Replace Dead Cooling Units with Air Conditioners

old refrigerators upgrade
You can repurpose retail refrigerators

I have an old Hussmann refrigerator with two sliding glass doors, that was originally used as a refrigerated produce case in a grocery store (I use it to store eggs from my free-range egg farm). This was a nice unit in its day—it’s built like a battleship—but its refrigeration unit is shot, and was an inefficient dinosaur even when it ran properly.

These old refrigerators are good news/bad news. The good news is that their decrepit refrigeration units mean that you can buy them almost nothing. The bad news is that their decrepit refrigeration units mean that they’re worth almost nothing.

New Life for Old Refrigerators

After having mine repaired twice at about $350 each time, I took the advice of the HVAC technician:

“Get a window air conditioner, replace the thermostat so you can turn it down to 40 F, and stick it in the side of the refrigerator.”

So I did just that. For $179, I got a new 7,500 BTU air conditioner. I cut a rectangular hole in the side of the refrigerator with a saber saw and installed it, sealing the edges with aluminum tape.

Window air conditioners are cheap, energy-efficient, quiet, and lightweight. You can install them yourself if you know how to saw a rectangular hole in the side of a big metal box and how to do simple wiring.

Walk-in Coolers, Too

These same techniques work for walk-in coolers, either for existing or DIY walk-in coolers.

Sizing Your Air Conditioner to Your Refrigerator

For my purposes, the smallest unit I could find was actually too big, and I ran it on “low” most of the time. I would have been better off with a little 5,000 BTU unit for my 50 cubic-foot refrigerator. You could probably run a small walk-in cooler on a larger window air conditioner!

Converting the Air Conditioner to Refrigeration Work

The only thing you have to modify is the thermostat. There are several ways to do this.

The main problem to be solved is that your air conditioner doesn’t want to go below 60 °F, but we want it to go below 40 °F.

Best but Hardest: Direct Replacement of the Thermostat

All you do is replace the original mechanical thermostat with one that goes down to 40 °F or below. Simply unplug the original one and replace it with one that will go down to refrigerator temperatures.

This requires that your air conditioner has a mechanical thermostat. Most new ones have electronic thermostats, so may require an older unit.

You might be able to do a direct replacement, mounting the thermostat in place of the old one, and even use the original thermostat’s knob to there are no externally visible changes.

The business end of the thermostat, the capillary tube, needs to be mounted against the fins on the cold-side radiator of the air conditioner. This is the part of the air conditioner that ices up, but if that’s where the thermostat is, setting it above 32°F will limit how much ice can form before the thermostat shuts it off.

Fooling Electronic Thermostats

coolbot walk-in refrigerator controller
CoolBot cooler controller converts window AC unit to refrigerator controller for retail or walk-in coolers.

If you want to do things the easy way, you can fool the electronic thermostat with a CoolBot controller.

We added one to our cooler when our original A/C unit died and we replaced it with a unit with an electronic thermostat. Without an easy one-to-one thermostat replacement, we decided to use a CoolBot controller.

CoolBot has a probe for the cooling fins to prevent icing, plus another one for the interior of the refrigerator, and their secret sauce: a tiny heated cable that you attach to the AC unit’s existing thermostat sensor. This fools the AC into thinking that the room is hot and the A/C needs to be on.

Since the A/C unit’s thermostat sensor is on the front of the fins, all you have to do is pop off the front grille: you don’t have to disassemble the unit.

Here’s one farmer’s walk-through of his installation in his walk-in cooler:

The Night Light Trick

Line-voltage thermostatic controller
Line-voltage thermostatic controller

If you warm up the temperature probe on the A/C unit, it turns on.

Instead of buying a CoolBot, the farmer in the video below used an external thermostat to turn on a night light, which warmed up the A/C unit’s temperature probe.

He used a heater thermostat and a reversing relay, but you can also use an inexpensive digital temperature controller for a simpler installation:

  • Mount the controller’s temperature probe against the A/C unit’s fins.
  • Plug the night light into the temperature controller.
  • Mount the A/C unit’s temperature probe near the night light.
  • Plug the temperature controller and the A/C unit into the wall.
  • Set the temperature controller to the desired temperature.

