My bed bug death machine.(8 posts)
Standard disclaimer. I'm relating what I'm doing and I'm in no way advocating that other people do the same.
I was exposed to bed bugs at a hotel recently. The clothes and luggage I dealt with by washing and drying like crazy. The issue left was what to do with the non washables, particularly the electronics. The commerical solutions don't recommend that they be used for electronics. What I needed was something that would heat something up to bed bug killing temperatures, but not to electronics killing temperatures. Something higher than 106F but less than 140F. I also needed something that would keep the temperature constant without much variance. My initial thought was to build a computer controlled death chamber using an array of thermocouples and using a laptop to control the temperature. That's the engineer in me. Then I thought that I can't be the only person who's ever needed a low temperature oven. I'm not. It's actually quite common. There are commercial solutions which cost a few hundred dollars that will maintain the temperature and humidity. There are also a lot of DIY at home people making these things. People build these things all the time to do such diverse things as cure resin, make sausage, brew beer, incubate eggs, make yogart and cook meat. No matter what they use it for the requirements are the same and thus is the solution. Basically stick a light bulb in a box. The cheapest way to do this is to use a cardboard box. I've read people say this on this forum before only to be ridiculed. It is a widely used method. The middle method is to use a cooler, like for ice and beverages. The fancy solution is to use an old refridgerator.
I used an old ice chest aka cooler. It's insulated, making it easy to maintain a constant temperature. It's enclosed, sealing off any avenue of escape for the bugs. It's white, making it easy to find any runners. The rest of the setup is a light bulb, a dimmer switch, a small fan and of course a therometer. It took me about about 30 mins to set everything up. I know many of you are thinking that a light bulb gets really hot. It all depends on wattage. According to the Factory Mutual Insurance Company investigator's guide, a 40 watt incandescent light bulb gets to 252F and a 25 watt light bulb gets to 110F. A 25 watt light bulb raw gets hot enough to kill bed bugs but it's not so hot as to be very dangerous. I wanted more range so that's where the dimmer comes into play. It's basically the temperature adjustment. I use it with a 40 watt bulb. I have it set near the low end of the range so it's about 30 watts. Over a period of days, I did a series of dry runs. I adjusted the temperature using the dimmer so that it would be at 120f +/- .2 degrees. It's held that temperature for hours. The little fan ensures that everything is evenly heated. Even without it, since it's an insulated enclosed space, gravity convection alone will tend to take care of that. I did loaded runs by wrapping a few socks around the temperature probe. It took about 30 mins for the probe to come up to 120F from room temperature. I've done a bunch of dummy runs with electronics in cases. That also took about 30 mins to come up to 120F and it can hold that constant for as long as I want. The electronics come out fine.
Before I do it with my bed bug exposes items, I just wanted to get some feedback. I'm not that concerned about the electronics since 120F is well under the temperatures they are rated for. I'm soliciting feedback on whether this will kill the bed bugs if I say left it at 120F for an hour. Based on everything I've read, it should be more than enough. I am curious why more people haven't done this. Building a low temperature oven like this is well documented and not particularly difficult. It seems like a very easy solution but other than the guy who did something similar with a trashcan, I haven't found other people that have done this. Am I missing something obvious?
The difficulty of maintaining heat levels consistently and all over the aparatus would be my first issue and concern. If bugs can climb the sides, could they climb to the lid edge and simply walk out if it's not a zippered cooler? Or could they climb to a 105 cool spot and make it through your process?
Here's the thing: in my infestation and move, not 1, not 2, but 3 of the regular experts answered my questions about electronics with hand inspection is enough. They--both the bugs and the experts--are unlikely to want to live inside electronics. It's hot, it's small. It's unlikely. Did you use these items in bed? If not, then I would look at a lot of pictures of stages and hand inspect them outside, away from your home. While it's only as good as your inspection of each object, the odds are still not so high that you are running a terrible risk.
A few quick points:
1. You say you're an engineer. Many of us are not. What's easy for an engineer is a near impossibility for some of us. (I have a pair of married friends who are both English majors who recently bought their first house. They joke that they should be starring in a reality television show entitled Why English Majors Should Not Marry English Majors. The entire history of them talking to contractors and handypeople goes about like this:
Item in the home breaks.
