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Rotary Compressors - The rotary compressor used in HVAC applications for air conditioning and heating systems offer some of the most efficient air conditioner and heat pump systems one can find on the market.
Despite the rotary compressor being a key component of an air-source air conditioner or heat pump the efficiency offered by this compressor when used as a modulating compressor can exceed efficiency ratings of some geothermal systems.
When the compressor is coupled to an inverter and the proper inverter control system the efficiency of the air-source air conditioner or heat pump system spike to match those of some geothermal air conditioner or heat pump systems.
Comparison of Rotary Compressors Versus the Others
Like the reciprocating compressor and the scroll compressor used in HVAC applications, the rotary compressor compresses refrigerant vapor thereby raising its temperature and raising the pressure of the refrigerant as all refrigerants have a temperature/pressure relationship. This is referred to as vapor compression refrigeration. The rotary compressor is unique to high-efficiency refrigeration systems because it is ideal for use with inverter-type systems. Inverter-type air conditioners and heat pumps offer higher efficiency ranges because they can be modulated or stepped up and down based on demand.
Rotary compressors used in HVAC applications are mostly either rotary vane compressors or rotary screw compressors with the rotary vane compressors being used in smaller HVAC applications such as residential split systems and mini-split ductless systems and the rotary screw being used in larger HVAC applications such as commercial chillers including process and industrial HVAC applications. Vibration issues are negligible for the rotary screw making it ideal for larger HVAC applications.
Modulation is the Future
Both the rotary vane compressor and the rotary screw compressors are suitable for modulating making the two types of compressors ideal for running at demand load as long as they are controlled properly. While modulating controls add to the total cost of the modulating compressor system the system is much more efficient thereby reducing operating costs and saving energy and energy dollars over the life of the equipment that utilizes modulating compressors.
HVAC Rotary Compressors
Technical Resource: Refrigeration and Air Conditioning Technology
Advantages of rotary compressor Its main advantages are: because the piston makes rotary motion, the compression work is smooth and balanced. In addition, the rotary compressor has no residual volume and no interference of re-expanded gas, so it has the advantages of high compression efficiency, few parts, small volume, light weight, good balance performance, low noise, complete protection and low power consumption.
What manufacture of central air condition systems makes a ducted
system using a twin rotary compressor? The only one I know that I
can purchase in USA is Pioneer 36K BTU’s.
Hi –
For a residential A/C unit can you use a pumpdown to capture refrigerant in condenser — IF THE COMPRESSOR IS ROTARY??
R410 is refrigerant in the system.
Thanks
Yes……..as long as you have to right tools and know what you are doing.
I have worked on reciprocating compressors for a long, long time and was not sure if there are restrictions with rotary compressors. Given the higher pressures with R410A and my less familiar experience with rotary I wonder if the same procedure I have always can be repeated?
Thanks
Upon further investigation and discussion with
A/C mechanic i can advise you CANNOT pump down a rotary compressor for residential A/C. If you do attempt to do this an internal relief will be activated and pump down will not occur. Best to just recover the refrigerate and isolate the leak and repair. Finally you can reinstall the refrigerant.
Sorry dude but I’ve got to be snarky with you. Put on that Inspector Clouseau hat and do another investigation. I suppose if you are correct (or that A/C Mechanic is correct) then that chiller I worked on last week is not working correctly. It has a rotary compressor and uses a pump-down cycle when it shuts down. Guess the engineers and design people got that wrong on that chiller and the (literally) hundreds I’ve worked on. Now, lets get to the nut of the subject.
An internal relief valve opens on high pressure. What would cause high pressure? A blockage in the system or in the case of pumping something down, not enough coil, accumulator, receiver, or space to hold the refrigerant. If you have more volume (of refrigerant) than the place where you are putting it can hold I can see the internal relief popping.
So if you really know what you are doing you CAN do this.
So I can add some clarification. I am sure you are a correct when you say pump down is fine for your application. Respectfully I submit — a chiller designed to include for pump down with appropriate receiver capacity and other technical requirements, may not be the best equipment to compare to my case — a residential DX split.
The unit I was requesting clarification on did experience the conditions I described and results did follow the conditions as described by the A/C mech. When I starting a pump down the Freon did flood back from the high side to the low side due to the liquid line being closed for pump down procedure. ( a relief was not activated). Clearly pump down would not work in my case.
To clarify if pump down is recommended on these specific units, I decided to ask Carrier’s tech services for their input. The answer is here in quotation marks for my further DX split similar conditions.
“Hello Robert
This situation you describe in which you were only able to pump the unit down part way is normal to these compressors. Once the suction pressure gets to around the 60-80psi range (this number will very) the floating seal starts to bypass from the discharge to the suction. At this point you will no longer be able to pump down into the condenser and it will be necessary to recover the remainder of the gas using best practices.
Should you have any questions or concerns please respond to this email.
Best regards
Curtis Schierholtz | Technical Service Representative | Carrier Enterprise Canada L.P.
1515 Drew Rd, Mississauga, ON, L5S 1Y8
T: 1-800-237-3005
Thank you for the clarification.