3000W Chinese Gensets Info.
professor95 wrote: EDIT ADDED 45/5/2013- When this thread started in March of 2005, I never expected to see it survive this long or amass the quantity of information that has been shared here. In...
Forum Discussion
After deciding to go with an exhaust fan instead of a fan pushing air into the box, I knew I could go with a more powerful fan. I definitely wanted to go with something that specified the CFM that the fan could move.
My first try was 2 bathroom exhaust fans from the hardware store rated at 50 CFM each for a price of $12 each. I figured 100 CFM would be substantially more than I was getting with the household fan.
I removed the old fan from the side, closed up the two exhaust holes and then cut two holes in the top to mount the bathroom exhaust fans next to each other. This setup was a definite improvement over the original configuration, however I still felt that more airflow would be better.
The problem was that using more than two fans was not practical, and to go up to higher CFM fans significantly increased the cost. If I remember, a fan that pulled 100 CFM was close to $100 as opposed to the $24 I paid for the pair of 50's. My goal was to do this project on the cheap. If you start buying expensive parts, the cost adds up in a hurry and in this case I didn't want to end up in a situation where for just a little more I could have purchased a used Honda inverter gen.
So the search for an inexpensive fan that could move significantly more air continued. What I ended up with was a radiator cooling fan for a car that I bought on EBay for $25. It was advertised as 1000 CFM, though I doubt it moves that much in my setup. However it definitely moves way more air than any of my previous fans. Additionally, I feel good about using this type of fan since it is built to put up with the heat and vibration, etc of an automotive application. A bathroom exhaust fan could potentially be short lived when used in an environment it was not designed for.
Overall, I'm very happy with this fan, the manner in which it could be fastened to the box, the amount of air it moves and the price. The only problem has been the power source, since it requires 12v. The gen does produce 12v, but the manual states that the 12v feature should only be used to charge a battery, so I'm not planning to run the fan from that. So far, for testing purposes, I've been powering it with my camper's battery, but in the long run will be looking for a 12v transformer/rectifier.
After installing this fan and getting a feel for how much air it actually moves, I decided to remove the pipe that directed the engine exhaust out the bottom of the box. I figured it would be ok to let it mix with the overall air in the box since I would be completely exchanging the air in the box every few seconds. This further quieted the gen since the exhaust noise is no longer noticeable.
One concern I had was that if you have too great a suction and not a big enough entry, you could create a vacuum in the box that would effectively increase the altitude at which the engine feels it is operating. To test this, I made a basic barometer using a piece of plastic tubing with one end inside the box and the other end in a bowl of water. I got the water level in the tube to rise about 1/2" which is equal to .04 in Hg - completely inconsequential.
So how did it work? Very well! Even running the gen at high load, the air near the air filter and at the front of the engine never warmed above ambient at all. The exit air was around 100 degrees on a 70 degree day. I also checked the oil temp after shutting down and it was around 170 degrees, which seems reasonable. I do need to test it some more and see how that compares to running the gen without the cover on. I also felt around inside the cover immediately after shutting down to see how hot the plywood got. The hottest area by far was that right near the muffler, but it was not too hot to touch.
As far as noise, it is definitely far quieter than without the cover. I don't have a meter, but I would say it is roughly equivalent to a Honda inverter gen at moderate load. This was with a piece of plywood just sitting on some 2x4s to cover the fan. Once I build the top cover and carpet the inside, I believe the noise will drop further.
That's all I can think of right now, but I'll add more as I finish this project and after my next camping trip when it has been run in actual use.
My first try was 2 bathroom exhaust fans from the hardware store rated at 50 CFM each for a price of $12 each. I figured 100 CFM would be substantially more than I was getting with the household fan.
I removed the old fan from the side, closed up the two exhaust holes and then cut two holes in the top to mount the bathroom exhaust fans next to each other. This setup was a definite improvement over the original configuration, however I still felt that more airflow would be better.
The problem was that using more than two fans was not practical, and to go up to higher CFM fans significantly increased the cost. If I remember, a fan that pulled 100 CFM was close to $100 as opposed to the $24 I paid for the pair of 50's. My goal was to do this project on the cheap. If you start buying expensive parts, the cost adds up in a hurry and in this case I didn't want to end up in a situation where for just a little more I could have purchased a used Honda inverter gen.
So the search for an inexpensive fan that could move significantly more air continued. What I ended up with was a radiator cooling fan for a car that I bought on EBay for $25. It was advertised as 1000 CFM, though I doubt it moves that much in my setup. However it definitely moves way more air than any of my previous fans. Additionally, I feel good about using this type of fan since it is built to put up with the heat and vibration, etc of an automotive application. A bathroom exhaust fan could potentially be short lived when used in an environment it was not designed for.
Overall, I'm very happy with this fan, the manner in which it could be fastened to the box, the amount of air it moves and the price. The only problem has been the power source, since it requires 12v. The gen does produce 12v, but the manual states that the 12v feature should only be used to charge a battery, so I'm not planning to run the fan from that. So far, for testing purposes, I've been powering it with my camper's battery, but in the long run will be looking for a 12v transformer/rectifier.
After installing this fan and getting a feel for how much air it actually moves, I decided to remove the pipe that directed the engine exhaust out the bottom of the box. I figured it would be ok to let it mix with the overall air in the box since I would be completely exchanging the air in the box every few seconds. This further quieted the gen since the exhaust noise is no longer noticeable.
One concern I had was that if you have too great a suction and not a big enough entry, you could create a vacuum in the box that would effectively increase the altitude at which the engine feels it is operating. To test this, I made a basic barometer using a piece of plastic tubing with one end inside the box and the other end in a bowl of water. I got the water level in the tube to rise about 1/2" which is equal to .04 in Hg - completely inconsequential.
So how did it work? Very well! Even running the gen at high load, the air near the air filter and at the front of the engine never warmed above ambient at all. The exit air was around 100 degrees on a 70 degree day. I also checked the oil temp after shutting down and it was around 170 degrees, which seems reasonable. I do need to test it some more and see how that compares to running the gen without the cover on. I also felt around inside the cover immediately after shutting down to see how hot the plywood got. The hottest area by far was that right near the muffler, but it was not too hot to touch.
As far as noise, it is definitely far quieter than without the cover. I don't have a meter, but I would say it is roughly equivalent to a Honda inverter gen at moderate load. This was with a piece of plywood just sitting on some 2x4s to cover the fan. Once I build the top cover and carpet the inside, I believe the noise will drop further.
That's all I can think of right now, but I'll add more as I finish this project and after my next camping trip when it has been run in actual use.
