EER vs. SEER

[pines]

How can I convert 10 EER to SEER?

The unit I am using is 14,300 BTU

I was told to use: 10 / 0.09 = 11 SEER ?

[htrguy]

The label EER is measured at 80 indoor air 95 outdoor air running continuosly.

The label SEER is measured by using an EER (not related to the label EER) measured @ 80 indoor and 82 outdoor and calculating in a factor for the unit running cycling on and off the same 80 indoor and 82 outdoor.

Since the SEER tests are done at a much lower outdoor temperature there is very little relationship to the EER at 95 outdoor.

[RoBoTeq]

EER is a refrigeration efficiency only calculation. SEER takes into consideration all electrical aspects of a system as well. With all standard psc motors the SEER is usually about 110% of the EER but the SEER can be increased with enhanced electrical components without affecting the EER.

[htrguy]

With all standard psc motors the SEER is usually about 110% of the EER

Is that your rule of thumb. Kinda like 1 ton for every 400 sqft.

[RoBoTeq]

Is that your rule of thumb. Kinda like 1 ton for every 400 sqft.

That is very rule of thumb, which is why I stated it as I did.

[skippedover]

The label EER is measured at 80 indoor air 95 outdoor air running continuosly.

The label SEER is measured by using an EER (not related to the label EER) measured @ 80 indoor and 82 outdoor and calculating in a factor for the unit running cycling on and off the same 80 indoor and 82 outdoor.

Since the SEER tests are done at a much lower outdoor temperature there is very little relationship to the EER at 95 outdoor.

You got it right on the EER being a measurement of Btu's produced at 95*F divided by the watts used at 95*F. However, I believe the SEER rating involves a calculation of total Btu's used over a full season divided by the number of watts-hours used over that full season. Both relate to cooling whereas heat pump efficiency ratings are HSPF. As you pointed out, SEER is a higher number because of the lower outdoor temperature used, which is supposed to represent an average temperature over the full summer of use. EER is supposed to be a 1-hour, worst case.

[htrguy]

What I posted is how it is calculated by the ARI standards, by manufacturers.
If a unit is sized for a given load it will run almost continuosly during peak periods of energy usage at the efficency stated in the EER calculation.
SEER states how efficient the unit is cycling on and off at a light load at set laboratory conditions at set periods of time.
Annual fuel usage is another calculation that uses EER, SEER and regional heat load zones to calculate how much it will cost you to operate seasonally in a given zone. It is a basis for another educated guess on how it will apply to your individual application but it is the sanctioned method.
There are many arguable methods of how to calculate power usage over a season and numerable opinions of how to use SEER and EER to guess what a unit costs to use that depend alot on where you live and what you are using the unit for and how a unit is installed.
I don't like rules of thumb handed out to people as good info. It adds to confusion in making an informed decision.
Commercial units are not SEER rated only EER. Why? I would guess that these units are used in applications where they remain on for a longer period of time and EER is more important.

Running with 80 indoor 95 outdoor is not a 1 hour scenario. I like my house at 75 indoor when it's 105. Sizing is based in my area for 96 outdoor. When it's hot it will run more than an hour. My selection of a unit is based on the highest EER I can get with the highest SEER I can get in most residential applications. I put more wieght in EER because it is hotter where I live for extended periods of time and I plan for sizing just big enough to satisfly the load on design days. When I recommend a given unit I state why I recommend what I do. If a customer has a high latent load that drives the unit size up only when alot of people are in the building then I want a higher SEER unit.