New gas furnace/AC recommendations?

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Steve full-quoted:

What-ever they are, they're not going to last as long as the ones being made 30 and 40 years ago - many of which are still functional even if they've been replaced by new garbage.

Don't give me that "correctly installed" crap.
A furnace is a box where you connect wires and ducting and turn the friggin thing on. It's a glorified barbeque.
Any new furnace that can't be plugged into any existing house's ductwork and work correctly is a piece of shit.
As bad as the existing ductwork is or can be, you shouldn't have to tear it down and re-do it just to satisfy the hyper-sensitive requirements of a new furnace or it's delicate, wimpy ECM blower motor.

Pathetic.

If you mean electronics *inside* it, it's that very fact that I'm bitching about. Just because you can't buy one that doesn't have a frakken motherboard in it doesn't mean you can't bitch and complain how unnecessary it is to have it.

My furnace is 36 years old and is original to the house when it was built in 1976 which I bought 11 years ago. I have no idea where this furnace ranked in the marketplace at the time, but obviously they made quality stuff back then, before the industry went into the toilet in the last 10 - 20 years.

I'm very happy with it, and if I ever have to replace it, I'm going to modify any new furnace I get by swapping it's ECM motor for a PSC one, and remove the electronic ignition and replace it with a standing pilot, and rip all the electronic flame and other sensors out of it, along with the frakkin motherboard.
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useable "old school" furnaces - you'll have a hell of a time modifying the new ones to take the old parts!!
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I don't know what you consider "cheapest, lowest efficiency", but I'm looking at quotes for a Rheem 120K BTU, 95% efficient furnace that meets the govt high efficiency standards for the tax credit. And it has a single speed PSC motor. Can also get the same furnace and AC system from Trane, for $800 more.
While I don't agree with Home Guy on everything, I do agree that in many cases the extra cost of models with an ECM blower aren't worth it. That's from two standpoints. First is that those models only save on the blower electricity. And then independent studies have shown that you get the 40% electricity savings if the duct work is ideal. If it's good, you get like 25%. If it's typical it's more like 15 -20%. And if it's poor ducting, you get 10% to -10%. So, for maybe a 15-20% savings, you have a significantly higher initial outlay, plus exposure to higher repair costs if the blower motor or it's added drive electronics fails.
I can see going with the variable ECM motor if you want to run the blower 24/7. Or if you highly value that it starts up quietly, can run at low speed longer to even out heat better with a two stage furnace on mild heating days. Or can run on slow speed with AC to dehumidify better. But none of those are that important to me.

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snipped-for-privacy@optonline.net wrote:

I'm guessing that it's increasingly high targets for energy efficiency (combustion and electrical) set by gov't regulations is the reason why we're seeing the use of ECM blower motors in consumer HVAC equipment, just as we see the same when it comes to saftey equipment (air bags, ABS brakes, CAFE and emissions standards) in cars. Probably the same reason for electronic ignition vs standing pilot as well.
I can't believe that we'd see widespread use of ECM motors under true free-market-driven conditions (ie - with no gov't efficiency mandates or constraints).
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A lot of us don't live where they have 9 months of winter sports, and humidity control is a huge issue. Where I am, we run A/C from March 1st until November 1st with average summer temps of 90F with 75% to 85% RH you can *DO* what you want, you can be as ignorant as you want....thats your problem.
I do this for a living, and I *KNOW* first hand what the benefits of the new systems are, and how much my customers utility bills have dropped, as well as their comfort level increasing.
You can *TRY* to re-engineer a new furnace by taking out the electronics, ECM motor, and electronic ignition... Just remember that as soon as you screw with it, you have voided the warranty, as well as the UL ratings and if you burn your house down, your insurance company will deny the claim.
Maybe you should get a job in the engineering department with the equipment manufacturers.
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On 12/11/2010 12:53 PM, Steve wrote:

Steve, you can verify something for me because you do more of this work than I do. I've noticed a dramatic drop in price for the ECM motors over a period of time and I assume it's because millions of the things are being produced now, economies of scale. I'm seeing an ECM replacement for PSC motors offered like the Genteq EverGreen and I'm wondering if you've converted any air handlers for customers or have considered it?
TDD
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The Daring Dufas wrote:

