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PowerGripe

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Reply with quote  #1 
Hi, I am new to this solar heating (Mechanical Engineer) and tired of the heating bills in an all-electric home. Baseboard heaters chew through power. I have programmable thermostats on them but still power bills run $200+ over normal in Winter.

I have been doing some reading here and this post jumped out at me.
http://simplysolar.supporttopics.com/post/show_single_post?pid=1290819644&postcount=2&forum=268122

We have a crawl-space and conventional uninsulated wood floors and I was thinking I would use a CPVC panel and need a storage tank for night-time warming. Then I read where Jeff mentions "It also supplies heat to a storage tank, but currently I'm not using it."

This has me thinking I may not need a storage tank. Can I block up the vents in the 4-foot high crawl space and use that as a thermal storage for the evening? The crawl-space walls are Cinder-blocks, so may need to insulate.

The first problem I think I see is that the heat will be unregulated. Too hot in the day and cooling fast at night.

Thoughts and guidance please.

stmbtwle

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Reply with quote  #2 
Welcome Powergripe!

There are several threads here about storing heat in the cellar, you might check them out, and I'm sure others will be able to help you.




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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
stmbtwle

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Reply with quote  #3 
Powergripe, you didn't tell us where you're located. So before we start chasing rainbows, how about putting that in your profile. IT MATTERS.

This "sounds" like a possibly old, poorly insulated frame house with lots of windows. If the floor is not insulated what about the walls and ceiling? Have you contacted your utility about an "energy audit"?

I think the complaint is the electric baseboard heat. In temperate climates a heat pump can provide about three times the heat as electric strip heat.

What comes to my mind is a bunch of water filled drums in the crawl space. They could absorb heat during the day and release it at night. There's more to it than that though.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Rick H Parker

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Reply with quote  #4 
You have attempted to conserve electrical energy by reducing consumption, the programmable thermostats.  Have you done anything to conserve the thermal energy it is converted into, by reducing the rate in which it is transferred to the environment outside of the house?

Your house is all electric, is there any particular reason you want to shift the energy load from electrical to thermal?  There is an argument that with solar photovatic panels going for as low as 74¢ per watt, it is more cost effective to produce thermal energy from photovoltaic panels then from thermal panels.

The shift toward string inverters and micro inverters is evidence in support of this argument. The cost of photovoltaic has dropped to the point that the amount of copper in the system is an significant portion of the total cost of the system. Both string inverters and micro inverter reduce the amount of copper required. It is the same economics as high voltage vs low voltage transmission lines and the deciding factor in the current war between Tesla and Edison. How the same is playing out between photovoltaic panels and thermal panels, that is why there have been so many attempts to produce plastic thermal panel. Copper the material that launched us into our technology age is still making the rules.

You all ready have infrastructure for space heating from electrical energy, you also already have copper to transfer the energy, so the argument for photovoltaic would be strong for your case.

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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
Rick H Parker

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Reply with quote  #5 
"Powergripe, you didn't tell us where you're located. So before we start chasing rainbows, how about putting that in your profile. IT MATTERS."

Specify, put your location in the Signature of your profile. That way it will show on every posting.

Click on your name, edit, click on Signature at the bottom.

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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
Rick H Parker

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Reply with quote  #6 
"Can I block up the vents in the 4-foot high crawl space"
The first problem I think I see is that the heat will be unregulated. Too hot in the day and cooling fast at night.

Unsealed foundation and uninsulated floor????

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Rick H Parker
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PowerGripe

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Reply with quote  #7 
Ummm, thank you I think. [smile]

Winters have seen 0F! Not often though, generally 15F is the norm for Lows.

Let's not assume too much!

Six-inch walls with fiberglass, no idea of the R-rating.
Ceiling 8" of blown-in cellulose, no idea of the R-rating.
Triple-glazed wood-framed windows all round, no idea of the R-rating
Crawl space has two 8" square metal louvered vents and a small access door.
Drums would be limited to the size of the crawl-space access door, 22" x 22" so probably a plastic lined wood-fabricated tank would be the option -- IF I went with water for storage.

Soooo, back to the original question...
Can I block up the vents in the 4-foot high crawl space and use that as **adequate** thermal storage for the evening until about 9:00pm?

I have just tested with 150' of garden hose full of water laying in the sun for an hour and it went from 68F to 121F. Not that I am planning to use a garden hose for the system, but just wonderd what I could expect as temp-rise. So the process looks doable.
stmbtwle

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Reply with quote  #8 
Sorry, I have no experience with your climate or type of home, maybe someone near you can help.

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Willie, Tampa Bay
gbwillson

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Reply with quote  #9 
Hi PowerGripe-

Welcome! It's normally not a good idea to block off any vents in a basement as they are there for a reason. The vents allow fresh air to circulate so that excess moisture from the ground doesn't turn the crawlspace into a breading ground for mold, rot, and possibly radon.

That being said, there may be little moisture coming from the ground in the winter where you live. Or the floor of the crawlspace may be sealed by a sheet of heavy plastic. My home has a full unfinished and unheated basement, so it is not much different than a crawlspace as far as retaining heat. But then again, it's not vented to the outside either. I draw a large amount of cold air off the basement floor(500+ CFM), out through the solar heater, and back to the basement. This action not only draws off the coldest air from the floor, but exchanges it for the warmest(45˚-50˚F DeltaT). This warmed air rises between the floor joists to heat the floor above. The mass of the joists, subfloor, and hardwood floor absorbs this heat during the day and slowly gives it back overnight. So the wood acts as a heat sink. Not quite as effectively as using water for a heat sink, but it is quite effective. On a sunny day, my furnace only runs dearly in the morning until the sun activates the solar heater and stays off until the next morning regardless of the outside temperature. Air heating won't add any moisture to the crawlspace. Kinda hard to limit excess moisture with heated tanks of water, unless the tanks are tightly sealed.

8" of attic insulation is not very much in many parts of the country. So you may want to check for your area. Adding a few inches more is cheap, easy, and worth the time. And make sure you seal any leaks or attic bypasses as any air leaks that leak air out through the ceiling, draw in an equal amount of frigid air from outside. So keeping the heat in and the cold out is job#1. But it sounds like the house is in great shape, especially the windows. Heck, I don't even have triple-paned windows here in Minnesota.

Greg in MN[wave]
stmbtwle

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Reply with quote  #10 
I can understand it over a closed basement, but why would the floor over a vented crawlspace NOT be insulated?

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
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