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.
A simple method for controlling the fan and the pump would be a solar panel. Once the sun comes up it will get enough light to provide power, and then when the sun goes down the power will stop and so will your fan and pump.
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