Stressbaby, Thanks for sharing your results and all your work on this. Very interesting. Could you provide a little more information on the conditions. Specifically, did the containers receive direct sunlight at times during the day?
Another interesting part of your study was the difference between the 0.5 and 1.0 gallon containers painted black (#1 and #2), which showed the 1.0 gal container working better. Would this lead to a conclusion that the larger the container the better, even though it has a smaller relative surface area?

Stressbaby
Thanks for the info on your test.
Did you check the temp early in the morning to see how much the water temp dropped. Since the black painted one gets hotter it should be better unless the paint insulates it and it don't release the heat at night.
It would be interesting to see what the difference is between the bottles morning and evening to see which one gave up the most heat.

Gardenerwantabe, in the morning the containers were all essentially the same temperature. They were within 1-2 degrees of each other and 2-4 degrees lower than the GH, presumably because they were up against the south glass GH wall.

Cuestaroble, I can't explain why the 1 gal #2 did better than the 1/2 gal #1. If you look at the subgroup with the other paint, the 1 gal did not outperform the 1/2 gal, rather, they were essentially equal.

Thanks, stressbaby! These results are about what I expected, but it's great to see them confirmed. I am a bit surprised at how much the black paint of choice makes a difference. I suppose next time I'll be using enamel. :)

Out of curiosity, why copyright, as opposed to copyleft? If you want attribution, why not, say, Creative Commons Attribution license? Data sharing is a good thing. :)

A lot of the water jugs in my GH will not be getting hardly any sun they will have to absorb heat from the air so I doubt that painting them would help much. Only place available is under the benches.

Karenrei, I'm all for data sharing. But if you were around the first of the year, you remember the hullabaloo about the new GW policies regarding ownership of stuff posted here.

The better paint covered more easily...it almost looked "darker" from the moment it went on.

Gardenerwantabe, you are exactly right. I've been measuring the temps of unpainted and painted 1 gallon containers under a bench, out of the sun. They don't gain much in the way of temps and there is little in the way of advantage to black paint. In the morning day 1, black 57F, unpainted 58F; in the evening black 64F, unpainted 65F...no difference. Day 2 morning, both containers were 59F; in the evening black 70F, unpainted 69F. On day two the containers in the experiment above, in the sun, were almost all over 100F.

SB

If I understand this question, if I follow through with my plan to set a 300 gal. black fiberglss watering trough in my GH, I will get a big tank for cultivating aquatic plants and growing out baby fish, and concurrently; a heat source?

Of course, I will have to keep the tank water heated anyway, so am not sure if it would be an energy plus, minus or neg., as I might save on gas for the furnace, but still pay the electric bill for the tank heater.

Right, Birdwidow. Is there a maximum temp for your plants and fish? Do you plan to use the trough in the summer?

Your tank will likely be favorable energy-wise in the winter. But in the summer I can see it getting too hot...you don't want to turn the thing into a slow cooker! One idea would be in the summer to cover the trough with foil or something reflective so it wasn't gathering all that heat.

On Stressbaby's advice, I am actively monitoring the temps of the water in my containers to watch BTU's release.

I will monitor one of each size; unfortunately I can not monitor them simultaneously.

Right now I am monitoring the temp of a painted black 2 liter bottle. 4.4 pounds of water

Right off I noticed something I should have guessed, but never thought about

The bottle stopped gaining temp at 2 PM at 117 F, with outside temp of 73F although the Greenhouse peaked at 4pm at 87F

The bottle dumped 75 BTUÂs (water temp down to 100f) by 5 pm with the GH temp still at 67f and outside air temp at 60F

By 9 pm the bottle dumped another 118.8 BTUs (water temp down to 73f) with the Greenhouse Temp at 62f and outside air temp at 48F

At Midnight the water temp was down to 63F (additional loss of 44 BTUs, with the GH Temp at 58F, and outside air temp at 43F.

Now these measurements are all just with one of about 40 2 liter bottles I have lining the walls of the Greenhouse.

I will post the final temp of the Bottle later.

But it is sad that one bottle releases nearly 200 BTUs, before it is really needed, but I guess it still helps buffer the Temp drop in the greenhouse.

Once I have gathered the Temp ranges for all three containers, I will calculate the relative efficiencies of each container.

Birdwidow, it is easy to keep water cool - just regulate the dew point in the greenhouse to be the desired temperature, the water will stick to that temperature quite closely (indeed you'll struggle to heat it unless you do control the dewpoint).