I think that's still made by GE

At least tell us what the over-the-counter (cash and carry) price is for an ECM drop-in replacment 1/4 hp NEMA-48 1700 rpm PSC motor.
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They are not interchangeable.
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------------------ http://www.aosmithmotors.com/uploadedFiles/Website/Products/Distribution_HVAC-R_Motors/6850_Web_9-10.pdf
The Comfort Select FB motor is a brushless, direct current (BLDC), permanent magnet, electronically commutated motor (ECM). The motor is controlled by integrated electronics providing high efficiency, advanced motor protection, and has the same performance characteristics as a PSC motor. The Comfort Select~FB motor is designed as a direct replacement or retrofit product for a PSC motor. ------------------
This brochure is confusing, because on the last page it lists 5 different HP sizes, while seeming to indicate the availability in only 2 HP sizes (1/2 and 1 hp) which is strange since I wouldn't think that a residential furnace would need anything larger than 1/3 hp.
The power consumption of the 1/2 hp unit (6.3 A at 115 V) seems excessive.
Example retail pricing:
------------------------ http://www.alpinehomeair.com/viewproduct.cfm?productIDE3062575
Upgrade your furnace or air handler to a high efficiency, variable speed blower motor without having to make complex changes to your system. The RESCUE EcoTech motor drops into existing PSC (multi-speed) induction-blower applications, without making complex wiring modifications or changes to the system controls. Just connect the leads, and youre done! No 24-volt signal leads or setup required its plug and play.
With the increased efficiency and available low circulation of this motor, you will be free to cycle air continuously without a significant increase in utility bills. Continuous fan operation supports improved filtration, helping to clear the air of dust and allergens all the while making your home more comfortable by working to reduce temperature variations throughout the home.
The RESCUE EcoTech motors advanced design also features active airflow management, which allows the motor to compensate for static pressure changes to help maintain airflow. This means that as vents are closed or the filter becomes full, the motor will attempt to maintain the same airflow, helping to keep the system operating efficiently and the home comfortable.
Standard Features
* Easy Installation - Drops into existing PSC (multi-speed) direct drive induction-blower applications without making wiring modifications or changes to the system controls.
* Quiet, Efficient Circulation Speed - The advanced motor design provides a low, 600 rpm circulation speed, so you can cycle air continuously without the noise, draft or electricity cost of a PSC motor.
* Money Saving Efficiency - Save money on your electric bill just by replacing the existing PSC blower motor in your furnace or air handler.
Product Specifications
Volts 115 VAC Blower Motor Horse Power 1/2 HP Rotational speed in revolutions per minute 1140 RPM Number of Blower Speeds 5 Motor Warranty 2 Years
Your Price: $323.99
Emerson EcoTech Estimated Electricity Savings:
http://www.alpinehomeair.com/_viewresource.cfm?ID#27 ---------------------------
They estimate annual savings of either $38 (fan runs only during heating or cooling) or $106 (fan runs continuously). This is for the 1/3 hp model, based on 14 cents /kwh.
This place:
http://www.patriot-supply.com/products/showitem.cfm/196266
Also lists the 1/2 hp Emerson 5530ET motor for $323.
The Emerson 5520ET is listed as 1/3 hp by some sellers and 1/4 hp by others. It's priced at about $300.
This is a brochure for the Fasco / Evergreen Motor:
www.fasco.com/fasco/documents/NewsletterJanuary2010.pdf
----------------- Fasco is proud to introduce the new Evergreen motor: the worlds first universal aftermarket Electronically Commutated Motor (ECM) specifically designed to save energy in residential heating and cooling applications. Like compact-fluorescent replacement bulbs now offer an energy-saving alternative to traditional incandescent lightbulbs, the new Evergreen motor is a new high-efficiency alternative for standard replacement motors. It uses proven ECM technology to save energy and moneyevery time a residential HVAC system is in use.
On average, consumers can expect to save over 25% on annual motor operating costs or about $60 in annual heating and cooling operation based on 10/kWh. Even better, consumers can also expect to use up to 74% fewer watts with an Evergreen motor when they run their fans between heating and cooing cycles. -----------------
So basically you're going to spend $300 and probably save $100 a year in electricity if you're lucky, and probably only if you can get an actual 1/4 or 1/3 hp unit - not a 1/2 hp one.
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On 12/11/2010 10:46 PM, Home Guy wrote:

http://www.aosmithmotors.com/uploadedFiles/Website/Products/Distribution_HVAC-R_Motors/6850_Web_9-10.pdf
From looking at the information, I understand that the 1/2hp ECM motor is the replacement for 1/3 through 1/2hp PSC motors and the 1hp ECM is the replacement for the 3/4 through 1hp motors. The ECM motors are adaptable according to the literature and have the programming to learn how to operate much like an automotive engine control unit. It's very interesting what has been done with these new motors. It reminds me of the way switching power supplies have taken over the work once done by less efficient shunt regulated power supplies.
TDD
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The Daring Dufas wrote:

Would you even use a 1/2 hp ECM motor for a home furnace? You certainly wouldn't save any money if you were replacing a 1/4 hp single-speed PSC motor with these 1/2 hp ECM units.

