Great video!! i learned quite a lot about all the different type of motors in furnaces. Regulation from Department of Energy- New furnaces built after July 3rd 2019 cannot have PSC motors inside of them. condenser
True, PSC motors no longer meet the minimum efficiency requirements of the DOE for furnaces. However, PSC motors do make up the bulk of the existing furnace installed base.
@@TECTubefilms Okay But does that apply to newer AC Condensers build on/after 2019 as well? Since they too use similar motors like you find in Furnaces.
@@d6487 No, that DOE fan motor efficiency rule only applies to furnace motors. AC Condenser motor efficiency is already built-in to the SEER rating so a sperate rule for their motors specifically is not required. Whereas furnaces only had AFUE which was for the combustion efficiency only and electric efficiency had nothing previously.
Funny I didn't hear anything about replacement costs you're going to play triple if not four times as much for those other motors so all the savings and electricity straight down the tubes
Wow you’re the only one to explain the difference between variable speed and ecm.. thanks! I know with an increase in static pressure psc motors aren’t affected but It can kill an ecm motor. Do variable speed motors have the same issue with high static pressure? Thanks
All motor types are affected by high static, but the issues are different. For PSC and constant torque ECM, the higher the static the lower the CFM for a given speed setting. For variable speed ECM, high static won't affect the CFM, but the fan will be forced to run at a higher speed and hence it will be lounder than expected, generate more waste heat than normal, and possibly fail sooner.
I'm looking at a Bryant 80% evolution with a 4 ton VS drive. I have a couple of question. 1st can I use any thermostat with this furnace or do I have to use the EVOLUTION CONNEX CONTROL? 2nd I'm looking to put a Bryant 3 ton condenser with this unit. Can I use this 4ton VS drive with the 3 ton condenser? Will the VS drive still give me what i need? Thanks
How does the PWM motor know when to adjust speed? Is the PWM motor's initial speed set by the tech based on the required CFM that the system requires? So, the tech would measure static pressure, then look at the blower chart and set the switches on the motor that corresponds to the existing static pressure and required CFM based on the load calc and equipment, then the motor adjusts itself based on changes in what monitored information? Changes in amp draw?
Everything you said is accurate EXCEPT the last part. The motor does not monitor conditions or adjust itself. A PWM motor (at least as used in a Carrier furnace) is a constant torque motor, not a constant airflow motor. The tech sets speeds with dip switches for the desired airflow. Then after that, the speeds only change as the system calls for different modes or stages. If something happens in the system (dirty filter, shut vents, etc) the motor does not know that and does not adjust for that.
Unrelated to PWMs, there are true variable speed motors in higher end Carrier furnaces. With those, the motor tracks static, RPM, and CFM and makes adjustments. It is a constant airflow fan instead of a constant torque fan. So if a filter gets dirty, the fan will run a higher speed/torque to get the required airflow.
From an energy standpoint, they would similar. However, from an operation standpoint it would be very different. At our own houses, most of us have a fully variable speed communicating ECM.
Replacing a PSC with an ECM is pretty straight forward. There are retro-fit kits for that. Going to variable speed would be harder and in some cases not possible.
@@TECTubefilms thanks for responding. I have a Tempstar furnace with an Emerson motor and just 4 wires. Red, blue and yellow plus a ground. The schematic shows it's DC and it has a control board which feeds a speed control, then the motor. I believe my problem is with the speed control, as I'm not getting any voltage to the motor, but when I connected a power supply to the motor it moved.
Motor type will not solve an issue with undersized ductwork. PSC, ECM, PWM, and VS ECM will all exhibit various symptoms in a poor application like that.
We would ask, is the duct work undersized to move the air needed to keep the furnace online? Or is the ductwork undersized relative to the space load? That answer will determine different potential solutions.
How do you determine if your ducts are undersized? Do you use Manual D to calculate the cfm that the ducts will move and compare that result with the cfm required from the load calc? Ive heard that youre supposed to size equipment to the ducts, even if theyrr undersized.