I'd like to see rusted iron tins in this experiment. An easy way is to chuck an old fuel can (empty!) into a fire to burn off the paint. If you are concerned about the iron rusting on the inside, pour some oil in the can on top of the water. Tin cans stack better than milk containers :)

I'm not convinced there is any great merit in trying to get the temperature of the water up without insulation - most of the heat will be lost in the first few hours anyway (when you generally need it least). Better is to keep your hot store separate from your regulated area - this means insulating the containers. A simple solution would be to make a clear tent around the containers to reduce the air circulation. Then we can start thinking about bubble wrap and whatnot. Jimmy's measurements seem to corroborate this.

Then we can start to talk about day-night stores and weekly stores. There is a lot of rubbish published on the web about how to do this, so think carefully about the claims made on many otherwise reasonable (perhaps) sites on greenhouse planning and energy. (For example, trombe walls are almost invariably suggested, yet they have lousy performance in practice!)

By 6am the 2 liter bottle bottomed out at 55F with the Greenhouse at 55F, and the Outside Temperature at 36 degrees.
That gives a total Temperature loss for the 2 Liter bottle of 62 degrees or 273 BTU, but only 18 BTU per gallon is being released when it is needed.
After Nathan's Comment I realized that painted black small containers in the sun may not be helpful to me.
As long as the bottle is warmer than the greenhouse (Which in my Situation, the water is warmer than the greenhouse by 9 am, it will be releasing BTU's into the greenhouse, which in my case means excess heat from about 10 am to 5 pm which is when my exhaust fans are running.

Perhaps in some of the colder climates that you do not open your exhaust fans during the winter, this would not be an issue for you.
It might be more efficient to have these smaller bottles in shaded areas of the greenhouse, just to absorb ambient heat from the greenhouse, and possible these bottles should be clear (does painted or Clear absorb ambient heat better)

This does give weight to NathanÂs theory on a separate store area for the hot water so that it could be released when needed.

Just insulating the bottles with Pool cover would not help, because it would also slow down the release of heat when it is needed.

So a system of Water walls, with a way to pump the hot water to an insulated container, and replenish the water walls with cold water during the day, and then at night pump the hot water into the water walls, transferring the colder water to the insulated container, as needed

I imagine a box with two bladders, one full and one empty. as the water in the full bladder gets hot, the hot water gets pumped to the insulated container with two bladders.

The hot water is pumped into the empty bladder forcing the cold water down into the empty bladder in the water wall.
When the BTU's are needed, then the hot water in the insulated storage container is pumped back to the empty bladder in the water wall, forcing the cooler water that is currently in the water wall, back into the insulated container.

Obviously this would require some engineering...

The Daytime pump could be an inexpensive solar pond pump,
and maybe the nighttime transfer could be based on gravity feed.

As for the Containers, that might take some more thought (insulated camping coolers might work for the storage box).
Perhaps abandoned fish tanks could work as the Water walls'

I am hoping to find that the Larger containers will be able to contain more BTU's without have such a high temperature during the day.... That Experiment is starting today, and I will be checking the Front and the back of the large containers.
More Data to Come Later

Stressbaby:

I keep my fish tanks at 80 degrees on average, but with insulation and a powerful and efficient furnace in it, I have come to believe that the real challenge for my GH won't be keeping it warm enough in winter, but cool enough in summer.

As I have yet to experience it in summer, I can only hope that with the roof vents, powered intakes, exhaust fan and the big ceiling fans, I will be able to keep my GH under 85 degrees in the heat of the day during our hot months.

I'm also thinking of a roll-up device on the SW side, to allow me to drop and rewind shade netting quickly and easily.

Actually, my GH has been on hold all during October, as we have been trying to catch up on yard and field work put off during constant September rains.

It's sealed up, but nothing is done inside. However we have juice, and with it, can run an electric heater and work lights.

Once we get the furnace up and running, the rest will be pretty much SOP: install all the electrical lines and connections, lights, water connections, lay the quarry tile, etc. It will be an inside winter project.

Except that we will have to either bundle up or run like the dickens through the cold in only shirtsleeves to get to & from the house for bathroom calls. LOL!

Okie Dokie, Here are the Next set of Results.

This is for a 68 Liter 15"H x 17"W x 24"L, Rubbermaid style Storage container with a lid, painted black. This comes to about 150 pounds of water

Two of these containers fit snuggly under my plant benches, so I have these along both sides and the back wall. Because of the location of these they do not receive as much direct sun.

