A7K Ozone Generator, Repeat Timer 1, 12 or 24 Hours

This ozone generator is amazing. I've used an older ozone generator for about 25 years. Ozone generators are great for shock treatment of areas that have developed problems, especially mildewy smells. For example, I typically run an ozone generator in the basement one day in the spring and one day in the fall when the air is most prone to get musty. Or when I added a bunch of used books from a book sale to my home library and the air got a mildewy smell, I used an ozone generator and it took care of it. I've also used an ozone generator inside my car to take care of musty/mildewy smell, and even ran one inside my front-loading washer to get rid of the smell. In short, I've found an ozone generator to be a very effective way to treat musty, mildewy smells.So what's different about this A2Z A7K ozone generator? Power. With my old Panda ozone generator, I generally had to run the machine for several hours or overnight in a 15x15 foot room to really get an effective shock treatment. This A2Z model is much more powerful. I ran it for one hour in a 15x15 foot room and the result was better than running my old machine overnight. This thing puts out a lot of ozone. I also tried it an a more unusual application. When our furnace started running again this year, the air from the vents smelled musty. So I opened up the plenum in the basement, turned the A2Z ozone generator on, and set the furnace fan to run continuously for an hour. It did a surprisingly good job of freshening the whole house's ductwork in an hour. In fact, the generator produced enough ozone, even when distributed through the whole house, that I had to wait out the process on the front porch.This machine generates enough ozone concentration that you'll really want to seal off the room where you're using it, run the machine, then come back in and open a window for an hour before you open the room back up.One issue: When the machine's timer runs down, the fan keeps running. This creates the impression that the ozone generator is still running, but it's really just blowing air at that point, not making ozone. (I wonder whether this might be the reason that some users reported still having smells, even after running the generator for hours?) Personally, I wish the fan would shut off when the timer runs down, so that the unit shut down completely, but it's no big deal.Bottom line: This is a seriously powerful ozone generator, with a convenient timer and a powerful circulating fan. It's very effective at solving, not just masking, musty odors due to mildew.

Bought this 3 months ago since I have a lot of rental property. Haven't needed it until today. Opened the box to play with my new toy and it doesn't work...at all. Won't even power on. When you push the buttons on the front control panel, the lights that come on don't even correspond to the button being pushed. I would guess a bad control board. I hope someone from A2Z Ozone is following this. I am way past the Amazon return window so now I have to rely on them. Lesson learned...even if you aren't going to use it right away, open it and make sure it works!

this was a great ozone generator til the off/on switch broke....ordered 2 of these...same thin happened to both

