View Full Version : Variable speed settings
Pvencius
Dec 11, 2008, 05:37 PM
New Goodman 95% V/S furnace s not cycling as the brochure stated. States it runs 90% of the time to circulate air. My contractor says to fun the fan on the ON position to achieve but that will make it run 100% of the time. When in the auto setting it seems to cycle similar to the old heater, on for a while then off, nowhere near the 90% like it is supposed to be engineered? Should it be set in manual vs auto and in auto should it run more often?
MarkwithaK
Dec 11, 2008, 05:40 PM
And here we go! VS motors are, in my opinion, more trouble then they are worth. I tend to shy my customers away from variable speed motors.
KC13
Dec 11, 2008, 08:42 PM
I'm a big fan of variable speed equipment myself, and my home is equipped with such. I have seen a few failures over the years, but they were usually attributable to something external (moisture, incorrect voltage, etc.). Automatic vs. continuous operation is a matter of personal preference-if comfort is improved with continuous operation, then go with it. I do and the comfort level is much more consistent throughout my home, but this is not always the case. If you use the auto selection, the blower only runs during heating and cooling cycles. In the continuous mode the speed will ramp up during a cycle, then ramp down to a lower speed in between cycles. Variable speed motors typically convert the AC power supplied to DC, and at low speed measurable power consumption is greatly reduced. When I say measurable, I am referring to your electric meter-it is designed to measure power consumption in the form of a wide-band elliptical sine wave. Conversion to DC narrows and squares the sine wave, hence the meter doesn't recognize as much power consumption. P.S. I do not wish to discredit MarkwithaK's statements-variable speed is not necessarily for everyone, and perhaps he has seen a high failure rate in his area. Strange as it is, some things work well in some areas, not so well in others.
Pvencius
Dec 12, 2008, 02:57 AM
So the brochure "runs 90% of the time" is not correct?
KC13
Dec 12, 2008, 04:34 AM
Well, I would hope that the manufacturer knows their own product. They may have some quirk that varies from others, but the operating scenario I described before is pretty typical of most variable speed units. Does the brochure give any specifics on the other 10% when the blower might not run?
Pvencius
Dec 12, 2008, 06:18 PM
No
hvac1000
Dec 12, 2008, 07:04 PM
Strange as it is, some things work well in some areas, not so well in others.
It has to do with power conditioning by the utility. Factory variable speed is junk and the price of replacement parts is out through the roof when it is out of warranty. I prefer the add on type since you just use the same standard 3-4 speed motor. Been using variable speed of the add on type for over 30 years and never lost a unit or motor because of it but the factory GE/Regal-Beloit setup that is in the variable speed units now by all the manufactures is just to expensive to repair. There is NO reason to convert to DC just for variable speed.
MarkwithaK
Dec 13, 2008, 12:34 AM
My point wasn't about the quality of VS motors but more in line with the cost of replacement/repair. I have priced a replacement VS motor from my supplier and at my cost you can damn near buy a new furnace... without a variable speed motor lol. Factor in markup and labor and that supposedly money saving device just cost you a butt load of money.
hvac1000
Dec 13, 2008, 12:46 AM
Eventually there will be no savings with a factory variable speed setup. The replacement parts will take care of all that savings. LOL
MarkwithaK
Dec 13, 2008, 09:50 PM
I'm sure that sales reps will show a customer all the numbers outlining their potential energy savings but I would bet my last beer that nowhere in the companies literature do they layout the high repair costs of the units with variable speed motors.
KC13
Dec 14, 2008, 09:23 AM
Whoosh! What was that? Look! Up in the sky, it's.. it's... VARIABLE SPEED MAN! Yes, Variable Speed Man, defender of the virtues and benefits of variable speed HVAC equipment. Together with Bryantman, he battles the forces of skepticism and discomfort...
