would 2 5000 BTU air conditioners be equivalent to one 10,000 btu unit (asuuming other things equal such as EER)? Both in terms of cooling, and cost to run.
If they were, I see a some advantages to using multiple units: the smaller btu models tend be the most efficient (10+ EER). On cooler days, running just one 5000 at max output might be more efficient than running the 10000 at half output. Finally, if one unit of a pair fails, the replace cost is halved.
minor disadvantages might include higher initial outlay and you need 2 windows.
I actually had a salesman tell me that, no, 2 5000’s running in the same area would still only cool like 1 5000, iow that the effect is not additive.
I’m no professional, but it seems logical that two 5000 BTU units in the same area would cool better than one. The air coming out is the same temperature, but there’s twice as much so it brings the room temperature down faster.
OTOH, I’m guessing that the 10,000 BTU unit can produce colder air.
With the same EER, two 5000 BTU units will produce the same amount of airflow at the same discharge temperature as one 10,000 BTU unit. Having two smaller units will give you at least three advantages.
You will have better cooling distribution(assuming the units aren’t side by side).
You will have more stages of cooling. In residential air conditioners, the units thermostat cycles the refrigerant compressor on and off. That’s all the control you have other than the manual fan speed adjustment. Two smaller units will cycle both units on, one unit on, or both units off, as needed to meet the load.
You will have lower replacement costs (as previously mentioned).
The bottom line is that the total energy usage will be about the same but the room will be more comfortable with two smaller units because there will be fewer hot and cold spots.
All of the above is correct, plus you get the added benefits of redundancy and smaller, lighter, easier to handle units.
If one AC craps out at least you still have some cooling, and anyone who’s manhandled a window AC into place can vouch for the advantage of smaller, lighter units.
Larry Kapigian confirmed to me by e-mail that BTUs are cumulative, and that two 5,000 BTU units will do the same job as one 10,000 BTU unit, and more efficiently. For those who might not know, Larry is the Cecil of HVAC.
>> I actually had a salesman tell me that, no, 2 5000’s running in the same area would still only cool like 1 5000, iow that the effect is not additive
I would talk to his manager. That guy should be shot … er… I mean… fired on the spot
ok, 2 questions still stand out and they are linked. Is it axiomatic that 2 5000’s at the same EER necessarily cost the same to operate as the 10000 (guess thats a matter of checking the amperage)
If so, why is it that the higher capacity units tend not to be able to reach the highest EER ratings? (ie, why couldnt the manufacturer simply ‘double up’ the small units).
I guess they can, but it becomes an issue of size of the unit, and/or initial outlay cost. IOW, higher end units arent as efficient because the size and prices are not scaling linearly with btu.