Other Tips

In general, a refrigerator is just a big insulated box, so you can saw holes in it wherever you want. However, there might be heater cables here and there to prevent the unit from freezing up, and wires to run fluorescent lights and such. These are usually in obvious places, but unplug the unit before using the saw! If you find any severed wires, you have the choice of not using the fancy-pants features like lights and defrosters, or opening up the junction box and disconnecting anything you broke.

Don’t bother removing the old refrigeration unit, fans, or anything else you’re not using. They’re not doing any harm.

The air conditioner will drip on the outside with water it’s condensed out of the cold air. Put a drip pan under it.

Brush or blow the crud out of the air conditioner once in a while.

How Well Does It Work?

My first A/C unit died suddenly after four years of continuous operation, which was about what I expected. The second A/C unit, with CoolBot, has been in place for eight years or so. (The original refrigeration unit broke every year and averaged $350 in repairs.)


The seals on the refrigerator doors aren’t what they used to be, and on a very hot day the air conditioner is on for hours at a time. Gotta fix that someday. But the same techniques (and the same air conditioners) can cool a walk-in cooler with tight-fitting doors.

Living With a Low-Yield Well

Slow wells and running out of water are no jokeSlow, low-yield water wells are no joke, as I learned when I nearly ran out of water one summer. Yikes! Running out of water is seriously Not Fun.

How did we fix our problem? More importantly, how can you fix your problem?

Can you need a new well? Maybe not! With the right setup, you can have all the water you need with a very slow well. We do fine with a well that gives only a quart per minute.

Table of Contents

What is a Low-Yield Well?

A low-yield well (also called a “slow well”) is a water well that has delivers water more slowly than you need. Since a well is basically a hole in the ground that water seeps into, if you pump the water out of it faster than it’s flowing in, eventually the water coming out of the pump falls to a trickle or stops altogether.

Symptoms of a Low-Yield Well

If you have a low-yield well, you’ll have at least one of these problems:

  • Running out of water. Everything is fine for a while: you have plenty of water and plenty of pressure, but after a while the flow and pressure fall dramatically, possibly to zero. If you turn off the taps and wait, everything recovers after a while.
  • Low water pressure, low water flow. For example, shower dribbles instead of spray.
  • Dead pumps. Your water pumps don’t last long before burning out.

When I first moved to my farm in Oregon, we could water the lawn for about an hour, and then our water pressure would fall almost to zero and we’d get only a trickle of water. If we turned off the hose, our water pressure would recover in about twenty minutes, but would quickly fall again if we turned the hose back on. We’d have to wait hours to get another chance at watering the lawn.

Depending on your particular well, you might run out of pressure even faster: partway through a shower, for instance.

Also, the problem may be seasonal, with plenty of water during months where the water table is high, and little when the water table is low. Your well may still give water during the driest months, but not enough—unless you take the steps I describe later on.

It’s All About Your Local Geology

If you’re in an area where it’s easy to drill a well that gives you all the water you need, you’re lucky! Here in the Pacific Coast Range, we suffer from the irony that we get a lot of rain, but the aquifers yield up water grudgingly. Good wells are few and far between in my area, so we learn how to get the most out of poor ones.

Anatomy of a Basic Well System

A home water system is a pretty simple proposition:

  • Drill a hole in the ground until you hit an aquifer and water pours into the well.
  • Drop a pump down the well and connect it to your household pipes.
  • To keep the pump from running 24/7, add a pressure switch to turn the pump off when no water is being used.
  • Add a pressure tank to hold enough water at pressure so the pump doesn’t have to turn on every time you open a faucet.

Typical domestic water well


If water pours into the well faster than you pump it out, you’ll always have plenty of water and plenty of pressure. You don’t have a low-yielding well.

How Much Water is Enough Water?

When I bought my farm, the rule of thumb lenders preferred was that the water system should be able to produce 600 gallons over the course of two hours, or five gallons per minute. It can be difficult to finance a home purchase if you can’t pass this test.

What if your aquifer is stingy, and simply can’t deliver this much water?

