Scroll Compressor vs Screw Compressor

[ESV]

I have a 2 story home with tall ceilings that is located in the midwest. Cooling the upper story has been a problem, but we have the builder grade model currently. I am planning to purchase a new central air and gas furnace. I am especially interested in the two-stage compressor and the variable speed fan system. I had decided on the Carrier Infinity Series system and I feel very confident in the installer I had selected. However, I just discovered that only the 21 SEER version of the Infinity Series A/C has the scroll compressor. All the other Infinity Series models have what Carrier calls a screw compressor. At the lower stage, the screw compressor is using half the power whereas the scroll compressor uses one third less. I had read all of the positive reviews on the scroll compressor, should I let this discovery that the Carrier Infinity unit I was considering does not have the scroll compressor result in my beginning my selection process again? My installer has promised in writing, that if I am not completely happy that they will install a different Carrier model.

[Shophound]

A screw compressor on a residential unit? I haven't heard of such a thing. I can't imagine a screw being on a resi system ...they are noisy compressors and most often are found on chillers. If you've ever heard one run, the sound is unmistakable and wouldn't last five minutes in most any neighborhood as far as neighborliness goes.

[mark beiser]

The infinity doesn't have a screw compressor, it is a Bristol TS, a recip compressor.

[CottyGee]

The infinity doesn't have a screw compressor, it is a Bristol TS, a recip compressor.

It appears there are both scroll & reciprocating compressors in the Infinity series...

http://www.residential.carrier.com/p...infinity.shtml
http://www.residential.carrier.com/p...infinity.shtml

Click the "Product Specs" tab below the pic of the condenser unit.

[ESV]

I know the specs say reciprocating compressor for the version I am looking at. A Carrier tech person is telling me on the phone it is a special compressor that is more like a screw compressor that they created before the scroll compressor was able to handle two stages. Regardless, do you think that the fact that it is not a scroll compressor should keep me shopping for a different model. Carrier and the installer promise it will do everything I want it to do or they will replace it. Should I give it a try or am I just looking for headaches?

[mark beiser]

It appears there are both scroll & reciprocating compressors in the Infinity series...

http://www.residential.carrier.com/p...infinity.shtml
http://www.residential.carrier.com/p...infinity.shtml

Click the "Product Specs" tab below the pic of the condenser unit.

I realize that, he was specifically asking about the ones that don't have a scroll compressor though.

[mark beiser]

I know the specs say reciprocating compressor for the version I am looking at. A Carrier tech person is telling me on the phone it is a special compressor that is more like a screw compressor that they created before the scroll compressor was able to handle two stages. Regardless, do you think that the fact that it is not a scroll compressor should keep me shopping for a different model. Carrier and the installer promise it will do everything I want it to do or they will replace it. Should I give it a try or am I just looking for headaches?

I wouldn't say it works like a screw compressor, lol.

It has 2 pistons, and the motor in the compressor can spin in either direction. In one direction, one piston is unloaded, in the other direction, both pistons are loaded.

The Bristol TS compressor is more complex than a 2 stage scroll, both mechanically and electrically, but I wouldn't get hung up on compressor technology when picking a system. Modern recip and scroll compressors are pretty much equally reliable.
The truth is, both compressor types are technologically antiquated in comparison to what the Asian compressor manufacturers are doing with inverter driven rotary compressors, lol.

[StealthSuitStan]

The truth is, both compressor types are technologically antiquated in comparison to what the Asian compressor manufacturers are doing with inverter driven rotary compressors, lol.

I would totally disagree with this statement. Rotary technology has grown significantly, as have both screw and scroll technologies. The problem that comes from your situation is that rotary is not applicable in the capacity range used in residential A/C. Asian rotary compressors are mostly applicable in the 12k BTU capacity and smaller. Scroll is more applicable in the 20-40 ton range, as in U.S. residential A/C. Screw is very large capacity, as mentioned before, mostly seen in commercial and industrial A/C and refr. Emerson Climate Technologies has scroll technology that varies in capacity from the rotary range to the screw range. As far as technology goes, I recommend Copeland UltraTech. If you are looking for efficiency and low noise, this is the way to go. It also includes performance monitoring technology that increases technician accuracy when troubleshooting.

In residential A/C applications, I would always recommend scroll technology.

[Shophound]

I would totally disagree with this statement. Rotary technology has grown significantly, as have both screw and scroll technologies. The problem that comes from your situation is that rotary is not applicable in the capacity range used in residential A/C. Asian rotary compressors are mostly applicable in the 12k BTU capacity and smaller. Scroll is more applicable in the 20-40 ton range, as in U.S. residential A/C. Screw is very large capacity, as mentioned before, mostly seen in commercial and industrial A/C and refr. Emerson Climate Technologies has scroll technology that varies in capacity from the rotary range to the screw range. As far as technology goes, I recommend Copeland UltraTech. If you are looking for efficiency and low noise, this is the way to go. It also includes performance monitoring technology that increases technician accuracy when troubleshooting.

In residential A/C applications, I would always recommend scroll technology.

20 to 40 tons for residential?? My last facility had a 40 ton split system, and there wasn't a scroll in the condenser. It was an 06E Carlyle semi-hermetic. It's been a long time since I've seen a semi-hermetic used in a residential application.

See my post re: the Nordyne IQ drive in this section. It was a three ton rotary inverter driven compressor we observed running last night. Unimaginably quiet. No scroll or recip on the market can touch that, nor has the ability to vary its speed to precisely match the load, vs. the more common unloading strategies mentioned in this thread.

I'm with Mark...Nordyne, Daikin, and others are knocking on the U.S. door with their high tech stuff. It's likely to be a slow intro, but money talks. As utilities continue without letup to drive the stock of KY Jelly up, this technology will become more attractive and affordable.

[mark beiser]

I was referring to scroll and recip compressors used in current residential equipment, all 5 ton and under, as compared to the inverter driven rotary compressors currently in use, which are currently available in up to a 4 ton residential split system.

[CottyGee]

As utilities continue without letup to drive the stock of KY Jelly up, this technology will become more attractive and affordable.

Your utility uses KY? Man, you've got it good - they just stick it to us without anything to ease the pain around these parts...

[Shophound]

Your utility uses KY? Man, you've got it good - they just stick it to us without anything to ease the pain around these parts...

Actually, the utility is hands off regarding the KY. An indirect consequence of their rate hikes, so to speak, brings glee to the stockholders of KY. Folks see it coming and are prepared. Since our great state in all of its infinite wisdom opted to deregulate electric utilities, this has become a repeat event that moves the ones averse to pain to seek ways to mitigate the inevitable.

[CottyGee]

Wow! Deregulated power, eh? Our state and the utilities are moving toward that as an ultimate goal. Man, that's gotta be one painful transition. How many providers do you have to choose from? I hope it's more than two.