PROS:* A2Z Ozone has an office in the US, a web site, and easy-to-find contact information. Names of most other ozone machine brands do not return anything meaningful in Google.* A2Z Ozone machine is specified to produce up to 7 mg of ozone per hour, which is twice as much as the majority of other machines on the market. This may come handy for treatment of large areas.CONS:* Design of the controls. All settings are controlled by buttons and displayed by LEDs. One has to both flip the main power switch in the back and press the power button on the front to bring indicator lights to life. Unfortunately, there is no separate switch for ozone generation – as soon as the power is on, the generator start producing ozone. You end up fiddling with the settings while breathing in unhealthy ozone. The positive side is that the unit remembers the last settings, so if you never change them – you do not need to do anything other than pressing the power button.* Remote is included by it is next to useless. It duplicates buttons on the control panel, but since you have to see the text above the LED lights to know which setting you chose, you still have to be within several feet from the unit to control it. Remote seems to be more of a nuisance than convenience.* I did not like how A2Z Ozone associates this product with the word “USA”. The country of origin is not indicated anywhere on the box or on the unit, but “A2Z Ozone, Inc. USA” is written in big letters everywhere – on the shipping carton, on the unit, and on the manual. I see this as an attempt to associate it with US instead of China. I personally consider such practices as unfair. The machine is made in Asia (even the file name for the manual on A2Z web site at the time of this writing had file name in hieroglyphs (I am guessing, Chinese)), and one can get it directly from China through the know-to-everyone auction web site).* The quality, at least of the unit that I got, implies insufficient quality control. In my unit, the contact between power cord and receptacle which it plugs into in the unit was poor. I had to wiggle it every time to make the unit work. The rest of the unit appears solid.* The manual and sticker on the unit contains an incorrect and misleading statement that “ozone has half-life of 20 minutes”. This is wrong because 20 mins is half-life of ozone in distilled water, but not in the air. The half-life time of ozone is the amount of time it takes to reduce the initial concentration by half through recombination of ozone molecule back to oxygen. It was reported in technical literature that half-life of ozone in air depends on temperate, humidity, and air movement. Reported numbers vary from 40 hours (still air, zero humidity, 24 degrees C) to 8 hours (still air, 87% humidity, 24 degrees C) to about 40 mins with very high fan speed. Other sources report half life time from 3 days in dry still air to 11 hours in still air with 50% humidity. I’d say, 8-12 hours is a realistic average number, but not 30 minutes. This is a very important number because it defines what concentrations of ozone can be reached over time for a given output, and how quickly generated ozone will dissipate after shock treatment.A FEW FACTS ABOUT OZONE.Ozone is a gas which consists of 3 oxygen atoms (oxygen gas contains 2 atoms). It is one of the strongest oxidants available, which in plain terms means that it is extremely reactive. Its odor is detectable at 0.01 ppm and (according to MSDS sheet) becomes “disagreeable” at 1 ppm. A2Z Ozone generator, per its manual, enables one to achieve 1 ppm in a 100 ft2 room.Exposure to low ozone levels creates discomfort and irritation of the mucous membranes, concentration over 9 ppm could cause pneumonia, even higher concentrations could be fatal. American Conference of Government Industrial Hygienists limits exposure to 0.1 ppm (0.2 mg per cubic meter) for an 8-hour exposure of industrial workers. FDA limits acceptable concentration of ozone at 0.05 ppm in enclosed spaces intended to be occupied by people for extended periods of time. While some people refer to low concentration ozone smell as “smell of freshness”, this smell is an indication ozone is still present in the air and the room should not be used yet.Ozone is used to shock-treat smells. Smell comes typically from volatile organic compounds (which is a much broader term in chemistry than what we got used to see on stickers on paint cans), chemical vapors, dust, or molecules. We feel smell because of reaction of offending species with sensors in our nose. Depending on the chemistry of the smell generating matter, our detection limits vary in a huge range – for some species, we may be very sensitive, for others we are not.Ozone reacts with almost anything by oxidizing molecules, thus transforming them from one species to the other. The hope is that after shock treatment, either of the two things will happen: (1) the offending VOC will be converted to a nonvolatile species, or (b) a smelly volatile species will be converted to another volatile species which we do not sense as annoying smell and which is benign for our health. Ozone treatment comes with a risk because of the third possible scenario: reaction with ozone could convert VOC which we smell to something that we do not smell in low concentrations but which is dangerous to humans. As an example, ozone treatment could form formaldehyde if proper precursors are present.One thing that ozone does not do – it does not remove molecules and particles responsible for smell from the air. It just masks them, makes them “invisible”.Another drawback of ozone is that it reacts not just with smells but with anything in the room. 2-hour or 4-hour shock treatment will not do much harm, but if one overdoes it by running it often, or by producing too much ozone in a confined space, one can see deterioration of about anything that can be oxidized – including plastics, plumbing, and electrical wiring.Scientific data on germicidal effectiveness of ozone (i.e., ability to kill mold and bacteria) are contradictory, but it appears that ozone in air becomes somewhat efficient as germs and bacteria killer in concentrations over 10 ppm (especially with high humidity) and exposure times in excess of 24 hours. It becomes very efficient with ozone concentration in excess of 150 ppm (at this level, it would probably kill a human as well). 