Bedroom A/C Sizing

[Super Mech]

About 13 years ago I had the upstairs of my home dormed out and at the same time had the contractor install 4 thru the wall a/c units (one in each room). All the units worked properly except for the one in my master bedroom. I belive it was oversized. It always cycled on and off too much for my liking and now it runs for a while then cycles off and you can notice an increase in room temps before it kicks on again. I'm sick of it! The room size is 19' x 12' with a slanted ceiling that ranges from 8-12' high. The long wall faces north and one short wall faces west. There is one window on the north wall and another on the west wall. the roof is right on top of the room and it is insulated and has ridge venting. Walls are also insulated. The sticker on the unit says 15000/14500 btu, 220 volt. I personally think it is too large. Any opinions?

 

[JakeKohl]

15k btu is a gigantic unit for a 19' x 12' room. I'm heating and cooling a 24x36' garage with 10 foot ceilings with an 18k btu mini-split unit and it's overkill. You should be able to heat and cool that room with an 8k btu unit or smaller.

 

[tylernt]

Jeepers that's huge! I agree with JakeKohl, 8,000BTU would be about right. You'll probably need to convert the 240V outlet to a 120V outlet, but that's an easy job as you can use the existing in-wall wire -- just reconfigure them inside the breaker panel and pop in a new receptacle.

In the meantime, some A/C units have a "econo cool" mode. You don't want that. If you turn OFF econo mode, the fan will run all the time and only the compressor will cycle on and off with the thermostat. Since the fan runs all the time, a more even temperature will be maintained in the room.

 

[PatDoody]

rule of thumb is 1cfm of per sq'. 1ton of ac is 12k btus. Newer construction with good insulation and windows Figure around 1 ton per 600sq'. With that you can easily adapt the numbers to fit your room dimensions.

 

[pattenp]

If you look at the specs of a 8000BTU window A/C it cools about 350 sqft of room size. A 15000BTU cools about 900 sqft.

 

[Super Mech]

Jeepers that's huge! I agree with JakeKohl, 8,000BTU would be about right. You'll probably need to convert the 240V outlet to a 120V outlet, but that's an easy job as you can use the existing in-wall wire -- just reconfigure them inside the breaker panel and pop in a new receptacle.

In the meantime, some A/C units have a "econo cool" mode. You don't want that. If you turn OFF econo mode, the fan will run all the time and only the compressor will cycle on and off with the thermostat. Since the fan runs all the time, a more even temperature will be maintained in the room.

Yeah it is huge! I am gonna change to a smaller unit within the next 2 weeks and switch over to a 120 outlet as you mentioned. The only problem I have is that the new unit will be smaller and if I change the sleeve I have to resize the hole in the wall and patch in new siding. The unit is on the second floor about 20 feet from the ground. Patching the inside is not a problem.

This ac does not have a econo feature, the fan runs all the time.