Is a spare fan a good plan?

Discussion in 'HVAC Heating & Cooling' started by jadnashua, Jul 23, 2010.

  1. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,180
    Location:
    New England
    I have a variable speed Trane air handler that I keep the fan on nearly 100% of the time. The thing is now probably close to 20-years old, and the fan still works fine with one exception: if I go away for awhile and turn it off, it doesn't always start up right away when I turn it back on. It doesn't make any noises indicating the bearing is going or anything. I was wondering if ordering a new fan motor and having it around as a spare is a prudent thing. I'm pretty sure I could get one locally, but at a considerably higher price than ordering one on-line. The p/n is Trane MOT05429 or MOT11974, and lists for about $400. I've seen it for $250 or so (anyone have a better price?), and some websites actually list it for even more. This is the bare motor, without the controller. The controller costs about the same as the motor (it's a 1/2Hp, 1200RPM variable speed motor).
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,874
    Location:
    Cave Creek, Arizona
    Obviously, buying something when you do NOT need it is usually less expensive because you can shop for the best deal, regardless of shipping times. That being the case, and assuming your present motor is not going to outlast the air handler, it seems to be a prudent course of action.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Generally, it would never pencil out for a homeowner to stock replacement parts. Another reason it is not a good idea....lets say you bought a widget and 12 years later you need it. The manufacturer by this time may be offering a newer improved model of that widget, which you would miss out on.

    In your present circumstance, you are considering a possible more immediate need. The one question I have is do you want to invests hundreds of dollars on a motor, and find that in 6 months the whole air handler actually has to be replaced? For starters, how old is the outside condensing unit? Assuming it is several years old, if it croaks, the SEER difference and the R410 situation would negate any possibility of keeping the old air handler. SO, you have a crap shoot.

    A Trane OEM variable speed motor will be pricey. I would be suspect of any ".....list" or "......bay" offering that is too cheap!!!!
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,180
    Location:
    New England
    The compressor has already been replaced - about 4-years ago. So, I'm still up in the air on this. The evaporator coil on this unit came separate from the box, so I'm assuming it could be replaced separately if it were to fail. Other than that, what's left are the power supply, logic board, motor controller, and the motor. Unless the fan got mangled if the motor shaft wobbled too much, it should survive. Thus, the only real 'wear' part in the thing is the motor. Not sure if this is something they normally stock locally - may call around on Monday, and check the prices. Sitting without heat or a/c for a couple of days if one had to be ordered would not be good either, and paying for 'emergency' pricing and repair may just pay for having one sitting around. Still haven't made up my mind. As to electronics, I have a couple layers of add-on safety - a whole -home surge suppressor and on the air handler, an ICD power monitor that won't let the power be applied to the fan or compressor if there is a brown-out/excessive voltage, or intermittent power (like after a turn-on after an outage). You can adjust it to delay restart to give the power a chance to become stable. So, hopefully, the electronics themselves will continue to last.
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    You have thought it out pretty well. A Trane master distributor would have the motor, or could get it probably overnight. But the $$$ kicks in!
  6. CarlH

    CarlH New Member

    Messages:
    175
    Location:
    Northern VA
    If the current motor is not starting up like it should, I would certainly consider having a replacement on hand or knowing that one is available on short notice. You might even consider replacing it soon since I suspect that the bearings may be going bad. You might want to check it by shutting the fan down, letting the motor cool off, and then spinning the blower by hand to see how freely the motor fan spins. The other thing to consider is how long you plan to keep this system. A couple of years ago I had to replace my blower motor because the bearings seized up. Got a replacement from one of the local HVAC services for a reasonable price. Before ordering a replacement, you might want to check with you local HVAC shops to see if they stock a replacement and what the price is. I've seen a large variation in the prices when I have shopped for parts online.
    Last edited: Jul 24, 2010
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