Two English majors stare forlornly at the object in bafflement.
One of the English majors calls someone who might know something about it.
Mechanically inclined professional on the phone says "Oh, that's really easy. First you do this thing."
English major on phone is lost by the end of that second sentence and schedules appointment for someone else to come out and fix the broken thing.
I tell this story to point out that what's easy for an engineer is definitely not easy for the general public.
2. If done improperly--esp. by people who are not mechanically inclined types, the kinds of creations above could be fire risks. People who know what they're doing with electricity are generally able to be safe, but a lot of people (like me) don't know enough to know whether we're safe or not.
3. People who are more mechanically and manufacturingly inclined than I am--and those with hands on professional experience in using heat to kill bed bugs will likely tell you that the trick is engineering the container you're using for the heat to circulate the heat properly, to assure that the temperature inside the container is raised at the right speed, and to make sure that the container is entirely impermeable to bugs fleeing the heat.
All three of those criteria have to be met for the device to be successful.
With heat treatment, the temperature is raised inside the structure or container at a certain speed. If the speed of the temp increase is wrong and there's a way out, the bugs will just flee the item and get back into your residence. I personally don't know how sealable a cooler would be against escaping bed bugs. I would guess that the problem would be in whatever hole is made in the cooler to insert the heating element. A fridge sounds like a better bet, but that's beyond the skill level of many people, and it may still run into the same problem.
Again, none of that is to discourage you personally. But what you asked was why don't more people design DIY cooker devices. That's the answer as to why I don't. Personally, I would rather pay someone else who knows what he or she is doing to put together a safe and effective device because I know how much I suck at that skill set. I suspect I'm not alone in feeling that way.
When something comes easily to us personally, it's often the case that it's hard for us to see why it doesn't come easily to other folks. I'm daily baffled at how much people struggle to use printed or typed words to say what they want to say because writing comes quickly, easily, and naturally to me. As a result, I don't always understand why it's a struggle for other people to get the grammar right or learn a grammar rule when it's pointed out to them--even though I see plenty of evidence that the way I relate to language isn't the way everyone else relates to language.
How do you get to carnige hall?
The reality is that you system would need to be soak tested for 50+ cycles. Run in different environments, tested with different materials and also tested with real live bedbugs.
The engineer in you seeks a mathematical solution to a biological problem and they simply don't work that way.
I can't go onto details of who, what or when but there is already a corner of my testing facility in London littered with products that do not work for various reasons.
I appreciate that you mean well but for something to be of value to people with bedbugs it has to be known to work time after time and that takes long days and testing. In your case where you are putting out just an idea you still need to think about your personal liability and the safety of others who may try to copy what you do and harm themselves.
However as others have said the fear of bedbugs in appliances is greater than the probability of it happening in anything other than a massive infestation.
Bed Bugs Limited
Thanks for the replies. I appreciate it.
To address some of the concerns. The way I will be using this is that I will preheat the death chamber to 120F. I will then put in the item to be sterilized. My understanding from reading this forum is that bed bugs will run to where it's coolest. The coolest thing at that point will be the item. The heat will work in from the outside in so they should just keep trying to dig in deeper. I've also read that faced with a blowing hot wind, that they will retreat further in. That's what's happening inside due to the fan. In case they do try to make a run for it, a variety of things will stop them. One, the side of the cooler is smooth slippery plastic. Much like a bathtub, I'm not sure they can make it up. Two, I've lined the edge right below the lid with double sided sticky tape. Think of it as a bug trap all the way around. Three, the lid is sealed pretty tight. I even made it tighter by lining it with weather strip. As for escaping through the hole that the probe and cord go in. The hole has been sealed with caulk. Nothing's getting out through there.
As for cool spots. There really aren't any. That's a big reason for using an insulated container and allowing the temperature to stabilize. The entire interior is effectively the same temperature. If it wasn't a sealed insulated container, then there would be cool spots as the heat radiates away. Of course no container is a perfect insulator so some heat does leak away, but the gradient is relatively small. Even with the heating source (light bulb) off, it maintains the same temperature for quite a while. The little fan inside also eliminates hot/cool spots by moving the air and thus conducting the heat about. I did try positioning the thermometer in different spots and taking samples. After allowing the temperature to stablize each time, the readings were consistent. This is a prototype and I plan on building a bigger better version. I've ordered a bunch of thermometers for that so that I will have an array of them all over the container. I will also do away with the dimmer switch to set the temperature manually and will replace it with a computer controller. I'll set the temperature and the controller should keep it there with no further interaction from me.