My well produces only about a quart per minute, or 360 gallons per day. How can I pass a 600-gallon flow test, let alone have enough water during peak usage periods during the day?

Water storage, that’s how. Clearly, through the miracle of a full-to-the-brim 600-gallon storage tank, anyone can pass a 600-gallon flow test. You could have a dry well and still pass, if you have a water holding tank and pay someone to truck in the water to fill it with.

So the test the lenders use doesn’t actually measure the water well yield. Which is nice, but what about after you move in? If your lack of water is driving you nuts, it’s time to do something about it.

The Slow Flow Paradox

One thing about my quart-per-minute well is that a quart per minute is somewhere between a trickle and a dribble. It takes more than six minutes to cycle a 1.6 gallon/minute toilet, and taking a shower is almost impossible.

On the other hand, there are 1,440 minutes in a day, and in that time my quart-a-minute well produces 360 gallons. This is plenty of water for a family of four. So if I capture all the water my well is capable of yielding, we have plenty of water.

How do we capture 360 gallons per day, so we can use it whenever we want? We need to acquire some storage. A cistern, a reservoir, a storage tank, a holding tank—call it what you will.

Why? Because, unless you have an artesian well that has water flowing right out of the top, without a pump, every well fills itself up to a certain level (the static water level), and then stops. No more water flows in. If you pump some water out, more flows in. But once it’s filled to the static water level, it stops.

I need to be able to harvest my well’s pathetic dribble of water. I can’t afford to have it sit around at the static water level most of the time, not producing water for me. So we need to do one of two things:

  1. Drill the well with a large diameter that there’s plenty of water storage inside the well itself.
  2. Add a storage tank for the well water, and run the pump often enough that the water in the well doesn’t reach the static level.

Storing water in the well itself

Storing water inside the well shaft works just fine with a simple well setup: well, pump, pressure switch, pressure tank. The pressure tank really only stores a few gallons, so that’s no help. But you can store water in the well itself. That’s what a well is: a hole in the ground with water in it. You can create storage by making the well wider, or deeper, or both.

My older well has the aquifer at 85 feet, but the well is 145 feet deep. That extra depth acts as a reservoir that holds about 150 gallons. Using extra depth for storage is a side effect of the luck-of-the-draw nature of the well-drilling process. You’re never sure what you’re doing to get, and if you hit a shallow aquifer with a disappointing flow rate, you tend to keep going, hoping to find more water further down. If you don’t, at least you’ve created some water storage.

So let’s do the math. If my well yields a quarter-gallon per minute, and the well has 150 gallons of water capacity, how long until it’s full again? Ten hours (600 minutes).

How long until I have water pressure again? Depending on how things are set up, you might have a dribble of water continuously, but the water pressure won’t rise to normal levels until you’ve been using no water at all for a while. For example, a low-flow toilet uses 1.6 gallons of water, and if the toilet is flushed after the pressure has fallen to zero, the household pressure won’t rise until sometime after it fills. On a well like mine, pressure doesn’t come back for tens of minutes.

Using a Storage Tankplastic_water_tanks

Our original well, with its 150 gallons of in-well storage, worked okay for us for a couple of years, once we gave up on the idea of watering the lawn during the summer. Later, as we got into the broiler butchering business, we started running out of water at inconvenient times. So we added a 1500-gallon holding tank. We got one that’s basically a big black plastic tank about eight feet in diameter and six feet tall. They’re light. The guy who delivered it just rolled it off his trailer by hand, rolled it across the grass to where we wanted it, and got a couple of us to give him a hand in tipping it upright. Easy.

In my mild climate, you can just set one up outdoors and forget about it. In a climate that’s hotter or colder, you’d either build a shed around it or get a concrete tank instead and install it underground.

With a storage tank, you have a two-pump system. One pumps water from the well into the storage tank. The other pumps water from the storage tank into the house. The well pump is controlled by a float switch in the storage tank. The household pump has a pressure tank and pressure switch, just like the basic water well setup.

When we installed the tank, it went from being empty to having 400 gallons in it overnight, which was wonderful. In a few days, the tank was full, and it stayed full from then on, unless we did something that used a great deal of water (usually leaving a faucet on by accident).


