Great video, very informative, thanks for comparing the two compressor types so thoroughly. We've had issues with acoustics of the VCC when located on the roof of a residential building.
It's a very simplified and illustrated way of explanation. Hats off, sir. Do we need a minimum charge quantity of refrigerant in both VCC and VFD Scroll compressor ?
Very helpful video. Do many manufacturers use the digital/VCC/PWM compressors? It seems mostly what I see for residential is either referred to as Inverter, 2-stage, or single stage.
Variable capacity is a more generic term. Variable speed is a type of variable capacity. Digital compressors do it by PWM over a 15 - 20 second cycle. Variable speed does this by changing the speed of the motor.
Can you explain how a variable speed compressor in a car works without having any of the fancy communication and control systems that are needed when VRF is used for residential and commercial buildings? The compressor in a car is usually directly driven from the engine. The engine speed typically varies somewhere between 500 RPM and 3,500 RPM under normal conditions. A receiver and expansion valve appear to be all the equipment necessary to keep the system in balance even when there are wild swings in load and capacity (compressor speed). The cabin is maintained at a comfortable temperature and humidity level even with massive swings in heat and humidity demand over short periods. Thanks
The car A/C will cool more the faster the engine spins. If this would result in overcooling the heater is often at the same time. This is obviously inefficient but nobody cares.
I prefer a Varible speed compressor for reliability. The digital scroll has a top moving MECHANICAL PLATE with a hot gas solenoid that gets on/off. This will eventually fail much sooner. Turn down on VFD compressors I have been working with have the ability turn down to 12% capacity. That's very low. I have worked with both Danfoss and Copeland VFD drive compressors. I just don't see digital scrolls lasting very long life with being replaced just because of the plate wearing out eventually
I disagree. I have seen digital scrolls last longer than inverter compressors....plus without a properly implemented logic the oil return on inverter compressors is bad. Plus costs associated with a digital vs inverter. Plus with the abuse customers put their equipment through....the inverter compressor is much more suseptible to break downs and service calls.
@jasonjohnsonHVAC Well that's OK I respect your opinion. I personally already seen the plates for the digital scrolls fail. They are a nice technology. I love how they are ability to change capacity quickly. I haven't had any luck with them. My VFD driven compressor have been extremely reliable so far. I have had a VFD fail. Electrical parts will fail.
If you are looking for good efficiency at lower system purchase cost, two speed compressor is best compromise. With new utility smart meters, more attention and regulations on appliance power factor, digital VCC compressors will not be around long as they are difficult to impossible to control utility grid load power factor. Oil circulation is an issue with both variable and VCC compressors. The short compression on-off duty cycle of VCC is not long enough to make an impact to average oil circulation. The critical oil circulation is determined by suction line vapor mass flow and by the time vapor exits evaporator, the VCC pressure pulses have smoothed out to an average (lower) mass flow rate. If the liquid pressure pulses of VCC are too great it would also cause problems for the EEV expansion valve refrigerant regulation into evaporator. The pressure pulses of VCC are pretty much smoothed out by gas compression in first part of condenser. It takes 10-30 minutes at full run speed to flush system distributed oil back to compressor. On most residential systems, when you drop below about 50% of capacity you end up with a net loss of oil in compressor. During low capacity run time you are running on compressor oil sump reserve. This is a primary reason why two speed compressors only drop to 60-65% capacity level.
I would take the digital over the variable speed any day. Inverter compressor...its not only the compressor, but the expensive boards and controllers.....digital is just a compressor and a controller....less expensive, better oil return and more readily available parts.
Excellent presentation. Gave very clear understanding of different types of compressors and their advantages and disadvantages. thanks.
Great video, very informative, thanks for comparing the two compressor types so thoroughly. We've had issues with acoustics of the VCC when located on the roof of a residential building.
Thanks for watching!
Great presentation!!
Thank you!
It's a very simplified and illustrated way of explanation. Hats off, sir.
Do we need a minimum charge quantity of refrigerant in both VCC and VFD Scroll compressor ?
I’m not sure if there is a minimum charge. Thanks for watching!
Extremely helpful! Thank you.
You’re welcome!
Why is an electronic expansion valve required with a vfd controlled scroll compressor?
Very helpful video. Do many manufacturers use the digital/VCC/PWM compressors? It seems mostly what I see for residential is either referred to as Inverter, 2-stage, or single stage.
Very good video btw.
It was really a helpful video
Variable capacity is a more generic term. Variable speed is a type of variable capacity. Digital compressors do it by PWM over a 15 - 20 second cycle. Variable speed does this by changing the speed of the motor.
Can you explain how a variable speed compressor in a car works without having any of the fancy communication and control systems that are needed when VRF is used for residential and commercial buildings? The compressor in a car is usually directly driven from the engine. The engine speed typically varies somewhere between 500 RPM and 3,500 RPM under normal conditions. A receiver and expansion valve appear to be all the equipment necessary to keep the system in balance even when there are wild swings in load and capacity (compressor speed). The cabin is maintained at a comfortable temperature and humidity level even with massive swings in heat and humidity demand over short periods. Thanks
The car A/C will cool more the faster the engine spins. If this would result in overcooling the heater is often at the same time. This is obviously inefficient but nobody cares.
Any job opportunity in Houston? I am a Sustaining Design Eng at Daikin…
I prefer a Varible speed compressor for reliability. The digital scroll has a top moving MECHANICAL PLATE with a hot gas solenoid that gets on/off. This will eventually fail much sooner.
Turn down on VFD compressors I have been working with have the ability turn down to 12% capacity. That's very low. I have worked with both Danfoss and Copeland VFD drive compressors. I just don't see digital scrolls lasting very long life with being replaced just because of the plate wearing out eventually
I disagree. I have seen digital scrolls last longer than inverter compressors....plus without a properly implemented logic the oil return on inverter compressors is bad. Plus costs associated with a digital vs inverter. Plus with the abuse customers put their equipment through....the inverter compressor is much more suseptible to break downs and service calls.
@jasonjohnsonHVAC
Well that's OK I respect your opinion. I personally already seen the plates for the digital scrolls fail. They are a nice technology. I love how they are ability to change capacity quickly. I haven't had any luck with them. My VFD driven compressor have been extremely reliable so far. I have had a VFD fail. Electrical parts will fail.
If you are looking for good efficiency at lower system purchase cost, two speed compressor is best compromise.
With new utility smart meters, more attention and regulations on appliance power factor, digital VCC compressors will not be around long as they are difficult to impossible to control utility grid load power factor.
Oil circulation is an issue with both variable and VCC compressors. The short compression on-off duty cycle of VCC is not long enough to make an impact to average oil circulation. The critical oil circulation is determined by suction line vapor mass flow and by the time vapor exits evaporator, the VCC pressure pulses have smoothed out to an average (lower) mass flow rate. If the liquid pressure pulses of VCC are too great it would also cause problems for the EEV expansion valve refrigerant regulation into evaporator. The pressure pulses of VCC are pretty much smoothed out by gas compression in first part of condenser.
It takes 10-30 minutes at full run speed to flush system distributed oil back to compressor. On most residential systems, when you drop below about 50% of capacity you end up with a net loss of oil in compressor. During low capacity run time you are running on compressor oil sump reserve. This is a primary reason why two speed compressors only drop to 60-65% capacity level.
I would take the digital over the variable speed any day. Inverter compressor...its not only the compressor, but the expensive boards and controllers.....digital is just a compressor and a controller....less expensive, better oil return and more readily available parts.