@@affinity1 This is a bit of a loaded question. Are you asking how to determine if the ducts are undersized for the home's needs or if the ducts are undersized for the existing furnace and A/C they have? Since ALL.. we repeat ALL... equipment is grossly oversized by the HVAC contractors, you won't likely have the right size ducts for both the house and the equipment. This is how the process SHOULD go... in this order: 1) "room-by-room" load calc to determine the heating and cooling BTUs needed to each zone 2) size the diffusers and branch duct for each room based on the CFM needed for the larger of heating or cooling BTU/h calculating in #1 3) size the main supply to carry the CFM needed for the sum of the branch ducts it feeds 4) repeat steps #2 and 4 for the return duct system 5) size the equipment for the total BTUh needed
@@affinity1 You will also know if your existing ducts are undersized (relative to the furnace and A/C) if you have some of the following symptoms: 1) furnace high limit trips 2) inability to install high MERV filters due to lack of airflow 3) external static pressure measurements in excess of 0.7" 4) high heat rise measurements on the furnace 5) low delta T across the evaporator coil 6) furnace heat exchanger cracks (even small ones) The solution is to either enlarge both the supply and return ducts to accommodate the oversized furnace OR do a more accurate... and aggressive... load calc to determine a smaller size furnace and A/C can be used on the house
X13 is a brand name of Genteq (now owned by Regal Beloit). It came out about 15 years ago. It is a specific version of an ECM with pre-programmed torque ratings. In terms of the high level overview of this video, there is nothing different about the X13 brand name that needs to be mentioned. It can be lumped in with all non-variable speed ECM. If this was a service video that dived into details, then more delineation might be necessary. Please take a look at our motor playlist with includes Regal's video series on X13. czcams.com/play/PLoR_O4JRNc26An0QF_ygah4LX72Vj8URd.html
Do new furnaces still use shaded pole motors? Shaded pole is less efficient than PSC motors... and PSC motors became obsolete due to FER a couple months after this video was published.
Don't confuse the marketing terminology habit of referring to various ECM motors as either constant torque or constant airflow to mean that only ECM motors are constant torque. A PSC motor is also constant torque. Torque is inversely proportional to speed. A PSC motor or a regular ECM motor are given a speed command which results in a certain amount of torque. That speed and torque do not change during that mode. Hence... constant torque.
@@TECTubefilms -- If you restrict the return air to a PSC blower, the airflow and current are both reduced. How could that be considered Constant Torque? A quick Google search turned up these and more like them: "What differentiates constant torque motors from PSC motors is their ability to deliver constant torque (i.e., rotational force or power output down a shaft). In other words, if the ESP changes, then the motor program will maintain the amount of torque for which it was programmed" "As static pressure increases, a PSC motor’s performance drops off, because it cannot adjust speed or torque" "What differentiates constant torque motors from PSC motors is their ability to deliver constant torque (i.e., rotational force or power output down a shaft)."
@@rpsmith The article you Googled was from 12 years ago and essentially written by Regal-Beloit... who only makes ECM motors. Of course, they tried distinguish as much between PSC and ECM. If you noticed, they never say that PSC is not constant torque.
@@rpsmith You even quoted the article specifically stating "As static pressure increases, a PSC motor’s performance drops off, because it cannot adjust speed or torque." If it can NOT adjust torque, then that means the torque is constant.
Great video!!
i learned quite a lot about all the different type of motors in furnaces.
Regulation from Department of Energy- New furnaces built after July 3rd 2019 cannot have PSC motors inside of them.
condenser
True, PSC motors no longer meet the minimum efficiency requirements of the DOE for furnaces. However, PSC motors do make up the bulk of the existing furnace installed base.
@@TECTubefilms Okay But does that apply to newer AC Condensers build on/after 2019 as well? Since they too use similar motors like you find in Furnaces.
