL. I think I had this discussion before. At this point, although I love the environment, I'm more concerned with cheap alternatives. I can get wood from local landscapers for free and I already have all the materials for solar window box heaters (except the celotex) left over from other projects.

If I had to buy wood I can get a cord of split hardwood delivered for $200-$275 depending on who I use.

Plus I'm getting a catalytic insert so I'll be as responsible as a wood burner can be.

Also consider the tree spent its life providing oxygen and I'm not buying something that requires extensive processing and transport.

[Botnst]

Coal is simply trees that spent their lives producing oxygen, too. They were just slow in going back to their constituent parts.

I completely understand and agree with your choice based on economic self-interest. Back in the olden days I tried making biogas. I got a flammable product but it was highly contaminated with other gases, especially CO2 because I had no efficient way to separate CO2 from methane. Also, I had no compressor so all I got was a weak yellowish flame. I was proud of it, but it wasn't worth the effort.

Since then I've thought of a way to scrub the CO2 that uses another waste product -- wood ash. Passing hot water through wood ashes puts potassium into solution forming KOH -- potassium hydroxide. This is why ashes make a good garden additive, plants like potassium.

It occurred to me that bubbling the biogas through the KOH solution would scrub CO2 (and sulfides and sulfates) from the system H2O + CO2 -> H2CO3 while H2CO3 + 2KOH -> K2CO3 + H2O. Potassium carbonate and water. KCO3 has low solubility in water and would mostly ppt out. This leaves the methane (and other aliphatics) untouched. Also, the K2CO3 would be less soluble in the soil, too. This would result in a slower release, lower toxicity fertlizer than aqueous KOH right out of the ashes.

Anybody have any comments?

B

[Chad300tdt]

Originally Posted by Botnst

Coal is simply trees that spent their lives producing oxygen, too. They were just slow in going back to their constituent parts.

I completely understand and agree with your choice based on economic self-interest. Back in the olden days I tried making biogas. I got a flammable product but it was highly contaminated with other gases, especially CO2 because I had no efficient way to separate CO2 from methane. Also, I had no compressor so all I got was a weak yellowish flame. I was proud of it, but it wasn't worth the effort.

Since then I've thought of a way to scrub the CO2 that uses another waste product -- wood ash. Passing hot water through wood ashes puts potassium into solution forming KOH -- potassium hydroxide. This is why ashes make a good garden additive, plants like potassium.

It occurred to me that bubbling the biogas through the KOH solution would scrub CO2 (and sulfides and sulfates) from the system H2O + CO2 -> H2CO3 while H2CO3 + 2KOH -> K2CO3 + H2O. Potassium carbonate and water. KCO3 has low solubility in water and would mostly ppt out. This leaves the methane (and other aliphatics) untouched. Also, the K2CO3 would be less soluble in the soil, too. This would result in a slower release, lower toxicity fertlizer than aqueous KOH right out of the ashes.

Anybody have any comments?

B

I'm not a chemist but I think I follow what you're saying. What did you start the biogas making process with though. Was it poop of some sort?

I want to get some chickens, but I don't think I'd have a good resource for that whole process.

[Mistel]

Originally Posted by Chad300tdt

Which system are you using? That site has a bunch of options. I thought you were doing a pre-heater system with a storage tank that would keep the water up to temp, but I'm thinking I may be mistaken based on your "soft copper" thread.

I am installing a system that looks pretty much like this

http://www.thermomax.com/October2001.php

I don't know what you want to call it. A solar pre-heater might be a good description. It uses a food grade glycol solution to warm a 65 gallon water tank through a heat exchanger in the tank. My hot water goes into the 65 gallon pre-heat tank, then into my old electric tank, then to the house. In the summer, the system should warm the water enough so that my electric tank will not turn on. I actually plan on just shutting it off during the summer. In the spring, fall and winter the electric tank will work as necessary. I used a 50 foot roll of soft copper for the run through the attic so there would be no chance of leaks.

I'm not done yet, but close. I am basically installing it myself. My house is the test bed. I work with a guy and we are trying to get into domestic solar hot water. We already install solar pool heaters. (very good return on investment, by the way)

[Chad300tdt]

That's pretty cool. So you have a closed system that recirculates and exchanges the heat to the water in the initial tank. I imagine the pump wouldn't have to work that hard to recirculate either. Is the system electric other than the solar collectors for heating the glycol solution?

WOW ... propylene glycol is like $30 a gallon. I guess it heats faster than plain water? I can only find info about it being used as a coolant.