How exactly do they do that?
How does a motor know how much CFM the fan is moving?
Are there pressure or flow sensors mounted in the duct work for that?
How would you use one of those replacement motors when you have an ordinary single-speed PSC motor in a 25+ year old furnace?
Can you apply 115 vac directly to those motors to the appropriate set of wires to make them operate - to hell with this learning crap?
I don't get this learning crap anyways. What is an ECM motor supposed to learn? Don't you just want it to turn at a given RPM? Why all the fuss about finessing the CFM?
If the controller can make the unit start at low RPM and then speed up, that's great. Do it. Why worry about CFM? If the house isin't reaching the thermostat set-point fast enough, then speed up the motor, or turn up the burners.
To me, the feedback the motor controller should get is the difference between actual house temperature and the thermostat set-point temperature. The smaller that difference, the slower the motor needs to turn and the less BTU's the furnace needs to put out. What the actual CFM is is neither here nor there. If the occupants want to over-ride the motor RPM to get ambient circulation, then fine, given them the option for low and medium speed constant circulation mode based on motor RPM - not on some sort of "learning" crap.
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It's been a long time since I've seen a 1/4hp residential blower motor 1/3 seems to be pretty well standard for heating, with 1/2 HP being very common with A/C

It knows how fast it is turning and how much current it is drawing. The current draw is a direct function of the load on the motor, which decreases as the flow decreases

If you have a belt drive blower you will need to replace it with a direct drive blower, or cobble together some kind of mount and pulley setup.

That's all you do - the learning" is built in.

For more economy of operation. Turning the fan too fast can just draw more power, without moving any more air.

That's fine if you are not trying to enhance efficiency.

hotter. Adjusting the amount of flame is what the motherboard you have been cuesing for the last week or two can do. Mine is a 2 stage burner, but there are "modulating" burners as well, that CAN control the amount of heat produced, according to the number of BTUs required (delta between current and desired temperatures)

You just don't (and won't - ever, by the looks of things) get it.
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The fun part is on an induced draft furnace with an in-shot burner set you can't reduce the gas flow without also slowing down the inducer motor so modulating furnaces and I assume your 2 stage have a small ECM for the inducer too that varies speed/flow to match the fuel flow.
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snipped-for-privacy@snyder.on.ca unnecessarily full-quoted:

You might be right.
The motor in my furnace is this:
Emerson SA55NXTE-4513 1/3 HP, 1725 RPM, 5.4 A
It's got a 5" pulley wheel on it, driving a fan with a 7" pulley wheel.

But the motor can't possibly know how many CFM of air is being moved with each turn of the fan rotor.

Actually, once you get the air in the house moving, you should also see a reduction in load. Also, I'm guessing that load will not increase linearly with air-speed or CFM.

If my existing motor is turning at 1725 RPM, and if I'm satisfied by the breeze generated by that RPM, then I sure as hell wouldn't want an ECM motor making it's own decisions about what RPM *it* wants to operate at.
The point of an ECM motor is that its supposed to be more efficient than a PSC motor at ALL rpm's. So if I drop in an ECM motor and wire it up for single-speed operation, I sure as hell would want that speed to be a constant 1725 RPM.

All you ECM-motor apologists are saying that ECM motors are *always* more efficient than PSC motors regardless what RPM they operate at. So now you're backtracking by saying that there's no savings when you replace a PSC motor with ECM if you force the ECM motor to operate at same, constant RPM that the PSC motor did.
What you're saying is that I'm supposed to allow the ECM motor to "learn" and to reduce it's RPM.
That's no different than if I were to replace my 1/3 hp motor with 1/4 hp and put a smaller pulley on the motor vs what I have now. I will use less electricity and the fan speed will be reduced.
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by RPM and current to the most efficient point - at least that's what I gathered. If it runs too fast so the fan is "throttled" the current drops for the speed it is running at, so the motor can slow down 'till the current/rpm ratio ballances out.

You are right - partly. The inertia of the air is not much af a factor, what with air being compressible and all, so there is not much change in power required from "startup" to "air moving" - but the load is not necessarily linear with air-speed or air flow. The counterintuitive thing is the load DROPS when the back-pressure increases. (partly because the actual air movement drops and partly because of the way air behaves in a centrifugal blower (any fluid, actually - look at cavitation in a water pump)

And it would be if that is the right speed - but it MIGHT move just as much air at 1500, or 1375. It might actually move marginally MORE air at a lower speed, because the blower itself may be more efficient at a lower speed.

No, not saying that. It will be somewhat more efficent at the same speed, but may be considerably more efficient, while movong the same amount of air, at a lower speed.

