ECM blower motors?

I was wondering how many of you have experience with the ECM (electonically commutated motor) variable speed blower motors in HVAC systems? My primary concern with them is reliability because the motors are much more expensive than standard drives. (Because of the tax credit for the highest efficiency furnaces, there is really no penalty for the initial install...only a maintenance, repair concern.)

Some of the HVAC folks complain about them having high failure rates. New tech often gets a black eye early on due to such problems and still carries they stigma in later years even when it no longer applies. So what are your experiences with ECM blowers? If you had a failure was it the drive's fault, improper system set up, improper maintenance, poor fit?

The ECM looks like a perfect fit for what I need to reduce stratification and therefore heating/cooling costs while at the same time using less electricity to drive the blower.

This is a bit like making the jump to a front loading washer was...maintenance/reliability rumours are the only major concern remaining.

 

I don't know as I'm not a EE. I've been under the impression that the way these are controlled they maintain power factor well--better than a standard lightly loaded motor. Came across the following quote "At full load the PRICE ECM motor is 20% more efficient than a standard split capacitor motor. In addition, its permanent-magnet, DC design, absence of rotor losses and high power factor allow it to maintain its high efficiency over a wide speed range." This is from a vendor site (Price) but is almost a direct quote from the GE 2.3 motor info. The 2.3 is the motor the unit I'm considering would have.

Brings back memories of redesigning reactor stirrers that used 200 or 300 hp variable speed drives...

I've wondered about this as well, but in defense of CFL's, wall warts are FAR worse. Pretty much all the electronics and wall warts I've tested that were running very light loads had power factors down in the 0.2-0.3 range. Consider they are often pulling current 24/7 where most CFL's are not, I believe the article's concern may be misplaced or too narrow. Many PC power supplies also have low power factors in the 0.65 range. So CFL's might be catching some heat for this, but I suspect they are not even the largest offenders in the average fully CFL home.

The article is very incomplete. The whole home network and typical residential distribution network should be analyzed before drawing conclusions. And I wish she had spelled "Kill-a-watt" correctly.

I've seen some other discussion that suggests CFL's phase lead while other devices in the home lag--effectively cancelling out some or all of the CFL effect. It's been about 20 years since I did electrical phase calcs and I was terrible at the EE stuff, but I still have a fuzzy recollection of some of it.

Would I be correct in assuming that the inverter set up of PV solar and the "on-site" generation makes this a non-issue for those with an array? The transmission loss effect would disappear or be reduced, correct?

I'm about 1.5 miles from the power plant so my line losses should be close to the minimum for a residence on grid.

Just did some tests and my Kill-a-watt meter is showing PF's as follow:
Double circline CFL on dimmer = 0.55 (low) - 0.63 (high)
GE 100W = 0.65
nvision 100W = 0.64
nvision 60W = 0.67
Sylvania micro-mini 60W = 0.62

 

That's what I intend to do for summer. Should use about a quarter as much blower power as it took last summer and be silent as well...plus I don't have to pay for the AC compressor to remove the wasted blower power being added to the home. This latter bit is ironic since running the blower in the peak months minimizes the stratification of the various levels so that the home is more comfortable AND the AC runs less than it would otherwise. This is an example of why you don't want a blower running all out except for those times when it actually improves furnace/compressor efficiency.

Another irony is that when folks sell the more electrically efficient ECM motor packages the given efficiency furnace will actually use slightly more gas. The reason is that the wasted electricity is entering the airstream as heat. Remove the heat source with a more efficient motor and you have to add more gas to compensate. This matters more for folks getting cheap hydro electric and paying more for their furnace gas. For me the trade-off is favorable because my natural gas is running lower on average while electric rates are being increased to fund powerplant replacement projects.

Thanks. That's what I'm hoping as well. I had bearing's seize in an old 60% belt drive blower a long time ago (I had lubed them several times a year...but I don't think any previous residents had because they took a lot of oil that first time and I had trouble clearing the dust from the ports.) I couldn't get a new replacement bearing set but with permission I was able to scavenge some from another vintage unit that the local dealer had just torn out. The blower frame narrowly missed fitting in my housing but I was able to swap out the bearings/arms.

 

Well, I certainly am in over my head, but the water is warm...not sure that I want to know why. :yuck:

As a follow up I read PF's for the two long tube fluorescent fixtures in the house. One is two bulb type in hanging fixture in the garage--pretty common, cheap looking shop style. It read 0.58 after warming up. The other is a very long 2x2 two bulb fixture providing indirect lighting. It read 0.99--interestingly it was pulling only about 108W rather than the 128W the bulb ratings add up to. I'm not sure if that is due to age of the bulbs, or if it is the ballast.

 

Calling on my very limited understanding of electricity...
The measured watts are the same, it's the volt amps that are higher (actually just the amps while the voltage wave form is distorted.) The lost portion is the reactive load. And this requires more current from the utility.

We each get charged for kwh power used, not the reactive component (1-PF). So we as consumers aren't paying for the reactive load directly.

Where exactly correction can be made for the reactive component is not clear to me. Obviously it is done in some ballasts like the one in my house (that I measured above.) But it might also be done in some fashion by the utility. I have the impression that the how and where determine the actual losses to the utility.

The losses: amps squared times resistance is what will determine the utilities losses. One can determine the actual amps for the bulb/device. But what is the resistance? Well, you've got the resistance in the home wiring...but then there is the bundled current to the house. Then there is the transformer, grid wiring, substations, and the actual generation facility(ies).

Add to this there are a lot of loads in the home, some are leading (capacitive), some are lagging (inductive) and some are resistive (PF=1.0). In an ideal world the leading and lagging would cancel each other out, but I doubt that is applicable here. So what I really want to know is what is the effective impact on the grid.

I came across the following undated (???--appears to be early 1990's) Berkley report about CFL harmonics. http://gaia.lbl.gov/btech/papers/33361.pdf Interestingly, they only show the sub 0.5 PF's for 60 Hz CFL's, and the higher PF's (like what I measured) for higher frequency CFL's. I think I smell a rat: Luminaire Testing Laboratory. I have to say I was VERY unimpressed by the lab not even testing the PF of a few bulbs before setting up their system. It's hard for me to take such a "test lab" seriously in the light of their lack of planning and this looks very much like grandstanding to draw attention to themselves.

I guess what we need is someone who really knows their stuff with regard to the real world utility grid and typical loads to give us some examples of what sort of calculated line/utility losses could be expected from converting a home/neighborhood from incandescents to CFL's. I suspect this has already been considered some time ago when CFL standards were set...