Which Split Type AC Would Be Better: 1 Ton or 1.5 Ton?

It probably be better to never switch the AC off so you keep the room at the desired temperature. Cooling a room down from being very hot is using more energy than to keep the temperature constant.

This might change dependend on the usage of the room, which you havent told us about.

Moneywise the 1 ton unit will be the better option. But I think you not giving us full information and at this point I'd say you phrased the question wrong.

If the 1 ton unit gets the room cool maybe a 0.5 ton unit will do as well when constantly run.

Somebody will come up with some links how to size a AC unit. But if you look in old threads you might find them by yourself!

Sorry Ideasmith but that's just completely wrong.

The amount of heat transfered depends upon the temperature difference between inside and outside multiplied by the time.

If you allow the room to heat up nothing more is transfered, if you keep the AC on it's continually pumping heat.

The amount of energy to recool the room the next day is a linear function of how much heat must be moved, so it's not more expensive.

I'd check the efficiencies of each AC, the most efficient will cost less to run. The installed size doesn't have any effect on the running cost (but a bigger unit will usually be more efficient).

"The installed size doesn't have any effect on the running cost (but a bigger unit will usually be more efficient)."

Of course, that's assuming the same amount of heat is being moved, the bigger unit will just be on for less time.

So are you saying that you let your room heat up until the aircondition needs 50 minutes to cool it down?

If you control temperature say in a range of 5 degrees there is no advantage of having a larger unit (given that the smaller unit is sufficent to cool the room in the first place, which it is otherwise it would not be able to achieve this in 50 minutes).

I still think that unless there is a lot of door open and door closing in the room or there is a need to power off the aircondition for a certain amount of time a smaller unit will do. But this all depends on how this is run and what has to be achieved.

By the way, all I wanted to say was that a bigger unit costs more as in: "when you buy it". The efficiency would make a difference in the running costs.

Get a 15-ton unit. It will reach temperature in 3 minutes....

whats the rooms size: sq ft (or m^2) and ceiling height and occupants use and insulation?

Air Conditioner (AC) Unit Tonnage Calculator
Tonnage Calculator - Bluestar
How you calculate the size of an air conditioner for a room
Making a leap of faith that you know what to do from here.

It depends on the SEER rating (which has transmogrified the COP) of the unit you are looking at. You want to make sure it IS an inverter driven system. This typically starts out with a SEER of 14. You want a system with an oversized condenser to reject heat, the intent being to lower the condensing temperature, as this allows the compressor to use less energy. The inverter driven compressor, will slow down, once the room has reach the set temperature. Along with this is the compressor fan and the inside unit fan. The idea is to keep the unit removing humidity, and not freeze the evaporator in the inside air handler. So look for a unit that has a very high SEER. But you pay for this, as larger condenser (outdoor unit) is generally the method of improving this.

For normal occupancy the 1 ton unit will provide better comfort, provided it can maintain the desired temperature under the worst case conditions. This is because the smaller unit will lower the humidity more than an oversized unit. If both units have the same SEER, the operating cost will be about the same, but the installed cost of the 1 ton should be a little less.

Generally speaking, from just an energy efficient standpoint, less run time equals lower bill...but an A/C system is not just about cooling the air, it's also about lowering humidity, again generally speaking...as you cool the air it becomes more dense, this then raises the humidity....If humidity is low where you live(10 to 30%), then go with the larger unit....Lowering the air temperature in a humid climate without sufficient run time can raise the humidity above 65% creating a clammy environment which is not only uncomfortable but unhealthy....The perfect comfort level is about 50% relative humidity, below 35% is uncomfortable and unhealthy as well....If you typically have low humidity, then you may need a humidifier to raise humidity and a larger A/C system would probably not be a problem, again generally speaking....

Actually, it is relative humidity that gives you the 'comfortable' feeling but yes, you need to run it enough to also control humidity. This is easily done with the new digital combined thermostat/humidistat combo and they are wi-fi so you can hook up with them on your smart phone and not have to walk all the way across the room to look at them.

However, last year I went retro and installed two LG 12K BTU wall (window) units in my 1000 sq. ft. frame house in SWFl by cutting a hole in the wall above an outlet in opposite ends of the house, set them on 'Energy Saving' mode at 70 degrees and never shut them off. I also leave my front door open 24/7 with the screen door latched to keep the dogs in.

With all electric Energy Star rated appliances including a low boy water heater and a well pump and 13w CFL bulbs in all the lights, my electric bill is $78 a month every month.

Don't need heat here by the way but maybe two or three nights a year! :)

Thanks to all for participation.

Thanks Tornado also whose comments always creates a Valuable in thread.

For AC, it is generally considered better to err slightly on the side of undersizing rather than oversizing. I'm glad you enjoyed my facetious way of putting it.

One other idea you may want to consider. Instead of an AC unit, take a look at an evap cooler, particularly a Bonaire Durango. They are 5,500 cfm units that will keep the room cool, but they do add humidity.

Here's a real life story. One of our rentals has a 5 ton split system. The next door neighbor invited us over one day and at an outside temp of 105, it was very comfortable and cool in her house. I asked what her elec bill was like and she showed me her Bonaire. For a 1700 sq ft house, it's about $75/month vs $300+ for an AC unit. The air is dry out here, so the evap unit works well. If you are in a humid area, you'll need to go with the AC unit.

If your concern is energy savings, of course go with a 1 ton vs a 1.5 ton. The 1 ton will use less electricity, due to a smaller compressor, condenser, air handler and A-Coil. This is of course comparing apples to apples, ie same SEER rating. Also, go with the highest SEER rating you can, while keeping within budget. Anything near 18 is very efficient.

Good luck.