This is awesome, I've had a damn near brand new one of those kicking around in my shop for over a year that I took from my father's HVAC system. I knew it was one of those things that was sitting in the corner of the shop forever but also super useful.
I was told the same thing. In my case, I wanted to use the blower as an air cleaner, so I built a cabinet for it that let me mount a 4" high-MERV filter and a 1" pre-filter in front of it. I don't have any way to know for sure that this is enough pressure drop to protect the fan motor, but since I am lazy about replacing the filters and they generally are a bit clogged, my bet is that I'm okay. :-) What I ought to have done was to measure the current draw of the unmounted fan and then after mounting it. I suppose it ought to be possible to look up the proper current draw for a fan and go by that. Two to three amps, maybe?
there would be a higher amp draw, or the same amp draw, there is more work being done, so it with either draw more current or lower the speed, or a combination of the two. but I am at a loss to think of a reason why making a fan do more work extends its life.
@@johng.1703well, it’s actually doing less work. Greater resistance means less work is being done. Think of it in purely DC electrical terms. Greater resistance means less current. I think it’s either the same current or lower, so no extending the life by limiting airflow. You could probably extend the life of the bearings that way though. I have one of those setups, but put a 3 way switch on it bc it was a multi speed fan. Low has plenty of airflow.
@@kempie9901 so if I strap 100KG of weights to your legs you are going to be doing less work running a marathon than without those weights right? blocking the exit is creating a greater air pressure, aka more dense air, which the blower has to work harder and compress the incoming air. so it doesn't turn as fast as it is doing more work to turn the blower. now there are going to be electrical connections that while not moving as fast, there is going to be more current flowing through them. if you really want to test this out, use a vacuum cleaning and restrict the intake, it isn't going to like it and the power consumption is going to go up and the motor is going to get hotter.
@@johng.1703you should calm down my guy. I wasn’t saying anything negative towards you. When you restrict the airflow causing less air to flow, by definition, less work is being done. May be less work for the same amount of current, but it’s less work nonetheless. Your analogy of adding weight to a runner is not even close to the same thing because you are causing MORE weight to be moved.
This is awesome, I've had a damn near brand new one of those kicking around in my shop for over a year that I took from my father's HVAC system. I knew it was one of those things that was sitting in the corner of the shop forever but also super useful.
Very good to know, thanks for posting. I don't own a clamp on amp meter but it would be interesting to see the difference in amperage draw.
Why not a rheostat to adjust the RPM's?
I was told the same thing. In my case, I wanted to use the blower as an air cleaner, so I built a cabinet for it that let me mount a 4" high-MERV filter and a 1" pre-filter in front of it. I don't have any way to know for sure that this is enough pressure drop to protect the fan motor, but since I am lazy about replacing the filters and they generally are a bit clogged, my bet is that I'm okay. :-) What I ought to have done was to measure the current draw of the unmounted fan and then after mounting it. I suppose it ought to be possible to look up the proper current draw for a fan and go by that. Two to three amps, maybe?
Did you happen to take a measurement of the current draw before and after?
no i did not.. don't have a clamp meter..
there would be a higher amp draw, or the same amp draw, there is more work being done, so it with either draw more current or lower the speed, or a combination of the two.
but I am at a loss to think of a reason why making a fan do more work extends its life.
@@johng.1703well, it’s actually doing less work. Greater resistance means less work is being done. Think of it in purely DC electrical terms. Greater resistance means less current. I think it’s either the same current or lower, so no extending the life by limiting airflow. You could probably extend the life of the bearings that way though. I have one of those setups, but put a 3 way switch on it bc it was a multi speed fan. Low has plenty of airflow.
@@kempie9901 so if I strap 100KG of weights to your legs you are going to be doing less work running a marathon than without those weights right?
blocking the exit is creating a greater air pressure, aka more dense air, which the blower has to work harder and compress the incoming air. so it doesn't turn as fast as it is doing more work to turn the blower. now there are going to be electrical connections that while not moving as fast, there is going to be more current flowing through them.
if you really want to test this out, use a vacuum cleaning and restrict the intake, it isn't going to like it and the power consumption is going to go up and the motor is going to get hotter.
@@johng.1703you should calm down my guy. I wasn’t saying anything negative towards you. When you restrict the airflow causing less air to flow, by definition, less work is being done. May be less work for the same amount of current, but it’s less work nonetheless. Your analogy of adding weight to a runner is not even close to the same thing because you are causing MORE weight to be moved.