Air Conditioner & Heat Pump SEER Efficiency Ratings questions & ansswers.

This article series explains air conditioning SEER energy efficiency ratings for air conditioners and heat pumps along with related terms like BTUs, Watts and hourly operating cost, in easy to understand language.

SEER Rating FAQs

These questions and answers about the definition, values and uses of SEER ratings on air conditioners, heat pumps and similar equipment were posted originally

at SEER RATINGS & OTHER DEFINITIONS - home - be sure to read that article.

What is highest Seer rated air conditioner for commercial use

What;s the Highest Seer Ratio that is good for Commercial airconditioning ? On 2018-12-07 22:47:26.478672 by Juanita

Explanation by (mod) -

Juanita

I don't think that there is a single highest Seer rated air conditioner for commercial use number that I can give you because the ratings will vary depending on the type of equipment and your application.

I can tell you that while a few years ago a SEER rating of 10 was considered good, more recently I've seen equipment advertised currently with an SEER rating of 16 or better.

Which veents do I open or close for air conditioning?

I have top and bottom air flow vents. Which one do I block for air conditioning On 2017-05-15 by jean

Reply by (mod) -

Jean

You do not normally want to block air return inlets nor air supply registers in an air conditioning or heating system since doing so will significantly reduce overall airflow and in cooling mode can cause ice blockage of the cooling coil.

However it is the case that the optimum supply register location for cooling-only systems would be near the top of walls as that's where the air is warmest. For cooling I prefer to take return air near a different, well separated ceiling location because that's also where the warmest air resides.

For heating mode we collect return air at cooler locations - near floors.

Where to find the model on Nordyne Condenser Units

On Nordyne condensers (Gibson/Frigidaire/Maytag) , find the Model/ SKU- (ex: FT4BF-036KA). The first letter establishes make and in some cases, model (F=Frigidaire/J=Gibson/M or P=Maytag).

The second letter (and third, if Maytag) tells you if its either a Heat Pump or Straight Air unit (T=heat pump/S=straight air). The letter following "4B" indicates SEER (D=14/E=15/F=16/G=18). The last number, found after the dash-0, indicates the unit's tonnage when divided by 12 (18KA=1.5 ton/ 24KA= 2 ton/ 30KA= 2.5 ton/ 36KA= 3 ton and so on; up to 5 ton.
So,

Q: what does the example SKU: (FT4BF-036KA) tell us about the unit?

A: Frigidaire-heat pump, 16 SEER, 3 ton.

Frigidaire's budget model, "Builder's Line" have SKU's starting with an E.
(ex: ES4BE-018KA= straight air, 1.5 ton).

Maytag condenser SKU's begin with P on high-efficiency stainless steel models.

New straight air units will begin with the letter C. Currently however most Maytag condenser SKU's begin with an M.
(ex: MSH4BE-060KA). After the first letter will be either an SH or SA (SH=Heat Pump/SA= Straight Air).

The information following will again indentify SEER and tonnage. (ex: PSA4BE-060KA=

Maytag, stainless steel, straight air, 15 SEER, 5 ton. (ex: MSH4BE-048KA= Maytag, heat pump, 15 SEER, 4 ton.

Gibsons start off with a J, and like Frigidaire, indicate heat pump or straight air with a T or an S, respectively.
(ex: JT4BE-024KA= 2 ton Gibson, heat pump, 15 SEER). On 2017-05-10 by Brian James

by (mod) - The information following will again indentify SEER and tonnage.

Thank you Brian for the very helpful information. I will copy it to our articles on decoding HVAC equipment data tags

Confusion about just when the outdoor vs indoor equipment will be "ON"

On of your replies states that a heat pump's indoor evaporator and its outdoor compressor each operate "at different times" during each cooling cycle. That is untrue. The indoor component recirculates the indoor air whenever the outdoor component delivers heating (in winter) or cooling (in summer).

If the outdoor unit isn't delivering more hotness or coolness, then there's no reason for the indoor fan to run, and whenever hotness or coolness is being delivered, the fan must run.

Yes, as soon as the outside compressor finishes, the indoor fan does run 1 minute longer, but other than that, the two components (evaporator and compressor) always operate in tandem.

There's never any reason to run either one without the other. On 2017-03-19 by Ned Flaherty

Reply by (mod) -

Thanks for your comment, Ned, though, with respect, you're not quite correct. Now more than ever it's important to distinguish between opinion and authoritative facts.