@@d6487 No, that DOE fan motor efficiency rule only applies to furnace motors. AC Condenser motor efficiency is already built-in to the SEER rating so a sperate rule for their motors specifically is not required. Whereas furnaces only had AFUE which was for the combustion efficiency only and electric efficiency had nothing previously.
Thank you very much for another great video 🇺🇸👍
Amazing explanation My Brother!! 👏 👌 👍 thanks for all the knowledge very clear and understandable
thanks for all the info, love all your videos
Very informative !
Awesome explanation, thanks!
Thanks for good technical information.
Funny I didn't hear anything about replacement costs you're going to play triple if not four times as much for those other motors so all the savings and electricity straight down the tubes
A lot of customers want efficient equipment for reasons other than "monthly utility bill" savings lol.
Wow you’re the only one to explain the difference between variable speed and ecm.. thanks!
I know with an increase in static pressure psc motors aren’t affected but It can kill an ecm motor. Do variable speed motors have the same issue with high static pressure?
Thanks
All motor types are affected by high static, but the issues are different. For PSC and constant torque ECM, the higher the static the lower the CFM for a given speed setting. For variable speed ECM, high static won't affect the CFM, but the fan will be forced to run at a higher speed and hence it will be lounder than expected, generate more waste heat than normal, and possibly fail sooner.
I'm looking at a Bryant 80% evolution with a 4 ton VS drive. I have a couple of question. 1st can I use any thermostat with this furnace or do I have to use the EVOLUTION CONNEX CONTROL? 2nd I'm looking to put a Bryant 3 ton condenser with this unit. Can I use this 4ton VS drive with the 3 ton condenser? Will the VS drive still give me what i need? Thanks
How does the PWM motor know when to adjust speed? Is the PWM motor's initial speed set by the tech based on the required CFM that the system requires? So, the tech would measure static pressure, then look at the blower chart and set the switches on the motor that corresponds to the existing static pressure and required CFM based on the load calc and equipment, then the motor adjusts itself based on changes in what monitored information? Changes in amp draw?
Everything you said is accurate EXCEPT the last part. The motor does not monitor conditions or adjust itself. A PWM motor (at least as used in a Carrier furnace) is a constant torque motor, not a constant airflow motor. The tech sets speeds with dip switches for the desired airflow. Then after that, the speeds only change as the system calls for different modes or stages. If something happens in the system (dirty filter, shut vents, etc) the motor does not know that and does not adjust for that.
Unrelated to PWMs, there are true variable speed motors in higher end Carrier furnaces. With those, the motor tracks static, RPM, and CFM and makes adjustments. It is a constant airflow fan instead of a constant torque fan. So if a filter gets dirty, the fan will run a higher speed/torque to get the required airflow.
Do you recommend fixed ecm or variable? Would they be fairly similar for the consumer?
From an energy standpoint, they would similar. However, from an operation standpoint it would be very different. At our own houses, most of us have a fully variable speed communicating ECM.
Can I do retrofits on these? Like for example take out a PSC motor in a system and then install a ECM or VSD?
Replacing a PSC with an ECM is pretty straight forward. There are retro-fit kits for that. Going to variable speed would be harder and in some cases not possible.
@@TECTubefilms Thanks for the reply
It would be great if you could tell us if each type was AC or DC.
PSC is AC. All others are DC.
@@TECTubefilms thanks for responding. I have a Tempstar furnace with an Emerson motor and just 4 wires. Red, blue and yellow plus a ground. The schematic shows it's DC and it has a control board which feeds a speed control, then the motor. I believe my problem is with the speed control, as I'm not getting any voltage to the motor, but when I connected a power supply to the motor it moved.
i had same question. thank you
What type of ECM motor is best for undersized ductwork?
Motor type will not solve an issue with undersized ductwork. PSC, ECM, PWM, and VS ECM will all exhibit various symptoms in a poor application like that.
We would ask, is the duct work undersized to move the air needed to keep the furnace online? Or is the ductwork undersized relative to the space load? That answer will determine different potential solutions.