And , depending on your furnace and setup, it may actually be more effective that way.(as well as more efficient)
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snipped-for-privacy@snyder.on.ca wrote:

Sure, the motor can know a lot about it's own current useage as a function of it's own RPM.
But it can't know anything about RPM and fan CFM - without getting feedback from air-flow / air-pressure sensors mounted in the ductwork.
ECM motors can't reduce their RPM to, say, 1600 RPM and magically give me the same CFM as my motor running at 1750 RPM - both given the same fan to turn in the same duct system.

Who says what the right speed is?

Ok, you need to step back and re-think this.
Within a normal range of operation, there is no way that I can turn a given fan at a slower speed and yet get more CFM being moved by that fan.
Again, you think that ECM motors can magically make a given fan move more (or even the same) CFM at a slower rotational speed than a PSC motor at the same speed. You're going to have to explain the physics behind such a phenomena.
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The right speed is the speed that 1) - moves the most air with the least power or 2) allows the most heat to be extracted from the heat exchanger by optimizing the air flow.
Moving more air does not necessarily translate to providing more heat.

Counterintuitive, yes - but if YOUR fan is turning too fast, turning it slower CAN provide the same or even higher air flow - and use less power to do it.

have the same effect.. You could use a brushed DC motor and variable voltage to get the same effect - but ECM motors are less maintenance intensive, longer lived, and (can be)more efficient.
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snipped-for-privacy@snyder.on.ca wrote:

A drop-in replacement ECM motor that's replacing a single-speed PSC motor can't know how much air it's moving, because it doesn't know the size of the fan it's turning nor does it have duct-mounted sensors to tell it the CFM of air being pushed through the ducts.
A drop-in replacement ECM motor can't know anything about how much heat is being extracted by the heat exchanger, because it doesn't have temperature sensors telling it the input and output furnace air temperature.
A drop-in replacement ECM motor can "learn" it's energy-useage vs RPM curve is once it's been installed into a given home's furnace, but that doesn't mean that the most efficient RPM will be satisfactory for the comfort or desire of the home owner.

A drop-in replacement ECM motor will not be getting any feedback from any temperature sensors, so that point is moot.

You actually believe that a 1/3 HP motor running at 1750 rpm though a reduction pulley is going to be turning the furnace fan too fast - to the point that it's actually pushing *less* CFM through a "normal" home's duct system as compared to if it was turning slower?
I said given a normal range of operation - not given some ridiculously high RPM.

What effect?
If I slow down any motor, the fan will turn more slowly, and I will get less CFM.
You keep wanting to insist that in every case where there is a PSC motor, that it's almost certainly turning it's fan faster than it needs to, or faster than the home-owner wants.
Just because an ECM motor *can* run slower than a PSC motor doesn't mean that the resulting CFM is what the home-owner wants.

Tell me why an ECM motor is longer lived - given that we've really only had them in consumer furnaces for the past 10, 15 years max.
PSC motors don't have brushes, nor do they have sensitive electronics that are vulnerable to power surges and nearby lightning strikes, nor do they care much about pushing air though high-resistance ductwork.
What is it about the construction of a PSC motor can you point to as being more sensitive or less durable or more prone to failure vs an ECM motor?
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That is not NECESSARILY true.

I didn't say in EVERY case

And the homeowner is often too stupid to realise that what the FURNACE wants is more important than what he thinks he wants, in some instances.

Lets see. How long have electronically commutated motors been in common use elsewhere???? DC "muffin" fans have been in use in computer power supplies since before the IBM PC came on the market some 30 years ago. If the bearings don't seize up they run virtually forever.
And the ECM, or "Smart Motor" was first marketted for furnace use by general electric in 1969. That's FORTY TWO YEARS of history.

And nor are they anything approaching anyone's definition of efficient.

Because of lower efficiency they tend to run hotter.
Installed PSC motor efficiency is generally in the 12-45% range, which means a LOT of heat is produced. ECM motors generally run 65 to 72% efficiency as installed.. That means a LOT LESS HEAT. Add to this the FACT that a majority of the heat in a PSC motor is produced in the rotor, whech means a lot of heat is transferred out of the motor through the shaft and bearings. This reduces bearing life and stresses bearing lubrication.
I'm not saying PSC motors are failing at extremely high rates - but I have had them fail in signiificantly less than 20 years, and I reject yout hypotheses that ECM motors are either "puny", short lived, or intrinsically trouble prone.
I just saw a few weeks ago a ECM less tham 4 inches in diameter and less than 4 inches long that will put out 14 HP.
In the 20-200 HP range, Brushless DC motors (ecms) are actually less costly than brush DC motors or any other variable/controlable speed AC motors and are extensively used in industrial applications
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On 12/13/2010 10:32 PM, snipped-for-privacy@snyder.on.ca wrote:

ECM motors are being marketed to replace common evaporator fan motors in commercial refrigeration. Those refrigerated cases you see in the grocery store are getting ECM fan motors.
TDD
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