Pvencius
Dec 14, 2008, 10:15 AM
Guys, Thanks to all for your comments but the main questions have yet to be answered as with my contractor. Are these units that new that we really don't know how they are supposed work? If the 90% run time per the MFG is supposed the be achieved in the auto setting why can't that be without running in the ON mode which again is 100% run time? The point of repair costs is appreciated but I'm beyond that now and just want the unit to run the way it is engineered.
hvac1000
Dec 14, 2008, 10:24 AM
The difference between 90% and 100% is a no contest overview. Is the 10% really bothering you? The reason I say that is brochure's have been known to be wrong. Get the installers manual if you really want the strait story. Post the Real/Exact model number and I will see if I can find one on the main frame. I might get lucky and find one but no guarantee.
Pvencius
Dec 14, 2008, 06:14 PM
Thanks... GMV950704CX. Look forward to your reply.
hvac1000
Dec 14, 2008, 06:39 PM
Thanks...GMV950704CX. Look forward to your reply.
Goodman variable-speed furnace runs 90%
of the time in the low-heat capacity on most days,
but when the weather is very cold, ramps up to
high-heat capacity so that your family stays
warm and snug.
QUIET OPERATION
Your Goodman High-Efficiency Furnace uses
a multi-speed induced draft blower motor and
variable-speed circulating blower to reduce the
noise levels common in other furnaces. Since this
unit runs in low-heat stage 90% of the time, the
impact of the normal high-fire sound is eliminated
90% of the time. Add to that a fully insulated,
heavy-gauge steel cabinet, and the result is…
extra-quiet comfort.
YEAR-ROUND
ENERGY SAVINGS
Energy efficiency
All it states is when the unit runs it will be in the low stage heat mode 90% of the time. The blower is not to stay running 90% of the time just the furnace WHEN it has a call to run.
Here is a link to the paper you were talking about.
Your furnace is operating properly.
https://www.acwholesalers.com/EasyEditor/assets/gmv95brochure.pdf
Pvencius
Dec 16, 2008, 02:42 PM
Thanks to all!
hvac1000
Dec 16, 2008, 03:07 PM
Yep
MarkwithaK
Dec 16, 2008, 07:13 PM
So can we go back to VS motor bashing now? Lol
KC13
Dec 16, 2008, 07:17 PM
Perhaps an online roundtable debate... with mudslinging and everything!
MarkwithaK
Dec 16, 2008, 07:19 PM
No mud in NW Indiana. But w are getting a nice snow fall right about now. How about a snowball fight instead of the mudslinging?
hvac1000
Dec 16, 2008, 07:23 PM
Read
http://www.alpinehomeair.com/related/Goodman%20GMV95%20Technical%20Information%20Manual .pdf
KC13
Dec 16, 2008, 07:29 PM
No snow here. You throw snow, I'll throw mud back...
MarkwithaK
Dec 16, 2008, 07:30 PM
Fear the Ice Ball!!
hvac1000
Dec 16, 2008, 07:33 PM
Crap weather here also.
MarkwithaK
Dec 16, 2008, 07:39 PM
Crap? I love this weather! Better to be snowing then raining.
hvac1000
Dec 16, 2008, 08:48 PM
Crap? I love this weather! Better to be snowing then raining.
I hope my set back is still working
KC13
Dec 16, 2008, 08:51 PM
Excellent Igor, excellent! We just need a brain and some lightning...
hvac1000
Dec 16, 2008, 08:54 PM
Excellent Igor, excellent! We just need a brain and some lightning...
No problem it is only controlling the back up.
KC13
Dec 16, 2008, 09:00 PM
Looks like dual-fuel with a vengeance...
hvac1000
Dec 16, 2008, 09:07 PM
Looks like dual-fuel with a vengeance...
The hardest working boilers in show business. My layouts always work. If they fail I blame someone else.
KC13
Dec 16, 2008, 09:10 PM
"To err is human. To blame someone else shows good management skills."
MarkwithaK
Dec 16, 2008, 09:56 PM
I hope my set back is still working
The only potential problem I can see with your system is the Snoopy thermometer. Could get a little hinky in high fire.
heating1cooling
Dec 20, 2008, 08:31 AM
Your contractor is correct in telling you to turn the fan to on. Yes it will run 100% of the time that is just what you want. Just to mention a few benefits 1- More even temperatures from room to room 2- Better air filtration 3- Less temperature swings between the on and off cycles.
When the fan switch is on the on position the motor runs at a much lower speed and uses depending on the model about the same as a 50 watt light bulb.
