James:
Greetings from the rural Northeast, destination of choice for fleeing urban hordes!
I enjoyed the article from Australia a while back on converting a small chest freezer into a low-power refrigerator. I had planned to undertake a project like that this summer. I admired the elegance of the circuit design and the use of a latching relay to lower the power consumption as low as possible.
When I read the letter about using a brewer’s thermostat instead, though, I had the same epiphany you did. Your BFO award is certainly appropriate, and I commend Kurt for bringing the idea forward. The reasons may not readily apparent to the majority of your readership however. I see the benefits of
the most recent solution as several:
* The switch is activated by capillary action from the temperature probe; it requires no electricity whatsoever and is totally EMP-proof.
* It is an off-the-shelf solution at reasonable cost.
* It has a nice dead band (difference between on and off). This should be consistent enough for food and medications, but not tight enough to cause overly frequent cycling of the compressor.
* It is completely set-and-forget.
The only cons I would warn your readership about are:
* Because the switch is mechanically activated it will eventually fail.
Based on having used a couple these switches for monitoring outdoor temperature in HVAC systems I would plan on a 10-15 year life span. Put a spare on the shelf. I would probably dial the spare up to 80 degrees and store it someplace cool and consistent like a root cellar to minimize the action on the diaphragm and lengthen its life. Remember that these are
working whether they are plugged in or not. Someone more informed on these may have a better opinion on how to store them long-term.
* If you crimp, crush, or break the tubing the unit will be completely and irreparably dead. Run the tubing carefully through something like surface-mount wire mold to protect it from falling objects, etc. Don’t make any sharp-radius bends. Paint it with lacquer or nail polish in corrosive
environments.
* It will require a separate temperature monitor for you to see what the fridge is doing. I would recommend a digital thermometer with a remote probe for day to day use and a mechanical (alcohol) backup inside the fridge for TEOTWAWKI and double-checking. Both held in place with industrial Velcro for easy swap-out. An example: this solar-powered fridge thermometer. (I have no first-hand experience with this product.)
Overall, a simple and elegant elegant solution. I think I will pick two up for my project this summer instead of going electronic; one for use and one for the shelf. I am also thinking of gluing rigid foam insulation to the sides and top of the fridge and wonder if other readers have an opinion on
the pros and cons of that.
Speaking of fridge thermometers, keep an eye out for health care expos, etc. in your area. My brother was able to get nearly a dozen 2xAA-powered dual-display LCD thermometers for free at one. They were geared toward refrigerators in doctors’ offices. These are promotional items branded by a vaccine company but work just fine nonetheless.
On a completely unrelated note, a friend of mine with a remote camp here in Maine is considering a hand pump as a backup for the well pump on his well. He found a company, Bison Pumps, that has solutions for drawing water from up to 300 feet down using hand power. I have no firsthand experience yet with the company or its products. They appear to be using a stainless steel rod to actuate a moving foot valve inside a 1 1/4″ schedule 80 PVC tube that parallels the discharge tubing from your regular well pump. I thought this was a practical solution.
I am relying on a generator to power my well pump in an emergency now but I agree that noise discipline will be critical in a SHTF situation, and hand power certainly trumps gasoline power for long-term peace of mind. Their pump looks very well made, but at about $2,200 to get water up from my 180 foot well, it ain’t cheap. Having a couple hundred gallons of water already stored and a list of other preps to finish leaves something like this somewhat lower on my list, but it is on the list. Thanks for a great preparation resource and keep up the good work. – Mike in Maine
JWR Replies: A hand-powered sucker rod pump will indeed work, but will be very labor intensive. Typically, these pumps only lift the water two or three inches with each stroke of the pump handle. So the first time that you raise the water that 180 feet, you may have to actuate the pump handle as many as 1,000 times. And if the foot valve ever starts to leak, the water in the service line will drain overnight. (Read: Possibly 1,000 extra strokes per day!) A more practical solution for deep wells is to either use a jack (“cricket”) type pump or a windmill to actuate the sucker rod. Traditionally, sucker rods were made from hardwoods such as white ash. More recently they’ve been made with metal or fiberglass. Even with ash wood, their service life is measured in decades. The pump cylinders are made of brass and will last many decades. However, the pump leathers will eventually wear out, so you should consider buying a couple of spare sets and storing them someplace safe from mice and moisture/mold. Unfortunately changing all of the leathers on a down-hole sucker-rod actuated pump means yanking the entire sucker rod and then the weight of all 180 feet of your service line. That is a lot of weight, requiring a heavy duty hoist and of course all the usual “mind your head, fingers and toes” safety precautions and protective gear. Lifting a 1-1/2″ or 2″ diameter 180 foot long pipe is no problem for a pump company, but it would be a challenge for a typical rural family working with an improvised hoist. I recommend that you watch your pump company man carefully as he installs the pump in your well for the first time. You will notice that the crucial piece required is the flange that catches the pipe unions on each 20+ foot long section of service line pipe as they are raised or lowered in the well casing. I’ve previously owned a jack type pump, and in my experience I found them problematic. I would much rather use a submersible pump. Shallow wells can use DC submersible pumps, but because of the rapid voltage drop in DC cabling, deep wells are limited to AC well pumps. (Either run by an AC generator, or from AC power supplied by an inverter in an alternative energy installation.)
Jim,
Regarding the refrigerator construction article, The Kill-A-Watt device measures power usage and (among other things) RMS [root mean square] current draw. It does not appear to measure peak current draw, which is a critical input when sizing a stand-alone PV system. The compressor cycling on the freezer mentioned (which may be exacerbated by the external controller) will make demands on the supply of current that far exceed those implied by a 1 KW average power consumption. I didn’t know if this would be obvious to your readers.
Keep up the good work. – Michael W.