Window Air Conditioner supplement?

[lucigo]

I'm hoping some to get some budget friendly advice. I bought this house at 1100 sq ft, and then opened up the walls and finished the oversized garage, making it 1800 sq ft. Of that, the small bedroom and even smaller laundry room have their own AC, however the large family room just isn't getting cool and our electric bill seems really high, so I'm wondering if we were to get a window AC unit for that room would that save our central unit from working so hard, and would it lower our AC bill or would it be higher? Best I can tell I would need a 12,000 BTU unit. We have been told $7K for a new whole house AC so thats not happening until its dead.

Thanks for looking!

 

[ilovemk76]

A window A/C would work. How old is the central air unit? I would expect your electric bill to go up because window units are less efficient (unless you have a really old A/C). Where is thermostat located?

 

[lucigo]

A window A/C would work. How old is the central air unit? I would expect your electric bill to go up because window units are less efficient (unless you have a really old A/C). Where is thermostat located?

The inside part of the AC is original (1991) and the outside unit is about 8 year old. The thermostat is located on the opposite end of the house from the new room, in the hall. The bedrooms stay cool, the middle of the house (living room/dining/kitchen) are just ok, and the new part is just downright hot. Our electric bill was $357.

 

[ilovemk76]

The inside part of the AC is original (1991) and the outside unit is about 8 year old. The thermostat is located on the opposite end of the house from the new room, in the hall. The bedrooms stay cool, the middle of the house (living room/dining/kitchen) are just ok, and the new part is just downright hot. Our electric bill was $357.

The outside unit is usually good for about 10 years.

This could be a BTU (A/C is not too small) and balancing problem. It would be better if you put in two or three zones when you replace your A/C unit.

1- Bedrooms
2 - New room
3 - Rest

You could do zones now but it will be costly. The board is $500+ and you need to install dampers in all the rooms sources. Some even put them in the returns.

Does each room have a return or is there only one? If you have multiple you could try blocking off part of the returns close to the unit and then have the one farthest way be the completely open.

 

[lucigo]

The outside unit is usually good for about 10 years.

This could be a BTU (A/C is not too small) and balancing problem. It would be better if you put in two or three zones when you replace your A/C unit.

1- Bedrooms
2 - New room
3 - Rest

You could do zones now but it will be costly. The board is $500+ and you need to install dampers in all the rooms sources. Some even put them in the returns.

Does each room have a return or is there only one? If you have multiple you could try blocking off part of the returns close to the unit and then have the one farthest way be the completely open.

We only have one return. I've been doing what you mentioned with blocking returns, and we have been using fans to pull the air into the rest of the house. I think I am going to try the window AC. We end up not using our new family room because its hot, so this will give us our house back. It will be interesting to see if the electric bill goes up or down, or stays the same.

Thanks for your input!!