Thermal mass...

Xeramthem, on another thread, mentioned the fact that black water bottles beneath pots or flats promoted growth of the plants. The beneficial effect was due to warmth provided by thermal mass of the water in the bottles.

The best thermal mass is water, which can store more heat than most any other available material. I've heard of a fellow who has enough thermal mass in his greehouse water barrels that for every degree drop in the barrel water temperature 42,000 BTU of heat is released. Similarly, on a hot day, that same 42,000 BTU of heat is absorbed as the water temp in the barrels rises. Thus, the thermal mass moderates the GH temps.

There are other types of thermal mass. I have a good deal more soil, in the form of my raised beds, than I do water... but the soil is not as efficient at storing heat.

Are forum members using thermal mass? What kinds? A water garden is an elegant way of taking advantage of thermal mass and gardening at the same time...has anyone tried it?

SB

Yes,I have a water garden,6x8ft,a foot deep,seems that the water is always cold,altho the leaves on the water lillies are as green as if it was summer time.
I have swamp lillies and papyrus growing in it also.
Makes me wonder where if any heat is stored,when the water is always cold to the touch,but is great for keeping up the humidity in the greenhouse.

Tropicman, would you have any pics to post? This is a project (one of many) I'm thinking about. Thanks. SB

Stressbaby, I went out this morning before the sun hit the greenhouse and took the temperature of the soil of some of the plants on waterbottles and some not on waterbottles. I used the thermometer I used to use when I did photography the old fashion way with chemicals. I was startled to see an average of 5 degrees difference! Around 40 degrees off the bottles and 45 degrees on the bottle for the ones in 5" plastic pots. The lowest temp in the greenhouse last night was around 39 degrees and the highest was 97 yesterday. Those highs & lows have been pretty constant for the last week give or take 2 - 3 degrees either way.

X

Nice! Thanks, X. Nice surprising to me, tho. With temps up to 97 you have the capability to store tons (literally) of heat in your GH. And you gave me an idea for another thread...

For more thermal mass, I'm going to pick up 4 55 gallon drums on Saturday. Then I'll just have to find room for them in the greenhouse!

SB

Woah SB, considering where you live and the angle of the sun, I do not think 55 gallon drums of water can store enough heat in the day time. Better you get 5 or 6 10 gallon containers.

When I lived in England, they had what was called a trickle down heating system for flats. In the daytime this thing on the wall with bricks would store up heat using low voltage then release it at night. I often wondered if a modified system like that would work in greenhouses that have a problem with lack of humidity. My idea was to get window boxes, put bricks in them then fill with water (obviously seal them so they hold water) and put them around the permiter inside.

I'm sure there is some formula somewhere that tells you the intensity, duration and angle of the sun required to heat water to certain temps.

X

Hi X,

The thing is that its a lot easier to store rainwater in 55 gallon drums. ;-)

I'd love to see a link. I googled and didn't come up with much. I know a lot of people use 55 gallon drums. Others favor 5 gallon stackable containers for this because of the flexibility of the smaller, stackable container. My GH is slowly filling up with 1 gallon containers of water, but I haven't gotten around to painting them all.

I'm not following you on this trickle down, low voltage thing...SB

SB,
At 10pm,it is 75* still in the greenhouse,but here is a pic of the pond.

This is what it looks like in front of the pond,well you can't even see it,greenhouse is so full of plants.

Temperature is still75.2* in there now,at 10:20pm,still 46* outside now also.

40 outside with a strong north wind, no heat at all in the greenhouse. temp is 80 degrees inside and the exhaust fan is coming on. Just finished up this GH this week. I also lined the top 2/3 of the north wall and 1/2 the ceiling with a product call tek-foil which is a foil lined light bubble wrap

this is the building in progress

Very nice-looking g-house, jackieshar! Good job!

I imagine you have double layers of plastic (inflated), however, I can't tell what it is you put on the ends...is it some type of rigid poly?

That's lots of thermal mass, nice going!

Whatcha got there lining the walk by the door, wine bottles? We'll be right over... SB

hollow walled hard poly on the end walls..and you're right, double inflated sides....gonna be a raised bed lined by pretty green piesporter bottles....but I have to empty a few more as u can see.....:>).
Artic cold front last night , down past freezing.....only have the heat from the radiant foil and the black water barrells...... .went out this morning and the inside was 80 degrees and the exhaust fan was running to cool it down...........

New here, and just purchased a Sunglow 8' X 12'. What size greenhouse do you have SB and X? I'm considiering thermal mass as well, but with 8 X 12, where the heck do I put the plants??? ;)

Shine

Welcome Shine. My GH is 20' x 23'. Anywhere you have space that cannot be occupied by plants, try to put some thermal mass. Many people use 55 gallon drums filled with water, then they built the GH benches on top. A row of drums along the back wall, with a bench built on top of the durms works well. The drums should be a dark color, black or dark blue, at least on their south side. I also use 1/2 and 1 gallon milk jugs under benches, on the knee wall, and so forth.

I learned of another advantage of thermal mass today when I went to my GH and I had no water. I don't know if the well pump is broken or if the line is frozen. But I have plenty of stored water to last a while.

Good luck and have fun, the adventure is just beginning...SB

I know. I'm so excited. I can't wait for them to ship my Sunglo. I went back and forth between Sunglo, Juliana, and my Hubs building me one, but the Sunglo came with so many goodies from Costco, I couldn't let it go. I already called the company and upgraded the Greenhouse from 8 ft to 10 ft Wide X 12.

Thanks for the warm welcome and answers.

Shine