Protecting the Pump and Well

“Is my well dry, or is my pump bad?” Preventing the pump from going bad is the simpler part of that question. Electric pumps rely on the water passing through them for cooling. The pump in a slow well tends to have long periods when it’s running, but not much water is passing through it, so it overheats. This also tends to use up electricity to little purpose. What to do?

There are several solutions for this:

  • Use a float switch or water level sensor down the well that turns off the pump when the water level gets low. End of problem, but it involved dropping an extra cable down your well. I’ve never tried this.
  • Install a Pumptec pump-protection box. This is what everyone actually uses. The Pumptec basically does what a down-the-well float switch would do, without putting anything down your well. It’s an electrical box installed in series with the power to the pump. It monitors the current load of the pump, and if it sees it running with very little load, it infers it’s running dry and shuts it off for a programmable interval. More on this later.
  • Install a cycle timer that only allows the pump to run a set number of minutes every hour or half-hour. If you set this right, the pump will never quite have enough time to pump the well dry. I used to do this, but it confused the electrician and he took it out, and I haven’t put it back. More on this method later.
  • Use a smaller pump that can’t over-pump your well. The 3/4 horsepower submersible pumps I have in my wells pump water 20 times faster than my wells can deliver it. A tinier pump would be better-matched to the task.
  • Put a valve inline with the pump and close it most of the way so the output of the pump is about the same as the production rate of the well. Seems sorta wasteful…

Protecting Your Pump with a Pumptec

protect your slow well with a pumptecIf you have a low-yield well, you want a Pumptec unit to protect your pump. This is a device that sits up in your pumphouse and monitors the load on the pump. If the well runs out of water, the load on the pump goes to zero, and it can burn out. The Pumptec box turns off the pump as soon as it detects the no-load condition, and won’t let it come back on for a while, at which point there will be more water. Mine is set for a two-hour delay, but you’d set it for a shorter delay if your well isn’t as minimal as mine.

Protecting Your Well With a Cycle Timercycle timer for slow wells

But it’s better if you don’t pump the well dry: the well lasts longer if it’s mostly full all the time. If you have one gallon a minute (I wish!), and a pump that delivers ten gallons a minute, you’d never pump the well dry if the pump was allowed to remain on for only six minutes out of every hour. I’ve used a timer with a 30-minute cycle, which would be set for an on-time of three minutes out of every 30 in this example. When you have an external storage tank, you don’t much care exactly when the pump is on.

I don’t know how much this actually helps, and neither of my wells have a cycle timer on them anymore, though both have Pumptec units.

All-in-One Solutions

I’m aware of two companies that create packaged solutions to take care of the entire problem, using fancier controllers than mechanical cycle timers or even Pumptecs. These are:

  • Well Manager, which emphasizes its compact rectangular water storage tanks that you can sneak into your basement, behind the stairs, etc., in addition to its controllers.
  • Well Booster, which controls up to five wells with a single controller.

Redeveloping Your Well

With a storage tank, a Pumptec unit, and a cycle timer, all was well for several years. Then, one day, I discovered one day that the tank was nearly empty. A day later, it had gained only 50 gallons from the day before. Hey! It used to gain 400 gallons overnight! Our well had clearly become less productive over the years.

redeveloping a slow water well with compressed airSo I went down to Mainline Pump in Philomath and got on the calendar to have them show up, along with Corvallis Drilling, to “blow out the well.” This is also called well redevelopment or well rehabilitation. Wells can get themselves crudded up over time with silt and harmless slime bacteria, and this can often be reversed by removing the crud by one means or another. I knew I had a slime bacteria problem. This is not a subtle problem, since the hydrogen sulfide smell in the water and the slime on the water filters and in the toilet tank are a giveaway.

When the day arrived, Mainline pulled the pump, and we removed about a bucketful of slime was clinging to the pump and drop pipe even before the main event started, and plenty more came out after Corvallis Drilling dropped their hose down the well and blasted it out with a combination of compressed air and water (airlift pumping). It was an impressive spectacle, but unfortunately the yield we measured at the end of the operation was under a quart a minute. Sigh. There are no guarantees in the well business. You give it your best shot, and you get what you get.

