Solar hot water - Aquaponics - interesting consistency

I've only put half the measures I have in mind to put, but it seems I'm winning.

I planed on trying a few different things in an attempt to stabilise my grow house temperatures. One was adding thermal mass, another was shifting heat from the top where it was hottest, to the bottom where my thermal mass is, and where it is coolest.

So far I've added around 45L of water as additional thermal mass, and have a coil of black 4mm poly pipe at head height (mine not yours), with water flowing through and into the fish tank, gathering some heat as it does. I also have a 12 volt computer cooling fan blowing some air down from the top.

I turn the fan off at night so it isn't blowing cold air around, and stop the flow of water through the coil of polly pipe, so it doesn't act as a fishtank cooler at night. I'll figure out some what to control both of these automatically at some stage.

This morning was my first real test of the hothouse in the last week, as its the first cold rainy, overcast, and generally wintery day. The last few days have all been sunny even when they have been cold.

The fish tank temperature, and the grow house air temperature were both 17c this morning, and gradually lost heat over the day. It's sundown, and they fish tank and air temp are both 16c.

That's an amazing result as far as I can tell. Even though the world was trying to cool the system, it did quite a good job of hanging on to whatever gains it had saved from past days.

I think this is going to work.

I hope we get a few miserable days in a row so I can see how long it's heat reserves last.

Solar hot water - Aquaponics - grow house min max graph

I've been taking some regular notice of the minimum and maximum temperatures of the water in the fish tank since I put it under a grow house.

I made a graph.

I like graphs.

It looks like this....

The red line on top indicates the maximum, the blue line on the bottom, the minimum, and the yellow line in the middle is largely meaningless.

But it does sit in the middle of the other two.

Which is nice.

There is also a thin red trend line and a thin blue trend line which clearly show that my grow house will be hotter than the sun within only a few years, if the trend continues.

I don't think the trend is going to continue.

But it does seem to be stabilising a bit. That could be an illusion due to unseasonable fine weather. It could also be that my concrete has warmed up a bit and is now supplying some heat during the night.

I really have no idea.

I just thought you might like to see my graph.

It will make a bit more sense once I have some more data. After a few weeks, I should be able to make some kind of statement about what it has achieved. I should also be able to do another comparison to the graph I did earlier of a day in the hot house.

I figure, if I pick a similar day, I should be able to read some meaning into a second set of stats, even where there is no meaning.

Poor quality science can do that.

Solar hot water - Aquaponics - a day in the hot house graph

This graph really speaks for itself, but I like the sound of my own typing, so I'll be adding a bit as usual.

This graph represents my attempt to do something every hour, on the hour. If you click on it, it should open up to slightly bigger version that might be a bit more readable.

If you read all the times off the top line, you'll see I'm not so good at doing stuff to a schedule.

There was also a big chunk that should have extended out to the right for another 8 hours or so, but I went to sleep. Not a lot would have happened overnight. There have been some times where I have taken readings in the middle of the night, and the readings fit within a gradual decline over night to a point where they would roughly meet up with the 8am start data. I would expect the changes to be quite straight forward and gradual as the system radiated heat.

The cells with the yellow background represent daylight. Actual daylight at this time of year is from roughly 6:30am to 6:00pm. Roughly.

The solar heater output (graphed in yellow) comes about, as a result of a 10 metre length of 4mm black poly pipe, that I have coiled, and parked near the roof. It siphons a small trickle of water from the tap input to the glass house, up through the coil, then down to the fish tank. As far as I can see, I could just add a few more to shift any amount of heat I desire down into the fish tank, or storage, to be released slowly at night. Obviously there is a limit, but that limit comes down to how hot I want the air to be. I don't really know how hot a hot house should be, so I guess that's the next thing I need to study. It's one thing to decide to work on temperature stability, but I have a feeling I might be better off knowing the temperature I'm seeking to stay stable at.

It's interesting to note how wobbly the temperatures are outside, as compared to inside. Its also interesting to note that they seem to be getting even more stable over time.

Given I'm aiming for temperature stability, that's a good thing. I might not have to do as much as I thought. I might just have to sit down for a bit and wait.

I'm not very good at waiting, but I consider myself an expert at sitting down.

On this day, the hot house didn't see full sun until 3 hours before sunset, but when it has seen sun as soon as It could, it behaved by just being a bit hotter all round.

Sitting in a hot house is very, very nice.