The one I took the measurements from has one plant in a 7 Gallon Pot sitting over it.
The benches have "grid" tops, so the benches themselves do not block much sunlight.

Here are the Temperature results for one of these buckets

2 PM 68 Liter at 77 at 2 pm greenhouse at 82, outside at 75
I had a second 68 liter container behind the one being measured and it hit 72

5 PM 68 Liter at 76, outside at 68, greenhouse at 71

9 pm 68 Liter at 72, outside at 53, greenhouse at 65

Midnight 68 Liter at 69, outside at 50, greenhouse at 61

3 am 68 liter at 66, outside at 46, greenhouse at 58

6 am 68 Liter at 65, outside at 45, greenhouse at 56

68 Liter bottomed out at 64 at 7 am, outside at 47, greenhouse at 56

So the heat loss of the water in the 68 Liter container from itÂs max to min temp was only 13 degrees, but this works out to 1950 BTUÂs per bucket.

The nice thing about these buckets is that they do not seem to get much hotter than the greenhouse during the day, so buckets are not heating the greenhouse as much during the day.
Additionally each bucket only released about 600 BTU when it was not really needed, with the remaining 1350 being released when it was needed.
Also the buckets did not ever get down to the same temp as the greenhouse, so there were still BTUÂs available for colder nights (the night I tested the buckets, did not get near as cold as the night that I tested the 2 liter bottle, about 10 degrees warmer). So even if the Greenhouse did not get colder, the buckets had actually about another 1650 BTUÂs available to release for a colder night.
These buckets are right under the Plants, so this heat is heat there root zones first.

Over all, these buckets seem pretty good

I will be posting the results of the metal painted black 55 gallon drum tomorrow.

Jimmy, that's good stuff. The larger container appears to gain and reemit heat more slowly. It will be interesting to see the 55 gallon metal drum results. The metal may be a better conductor and I wonder if you will lose heat as fast, or faster, than the Rubbermaid container.

About that shade cloth on a roller --

When we took down our used greenhouse, we noted that the previous owner had rollable shadecloth on the outside.

It looks like he laid out the cloth and stapled it to pieces of wood at the top and at the bottom.

The top piece he then screwed to the outside wall of the greenhouse. The bottom piece of wood, when unrolled, comes almost to the ground. The cloth did not blow around because the wood was sufficiently heavy.

He attached pulleys on the top piece of wood, and looped the rope over the ends of the piece of wood at the bottom.

Pulling on the ropes rolled the shadecloth up nicely, with the bottom piece of wood tucked inside so as not to scratch anything. It operated just like one of those bamboo roller shades.

He tied knots in the loose ends of the ropes with 3-4 heavy bolts so that they would not swing, and could be easily grasped.

The system worked well from what we observed. The 2 pieces of cloth were each about 12 feet long.

:)

plant.babies, you mean like this:
Shade roller

You can reduce the weight of the wood a lot if you are willing to run extra string down to the ground.

I actually use an even simpler design now - I just have a piece of string going through the bottom of the shade cloth and I tie it on both on the left for no shade, or to both sides for shade. cheap, simple, doesn't blow away; but not easily automated.

Ok, here are the results for the 55 Gallon Drum

Metal 55 Gallon drum painted black, covered, standing in the southeast corner of the greenhouse, with nothing on it.
205 liters, 450 pounds

2 PM Drum 85F, outside 76, greenhouse 90
6 PM Drum 84F, outside 64, greenhouse 75
9 PM Drum 81F, outside 57, greenhouse 66
Midnight Drum 77, outside 55, greenhouse 61
3 AM Drum 74, outside 50, greenhouse 58
6 AM Drum 70, outside 47, greenhouse 57

So in summary;
2 Liter Bottle releases an average of 17 BTU/hour or 3.86 BTU per pound per hour
68 Liter Bucket Releases an average of 114 BTU/hour or .76 BTU per pound per hour
55 Gallon Drum Releases an average of 422 BTU/hour or .94 BTU Per pound per hour

So per pound, the 2 Liter stored and released the most energy, however, the speed is detrimental. The bottle gets too hot too soon, actually heating up the greenhouse during the heat of the day, and then released the majority of the stored heat before it was needed

Both the 55 gallon drum and the 68 liter bucket, stayed below the greenhouse temps until the greenhouse begins to cool for the evening. The result of this is that they both will also be absorbing excess heat from the greenhouse, as well as heating from solar radiation. The 55 gallon drum is marginally more efficient, possibly due to itÂs height, being metal, or not being under the benches. The 55 gallon drum is definitely the most efficient at containing water (unless you want to pack a bunch of barrels close together round is not an efficient shape)
Both the drum and the bucket still had plenty of BTUÂs to release, by sunrise, indicating that if it got colder, they could release more BTUÂs (I noticed that the rate of BTUÂs released increased with a greater temperature differential between the water and the greenhouse.)

