Terry Ruth wrote:
Where did you get the ground temp graph?
Terry Ruth wrote: Do you have a pic of how you mounted the fan to the tube?
Terry Ruth wrote: I would think if efficient DC motors PV tied no inverter that would very efficent and as you said intake to minisplits even better. If fresh outdoor air along with indoor could be tee' d in at the intake it could be a heat recovery ventilator using the ground temps vs heat xchanger like plastics they use in air-to-air HRV's/ERV's.
darren summerson wrote:Interesting stuff!
I imagine that unless you throw some serious money at this kind of system, there will be a month or two in winter when it struggles to work and stay warm, the opposite with cooling in summer. So conventional venting may be needed and some kind of heating too.
darren summerson wrote:There seems to be so much logic in this kind of system, but so little hard data available too.
Terry Ruth wrote:Thanks, seems like the trick is looking at your local ground temps guesstimating how long a run at what depth, what CFM out the fan would get out to the building. Seems like if your doing a basement might as well run the lines next to the french drain lines, when it rains the drain lines may help transfer some heat? Then run some test with fans. Run them in a wall to a nice register. This seems like a good concept just needs some developing. And it's fairly cheap!
Aluminum transfer better than plastic but corrode. Then put nasty stuff in the air. I wonder how natural ceramic or concrete lined ductile iron drain pipe would perform? If it can be found. From what I read the biggest issues with these earth tubes in condensation and mold. Perhaps not a big deal for a greenhouse.
Rose Gardener wrote:
Terry Ruth wrote: With condensation, mold is just a matter of time, isn't it?
mine isn't up and running yet, so I can't confirm my theory, or what I've read on it.
But, the pipes I'm using are drainage pipe 3", which are perforated and water runs through easily. I'm burying them with a little clean gravel above and below, so any water will drain out. Also thinking about the angle so I literally don't drain the ground and cause the water to flow back towards the greenhouse. The only solid pipe I'm using is from the ceiling height to ground level of the air intake pipes in side the greenhouse, as I want to extract the warmest air from the top, however in winter logically you want the coldest air from ground level, I'm yet to find a solution here, other than a half way house of a mid height pipe.
In summer with the air cooling there should be water draining out of the pipes into the gravel, in winter when I hope the air to be warming, potentially the air will pick up any moisture in the pipe.