You can close doors to unused rooms if there is enough space under the door to allow for sufficient air circulation. If you do decide to close some registers, never close off vents to more than 10% of your total conditioned space.
The following two factors cause this to be true:
- The cooler outdoor air temperatures of winter are easier on the compressor resulting in increased efficiency and lower energy consumption.
- The heat generated by the motor of the compressor itself is added to the air delivered to your home, resulting in increased capacity. What this means is that during winter the capacity of your system increases and the energy consumption decreases.
Next, try to determine what portion of your monthly bill actually went to air conditioning. To do this, subtract your March bill — a month when people typically do not use any cooling or heating — from your July bill. The difference between these two months gives an estimate of your cooling cost.
Although you replaced other appliances, their impact will be minimal. However, changes to your windows can produce very large returns for a small investment. Almost 40% of all the heat that enters your house in the summer comes in through the glass. Installing simple and inexpensive exterior window shading on sun-struck windows can dramatically reduce the load on your air conditioner.
Another kind of disposable filter uses pleated paper as its filtration medium. The pleats enable a large amount of filter paper to be installed in the filter frame thus increasing the filter’s efficiency. Even though it has more filtering surface area, it still needs to be checked monthly and replaced when necessary.
There are also permanent filters that can be operated by natural electrostatic charges or by electronic circuitry. While these filters do not need replacing, they can be expensive to purchase.
The bottom line is, unless you have a medical condition that requires high levels of air purification, disposable filters will work just fine. The thing you have to remember is that they must be replaced regularly. If they become clogged, your air conditioning system will not get the air it needs to run efficiently, resulting in higher-than-necessary cooling costs.
To determine what size air conditioner a house needs, a contractor will conduct a heat gain/heat loss calculation, which enables the contractor to match the size of the unit to the BTU requirements of the specific house. A general rule of thumb for an average home is about 500 sq. ft. per ton.
Bigger definitely is not better. A larger-than-necessary system will turn on and off more frequently and cost more to operate than a properly sized system. A unit is operating at its lowest efficiency when it initially starts. The longer a unit runs the more efficient it is. Be sure to look for a properly sized system.
The continuous operation of the unit is actually very efficient. Without all the starts and stops of a typical cycling unit, you’re able to run the system at its peak efficiency. However, setting the thermostat at 85 will also save you money (perhaps not as much as turning the unit off), while not taking as long to re-cool your house. Both options work, it’s just a matter of how much discomfort you’re willing to put up with.
A general rule of thumb is that one ton of air conditioning can handle 500 sq. ft. of conditioned space. So your 1,550 sq. ft. house should have a little over three tons.
Considering that your unit appears to be oversized and yet is not able to provide adequate cooling, I recommend that you have the system tested and your house inspected.
Any pre-cooling strategy has to be operated long enough to cool the structure and not just the air. If your house is heavy, I’d recommend pre-cooling it down eight to 10 degrees for a good four to six hours prior to the on-peak period. If your house is light then a four- to six-degree pre-cool for a couple of hours should be fine.
While SRP recommends a minimum of 13 SEER, you should rely on your contractor to help you decide what level of efficiency is best for you. Before you buy any system, make sure that the contractor performs a heat gain and loss calculation on your house. This will ensure that you buy the correct unit size for your house. Systems that are larger than necessary will not only have higher initial equipment costs but also higher operating costs.
With regard to the manufacturer, all the major brands manufacture high-quality equipment that will last 15 to 20 years. When shopping, manufacturers, look at their warranties as a sign of their quality.
The industry says that Freon R12 will be around for many years, but there is no guarantee of how much it will cost. I recommend a system that uses the new refrigerants, as they are not limited to quantities on hand. In addition, a SEER 12 will save you approximately 10% in cooling costs over a SEER 11 system.
As your warm indoor air is drawn up through the filter, it passes over a very cold coil that removes the heat and moisture. If you’ve ever noticed a plastic pipe running off your roof that drips water, that is the moisture the unit has removed from the inside of your home.
To see if your system is performing as it should, get a hold of a couple of quick response thermometers and put one in the return grill (the grill where your filter goes) and the other one in the supply register (the vent that blows the cold air into the room) closest to the return grill. You should see about a 20-degree difference between the two readings. If not, it can indicate that you have refrigerant or airflow problems.
It is very hard to determine if your cycling pattern is normal without an inspection of the system. I recommend having a contractor inspect the unit.
Proper sizing is very important. A larger-than-necessary unit will cost more to purchase and will also cost more to operate each month. Make sure your contractor performs a heat gain and loss analysis on the house, which will help you select the proper size unit.
During normal operation, the evaporator coil located inside your air conditioner becomes very cold. As the air from inside your house is drawn through this coil, the air is cooled and the moisture is removed. The cold air is returned to your house through the supply registers and the moisture drains to the bottom of the coil, into a drain pan, and out the condensate drain.
Several things could be wrong with your unit:
- There is a drainpipe, usually a white plastic pipe, coming out of your unit that should be dripping water this time of the year at a pretty good volume. This water is the moisture from your house. If it isn’t able to discharge this water when your air conditioner is running, it will continually put it back into your home, increasing the humidity level.
- There could be a leak in the ductwork that distributes the cold air to the rooms of your house. The leak can add hot, humid air to the air being distributed to the rooms.
By turning your thermostat up and not turning it off completely, you will protect any fine wood furniture or other items that can be damaged by the heat and dryness. I also recommend placing several buckets of water in your bathtub. The water will slowly evaporate and add moisture to the air.
If you have an older, less insulated home, you should continue to turn your air conditioner up to a high setting as you have in the past, as the temperature in older homes can rise into the 90s.
You should also turn off the power to your refrigerator, prop open the door, and turn your electric water heater off. If you don’t, the higher temperatures can cause your refrigerator to run twice as long and the water heater will continue to cycle on and off all summer.
About 40-50% of the heat comes in through the windows. While your awnings help divert sunlight, you might want to consider adding shading screens to the outside if any of your windows receive direct or reflected sunlight.
If you’re going to be gone for the summer, in addition to setting your thermostat to its highest setting or turning it completely off, you should consider emptying out your refrigerator, propping the door open, and unplugging it. If you leave it operating, it will run almost 24 hours a day because of the hotter temperature inside your home. This can add a significant amount to your monthly bill.
Because heat travels from hot to cold, the heat that is entering through the window remains in the house and therefore has to be removed by the air conditioner. Even with the door closed, the heat that builds up in the room will eventually travel to a cooler section of the house to be removed by your air conditioning.