KC13
Dec 20, 2008, 08:39 AM
Your contractor is correct in telling you to turn the fan to on. Yes it will run 100% of the time that is just what you want. Just to mention a few benefits 1- More even temperatures from room to room 2- Better air filtration 3- Less temperature swings between the on and off cycles.
When the fan switch is on the on possition the motor runs at a much lower speed and uses depending on the model about the same as a 50 watt light bulb.Finally, someone who gets it... You're new around here, huh? Careful of the variable-speed bashers, they will try to turn you to the Dark Side... :D
hvac1000
Dec 20, 2008, 10:12 AM
Someone missed the point. Reread the first post. LOL
MarkwithaK
Dec 21, 2008, 12:51 PM
heating1cooling, if you had bothered to read through before jumping the gun on the rate button you would have read that my issue with VS motors is their repair/replacement costs and NOT their quality. Much higher repair/replacement costs are a fact on these motors not my opinion.
MarkwithaK
Dec 21, 2008, 12:52 PM
Finally, someone who gets it...You're new around here, huh? Careful of the variable-speed bashers, they will try to turn you to the Dark Side...:D
The Dark Side eh? Is that when your VS motor goes out and after replacing it you cannot afford to pay the light bill? :p
KC13
Dec 21, 2008, 01:21 PM
Good one... we should take our act to the comedy forum!:D
heating1cooling
Dec 21, 2008, 03:24 PM
Mark,
If you use good reliable equipment you have at least a 5 if not 10 year warranty on the motor.
We use Trane and have been VERY PLEASED with the reliability and performance if you take the time to set up the unit properly.
KC13
Dec 21, 2008, 03:32 PM
Mark,
If you use good reliable equipment you have at least a 5 if not 10 year warranty on the motor.
We use Trane and have been VERY PLEASED with the reliability and performance if you take the time to set up the unit properly.Several of us respectfully disagree regarding the virtues and/or drawbacks of variable speed, but the rib-poking has been good natured fun for the entire family. I, for one, wouldn't want it any other way.;)
hvac1000
Dec 21, 2008, 04:54 PM
Mark,
If you use good reliable equipment you have at least a 5 if not 10 year warranty on the motor.
We use Trane and have been VERY PLEASED with the reliability and performance if you take the time to set up the unit properly.
In the tests at the university the factory variable speed units (GE/Regal-Beloit) do work but there cost benefit ratio including replacement at a given point and time does not balance out in the customer favor. Parts warranty or not since labor has to be calculated into the mix. Almost all manufactures give a 5 or 10 year warranty so that is not a problem even with the lesser priced equipment. Service is also a problem since most service trucks are not equipped with the proper tools/spare motors and electronics or manuals to properly test out the entire circuit on the variable speed DC drives.
Variable speed drives of this type also have a difficult time if asked to work out of range as may happen on a replacement system with restricted or extended duct work. They bounce up speed and down trying to find a comfortable speed during this time of additional stress. I am not going to write a book but I have had the opportunity (as a gift from GE) to equip my entire home system (all 3 air handlers) with there variable speed products for free as a demo. I passed on that offer and still stay with my Fan Handler/A-1 style units with Baldor motors.
MarkwithaK
Dec 21, 2008, 07:10 PM
Mark,
If you use good reliable equipment you have at least a 5 if not 10 year warranty on the motor.
We use Trane and have been VERY PLEASED with the reliability and performance if you take the time to set up the unit properly.
I understand what you are saying and again I am not commenting on the quality or dependability of a variable speed motor. Let me say that one more time just so we are clear... I AM NOT COMMENTING ON THE QUALITY OR DEPENDABILITY OF A VARIABLE SPEED MOTOR.
My beef with VS motors are their high replacement costs. I've priced a replacement motor and it came in around $700.00 MY COST. Factor in the usual mark-up, taxes and labor and your looking at well over $1200.00. Compare that with the cost of replacing a normal 4-speed motor. Now you tell your customer that it'll cost over $1200.00 to repair his VS equipped furnace that he bought 5-10 years ago.
For comparison reasons, I can buy a non-VS high efficiency unit for $700.00 - $800.00.