I can't afford this.
January 13, 2009 7:00 PM   Subscribe

Why does my electric furnace use twice as much energy as my neighbor's? I live in a townhome development and we have the same floor plan.

My electric bill for the past two months has been $400 each month and I can't figure out why. I live a roughly 1900 sq ft townhome that is new; construction finished around October 2008. My neighbor's electric bill was about $200 over the last month. The only relevant difference I can think of is that I have the end unit in our row and he doesn't. I keep the heat set at 66 degrees in the house and the average temperature in my city was 41 degrees in December, for what it's worth.

I have been checking my meter since I got my latest bill and I am on pace for another $400 bill this month. Through switching breakers off and the process of elimination, I determined that the heater is the issue. I averaged about 5 kwh per hour of electric usage over the last couple months, compared to 1kwh per hour when I shut off the heat or cut the breaker. There was one hour where the heater was running full-time to re-heat the house after cutting the heat off and that used 16kwh for that hour.

My neighbor is using about 2.5 kwh per hour on his last bill compared to my 5kwh.

My heater isn't blowing all the time, but when it does it uses an insane amount of power.

Is my end unit the culprit? I have a hard time imagining that it would cause me to double my heating costs. Does it make sense that my heating unit would draw more power than it should when it's running, but no power when it's not?

Oh, and a final data point. I was not the first person to move in to my section of townhomes, and the other end unit was occupied well before mine. My electric meter is reading more than twice is high than everyone else's. If it was an increased bill due to having the end unit, the other end unit would have a reading like mine, wouldn't it?
posted by PFL to Home & Garden (14 answers total) 2 users marked this as a favorite
Electric meters can be wrong. Call your power company and ask them to come out and check it. Thermostats can also be wrong. I'm not doubting you, but I hear it all the time from relatives of mine that they keep the heat on 65 or some low number yet I always sweat in their house and I don't in my 72 degree house. Do you have the same furnace or is your neighbor's a more efficient unit? If their the same, is something wrong with yours? These are all the things I can think of off the top of my head.
posted by AstroGuy at 7:17 PM on January 13, 2009 [1 favorite]

End units have more walls exposed to the outside world and likewise don't benefit form neighbors' heating. You might also have a dirty furnace filter that's making it harder for the furnace to move warm air around.
posted by drmarcj at 7:25 PM on January 13, 2009 [1 favorite]

It is also possible that some of the shared facilities (exterior lights, laundry room) might have been accidentally wired to your unit.
posted by Monday at 7:46 PM on January 13, 2009 [1 favorite]

Check to see if your windows are properly insulated. Lots of heat loss can be attributed to windows.
posted by aeighty at 7:47 PM on January 13, 2009 [1 favorite]

Do you have a clock thermostat and are you using it? If your neighbor's heater turns off during sleep and while he or she is at work while yours is just on all the time, that would easily explain the difference.
posted by Slarty Bartfast at 7:54 PM on January 13, 2009 [1 favorite]

At first I thought the end unit, but this does seem suspect. It is hard to know how much you would be spending on electric for non-heat purposes, but if that number is about $100 (which seems a reasonable guess to me), then the difference for heat is actually $300 vs. $100.

You indicate you have isolated the problem to a circuit with the heater on it. Have you confirmed that the meter isn't turning/advancing when the heater is off? If so, then you know it is the heater. Other thoughts are that the heat isn't getting distributed into the house properly. Someone mentioned clogged filters, are there other fans or ducts? Does the room where the furnace is located get extremely hot? Is there anywhere your heated air may be getting exhausted directly outside?

To go back to my original idea:
Have you checked with other end unit owners? If your units are 2 floors by 20' wide by 45' deep, then the end unit indeed does have more than twice the exposed wall area, and depending on the construction could just take twice the energy to heat.

(Overall these numbers all sound unfortunate to me and a good sign of why we need better building codes and realty laws that let people know what to expect to heat and cool their homes.)
posted by meinvt at 8:04 PM on January 13, 2009

My thermostat happens to be near a bathroom. Generally we keep room doors open in the house, especially at night. However, I learned that this particular bathroom would heat up quickly and the overflow warm air would shut the thermostat down too soon for the rest of the house to be adequately heated. As a result, we were keeping the thermostat too high (to keep the warm air blowing longer). We saw significant results from closing that one bathroom door. Basically, we were unknowingly gaming the thermostat to not read the overall house temp well. Perhaps your neighbor has different habits/procedures in his home than you do.

