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russp · Mar 25, 2007, 08:22 PM

Ok, a recent thread mentioned something about upgrading the blower motor. That's exactly what I want to do. My reasons are that, while the air gets cool enough, the flow is just not what I would like probably mostly due to the crappy flex ducts the builders use these days. One solution that has been suggested is to upgrade the blower motor on my Trane. I looked at the furnace and the current blower is already connected to run at the maximum speed on the circuit board so any increased CFM would have to be from either a new furnace, replacement of flex ducts with sheet metal, or new blower.

Where might I find suitable blower replacements for this Trane air handler? I probably can figure out what the max load the circuit board can handle by looking at the installer handler which I own, but I have no idea how to identify which blower to buy and what will fit in this Trane.

Thanks,

- RP

letmetellu · Mar 25, 2007, 08:54 PM

More of a problem than what the circuit board can handle is the amount of air that your AC can handle. When you are running the AC you want enough air going across the Evaporator coil to lower the temp of the air entering the return grill around 20 degrees F. where it leaves the Evaporator coil. Speeding up the air flow will only raise the temp of the air coming out of the duct work. Lowering the speed will lower the temp and if slow enough it can result in freezing tanking place in the Evaporator coil, thereby slowing the air even more and causing more icing leading eventually to a completely blocked evaporator coil.
It could be that you have too many opening for the amount of air that goes through the duct work or maybe that your system needs to be balanced so that the fight amount of air goes to each room.

labman · Mar 26, 2007, 04:12 AM

Your first step might be to look at the coil inside and make sure it is clean and free to cool the air. If it is blocked with a bunch of crud, the air coming out will neither best as strong or as cool as it should be. Then check the differential. It is possible they cut corners on the installation and you don't have enough air flow. It should have been checked and the jumpers set to give adequate air flow. However if the maximum speed you say you are using, wasn't quite enough, the installer may have left it that way hoping for the best.

If you have a clean coil, no leaks or restrictions in the ducts, the system isn't freezing up, and greater than 20 degree differential, then you may want to look at a higher speed motor. You could get all the data off your current motor and take it to an electrical or HVAC supply and see if they can help you. You could also go to the web site of the manufacturer of the current motor and check for a motor with the physical dimensions of yours, but a higher speed.

russp · Apr 3, 2007, 05:09 PM

Originally Posted by labman

Your first step might be to look at the coil inside and make sure it is clean and free to cool the air. if it is blocked with a bunch of crud, the air coming out will neither best as strong or as cool as it should be. Then check the differential. It is possible they cut corners on the installation and you don't have enough air flow. It should have been checked and the jumpers set to give adequate air flow. However if the maximum speed you say you are using, wasn't quite enough, the installer may have left it that way hoping for the best.

If you have a clean coil, no leaks or restrictions in the ducts, the system isn't freezing up, and greater than 20 degree differential, then you may want to look at a higher speed motor. You could get all the data off your current motor and take it to an electrical or HVAC supply and see if they can help you. You could also go to the web site of the manufacturer of the current motor and check for a motor with the physical dimensions of yours, but a higher speed.

Good advice. I know the coils are clean as I had them checked at the end of last year to make sure. He also checked the coolant levels and said they were fine. I think part of the problem is the flex duct has sagged in a few areas (I'll fix that). Then I'll measure the air temp to see the differential. If it's poor I'm going to guess it needs more coolant, despite what the last professional said.

Would there be any real benefit to replacing portions of the flex duct with true metal ducting? The flux duct seems like it just is too easy to restrict air flow given it's lack of a smooth interior.