Thanks for your feedback! To clarify, this worked flawlessly last year, so I consider the design validated. You raise good points, which I had taken into consideration:Canoe wrote: ↑Mon Mar 25, 2019 7:08 pm
[*]Shame you can't get more hole area going into the bucket. That's quite a restriction to pull air through.
- Great build quality!
- The upper-evap/lower-reservoir bucket (container) layout is known and proven on the playa, providing both a
- Also watch for sealing the lower/reservoir bucket so you're not sucking hot dusty air through the lower reservoir, or through any air leaks between the upper bucket sitting on the lower, up into the middle of the upper bucket, where it has bypassed the evap-media and goes into your accommodations. Any leakage limits efficiency while allowing some dust to sneak through.
- And I can't tell from the photo if the drain fitting sits up high enough in the upper bucket to ensure a minimum water level to keep the bottom of the evap-media submerged to prevent hot air sneaking under. In some setups, the bottom surface can sag, or not entirely level, and there's insufficient water level in the upper/evap bucket.
- The drain hole looks like it should be a larger diameter, in case something manages to clog it. Particularly as the pump line runs up through it.
- A second fail-safe drain hole would be a good idea. Intake slightly higher (a half inch?) than the main one, and wide enough to take the entire drain-back. It would only drain water if the first drain somehow clogs or is restricted and the water level in the evap-bucket rises. As such, don't plumb the fail-safe drain with a drain pipe, but let any water that drains through it fall into the reservoir bucket, making noise, to alert you that the first drain has developed an issue.
[*]If you got more pre-filter area and more area for air flow into the upper bucket, you wouldn't need such a heavy and power consuming fan.
[*]Your design does have a thermal short-circuit.
- Hot air through the pre-filters flows against the metal fan shroud, inside of which is the chilled output air.
As hot air going one way and chilled going the other, that counter-flow would be optimum for transferring heat from that hot air into the evap output, but it's even worse as the stack of pre-filters is supplying hot air along the full height of the shroud.
- This thermal short-circuit will limit the chilling capacity.
- It will be worse the hotter the playa air is, as the heat transfer through the shroud into the chilled air will be greater with a greater temperature difference.
- Any insulation you can apply to the shroud surface, ideally on both sides, will work towards minimizing that thermal short-circuit.
[*]A caution that the fan you chose is not for creating air flow, and particularly not for creating static pressure for sucking air through filters, but is for augmenting an already pressured air flow that has a long run. As such, the motor will be working harder than it is designed for, so its life will be reduced from its normal service. BUT, you're only running it for a week at a time on the playa - so how much will that matter...
I've not seen anyone want to fill their playa accommodation full of hot dust-free air. But if anyone wants to do that, and is willing to pay for the air filters and replacing them, it looks like it will work. It would be useful during those times where the ambient air is not too hot.
Nor do the recommended Dura-cool evap media have an issue with fouling, as that is what filters the dust out of the air, with the water flow washing the dust off of the filter. It doesn't become foul. Your pre-filters "solve" a problem that doesn't exist. And if the "grain" of the evap media is respected, there is no need to 'cage' the evap media, at least at the CFMs used in the existing designs.
For cooling their accommodation on the playa, needing air filters, a power taking fan and 120 VAC power to run it, won't be regarded as an improvement by many people. The upper/lower buckets is a great enhancement (I like it), but most people don't want that complexity. If you want a fan upgrade, you can use the Endless Breeze fan, but good luck sucking through those automotive filters. You'd have much better luck with pleated furnace filters.
The bad news
That writeup will not be usable by the majority of people.
What would be very useful is to have the photos surrounded by white space, with all components labelled and with their size given. The layout is so simple that people would easily be able to build one if they had that info and a few pointers added to the white space around the photos.
- Yes, do pay attention to "static head" when pump shopping, given that it needs to lift water some 30" inches.
- There is gasket sealing drain to bottom bucket.
- Drain is made of PVC electrical box adapter, with threads raised into evap sump enough to form shallow pool in which media sits.
- Drain could be made larger, though I tested with pump running full-out and it was able to keep up as is.
- Thanks to filters, there was zero junk in water at end of full week; buckets and Duracool pads were spotlessly clean.
- The 20 7/8" holes have nearly the same area as 4" duct, which is itself not close to taxed at this airflow.
- Fan is overkill, admittedly. However, a close-vaned design of this type is needed to overcome static pressure, and this is also one of few that's both quiet and fits within footprint of bucket stack.
- Yes, steel fan housing does reduce efficiency slightly, but contact is brief and I was seeing 20F reduction regardless. Spraying/wrapping with foam might net another... degree? Less? Fantech fans use plastic housings, but forget why I favored Vortex. Pretty sure I had a good reason.
- The fan is used 24/7 in grow operations, often with long duct runs. It's bulletproof and barely breaking a sweat here. I run it at a fraction of top speed.
- I reduced or stopped water flow during evening when cooling not needed. Pressurized with clean air at all times, my tent was absolutely dust-free and my lungs as well. That's the greatest benefit!
- The caging of the media is required to hold it a uniform distance from the outside of the bucket, for greatest air flow over/though entire surface area.
- At just under 100W, this may not be ideal for those running on battery, or small solar. Although, even a small inverter will power it with ease, albeit with attendant efficiency loss.
- I didn't want to increase stack footprint or (transporting from/to NYC) compromise portability; furnace filters are inconsistent with this design goal, and I suspect they're more porous as well. Regardless, these three filters flowed amazingly well, even at week's end. I could likely get by with only two.
But I'll consider your suggestion. A camp mate is preparing to replicate my design from my guide, so I'm expecting some constructive feedback as he goes.