5 ms·

There are standardized efficiency measurements that all A/C manufacturers must conduct and publish in the US. You'll see terms like COP, EER, and SEER. Those

by rplst8 9y ago

There are standardized efficiency measurements that all A/C manufacturers must conduct and publish in the US. You'll see terms like COP, EER, and SEER. Those allow you to compare pretty easily. Currently the minimum is a SEER of 13, but I've seen units as high as 22 advertised.

a_t48 9y ago
Higher is better in this case?
- kinkrtyavimoodh 9y ago
  Yes.
- rplst8 9y ago
  Yes.
- jdmichal 9y ago
  To elaborate on the "yes": SEER is a ratio of energy expended to energy moved. So SEER 13 means that the system spends one unit of energy to move 13. And you should expect a SEER 20 system to be twice as efficient as a SEER 10 system. EDIT: I should mention that SEER uses different units for each part of the ratio -- BTUs of heat moved vs watt-hours expended. COP is dimensionless, and EER is just SEER but for a specific operating point. SEER extends the measurement through an entire "season", and so it theoretically gives a more realistic picture of overall efficiency.
DannyBee 9y ago
Depends on the type of A/C You can get ground source heat pumps that are 50 SEER, 5.3 COP (and they'll provide all your hot water, too) There used to be a federal tax incentive of 30% of the cost, no max, but it expired at the end of 2016.
- rplst8 9y ago
  Yes. I was talking strictly about the air source style heat pumps and/or reverse Carnot cycle A/C units. Everyone knows GS heat pumps are more efficient.
mjfern 9y ago
A SEER 13-14 system can run $5-6K, while a SEER 22 system can cost upwards of $15K (as a guesstimate). In theory, a SEER 22 system can pay for itself over the long-term due to reduced electric/gas expenses. The issue is that higher SEER systems, above 16 I believe, rely on variable speed motors. My understanding is that they are inherently less reliable. A SEER 13-16 system might last 15-20 years (if you're lucky), while a SEER 22 system could break down much earlier at about the 10 year mark. You can sometimes replace specific parts, but depending on what breaks, it may not be cost effective. In short, the only way we're moving to more efficient AC systems is if costs come down significantly, we see some major innovation in the field, or the government provides significant financial incentives. As an aside, I also think we could achieve energy efficiencies by increasing the insulation in houses. It's unbelievable how much hot/cool air is lost through windows, doors, crawl spaces, and attics.
- EvanAnderson 9y ago
  I've had some major frustrations with poor reliability of the blower motor in a 14 SEER HVAC system (installed in 2006) with a brushless DC motor. I've replaced the motor 3 times in 10 years (conveniently failing shortly after the warranty expired each time). Had I not done the work myself that would have been between $600 and $800 per replacement. Brushless / electronically commutated DC motors are pretty interesting, though: https://en.wikipedia.org/wiki/Brushless_DC_electric_motor https://en.wikipedia.org/wiki/Brushless_DC_electric_motor
  - mjfern 9y ago
    Who's the manufacturer?
    - EvanAnderson 9y ago
      The air handler is a Bryant. The motors have been a General Electric X13 (the original patent-holder for the X13 electronically commutated constant-torque PWM motor controller), a Regal Beloit "Evergreen" X13 OEM replacement, and now a Nidec X13 motor. These motors are microcontroller-based. Apparently there was a rash of bad GE X13 motors in the early 2000's traced to bad thermistors. Unfortunately the board is potted in an insulating compound that makes board-level repair rather impractical. My first motor's controller failed after about 8 years. It was cheaper to just buy a new motor vs. replacing only the controller. The second motor's rotor started grinding against the stator after about 13 months. I pulled the controller from that motor and installed it on the first motor (since it was near-perfect duplicate of the original motor). That ran for 14 months before the second controller failed. I've been running the third (Nidec) motor for about 2 months. I'll be interested to see how to holds up long-term.
smacktoward 9y ago
> You'll see terms like COP, EER, and SEER Anytime there are multiple standards for manufacturers to choose from, customer confusion is guaranteed.
JeffDClark 9y ago
Its good the be aware that one component of higher efficiency in an AC/Heat Pump is thinner tubing. Thinner tubing is more prone to develop leaks and costly coil replacements and refrigerant refills. This seems to be primarily an issue with copper coils. I was bitten by this with a brand new system that I had installed about 9 or 10 years ago. It was pretty tough to eat the labor costs of having a new coil installed (that was covered under warranty) as well as a complete refrigerant fill (at the time ~$900 for the full R410A fill) on a system that was less than one year old. Its been good since then though!