Drilling a New Well

corvallis drilling rotary well drilling rigSo we asked Corvallis Drilling to drill us a new well, not far from the old one. Heck, the rig was already there and everything! The old well was blown out on Friday, and they drilled us a new well on Monday. This was done with a truck-mounted air-rotary drilling rig, which is pretty much the standard these days. The well is six inches in diameter, and after the first few feet, the whole operation was through rock. Most of it was crumbly, easily drilled sedimentary rock, with occasional barriers of harder sandstone. Usually the water is found above these harder layers. The drill turns very slowly. Water is injected as a lubricant, and compressed air blows out the chips as the drilling continues.

I kept sneaking out to watch the drilling in spite of a deadline that was supposed to be keeping me in my office. (But I met the deadline, too.)

In our neck of the woods, there’s no real reason to drill a new well very far from the old one, since everyone’s experience is that nearby wells don’t interfere with each other, and a well thirty feet away from an existing one may find water at depths and quantities totally unlike the first one.

After looking at the well logs of all the wells drilled in my neighborhood in the last forty years, it seemed like we’d probably find all the water there was within 100 feet of the surface, though there was an off-chance of finding more very deep—300 feet or more. Sometimes that deep water is salty, sometimes it’s fine.

We hit water at 55 feet (the old well, thirty feet away, had hit water at 85 feet), but the amount was disappointing, around a quart a minute. I wanted to quit at 100 feet, but the driller offered to go down to 130 feet, and if he didn’t find any more water, I wouldn’t pay for the last 30 feet (except for the 30 extra feet of PVC well liner). So we did, but no dice.

Mainline Pump showed up to put the old pump down the new well, and … it was a disappointment, about the same yield as the old well. Enough to scrape by on if we were careful. Sigh.

I was reluctant drill yet another well (among other things, the State of Oregon charges fees that cost nearly $600 per well, let alone the drilling costs), so we moved on to Plan C, which was to put both wells into operation. Mainline Pump came out yet again and put a new pump down the old well.

Success! In the 24 hours after both wells were in operation, the storage tank gained 500 gallons, and has basically been full ever since.

Hanging Onto the Last Few Gallons

If float_switch_water_storage_tanksomeone leaves a faucet open, all your hard-won storage can vanish in a few hours. But you can create a reserve supply easily. Here’s how:

  • Put a float valve near the bottom of your storage tank and put it in series with your household pump. Use the normally-closed version of a float switch, so when the water falls to, say, one-quarter of a tank, the switch opens and your household pump stops running. This will prevent your household pump from burning out and will also protect your last few (hundred) gallons.
  • twist_timer_for_wellsWire in a twist timer in parallel with the float switch. That way, you can go out to the pump house and bring the pump back to life for a limited time. Twist timers are available with durations up to six hours. (You could just install an override switch, but if you’re like me, you’ll forget to put it back in the “Normal” position after the water emergency has passed.)

Making Your Well Last: Disinfection

One thing that well owners are supposed to do is to disinfect the well to control bacteria, including bacteria that can cause disease and slime bacteria that can plug up the well. I’ve been doing this all along, but obviously not very effectively!

Shock Chlorination

use bleach to shock chlorinate wellsThe usual technique is shock chloriniation, where you dilute a appropriate amount of bleach (in my case, 3 quarts for each of my wells) in five gallons of water and pour it down the well, then circulate the water by running the pump and pouring the output back down the well. Then you let it sit as long as you can (at least eight hours, though 48 hours or longer is even better), and finally pump it out onto the grass, since you don’t want all that chlorine in your septic system. This beats back the bacteria. More on shock chlorination.

I recently learned a better system that’s available to those of us with storage tanks, which is to fill the well up to the top with water from the storage tank after adding the chlorine. This water will run backwards, into the aquifer, and kill off bacteria that are relatively far from the bore of the well. Then recirculate and wait as before.

