chickenranch
New Member
I am designing a utility vault for my off-grid solar system. It's going to be mostly buried with some insulation, housing charge controllers, batteries, and inverters for the system. I've done some fairly detailed energy modeling using AI to get a sense of the peak summertime cooling loads for this structure, and it's pretty small, sub 2k BTU. I was thinking I would just put a window AC through the wall, but I don't want it cycling on and off a ton, plus we have a lot of fine windblown sand that would probably ruin a unit sitting 12" off the ground pretty quickly.
So my current plan is create a DIY ground loop cooling system. This is how I'm imagining it:
300' of 3/4" PEX in a closed loop out and back, about 5-6' underground. Inside the vault, I would have a circulator pump and a heat exchanger with a fan mounted to it pulling air through with a shroud. The water would probably be between 45-60F during operation, and I might make it a glycol mix.
I'm sure there are other plumbing pieces I am missing. How do I fill this, especially with the glycol? How do I keep air out of it? Do I need something to bleed air? Do I need any kind of thermal expansion tank? Pressure relief? What else am I missing?
On the circulator pump side, I am thinking of going with a Taco pump. Haven't sized it yet, but 1-2gpm is what was recommended for flow rate. I was looking at their ECM option, but the manual says it isn't recommended for chilled liquid or continuous operation. Not sure what the parameters are on those conditions. Any thoughts? Thoughts on ECM vs a fixed speed, especially for reliability? Efficiency is valuable to me but in the cooling season I will generally have a lot of excess production.
Any other thoughts on refining the design or ways to calculate sizing of components are welcome. Thanks!
So my current plan is create a DIY ground loop cooling system. This is how I'm imagining it:
300' of 3/4" PEX in a closed loop out and back, about 5-6' underground. Inside the vault, I would have a circulator pump and a heat exchanger with a fan mounted to it pulling air through with a shroud. The water would probably be between 45-60F during operation, and I might make it a glycol mix.
I'm sure there are other plumbing pieces I am missing. How do I fill this, especially with the glycol? How do I keep air out of it? Do I need something to bleed air? Do I need any kind of thermal expansion tank? Pressure relief? What else am I missing?
On the circulator pump side, I am thinking of going with a Taco pump. Haven't sized it yet, but 1-2gpm is what was recommended for flow rate. I was looking at their ECM option, but the manual says it isn't recommended for chilled liquid or continuous operation. Not sure what the parameters are on those conditions. Any thoughts? Thoughts on ECM vs a fixed speed, especially for reliability? Efficiency is valuable to me but in the cooling season I will generally have a lot of excess production.
Any other thoughts on refining the design or ways to calculate sizing of components are welcome. Thanks!