by rplst8 9y ago

a_t48 9y ago

Higher is better in this case?

kinkrtyavimoodh 9y ago
Yes.
rplst8 9y ago
Yes.
jdmichal 9y ago
To elaborate on the "yes": SEER is a ratio of energy expended to energy moved. So SEER 13 means that the system spends one unit of energy to move 13. And you should expect a SEER 20 system to be twice as efficient as a SEER 10 system. EDIT: I should mention that SEER uses different units for each part of the ratio -- BTUs of heat moved vs watt-hours expended. COP is dimensionless, and EER is just SEER but for a specific operating point. SEER extends the measurement through an entire "season", and so it theoretically gives a more realistic picture of overall efficiency.

DannyBee 9y ago

Depends on the type of A/C You can get ground source heat pumps that are 50 SEER, 5.3 COP (and they'll provide all your hot water, too) There used to be a federal tax incentive of 30% of the cost, no max, but it expired at the end of 2016.

rplst8 9y ago
Yes. I was talking strictly about the air source style heat pumps and/or reverse Carnot cycle A/C units. Everyone knows GS heat pumps are more efficient.

mjfern 9y ago

A SEER 13-14 system can run $5-6K, while a SEER 22 system can cost upwards of $15K (as a guesstimate). In theory, a SEER 22 system can pay for itself over the long-term due to reduced electric/gas expenses. The issue is that higher SEER systems, above 16 I believe, rely on variable speed motors. My understanding is that they are inherently less reliable. A SEER 13-16 system might last 15-20 years (if you're lucky), while a SEER 22 system could break down much earlier at about the 10 year mark. You can sometimes replace specific parts, but depending on what breaks, it may not be cost effective. In short, the only way we're moving to more efficient AC systems is if costs come down significantly, we see some major innovation in the field, or the government provides significant financial incentives. As an aside, I also think we could achieve energy efficiencies by increasing the insulation in houses. It's unbelievable how much hot/cool air is lost through windows, doors, crawl spaces, and attics.

EvanAnderson 9y ago
I've had some major frustrations with poor reliability of the blower motor in a 14 SEER HVAC system (installed in 2006) with a brushless DC motor. I've replaced the motor 3 times in 10 years (conveniently failing shortly after the warranty expired each time). Had I not done the work myself that would have been between $600 and $800 per replacement. Brushless / electronically commutated DC motors are pretty interesting, though: https://en.wikipedia.org/wiki/Brushless_DC_electric_motor https://en.wikipedia.org/wiki/Brushless_DC_electric_motor
- mjfern 9y ago
  Who's the manufacturer?
  - EvanAnderson 9y ago
    The air handler is a Bryant. The motors have been a General Electric X13 (the original patent-holder for the X13 electronically commutated constant-torque PWM motor controller), a Regal Beloit "Evergreen" X13 OEM replacement, and now a Nidec X13 motor. These motors are microcontroller-based. Apparently there was a rash of bad GE X13 motors in the early 2000's traced to bad thermistors. Unfortunately the board is potted in an insulating compound that makes board-level repair rather impractical. My first motor's controller failed after about 8 years. It was cheaper to just buy a new motor vs. replacing only the controller. The second motor's rotor started grinding against the stator after about 13 months. I pulled the controller from that motor and installed it on the first motor (since it was near-perfect duplicate of the original motor). That ran for 14 months before the second controller failed. I've been running the third (Nidec) motor for about 2 months. I'll be interested to see how to holds up long-term.

smacktoward 9y ago

> You'll see terms like COP, EER, and SEER Anytime there are multiple standards for manufacturers to choose from, customer confusion is guaranteed.

JeffDClark 9y ago

Its good the be aware that one component of higher efficiency in an AC/Heat Pump is thinner tubing. Thinner tubing is more prone to develop leaks and costly coil replacements and refrigerant refills. This seems to be primarily an issue with copper coils. I was bitten by this with a brand new system that I had installed about 9 or 10 years ago. It was pretty tough to eat the labor costs of having a new coil installed (that was covered under warranty) as well as a complete refrigerant fill (at the time ~$900 for the full R410A fill) on a system that was less than one year old. Its been good since then though!