Hydrogen Peroxide

hydrogen peroxide to disinfect and deodorize well waterAnother technique I learned about more recently is the use of ordinary 3% hydrogen peroxide instead of chlorine. This hasn’t been adequately researched, so it counts as a backwoods rule-of-thumb technique rather than something that will put a smile on the face of an inspector. The way it was described to me was, “Pour a couple of pints down the well and a couple of pints into the storage tank, and forget about them.”

The theory is that hydrogen peroxide is safe at those levels and doesn’t put any annoying tastes or smells into the water, so you don’t have to dump the water in the pump and the storage tank. Simple.

I wrote two different state agencies in Oregon to get their opinion about this, and basically they feel it doesn’t have enough research backing to be considered reliable, though they didn’t see anything scary about it.

One thing is certain: hydrogen peroxide works great for getting rid of sulfur smells in water, and it’s used routinely for this. When I got a new water heater, I was plagued by rotten-egg small in the hot water, and it went away instantly when I put some hydrogen peroxide in the system.

Because sulfur smell has been a problem for me, I expect that I’ll shock-chlorinate my well every year to stay within the usual parameters (after all, I have a state-licensed chicken and egg operation here), and use the peroxide in between. While I hope that its effects are more far-reaching than this, I won’t count on it.

Water Conservation

I saved this until last because people who don’t have enough water are already conserving what little they have. Just a few tips:

  • It’s ridiculous, unbelievable how much of a difference a low-flow toilet makes. In a family of four, I wouldn’t be surprised if our old adorable antique toilet used 100 gallons per day! Compared to this, all other conservation methods combined were a bit of an anticlimax.
  • If you used to have low water pressure, you probably couldn’t get low-flow shower heads and faucets to work right. I sure couldn’t! But after I added a storage tank and had separate well pumps and household pumps, I had tons of pressure, and swapping out my fixtures worked great.
  • If you insist on sending precious well water through lawn sprinklers, always use one of those timers that shut off the water after the specified time.


More on the Blog and Newsletter Migration

Migrating the Blog

Converting my blog from its old format (b2evolution) into WordPress was not something I cared to do by hand, so I paid to do it for me.

The automatic conversion failed, but they stepped in and got it to work manually. I like the way the results came out. The whole thing set me back 48 bucks.

I’m toying with the idea of converting my old plain-HTML Web pages as well, since they don’t play nice on smartphones.

Migrating the Newsletter

Around the same time, I gave up on my old, Nineties-style Majordomo mailing list software for my newsletter, and signed up with Sendy. Sendy is a lot like Mailchimp, which I also like, but I have way too many newsletter subscribers for Mailchimp’s free service (which tops out at 2,000 subscribers). Sendy costs $59 up front, and hooks up with’s SES service, which costs $1 per 10,000 emails sent, where Mailchimp costs about $100 per 10,000 emails.

Yay! I’m in the right century now!

Online and Offline Predators

I logged into the blog the other day and was informed by the blog software that I had a quarter of a million comments awaiting moderation!

Of course, none of these comments seemed to have anything to do with my blog. I was just being victimized by one of the botnets, whose zombie army of infected PC’s was endlessly uploading exhortations to buy various kinds of junk.

I disabled comments altogether to keep it down to a dull roar. Since spammers are the worst programmers ever, the botnet hasn’t really noticed, anymore than they noticed that not one of their last quarter-million comments has been posted. You can see why these guys aren’t holding down a real job.

But never mind that. It’s just a nuisance.

In the real world, our egg production has fallen precipitously, down to about 20 eggs per 100 hens per day, which is really dreadful. We got twice as many last year.

We’re not sure what happened. Yes, it’s the natural molting season, but usually the hens drift into molt at different times, with no sudden cratering of production. A huge drop like this is triggered by extraordinary stress, not the ordinary changing of the seasons.

I think a busy predator, perhaps a dog, possibly a coyote, maybe a child, chased the flock around for some time and scared them half to death. This really distresses the chickens, far more than when a predator such as a bobcat nabs a single chicken and leaps the fence with it.

So we’re keeping our eyes open in case it wasn’t a one-time event.

I expect the rate of lay will start picking up any day now. Karen’s talking about using lights again this winter, to encourage the hens to start laying again, and maybe we will.

Lousy intruders.