One thing I have found is that I need to move the 2 liter bottles out of the direct sunlight.

It also appears that I have too more tests to do;
1. Two liter bottle painted not in direct sunlight.
2. Two liter bottle not painted, not in direct sunlight.

From StressbabyÂs experiments, we see that the painted bottles convert sunlight to heat much more efficiently than unpainted bottles. But I am wondering about absorbing ambient heat from the greenhouse.

Jimmydo, excellent once again!

I did the painted/unpainted bottles out of sunlight experiment, scroll back up. There is no difference between the two in heat gained or lost, and they didn't gain over 11*F. It would be interesting to see the results of continuous temp monitoring, I don't have the capability to do that.

Great thread!!!!

(sly smile...)

Sorry bout that Stressbaby, I did miss your response to gardenerwantabe. That is very good info, I can now stop worrying about painting my small containers.

I will go ahead and do a sustained test on shaded bottles and see if it turns up anthing unexpected

Cylindrical objects packed the same way waste the same amount of space no matter how big or small they are. Smaller objects have a greater surface area, and hence can transfer heat faster.

I'd like to see someone try a greenhouse around their storage to see whether they can get higher daytime temperatures (and hence store more energy). Bubble wrap might work, or a tent made from polyfilm.

jimmydo2
Thanks for sharing your findings. After reading all this info it makes me wonder if the water will really help me much. We all have a slightly different need in my case the GH will only be used from about the first of March till mid April. During that time the temp Will be 20-F at night and 50 to 60 in the daytime. This means that I will have to run the heater at night and then ventilate in the day time. I think I will try some water back under the bottom of the shelves but we don't have a lot of room it will be full of flowers in the spring. The wife and I agree that we did not build it to store water in but to grow flowers and in order to save 20 bucks a year on heating it would cost a 100 times that to install insulated tanks and pumps and then maybe it would not ever save what it cost to build so I think a few container of water under the shelves will be the extent of what I will be doing with the water.
Whatever it cost to operate it I will just have to pay and feel good about the fact that if I had bought them at the nursery they would have cost me a lot more.

Gardenerwantabe:

Yeah I am planning to try to make my GH a 4 season GH, since our winter temps only get down to the mid twenties, and not that often, my biggest concern is Venting daytime and summer heat (We have about two weeks during the summer when the Nighttime temps do not get below 80 Degrees)
(I think the GH will just become a Great big Shadehouse during that time...)

I am very happy that with the ammount of water I am currently using (about 1300 Litres), I am still able to maintain 55 Degrees in the GH, when it has gotten down to the mid thirtys.

Currently, with the exception of the 55 Gallon Drum, all my water is under my Benches, so you might wanna just put the occaisonal Bottle under your benches as you obtain then (Soda bottles, Milk jugs, etc, oh what about coffee cans, hmm)

Nathan:
I think I have some left over "Bubble wrap" from when I cut the cover for my Jacuzzi. (It is a clear pool cover with the Diamon shapped bubbles), so If I can find the scrap, I can try wrapping the 2 liter bottles, but with them already hitting 117 degrees, I think I will be losing a lot of efficency. Hopefully I can find enough Scrap to wrap one of the bins (I do not think I could move the 55 Gallon Drum to wrap it ;)

Stupid question! Wondering if a container could be filled with small rectangular pieces of something like cellulose sponge waste, then filled with water. Would it still gather heat efficently, then allow the container to release it slower?

Cellulose sponge is a wood product. It by design has many air holes through out it. Just wondering if it would slow down the release of stored heat.

Dan

Jimmy, the aim is not so much to improve efficiency of collection (Any black painted material is roughly 100% efficient at collection), but to reduce losses. 117F isn't very hot for something sitting in the sun - the tops of my evacuated tubes get to around 140C (280F) on a cloudy day, without load. The hotter you can get your water the more energy you can store for a given volume, but you need to reduce the losses or it will all leak straight back out into the greenhouse.

ironhat2, If you have a fairly good packing of sponge in the water you'll reduce convection which will reduce losses, but you need to get the heat into the water in the middle still. The sponge would block the incoming light, wouldn't it?