Also, your floor plan may be the same, but since you have an end unit, your vents/returns may not be laid out the same. It makes a difference. I do agree with your logic about comparing your end unit to the other one. An end unit may use *some* more heat, but not double. Not in modern construction (unless the builders did a REAL crap job on insulation; but again compare to other end unit). You would notice significant cold/drafty spots.

You asked: "Does it make sense that my heating unit would draw more power than it should when it's running, but no power when it's not?"

Maybe I misunderstand you. It makes perfect sense to me that a unit use no power when it is not running.

The top things I would check are:

1) Filters. Easiest thing to change and cheap. Make sure you know about all the filters.

2) Call electric co. to test meter. Hey, you might be due a credit!

You either have some great inefficiency within your home (duct layout; ill-thought-out air movement, a la my bathroom; dirty filters; faulty furnace) OR you have a faulty meter.
posted by skypieces at 8:04 PM on January 13, 2009

Is there snow on your neighbour's roofs? If yes, is there snow on your roof? If not, the builders may have forgotten to insulate your roof, which happened to a friend of mine. If not that, check the walls around the garage: are any of them particularly cold? If there's one thing I've learned from Mike Holmes, it's that new houses often have insulation problems, and the biggest place for insulation problems is the garage.
posted by carmen at 8:07 PM on January 13, 2009 [1 favorite]

Wow... lots of great responses. Some quick follow-up details here:

I have determined that it is the heater itself; my meter runs VERY slowly when the heater breaker is switched off or I have the heat turned off. The only time usage on the meter spikes is when the heat is on. This makes me think the electric meter is working OK.

Regarding weather... we haven't had any snow and it hasn't been all that cold, considering it's January.

Are the filters dirty? I checked the one in my bedroom and it looked OK but i'm sure it wouldn't hurt anything to change them out. I also haven't noticed any drafty spots or anything like that - for what it's worth, I had the heat turned off for about 6 hours today and the temperature inside dropped from 66 to 60 during that time period (it was about 30 degrees outside). My guess is that if I had serious drafts it would have dropped more than that, but I can't say for sure.

The neighbor doesn't have a clock thermostat; he and I have the exact same setup.

I need to check with the other end unit, but I'm guessing they won't have the same issues that I've had. Nobody has lived in these places for more than 2-3 months and my meter is at least 4,000 kwh higher than any other meter on the panel- this in itself is in indication that something is wrong. I wasn't even the first person to move in.

Bottom line is that the heater is working incredibly hard when it's on. I'm hoping it's due to a faulty unit, since that is at least under warranty.
posted by PFL at 9:39 PM on January 13, 2009

Seconding the suggestion to have the power company come out and test your meter (or replace it). The issue here is that your meter may be out of calibration — that is, it may be registering more electricity than you're actually using. Only the power company can tell for sure.

Also seconding a comparison of your daily electricity usage with the other end unit. Along with, of course, finding out what thermostat settings they use in the unit.

Also, which direction does the cold winter wind blow from? If it hits your unit head on, that could make a difference too.

Finally, if you're really concerned that the heater isn't working properly, do have a professional come out and check it, especially since it's still under warranty.
posted by exphysicist345 at 10:08 PM on January 13, 2009

Is it a heat pump or is it electric resistance heat? Sounds very high for a heat pump, not so high for electric resistance. Some heat pumps use electric resistance for backup. It's possible that it's stuck in this mode.
posted by electroboy at 10:15 PM on January 13, 2009 [1 favorite]

I'll second electroboy's comment. Make sure the thermostat is working correctly. Is the emergency heat button on all the time? Is the stat electronic or does it have the mercury switches?
I expect your bill to be significantly higher as the end unit, just not that much.
posted by rholly at 1:11 AM on January 14, 2009

Could be the blower motor in the heater is faulty and drawing too much electricity. Or yes, if it's a heat-pump system, the resistive heat is stuck on. Does your system have an outside coil/compressor/fan unit that (is supposed to) run when the heat is on? And/or, do your neighbors? Maybe this unit is clogged or faulty. Could be a low/leaky charge of refrigerant causing the heat pump to run inefficiently and/or cause the resistive heat to kick in.
posted by gjc at 8:00 AM on January 14, 2009

Well, we figured out what the problem was, eventually. The timer for the backup/emergency heat was set to 5 minutes, so anytime my heat pump ran for 5 minutes the electric heat strips would kick on and spike my electric bill. I set the timer back to 60 minutes and my electric usage dropped down to reasonable levels.
posted by PFL at 7:05 AM on February 19, 2009

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