Basically you're right that the fan on a heating system being operated automatically won't turn on until air in the supply plenum is sufficiently warm to avoid blowing cool air on occupants. Even after the thermostat has stopped calling for heat the fan will continue to run for a period to extract remaining heat from the heat exchanger- thus avoiding damaging it.

That's not so for cooling - there typically the fan starts as soon as the thermostat calls for cooling and stops when the call for cooling stops.

The blower fan will also run continuously in some situations, regardless of the state of the room thermostat:

Please take a look at CONTINUOUS BLOWER FAN OPERATION where you'll read an example of when and why an HVAC air handler blower fan may be left on continually for periods of time.

Some folks are also sometimes confused between the air handler fan that distributes warmed or cooled air to the living space and the compressor/condenser fan that is used to move outdoor air across the compressor/condenser coil.

There are, thus, in fact, reasons to run the fan manually at other times as we cite in the article above.

However there are also error conditions in which either of the fans I cite will run continuously when they should not: usually that's from shorted thermostat wires, a bad fan control relay or control board, or perhaps a manual FAN ON switch improperly set.

See FAN WONT STOP - LIMIT SWITCH

and FAN, COMPRESSOR / CONDENSER UNIT

for examples of other times when the outside and inside unit may not be running at the same time.

Another example is the use of defrost cycles.

Why can't I use SEER ratings in actual calculations of system's efficiency?

What should the pressure be on the low side of the unit that has a condenser Of 13 seer and a air handler with 10 seer rating

I'm trying to get a better understanding of SEER and EER.

The definition of SEER is the ratio of Cooling Energy Output (in BTU's) to Electrical Energy input (watt-hours).

SEER is the ratio of two Energy units and the conversion between the two units is 1BTU=0.293 Watt-hour.

So, it seems that the maximum SEER for a 100% efficient system would be, at best, 1/0.293 = 3.41.

This is clearly not right. Where is the flaw in my analysis? On 2016-07-30 by Rich olsen

Answer by (mod) -

Rich,

Fooling around with SEER and EER and COP and also ESEER is so irritating that most people toss in the towel.

I've read more and have tried to add some constants, formulas, and clarifying text into the article above. Thank you for asking.

For a couple of uncomfotable reasons we can't plug in simple math as you're trying.

1. The laws of thermodynamics and data about the most-efficient cooling system mean we won't have a 100% efficient cooling (or heating) system.

2. EER is an ugly ratio in that it's a ratio of two different units: BTUH & Watts. COP is nicer as it's "unitless" as we describe in the article above.

A closer but unattractive calculation you can use is detailed (now) in the article above. It's:

EER = -0.02 x (SEER x SEER) + ( 1.12 x SEER )

Comments by St. Paul

Rich 2016- you assume 100% is the best cooling efficiency possible.

For system wide energy, energy is conserved; however, nobody ever said that applied to cooling efficiency.

Cooling efficiency relates to how much energy is required to thermodynamically separate the hot and cold particles of air in the house, and to discard the hot ones outside.

This is a primarily a separation process, not an energy process (although we do have to power the compressor and fans). So odd as it may sound, cooling efficiency can exceed 100%.

Comments by (mod) - A cooling system is not exchanging particles nor moving particles of air, sending hot particles outside.

Thank you St P but permit me to add, as your comment will be confusing to some,

A cooling system is not exchanging particles nor moving particles of air, sending hot particles outside.

A cooling system is removing heat (heat is a form of energy, not particles) from the indoor air, along with removing some moisture at the same time.

Liquid refrigerant being released into the interior of the cooling coil evaporates into a gas. That state change, from liquid to gas, absorbs energy, thus cooling the coil's metal fins and tubing surfaces.

Building air, brought by duct work and an air handler or blower fan, is pushed through the spaced fins and tubing surfaces of the exterior of the cold coil. Heat from the air is transferred to the cooler coil surfaces, reducing the heat level in the air. That heat exchange is energy, not particles.

The warmed refrigerant gas, having absorbed heat from the air through the metal surfaces of the cooling coil, is sucked into an outdoor compressor - a pump - that compresses the low pressure refrigerant gas into a still-hotter high-pressure refrigerant gas. This is happening outdoors.