Perhaps use a gelling agent instead? Gelatine melts nearly boiling point and resets at a fairly low temperature, I wonder if we could organise it so that it melts on heating, conducting heat further inside, but sets when the sun sets reducing heat transfer to just conduction (radiation being blocked by outer layers, convection blocked by the gel).

The trick might instead be to suspend an absorber plate in the gel, and use the clearest gel you can find (perhaps agar would work better?).

My biggest concern is Venting daytime and summer heat

For summer, I simply leave my door wide open. When the nights don't get cold, passive circulation through a broad opening works well enough in my situation.

For spring/fall when it gets hot during the day but cold at night, since (like most people) I'm too lazy to be running in and out opening and closing it, I have a battery powered programmable vent. Caulked to the bottom of it are several 40CFM DC computer case fans that I had lying around, driven by solar cells that I have mounted to a barn nearby. It's a small greenhouse, and while I still don't have the recommend "circulate the air once every minute and a half" airflow, it's proven to be good enough for me. Which is good, because solar cells are expensive. ;)

The nice things about solar-driven DC fans are:

1) No long, heavily insulated cables to bury.
2) Less dangerous voltages.
3) DC fans are more energy efficient than AC fans. DC case fans are
4) An automatic "thermostat", so to speak, based on the current level of insolation.
5) Very "green" (and I think they look neat).

The big downside is price. At $5 per watt (unless you're buying in bulk), solar cells can get pricey. I get off easy with my little greenhouse, but most people won't be so lucky (nor will I when I scale up). Of course, they do pay back after two decades or so, but there's the upfront cost. Also, solar cells can be a bit tricky to work with. The type I used didn't have pre-attached leads, and they were a bit picky about what they'd accept. You also have to be very careful with thermal expansion.

karen, if you are using solar panels with motors you might buy a minimaximiser kit which impedance matches the panels to the motors, giving a dramatic improvement in useful work output. The kit is very cheap (probably $10 in components if you just make it yourself) and probably halves the cost of the panels.

Really totally off topic,

12v DC systems for small greenhouses.

I intend to add more 12v DC things to mine as it seems the way to go in remote/unpowered greenhouses.

My inflation blower does a wonderful job. Not solar powered though, I carry a fresh battery across the yard every few days.

Here is a link that might be useful: GW Solar Powered Fan thread from last year

"ironhat2, If you have a fairly good packing of sponge in the water you'll reduce convection which will reduce losses, but you need to get the heat into the water in the middle still. The sponge would block the incoming light, wouldn't it?"

Thanks for the responce nathanhurst. As I said "stupid question". I was actually thinking more in the line of rusty 55 gallon oil drums about 1/2 full of sponge pieces.

I am in the process of building a small 24' x 12' cold frame, probally no higher than 7 ft. In my zone, as a general rule our winters are pretty mild. It can get pretty warm in this type house. I wasn't sure if it would be warm enough to heat these drums enough to do any good.

Thanks again.

Dan

OK someone do waste fryer oil.

Someone in zone 7 or higher.

What does waste oil do for us? A bit of oil on top of the water would be good to stop rusting.

Anyone want to try the gel idea?

nathanhurst,

"What does waste oil do for us?"

The "ice" thing? Phase change.....

OK tomorrow I will do it.

Nathan:

What about using Lard "Crisco", Chris' thought on Fryer oil got me thinking, Fryer oil stays liquid at room temp, but Lard will solidify at room temp. It could possibly be obtained from restaurants, if they use lard for their deep fryers, or how about even Bacon Grease (I do not think restaurants are allowed to throw away their grease, you might be able to get some fairly large containers allready full of Lard or bacon Grease.

I could try a small container the next time I dump the Lard out of my Fryer.

Karen: Thanks for the tips, I have lots of Computer Fans laying around, I could pick up some Cheap SOlar Panels from HF...

Oh, I'd forgotten about phase change. A quite web search found nothing useful about the latent heat of fusion of fats. I wonder how it compares with water's specific heat. Apparently paraffin waxes are reasonably good. CaCl2 in water at high concentrations is good, and CaCl2 is a waste product and is very cheap. Transition temp is around 28C from memory.

Incidentally, I don't think there is much energy associated with melting and gelling of gels, the idea there was to control heat mobility.

But I think you are missing the point. We've already demonstrated storing a reasonable amount of heat. The problem is to hang onto that heat until you need it.

Well I'm certainly not going to be the one to do it but if you had a large insulated tank and a radiator with a fan blowing through it and a pump to pump the water you could heat the water in the tank in the afternoon when the green house was hot and a thermostat could turn the pump and fan on during the night to warm the GH. Nathan should be able to figure out what size tank you would need he likes doing that stuff.

