We purchased our new 1950 sq ft home in Feb. 2009. We just got our power bill for May and June that has really gone up. I had the power company pull the past 9 years and the our bill has increased $200 from the previous years.

I had the power company do a energy test and they said we had a problem with the HVAC unit because the charts show the high use at the middle of the day (up to 14 kwh).

I had a company come out and check the unit inside and out and could find nothing wrong except they said our ductwork is to small and needs to be replaced. They also said our 3 ton unit was undersized for our house. They also said that dirty filters could cause the high bill.

The unit is a carrier 3 ton that is 9 years old the rating when new was a 10. We have changed nothing from the previous owners and have set the temp on 80 degrees inside to save money and the bill went up from $411 in May to $505 in June.

We do not know what else to do?

Could the dirty filters have this much of a impact on the bill? Should we have another company come out to check the unit?

Thanks for all your help. We are broke and very hot in South Carolina!

Dirty filters can cause you to have higher bills but not like that. I would call another company out. It could be the unit is undersized and ductwork to small. But without being there I can't say anything for sure.
How old is the house? Did it always have central ac? Is it gas heat? Also keep in mind electric companies are raising their rates now adays. In PA we have seen a huge increase as of late. Also where are you located? What are the temps this time of year?

The more info we have we can try to help. You might need to do a heatload calculation. I don't have a link but if hvac1000 chimes in he will have one for you. Also any good hvac company can do one of these for you as well. Most companies do when when they come to quote an instal for a new unit anyway.

I can`t help but wonder, 1st the dirty filter can interrupt the quality of air flow meaning the heat or ac wasn`t doing the best it could do. But 200 $ worth! Wow!

But its not like you just had the to small 3 ton unit and duct work that's that's all to small installed since you moved in in Feb. 2009, so why didn`t the previous owners have the same probs.

Did the power company compare the KW cost rates from then till now? Has the kw cost per gone up ?

A second opinion from a different hvac company might be good, and don`t tell them what the other company told you. And if they do tell you about the same thing,, have them do a manial J to determine what size equipment you need, as I`m thinking How did the 1st hvac company determine that your existing equipment is to small without doing a manual J
Also ask questions like was all the ductwork intact with no heat/air being waisted /are the motors being checked to see they are pulling the correct amps/is the ductwork insulated correctly/do they think the roof/overhead insulation is OK
All this should be looked at when doing a Manual J
I`m also wondering why the kw usage is up in the middle of the day (the hottest ) time of the day, again is the insulation sufficient? But again why is this a problem that has just popped up after you bought the home and not there for the past owner

Let us know how /what has been done

Usually a power company will not divulge the previous owner’s power usage at least that is the way it is around here. It has something to do with customer privacy.

Tell us about all the other appliances running in your home since the base 411.00 bill from the month before seems way too high to start with.

Sounds like one or more of the electric heaters in the unit may be running with the A/C for the bill to get that high that is if you have electric heat. I cool 3000++ square feet with 3 separate central A/C units that are 25 to 30 years old and my bill is no where near as high as yours.

We need more info from you. Exact type of heat,one or two story, true age of home,construction style,etc. While we cannot be there to look for ourselves the extra info will better enable us to possibly help figure some causes of high energy usage.