The high temperature high pressure gas is then passed through the outdoor condensing coil. Outdoor air, blown through the condensing coil, even though it might be warm, is still much cooler than the high temperature high pressure gas inside of the condensing coil.

The result is that heat is transferred further from the refrigerant in the condensing coil to the outdoor air. That cools the refrigerant and condenses it back to a liquid refrigerant.

We are moving heat from inside air to outside air. Not particles. And not with separation.

I'm unclear how the efficiency of any system can exceed 100% if we are talking about the energy used to move heat from one place to another. That would violate the second law of thermodynamics. No engine can be so perfect as to convert 100% of the input energy it receives into output work.

So it is certainly the case that no engine or motor could exceed 100% efficiency either: Such an engine would have to use just 90 units of input energy (for example) as input to create 100 units of output energy.

Such a machine would be in effect "creating" energy out of nothing.

In sum, first way that the second law of thermodynamics was given or stated was by Sadi Carnot, who in 1824 showed that there is an upper limit to the efficiency of conversion of heat to work, in a heat engine. -paraphrasing from a recent Wikipedia entry.

 

 

Question: SEER rating of a Carrier Infinity HVAC system

There is a dispute about whether the SEER rating of a Carrier Infinity HVAC system installed in a home in 2011 is a SEER 21 or a SEER 16.

The condenser was a Model 24ANA160A0033030, 5 ton, 2speed fan, 2-stg, the evaporator was a CNPHP6024ATAA 5 t, horiz, tp, the Furnace was 58MVC100-F-1-20, 100 k, 2stg VS MP 5t clg, media cab.

Can you tell me from that information if this was a 21 SEER. Apparently someone is certain that there was a yellow sticker that was a 16 SEER unit even though a 21 SEER unit was paid for. (Dec 29, 2014) Dean

Reply:

Dean,

I don't find SEER data encoded in model numbers but rather the model number takes us to the manufacturer's brand and model for which we have to rely on what the manufacturer asserts is that unit's SEER. There is some confusion I find between SEER ratings given for a compressor/condenser unit and the SEER rating on a sticker affixed to the air handler.

I tried searching the Carrier site with your model numbers, hoping to find product literature, without success.
If you have the installation manuals for your equipment, OR the labels affixed to the equipment those should give a SEER rating for each device.

If you don't have that information - which should have been left with you by the installer - you can try contacting Carrier at carrier.com/ - you'll see the company does not really want to talk with you directly: at least it's difficult to find a telephone number or email, but the company does provide a contact or information request form online that should work.

Question: Energy audit comment

An energy audit allows homeowners to understand where they are using energy at home and where savings can be made.

Fortunately, making our home more energy efficient is not overly difficult.

The difficulty lies however with being able to identify those invisible leaks around the home in the first place.

Finding exactly where the cold air is finding its way into the home during winter and the cool air-conditioned air is lost outside during the summer is the key.

Annual energy consumption costs that could be saved by identifying drafts and undertaking some simple maintenance to stop air leakages and better insulate the family home. (Feb 16, 2015) Christopher Hale

Reply:

Thanks Christopher; indeed I am a fan of energy audits, provided the auditor actually audits by paying attention. In New York I was disappointed when the auditor reached conclusions and made assumptions with not a shred of information about the home we were inspecting. He pointed out that because the home was built in 1900 it would be uninsulated and thus blowing in insulation should be the first priority. In fact the walls all had blown-in insulation - which we could see just by looking.

So yeah audits are tremendously helpful if the auditor looks up from his or her checklist from time to time ... just an opinion

 

On 2018-08-29 by Paul Watson M.E. Errors in article details need correction

Your article has "Units Errors". See "Seasonal Energy Efficiency Rate" Para #2

"In the U.S. ... in BTU's (presumably BTUs/hr)..." This matters greatly.

It is important. It is either BTUs or else it is BTUs per Hr. It can not be both.

BTUs are raw energy. watt-hours is raw energy (because watt is power - i.e. a time rate of energy). Please amend your article to get rid of the "presumably" which is not correct. You have a lot of other unit errors spattered through the article.

If you need help fixing it, e-mail me paul-watson@sbcglobal.net. I am computing some cost numbers for different heating systems, and this units controversy is making my task more difficult. We need correct units before answers are correct. Thanks, PW

 

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