With the Lard, I was just thinking that when it was in a Solid State that if might release the heat more slowly

wantabe: I haven't had any experience with car radiators, the cheapest nonleaky ones I could find were around $100 here. I do worry that they are designed for much higher temperatures and compactness over efficiency. I would not be surprised that a single radiator would become the bottle neck in large scale storage system, however, it would be really great if someone with space, opportunity and weather did an experiement measuring how much heat they can extract from a radiator based on temperature.

Alternatively you might be thinking of house radiators - I think these would be a better choice with their lower air restriction. Does anyone have any ideas as to how else to make a heat exchanger for water-air?

jimmy: Solids are generally less effective at transmitting heat than liquids because they don't convect.

nathanhurst
The radiator on a car removes a lot of btu's from the engine but it requires a large water flow

So, once the lard or wax goes back to solid form, it should release the heat more slowly through the night...

wantabe: right, and it also has the water at around 80C - if a car radiator at 80C can dissipate 20kW into 20C, that's only 333W/K, perhaps making the small differential temperatures hard to work with. Having said that, 333W/K doesn't sound terrible, which makes me want to go and look harder for a radiator...Ok, a bit of ringing around and I've probably got two radiators to trial.

jimmy: yes, but the solid lard stores very little heat compared to the melting/freezing energy. You want to keep it liquid until you need the heat - that means finding something that melts at just about the temperature you want to maintain - 22C say.

Drat Lard is to high then :(
However, the melting point of various types of Coconut oils is between about 21 and 25 C,not surprisiDrat Lard is to high then :(
However, the melting point of various types of Coconut oils is between about 21C and 25C, not surprisingly palm oil is in the same range, but I would actually like to find something with a melting point around 15C or 16C but substances that melt at Standard temperature are not easy to find.
In Fact no pure elements melt between -7C (Bromine), and 27C (Francium) (Yeah I know unimportant trivia, but hey)

SO it would have to some sort of compound, however the deciding factor has to be cost and availability.

I vaguely recall that the Melting point of wax is partially determined by the ratio of Paraffin to Oil that is use in making the wax, but I dunno if you could mix in enough oil to lower the melting point of wax enough to reach Standard Temperature.

Although I remember reading somewhere that one of the problems with pumping crude oil through pipes is that it has to be kept warm to prevent a wax build up on the inside of the pipes, from the oil getting cooled by the pipe, the end result being a blockage similar to arteriolosclerosis, making me wonder if perhaps crude oil might be a feasibility, it is actually very cheap, heck even though we complain about the cost of Gasoline, it is one of the cheapest gallons of anything you can buy, heck with the price of a barrel of crude oil running between $50 and $80 dollars a barrel (I wonder if that includes the cost of the barrel...), it would not be too expensive to put a half dozen, or dozen or so barrels of Crude oil in a Greenhouse.

Unfortunately the only MSDS I can find for crude oil lists the melting point of Crude oil as -15c to +25c; Actually that might be a good thing, i.e.: various components of the Crude oil Transition from liquid to solid across almost the entire range of Temps that might be desirable in a Greenhouse...

Hey lets make sure those barrels are sealed tight, I do not want to have to have the hazmat team come for a 400 gallon oil spill in my back yard.

The sad thing is that this is not even what I came here to post tonight

Jim

Based on comments made on another forum, I started doing a another temperature test...

The soil temp of potted plants in my greenhouse..., now I understand that the soil is another heat sinc for our greenhouses, but if soil temps get to high, they can kill our roots. (I actualy started the test to see how cold my roots were getting, compared to the GH Night time temps).

I was concerned to find that a day that reached 80, the soil temp in a black plastic 5 gallon container hit 102 degrees. So I was going to experiment with various things to keep the temp down. (Like covering the side of the pot with aluminum foil, partialy, completely, etc), but on the second day of my tests, the weather turned and the outside temps were 15 degrees colder, blowing my test results...

When it warms back up, I will let you all know what my resluts are...

I got soil temps of 40C today. no wonder those alpine plants were struggling... A light coloured mulch or sand would probably be effective at cooling the soil.

There is a family of alloys that melt around room temperature: http://scitoys.com/scitoys/scitoys/thermo/liquid_metal/liquid_metal.html
(not really practical, but nifty)

I don't want to know what a reslut does.

Double Drat, I double checked both posts, and They were both correct, when I submitted them....

Where is the do-over button