Love you plan. I made my floor insulated concrete to try and trap some solar heat. At the time I didn't realize that the plants themselves blocked most of the sunlight. I have a row of black cast iron radiators against the exposed wall, under the bench, but think black water filled containers would do a better job. I've been thinking of scraping the iron and putting black barrels with water in there place.

This year instead of straw we taped insulation boards to the outer lower portion of the walls. I also purchased a solar cover that we will put on when we return from our trip. If we do it now I'm afraid it will get too hot since the automatic vents will not be able to open when it's wrapped and I won't be here to open the doors.

Eric4home said: ... I have a row of black cast iron radiators against the exposed wall, under the bench, ...

If you could put those where they would catch the sun during winter days, they would absorb heat really well.

Then, maybe with a small solar-powered pump, if you circulated water from some barrels or under-floor reservoir, through the radiators and back to the barrels, the water would heat up all day and then release heat at night. But the heat would be released slowly if the pumps stopped after sunset.

I always thought that water barrels could make good stands for putting tables on top. As legs for tables, but half buried in the ground, they would absorb a certain amount of heat from the ground. Better yet, two barrels connected together with at least one of them totally underground.

You may be able to dig a hole that easily in Florida but up here you'd need a backhoe.
Honestly, my dad lives in New Port Richey and I've done a bit of work at his place and I'm envious of how easy it is to dig fence post holes, or dig a new trench for a water line, but I do not envy the soil quality. Amending the soil (sand) there would be a full time job.

And that is what I am running into. We still have another 13 inches to dig out. It is red solid Rocky Clay .

That's what our top 13"s is like. I've gotten a half of a bucket of rocks from 1 post hole.

No kidding, Ric -- every time I come up with what seems like a pretty simple project, my poor husband ends up digging up large rocks (lucky he has a lot of experience working on RR tracks... good with a pick and pry bar!)

I've had my share of those stories. I learned to use a digging iron and pick too many years ago.

Yep, digging iron needed for sure. We haven't had to use the pick yet. When we left the hole was filled with water. It had just rained but I don't think that much rain came through the roof vents. Not sure why there was so much water in there. I'm hoping it will be gone when we get back.

If I'm right here the concept is the geothermal heat will warm the barrel at night. Are Temperatures at this depth constant at higher longitudes? Meaning up here in Mass would the ground heat at 4 feet deep be significantly different?

mcallis said:If I'm right here the concept is the geothermal heat will warm the barrel at night. Are Temperatures at this depth constant at higher longitudes? Meaning up here in Mass would the ground heat at 4 feet deep be significantly different?

That's a good question -- I've wondered pretty much the same thing but couldn't quite figure out how to ask it.

I'll probably try and get my solar cover on tomorrow, it's supposed to still be 71*F with scattered showers. This weather is just crazy, Holly saw a cherry tree in full bloom as well as roses on her way home from Christmas dinner. I just hope we don't get extensive damage once winter does get here.

I think the ground temperature would be pretty much the same for northern area but I'm no expert.

I can't find where I originally post about adding another fan. I added a turbo fan on the floor pointing straight up. It has evened out the GH temps so well the heater runs less and the vents almost never open. I had been having a problem with the vents opening because of the heat rising and the heater being on because the floor level was still too cool. A wasteful situation at best.

That sounds like a good solution, Ric -- and the air circulation in general can't hurt, either!

I'm going to try adding a fan to my gh. Right now the heat is rising, and the heater is staying on almost constantly during the night. Thanks for that idea. Where do you buy your fans? I also need a small clip on 6in or smaller one for my grow tent with LED light.

To tell the truth I buy most of my fans at second hand stores, like Salvation army, and Community Aid. A small computer fan would be ideal for your tent. You can use lamp cord to wire them, they only draw 1/4 amp or so. I have 3 other fans in my GH for air circulation, They just weren't mixing the air vertically.

I was wondering if the computer muffin fans would work. Great idea!

Yes Karen they will. Just be sure to check that they say 120 volt, there should be a small printed label on the side, and you can get the connectors at automotive or electronics stores. I use them for a bunch of different applications.