My Trane A/C heat pump is eating my electricity. $707 bill

Marilyn S
by Marilyn S
I got my electric bill for January and it was $707 for almost 6,000 KWH of power, about 5X the usual month. My electric company 1st changed out my meter but then said the problem is my furnace. I have a Trane air conditioner/heat pump with three zones. They said the auxiliary feature to generate extra heat is not turning off. I live in FL - it doesn't get that cold! The repairman said he fixed it yesterday but overnight, we used another 100 KWH of power! They came back today and said there's nothing wrong. Help!
EDITED TO ADD: The third repairman was the only one to go up to the attic. He found that a duct had split wide open and most of the heat was staying in the attic. As a result, the auxiliary heat was coming on and staying on and using enormous amounts of electricity. He repaired the duct and my KWH/day declined to an appropriate level. Hooray! Thanks to all who offered solutions for my problem. (And thanks to Shari for explaining how to edit a post.)
  10 answers
  • Shari Shari on Feb 16, 2014
    I hope, for your sake, one of the professionals here on HT in the heating/cooling business can shed some insight but short of that, I think I would be calling another repair company for a second opinion. Even if your unit is still under warranty, you should be able to request the warranty service people send a different repair company. I have had to do that for several of my appliances when the first company/repairman didn't get it right. Seems nobody can fix an appliance on the first service call these days.
  • The primary reason for high electrical is the emergency heat is running. While normally the heat pump can keep up with the house temps assuming its properly sized. When the temps drop below around 40 degrees there is simply not enough outside heat to keep up with the loss in the house. However that is not the entire story. One thing that affects heat pumps is ice. If the outside unit is not defrosting the emergency heat stays on as the heat pump side simply does not work. So that can be caused by a stuck reversing valve. What happens when it goes in defrost mode is the system converts back into an AC unit and the heat that blows outside melts the ice. While its in this mode, the emergency heat comes on so warm air still blows out of the grills. Another reason is snow build up against the outdoor unit. If you have experienced blowing snow and it has built up against the condensing unit, it simply cannot work thus the emergency heat comes on to keep things working. However I do not think you have been having this issue being in florida. Lastly a undercharged system again will not make enough heat causing the emergency heat to run. The bottom line is your heating your home with the emergency heat mode of the heat pump. Although it may appear that the system is running normally, something is keeping it on. Can be stuck, can be a thermostat issue, or any of the other things above. I suggest you get a HVAC pro in there right away to determine what is going on. You can trouble shoot this yourself by simply turning off the breakers that feed the emergency heat side of the system and see if the unit blows cold air while its running outside. If its iced up, the reversing valve is faulty. This is a common issue with heat pumps. And if you have had to have refrigerant installed in the recent past, that makes it more likely that is the issue.
  • Jean Adams Jean Adams on Feb 17, 2014
    My high electric bill turned out to be a freon line that was completely broken loose. My emergency heat was running for a month of snow & sleet weather. I was not happy with my air conditioning man or my new American Standard hp unit. I was sold a silver when if I had been told by this "friend" could have had a platinum for a few hundreds more.
  • We have an old heat pump unit which electric bills one winter were above $500 and I freaked and found out that the relay had gone bad and a good friend who has been a HVAC guy for over 25 years found this when others could not. The relay was causing my unit to heat and cool at the same time! He checked the temp of the air going into and out of the unit and found that the air temp was the same. So have them check this. 2 HVAC guys thought I was crazy when I said that the air coming out was not warm and they gave me the lecture again how heat pumps are not that warm. Only when I called a friend did he pinpoint it. Do not give up. I have used emergency heat and it did not burn that much electricity but when my relay was bad it used a lot and I had the temp set on 67. Then over the summer my electric bill was through the roof when the freon was not charged properly by another service technician. So these are two issues to check too.
  • Jean, the one thing you and others should understand. Make of system has nothing to do with how a system operates or how long. Its all about the quality of the install. Regardless of low cost units, or most expensive ones. They all work exactly the same. And need to be properly installed which again is exactly the same. But more low end units tend to be poorly installed as the contractor is cutting costs to make more money. Had he or she did their job properly, it will last just as long as the higher end units. The primary difference between the qualities is noise, efficiency and looks. Lower cost units simply do not have all the extras that make the unit more quite, or efficient.
  • Out of curiosity, have you checked the filters?
  • Bonnie Overman Bonnie Overman on Feb 17, 2014
    I have just the opposite..When it's below say 32 outside, the auxilary blows cold air for a very long time before it ever becomes mildly warm....Thank God I have a wood stove..If I didn't I be using portable heater to sub the unit which is only a year old...It's just the nature of a heat pump..
  • Bonnie in your case the size of the aux heat may be to small, or worse yet the feed wire that provides the power for that part of the unit may be undersized. To small of a wire will prevent a quick heat up of the element. I suggest that an electrical contractor check this out for you. Aux heat should be warm almost instantly. It should not take any time more then perhaps 10 seconds to provide warm air.
  • Bonnie Overman Bonnie Overman on Feb 18, 2014
    When they installed it,the installer did not run a separate line for the auxiliary...When they came to routine in the fall the guy caught it and ran the line. still blows cold
  • Then either the line is undersized, wired wrong or the heater is wrong. The aux heat should be as hot or hotter then the heat pump running alone. I suspect undersized line.