High SEER, large outdoor unit?

8 years ago

We upgraded to a 17-19 SEER AC unit. The outdoor units (2) are way bigger than any unit I've seen on our previous houses. The builder agreed they are big and he said the HVAC contractor said that high SEER units are physically larger.

Can anyone explain why that is? (If indeed that is correct.)

Thanks -

Featured Answer

User

8 years ago

last modified: 8 years ago

Seasonal Energy Efficiency Ratio (SEER) is a metric used to measure how much cooling a system puts out for each unit of energy it consumes. Basically, a higher SEER means lower cost for the same cooling.

The outdoor units are sized for the tonnage of cooling capacity and the needs of the system being installed. Increased SEER generally results in a larger unit due to efficiency improvement required to reach that higher SEER; caused by larger cooling circuits, possibly heavy duty motors and equipment and other items.

(Edited 6/29/18 to remove egregious explaination and make simple correction...apologies, OP and other posters)

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Comments (7)

Jake The Wonderdog
8 years ago
Generally, yes... the higher SEER units are physically much larger.
nanj thanked Jake The Wonderdog
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Elmer J Fudd
8 years ago
last modified: 8 years ago
When I had a new A/C system installed, the contractor told me the condensers would be larger in size than older ones are (of the same tonnage). And they are.
nanj thanked Elmer J Fudd
tigerdunes
8 years ago
higher eff=dimensionally larger outside condensers
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PRO
Austin Air Companie
8 years ago
last modified: 8 years ago
Why Higher SEER units are physically larger in size:

Efficiency comes in the form of heat transfer. The better the heat transfer (getting rid of heat from the structure) the more efficient the AC is because the less trips the refrigerant (coolant) has to make thru the system to do the work of removing heat.

The more surface area (on the outdoor and indoor coils) the better the heat transfer as the refrigerant charge is also more plentiful in these systems. Larger volumes of refrigerant = larger volumes of heat transfer = efficiency. However, this has a detrimental effect on cost. Not only to replace the unit, but also when it breaks (in regards to refrigerant leaks.)

The benefit is that it will reduce your electric bill. If your old system was 10 SEER or less an entry level machine (14 SEER) can reduce your cooling bill by up to 40% (for an entry level machine). How much this saves you depends on your utility rate.

Obviously the more surface area you have, the more materials and refrigerant needed to do the job. This is primarily why higher SEER units cost more. More materials, the more it costs.

Practicality: Make the system too large and then you have more and more problems getting it to fit in the space the last one sit. This also increases costs.

I service the Katy, Texas area.
nanj thanked Austin Air Companie
nanj
Original Author
8 years ago
Thank you all for explaining - makes sense now that I understand it. I had read that higher SEER units are more expensive to repair so now I understand that, too.

We are building a new house and we planned for the outdoor AC units and the generator to be in the same area, a place kind of tucked away out of sight. With the bigger AC units the generator will be more visible than planned. But that is okay - we are glad we went with the SEER upgrade.
tigerdunes
8 years ago
don't oversize the generator...just what your basic needs are on a power outage...