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The access to the crawl space for my house is through my shop. Could I suck cool air from the crawl space into the shop to cool it down a little? The house is a ranch, the crawl space is about four feet high from plastic barrier over the ground to the floorboards, there are six vents at ground level from the crawlspace to the outside.
I visualize a box fan blowing up from the crawlspace and another fan toward the workbench.
Yes you could, however the thermal storage capacity of air is very low, and the plastic over the ground reduces heat loss from the air to the ground.
Shortly after running your fan, you would run out of cooled air and simply start drawing in outside air.
Looking at your location John, you would draw in warm, moisture laden air, which is a bad idea.
Your best bet may be a window air conditioner, exhausting into the crawl space, if you have a fan to ventilate the crawl space.
Regards, Rod.
John,
I've been trying to come up with a way to draw in "fresh, clean" Houston humid air without killing the AC I pay so dearly for. One idea I had was to run some pipes underground and then duct it into the shop. Heat transfer was questionable, humidity was absolute. Next idea.
Current thought is to get a used, small chest freezer, place a container (aquarium, 5 gal bucket, etc) of automotive anti-freeze mix in the freezer, then, using a cheap fountain pump, pump the mix slowly through a junk heater core from a car. This would fit into a hole in my small garage door. I would then use a small exhaust fan in the ceiling to blow out the warm air collected at the ceiling, hopefully pulling in fresh air across the coil. It would take some tweaking, but I think I could get the heater core about 35 degrees F, which, with a gentle airflow, should remove a LOT of moisture from the incoming air, and probably drop it's temp by 10 degrees or so.
Funny thing is, after I came up with this idea, I saw vids of college kids doing about the same thing with a cooler filled with ice water, some copper tubing and a window fan. Condensation was dripping off the copper coil, so it was doing at least some work.
I'm hoping to keep all costs below $100. The fountain pumps are $10-20 at Northern and HF, anti-freeze, $20, hose, $10-20 at max, a working freezer and a heater core, ???. I already have a fan and leftover dryer vent hose for the exaust. The door is shot anyway, and needs to be replaced, so it's a good one to experiment on.
For your crawl space, metal duct would transfer heat best, but as Rod mentioned, the cool wouldn't last long, UNLESS.....
What about making lots of curves to get more linear feet? Could get expensive, but it would increase the exchange of heat (that's how ground-source heat pumps are installed).
If you warm the crawl space, will that effect the cooling of your home?
I've had geothermal heating for over 25 years. Last year we updated our system with a new unit to provide A/C. It works great. In fact we ran the A/C July, August and September last year and used fewer KW than the same months from the previous year and the house was a constant 74 degrees. I don't think you can build a unit from spare parts that will be nearly as cost effective as a factory built geothermal unit.
If you have an unlimited source of water you can connect a well to a radiator coil and blow air through it while running water through the coil and achieve a decent level of A/C. You will use a lot of water, which is not a problem if you have two wells and can return the "warmed" water back into the ground.
I have a neighbor who has two, spring fed lakes on his property. They constantly flow excess water so he submerged an old steam generator core (a butt load of coiled tubing), added a circulator pump, a car radiator , and a thermostatically controlled fan all hooked together by salvaged hoses. He had to add the thermostat because the setup got his living space too cold. Now if I only had about a thousand feet of hose......
; )
While potentially interesting from a MacGiver-esque point of view, this arrangement is going to be far, far less efficient than a simple small window air conditioning unit. My guess is that you're going to blow about 2 to 3 times as much electricity on such a set-up as the equivalent BTU removal from a condensing gas set-up (i.e., an air conditioner).Quote:
Current thought is to get a used, small chest freezer, place a container (aquarium, 5 gal bucket, etc) of automotive anti-freeze mix in the freezer, then, using a cheap fountain pump, pump the mix slowly through a junk heater core from a car. This would fit into a hole in my small garage door. I would then use a small exhaust fan in the ceiling to blow out the warm air collected at the ceiling, hopefully pulling in fresh air across the coil. It would take some tweaking, but I think I could get the heater core about 35 degrees F, which, with a gentle airflow, should remove a LOT of moisture from the incoming air, and probably drop it's temp by 10 degrees or so.