I'm most concerned about bed bugs hiding out in my laptop. There are a bunch of places for one to get inside and a bunch of places inside for one to hide. By the nature of it, it's hard to inspect. It's kind of like trying to figure out what's inside a box just by looking at the outside of the box. A couple of hours at 120F won't really do it that much harm if any at all. Yes, the Li Ion/Poly batteries don't like being at high temperatures, but 2 hours isn't really that much time. Most Li Ion/Poly cells are rated to operate at up to 50C or 122F. So 120F is even within their operating specs. My laptop is rated to work in an environment of up to 145F. I'm actually thinking about putting my laptop in their while it's on so that I can monitor the internal thermometers over WiFi. Many will be much higher since even at idle the CPU will be pushing 170F, but there is one thermometer in the chassis that just reads room temperature.
It's actually super easy to put one of these things together. Basically it just involves sticking a lamp in a cooler. The only electrical part comes from plugging it in the wall. Yes, the temperature definitely needs to be monitored in the cooler. If a 500 watt halogen lamp is stuck in there, that's going to be big problem really quickly. On the other hand, a 25 watt bulb tops out at 110F. It doesn't even feel that warm.
As often said, a picture is worth a thousand words. Here's a tutorial from someone who built a simple one. There's not much to it.
Here's a tutorial on building a fancy one using a controller.
I started using my bed bug death chamber for real today. I started running through the unwashables I bagged that were exposed to bed bugs. I've been conservative with my times. From tests with the probe stuck deep into things. The longest it took the probe to come up to 120F was when I hallowed out a space for the probe in one magazine and then surrounded it with 5 magazines on the top and bottom for insulation. Paper is a very good thermal insulator as well as being very dense. It took 1 hour and 20 mins to come up to 120F from room temperature. I left my first batch consisting of my camera and my phone in there for 4 hours. Considering that neither are close to being as thermally dense as the magazine stack, they were both at 120F for at least 3.5 hours. I'm thinking that should do it. Both the camera and the phone work just fine. Lacking live bed bugs, as a control, I tested with some ants. I have plenty of those. It's hard to find numbers on what temperature ants die at but I did find studies that showed they are active up to 111F and some survive up to about 160F. My dry runs generally lasted 3-4 hours since I wanted to make sure I could hold the temperature steady for that long. Every single ant I stuck in there was dead by the end of the run.
Personally, I'm confident enough by what I've seen to consider the stuff that's been run through it bed bug free.
Good luck! I couldn't assemble this....heck, I had to have help with my packtite (and that's EASY to put together).
I'm running my last batch through as I type. Everything went pretty smoothly. I would have finished yesterday but the fan seized up. I was using a fan I bought for a $1 at Radio Shack years ago. It was one of those tiny battery operated fans for people to use on the go. Somehow I don't think it was designed to run constantly for 12 hours a day for 10 days straight. I got a proper muffin fan at the industrial supply store and that's chugging along now.
The laptop seems to have suffered no ill effects from 4 hours at 120F. Since I travel a lot and am a fan of buying cameras at thrift stores, I'm going to build a bigger better version so I can routinely heat treat things. The one thing this experience has taught me is that just because I don't see signs of bed bugs during the room inspection, doesn't mean there aren't bed bugs.
This version was something I built out of parts I had lying around the house. The new one will be along the same lines. The big change is that I will replace the dimmer switch with a PID controller so that I can set the temperature and the controller will maintain it. It will also be much larger. I'm using a 48 quart cooler right now and I already have my eye on a 120 quart one. I'll also outfit it with an array of thermometers. All the parts, other than the cooler, have already shipped. A 120 quart cooler should give me enough space that I'll be able to put my travel bag in there without it touching the sides. I thought about using an old broken fridge, there are plenty for free on CraigsList. It would be much better in every way but would have taken up too much space. I already have one fridge in the garage. The cooler is small and light enough that I can stick it on top of the fridge in the garage when not in use.
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