Quote:
Originally Posted by MN Renovator
"Another question, would running the A/C in the cooler temps of the night be more efficient for it?"...
Yes.
My air conditioner is a cheap not too efficienct unit from 1986. Here is the power input to my 22,000BTU/hr air conditioner for different outdoor temperature ranges when the sun isn't pointing at the unit. This includes the furnace blower as well as the compressor so you are seeing the whole system.
77-81+? 2400 watts
68-76 2300 watts
60-68 2200 watts
<60 2100 watts
Not only does the lower outdoor temperatures cause less power to be used by my unit, if I operate the air conditioner at colder than 60 degrees outside and the supply temperature isn't warmer than 80 degrees, the coil will freeze. I've frozen the lines going all the way back to the condenser twice from evaporator icing. If you aren't familiar with your system, try to keep it from running when it is cooler than 65 degrees outside. In my case I should install a freeze thermostat to the evaporator coil but I'm really not interested in throwing money away at trying to save an old inefficient unit that took the abuse twice already so I'm just more careful...
What this means is better efficiency.
Runtime, last summer I made sure to run my air conditioner 2 hours at the coldest point of the night as long as the temperature didn't have a threat of getting below 60 degrees outside... This year the bills will be significantly higher... I don't know if I can allow the evening temperature to rise enough to run a nightly 2 hour run without dropping the temperature below where I really want it... the heat has this extreme conservationist a bit on edge over what will happen in the summer.
|
This sounds like a clear case for improvement over the status quo. If you are not getting enough dehumidification with what you have now, swap out that cap tube for a TXV. At low outdoor temps, the unit will move much more latent heat outdoors and not freeze your evaporator. Your power consumption will rise slightly in proportion while the unit is running, but overall your run time will drop. At daytime temps, this option will pay for itself quickly by matching your indoor coil load with all that the condensor can supply, again reducing run time.
If you don't want to mess with the refrigerant circuit, increase the airflow at night. Just find a higher rated blower for your air handler and wire the speed taps to a 3-way light switch. The evap will not freeze up at night while the unit is running at max airflow. Depending on... blah blah detail detail ... the system will still pull just as much water out of the air at night while cooling the air like it is supposed to. This option will not save you as much money, but is easier to accomplish with less work involved. But you'll have to flip the switch for night speed.
Or you can always just go and buy a 20 seer ac unit and have someone else put it in. This may or may not be considered throwing away money since the unit would eventually pay for itself in energy savings. Especially if you went and bought a heat pump.