150 ppm is well beyond the capability of portable household ozone generators (A2Z Ozone promises 1 ppm in a 100 ft2 room). Additionally, one would need catalytic ozone decomposition plates to get rid of ozone produced at such high concentration within reasonable time, and one would need a self-contained breathing apparatus to enter the space where ozone was produced at such levels. Hence, one cannot not rely on household ozone generators to kill viruses and mold through exposure to ozone in air (ozone dissolved in water is more efficient, but it is a different story).Ozone density of 2.14 kg/m3. It is heavier than air (1.29 kg/m3). This means that in a room with quite air, ozone will tend to stay at the bottom. This is why pets are in a greater danger than humans in a room filled with ozone. This is also why the bottom of the door and vents in the floor should be the first places to seal before turning on the generator.Some internet sites suggest that one has to leave door or window a crack open to avoid depletion of oxygen as it is converted to ozone. This is another example of misleading information. Since 20.95% of air is oxygen, 7 g per hour generated by the generator is tiny compared with 270 g of oxygen per cubic meter. A generator like this would never ever deplete the oxygen in a sealed space.Finally, we already talked about ozone half lifetime. This parameter is very important for two reasons. The first one is that it defines how long it would take to get rid of ozone. Due to ozone’s ability to penetrate into any porous matter, it takes a while until it outgases and recombines, it is not just a matter of ventilation. It may easily take up to a week to get rid of residual ozone with the half life time 8-12 hours. The second reason is that with ozone concentration in a room will continue building up as long up to about the half life time or as long as the generator is turned on, whichever comes first. While 7 g of ozone per hour is plenty, 4 hours with a generator which produces 3.5 g/hour would ramp ozone up to the same level as 2 hours with this generator. You need 7 m/hour only if you are exposing very large areas, like the whole house. For one-room purposes, output of the generator by far less important as it may appear (as long as it is within the range sufficient for shock treatment, e.g. over 2 g/hour).MY EXPERIENCE WITH THE OZONE SHOCK TREATMENTWe had two issues with residual paint smell. One room has notorious residual bad paint smell for over a year. The second space - small closet - was painted a week prior to treatment, but paint smell would not go away. These two residual smell instances were puzzling because paint came from different suppliers. Research on the internet revealed that alternatives to ozone were 4 layers of BIM smell blocking primer, or sanding paint off drywall, or replacing drywall altogether. As bad as ozone is, in this situation it was worth trying.Paint smell in the closet was gone after 30 min treatment with one plate. Paint smell in the room required two 2-hour treatments with 2 plates (plus 2 more hours of “hold time” after end of each 2-hour blast in a sealed room before I opened the window), but was also gone at the end – hooray!The most challenging part – surprisingly - was to get rid of the residual ozone smell. Ozone does not only stay in the air, it seems to penetrate anything that was left in the room. It took 5 days to get rid of the ozone smell in the room before it could be used. I used a combination of fans to recirculate the air and heaters during daytime to increase ozone decomposition rate (decrease its half-life time).SUMMARYThis tool is not very well designed and has some quality control issues, but it does produce ozone and (judging by how disgusting the ozone smell was after 2 hours), enough of it to go over 1 ppm in a medium size bedroom. At 7 mg/hour, it is one of the most powerful generators on the market and a good choice for large spaces. Ozone is not an air purification method and it does not remove pollutants from the air, it just makes them more difficult to detect through converting them to other chemical species (which are not necessarily less volatile or less dangerous). Ozone blast is a gamble with risk of converting just unpleasant substances in the air to dangerous for health but not detectable substances. It has right to exist as the last resort before replacing carpets or drywall or painting it with odor blocking primers. In concentrations produced by these generators, it would not kill germs or mold, albeit it may mitigate associated smells.Ozone blast is short, but it may take a fairly long time (days) to get rid of residual ozone smell. High humidity, elevated temperatures, and air agitation with fans can help with decomposition of ozone back to oxygen. Seal all doors and vents when running shock treatment. Stay away from the room if you still can smell ozone. As long as you can feel the smell of “freshness”, stay away – it is ozone and no ozone levels are healthy. Use the principle that less is better than more when using ozone. If you have other means, stay away from ozone treatment altogether.

Purchased about 10 months ago, only used twice in a garage and it worked well to get musty odor out. Put away and got it back out to use and it no longer works. Switch in back is powered on and is lighted to show it's receiving electricity but none of the lights come on in the front and the fan won't run. I will try to get support to fix problem if possible and will update my review based on support I get. Kinda expensive to only get 2 uses out of it.