You'd get off way, way cheaper by plugging up as many air leaks as possible, insulating the garage walls and roof, and installing said airconditioner that incorporates a thermostat.
It's efficient if you are getting the ice out of the dorm's ice maker. :D:DOtherwise no.Quote:
Originally Posted by David Keller NC
I have thought about something like this up at my inlaw's cabin in Northern Wisconsin. The need for air conditioning is rare, but occasionally very important for some elderly people. The water comes out of their tap from their well at around 50° year round. It could be used to cool one room of the house as a respite when needed. After the water is used as a coolant, it would go down the drain.
For all the good reasons above, I don't see how I could take advantage of my crawl space to cool my shop. I might go down and sit there some days when it's really hot though.
The efficiency comment had more to do with Greg's comment about using a freezer to cool a propylene glycol coolant that would then run through an old heater core. Compared to an air conditioner, it would be very inefficient.Quote:
"I have thought about something like this up at my inlaw's cabin in Northern Wisconsin. The need for air conditioning is rare, but occasionally very important for some elderly people. The water comes out of their tap from their well at around 50° year round. It could be used to cool one room of the house as a respite when needed. After the water is used as a coolant, it would go down the drain."
However, the well idea about using cold water from the ground is a different story. So long as a smallish pump was used to do the circulation, and the water's free, that set-up would be really cheap to run. Most of the power consumed by an air conditioner is the energy required to re-compress the freon after it's expanded and cooled the evaporator coil, not the fans used to blow air across the evaporator and compressor.
I do wonder how well a buried-coil recirculating loop of propylene glycol would work. I know that there are commercially-manufactured systems that use freon and a ground-reject condenser coil instead of the exterior air-cooled setup.
That's all done, plus radiant barrier in the attic. Cooling's not a problem, it's fresh air. I could spend hundreds of dollars on an air-to-air heat exchanger and ducting, which still wouldn't remove humidity, or try to find a window AC unit that has a fresh air option. That would mean a new AC unit plus modifying at least one of my existing openings. My idea is to bring a slow flow of fresh air into the shop across a cold coil to remove moisture. I can get a used small freezer real cheap, and the other components would also be cheap.Quote:
Originally Posted by David Keller NC
If there is a better way to remove the moisture in the incoming airflow, I'd love to find out about it.
BTW, I checked with a water well driller, and he said the deep ground water temp in this area is over 60 degrees. You folks that have that nice, cool water have a real bonus.
Greg - just about every window unit you'll find at the big box stores has a fresh/re-circulate switch lever. Even if you have to modify a window to get it to fit, this will be by far the least expensive option in the long run.Quote:
"or try to find a window AC unit that has a fresh air option.
While I"ve no doubt that you could get the parts for your proposed system very inexpensively, it will be very costly to run. Also keep in mind that a freezer's compressor is not designed to run continuously. I suspect you may be replacing the freezer on a regular basis.
But I have to ask - why do you think it's necessary to include a purpose-built fresh air option (either conventional window AC, or the system you propose)? Most shops, even in very new homes, have enough small air leaks and/or enough door openings/closings to make a dedicated fresh air exchange unnecessary.
David,
I installed my insulation, then a plastic air barrier that was sealed together at all the joints. The only penetrations are for the ACs, which are weather stripped, wiring for the main panel, the regular door and my overhead door. The only real leaks I have are from the overhead door, and then it's got to be windy to get much there. I even ran all my wiring in conduit to prevent any more penetrations in the air barrier.
I have good dust collection, but that doesn't do much for fumes, vapors, other odors, super fine dust, etc.
Greg - If it was me, I think in your situation I'd simply purchase a small de-humidifier. You can simply open a window or crack the garage door when you've a situation that requires letting out a lot of micro-fine sanding dust or chemical vapors, then your dehumidifier can be set to dry out the shop once you leave (and to protect your tools and projects).
This assumes that you've already got AC in the shop. If not, that'd be the first thing I'd buy (a small window unit with a fresh air lever). Besides making it considerably more comfortable to work, it will also protect your tools, and perhaps most importantly, your in-progress projects. Big changes in humidity and temperature can really cause issues when the boards are 4-squared and cut to size on one day, then the joints cut on the next, fitted on the 3rd, and glued up on the 4th.