$400 electric bill traced to heater - what could be wrong with it?

Question

Back in December/January, we got a real shocker; a $400+ electric bill. I thought there must be a billing error, so I went out to the meter, and found that not only was the number probably right, we'd used another 1000kW/h since the reading (which was about a week and a half prior). This is for a modest 1600 sqft 1.5-story house; WAY outta line. My next thought was a leech; someone hooking to our service unbeknownst to us. We turned off all the lights, computers, etc etc, leaving the service panel on, and... wait, now it's down to a crawl. OK, so it's something in the house. My wife and I were talking by cell phone, when suddenly I see the dial start its whizzing again. I asked what turned on, and she said, "well, the HVAC started a few seconds ago". Bingo. It's an all-electric home, so we have an electric heater, and when it's running the full system (not just the vent fan), it's really drawing some juice.

The heater is not original to the house (at least, it's a Lennox with logos and branding far newer than the Sears-Kenmore HWH which IS original). I can't tell you it's exact age at this moment. We replaced the filter; no change in electrical use. We REMOVED the filter; no change. We also noticed that despite the massive power draw, the system was not producing very warm air (though it is blowing pretty well). It seemed fine in October/November, but then, we had a relatively mild winter until mid-December. Whatever this is, it is NOT normal; we've had 1000+ sqft apartments and townhomes that we could heat very comfortably in the winter with $150 bills. An extra 500 sqft of house should NOT be costing $300 more to heat. As a reference, through the summer months in this home (including the hottest monthly average for August, ever), which generally produce much bigger bills than winter, we kept this same house around 75* and paid about $220/mo.

We have a home warranty agreement that would cover a fault in the HVAC unit itself, and MAY also cover wiring slipups. We picked a name of an HVAC company out of a city publication for new home owners, so we're not sure just how good they'll be. Knowing what I know right now, what would I expect to hear these guys say? My primary expectation is a short in the heating element or in the switching circuitry within the unit. If they say it's normal I'll be telling them to shove their normal up their [censored]; we've had the HVAC system off since we found the problem, using our fireplace instead, and after living in a house averaging 60*, our latest bill (including the week after the prior billing cycle) was still $250. Whatever it is, it is NOT normal.

EDIT FROM COMMENTS: It is a simple forced-air system with an electric heating element. The breaker marked for the heater is 220V 70A. That means that the max available wattage is 15.4kW. Running 24/7 at its max rated power for 30 days, the system would cost $1020... So maybe, just maybe, there's nothing wrong with it.

EDIT 2: The warranty repair guy showed up yesterday. When my wife showed him the heater unit we had, he knew exactly what she was going to say next; apparently this particular unit is infamous for its inefficiency. Nevertheless, he did a check of the system, and found that one of the 3 heating elements was disconnected. That was putting more voltage onto the other two coils, and decreased the effectiveness of the whole system, meaning we were using the same amount of power to do less work for a longer period of time. After reattaching the element, the house heated up to the thermostat setting quickly and we're noticing it's not running nearly as much. However, we should still be expecting $250-$300 bills for months that hover around freezing.

Answer 1

From the DFW comment, I'm guessing you implied Dallas/Fort Worth. If that's the case, then you'll have AC already installed, and a lot of winter days that are above freezing. For that climate, a heat pump would be much more efficient. The emergency heat setting on a heat pump is the same as what you already have and you'll want to use that when it drops below freezing. But all other times the heat pump will be more efficient.

Answer 2

First, talk to your power company. Because in a community full of all electric homes, it's likely that the power company has plans (tariffs) for people like you, especially since you're in the sunbelt where their peak load is actually defined by air conditioning. I've seen one power company tariff where the heating-season rate was "1 cent a kwh (!) plus $7/kw for your highest 30-minute period" (so that heater would add $110/month + $15/hour to your heating bill).

Unless something is broken, electric heat is 100% efficient. It has no exhaust stack and there is literally nowhere else for the heat to go. Every watt produces excatly 3.41 BTU/hour (which is the standard unit for HVAC, even though they call it "BTU" they mean BTU/hr). However, there are two ways to go "over unity" without violating the laws of physics.

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First, a heat pump is exactly what it says on the tin: it doesn't make heat, it only pumps heat. You already have two in the house. One is the refrigerator. The other is the air conditioner - it's a one-way heat pump, lacking the $6 reversing valve to be able to run backwards and heat. Stupid design. Yes, heat pumps provide air conditioning. The physics of heat are a little odd, and so this works: you can pump 2-6 BTUs of heat for energy cost of 1 BTU of electricity, so it is "over unity", often by quite a lot in favorable conditions. The best heat pumps are 38 SEER in cooling mode (loosely: 38 BTU/watt) and if you followed the above math of 3.41 BTU/watt, that's 11:1 over-unity. Really.

Ground-sourced (or groundwater-sourced) heat pumps are far more efficient still, because they interchange heat with temperate underground areas. Edit: Better air-interchanging heat pumps are really quite good these days. Chicago? No problem. But it can be said that they are always climbing uphill (edit: unless you run a clever schedule): in A/C mode, trying to dump heat into air that's already hot, or in heat mode, trying to extract heat from air thats already cold. Ground or groundwater is always temperate. Ground-sourced pumps also won't need an emergency heat mode, which is plain resistance heating - exactly what you have now.

Second, a resistance heating element doesn't need to be dumb. It can be very, very smart, and be optimized for solving crypotgraphic problems, one of which is mining "BitCoins" or other digital currencies. 1 BTU of electricity only gives 1 BTU of heat, but it also gives you some digital currencies you can sell to offset the cost of electricity. This won't be as profitable as the forums say, because you'd only run it when you want heat. If you ran it year round, you'd be paying peak rates not only for electricity to run the miners, but to run the air conditioning to cool them. OK, that's not over-unity thermally but it is over-unity financially.

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Your house was built at a time when nuclear industry executives were promising that nuclear fusion would be "clean, safe, and too cheap to meter". They were recommending America build out all-electric with all deliberate speed. They never imagined $400 heating bills. But other technologies (like heat pumps, especially ground-sourced) or dual-use machines ease the burden.

Why is a house so much more brutal than an apartment or townhouse? Exposed sides. In an apartment you have many walls in common with neighbors and 0 heat liss through those walls, because behind those walls is the same temperature. In a house you have all 4 walls, roof and floor/crawlspace exposed, that plus your larger square footage (of floor area) means your square footage (of exposed surface) is many times larger than an apartment. And thats what you pay for.

Answer 3

If your heating system has ducts running through the attic check to make sure one of them has not come loose. Blowing heat into the attic can keep the heater running a lot more than it should.