How do you determine if your ducts are undersized? Do you use Manual D to calculate the cfm that the ducts will move and compare that result with the cfm required from the load calc? Ive heard that youre supposed to size equipment to the ducts, even if theyrr undersized.
@@affinity1 This is a bit of a loaded question. Are you asking how to determine if the ducts are undersized for the home's needs or if the ducts are undersized for the existing furnace and A/C they have? Since ALL.. we repeat ALL... equipment is grossly oversized by the HVAC contractors, you won't likely have the right size ducts for both the house and the equipment.
This is how the process SHOULD go... in this order:
1) "room-by-room" load calc to determine the heating and cooling BTUs needed to each zone
2) size the diffusers and branch duct for each room based on the CFM needed for the larger of heating or cooling BTU/h calculating in #1
3) size the main supply to carry the CFM needed for the sum of the branch ducts it feeds
4) repeat steps #2 and 4 for the return duct system
5) size the equipment for the total BTUh needed
@@affinity1 You will also know if your existing ducts are undersized (relative to the furnace and A/C) if you have some of the following symptoms:
1) furnace high limit trips
2) inability to install high MERV filters due to lack of airflow
3) external static pressure measurements in excess of 0.7"
4) high heat rise measurements on the furnace
5) low delta T across the evaporator coil
6) furnace heat exchanger cracks (even small ones)
The solution is to either enlarge both the supply and return ducts to accommodate the oversized furnace
OR do a more accurate... and aggressive... load calc to determine a smaller size furnace and A/C can be used on the house
difference between FM-18 and HW-18 please
What is FM-18 and HW-18? Those terms don't sound familiar to us at the moment.
You didn’t show us a shaded pole blower motor or an X13!
X13 is a brand name of Genteq (now owned by Regal Beloit). It came out about 15 years ago. It is a specific version of an ECM with pre-programmed torque ratings. In terms of the high level overview of this video, there is nothing different about the X13 brand name that needs to be mentioned. It can be lumped in with all non-variable speed ECM. If this was a service video that dived into details, then more delineation might be necessary. Please take a look at our motor playlist with includes Regal's video series on X13. czcams.com/play/PLoR_O4JRNc26An0QF_ygah4LX72Vj8URd.html
Do new furnaces still use shaded pole motors? Shaded pole is less efficient than PSC motors... and PSC motors became obsolete due to FER a couple months after this video was published.
Very good video, thank you very much , I will be starting my third semester this fall in HVAC, once again, thank you.
@@TECTubefilms got em ;-)
5:22 -- PSC motors are not constant torque!
Don't confuse the marketing terminology habit of referring to various ECM motors as either constant torque or constant airflow to mean that only ECM motors are constant torque. A PSC motor is also constant torque. Torque is inversely proportional to speed. A PSC motor or a regular ECM motor are given a speed command which results in a certain amount of torque. That speed and torque do not change during that mode. Hence... constant torque.
@@TECTubefilms -- If you restrict the return air to a PSC blower, the airflow and current are both reduced. How could that be considered Constant Torque?
A quick Google search turned up these and more like them:
"What differentiates constant torque motors from PSC motors is their ability to deliver constant torque (i.e., rotational force or power output down a shaft). In other words, if the ESP changes, then the motor program will maintain the amount of torque for which it was programmed"
"As static pressure increases, a PSC motor’s performance drops off, because it cannot adjust speed or torque"
"What differentiates constant torque motors from PSC motors is their ability to deliver constant torque (i.e., rotational force or power output down a shaft)."
@@rpsmith If you restrict the return air to a standard ECM blower, what happens to the airflow and current?
@@rpsmith The article you Googled was from 12 years ago and essentially written by Regal-Beloit... who only makes ECM motors. Of course, they tried distinguish as much between PSC and ECM. If you noticed, they never say that PSC is not constant torque.
@@rpsmith You even quoted the article specifically stating "As static pressure increases, a PSC motor’s performance drops off, because it cannot adjust speed or torque."
If it can NOT adjust torque, then that means the torque is constant.