Power Bill kWh and wood stove use not adding up

[Eric Minnis]

Looking back over out power bills for the past couple years and am having a hard time understanding why our kWh is as high as it is when running my wood stove insert. It is a newer 2 story house and very well insulated. All electric appliances. I run the wood stove insert upstairs anytime night time temps are below 30. When we have consecutive cold days, I run it continuously. Upstairs heat pump never comes on.

Wood stove has a flue baffle and is one of the newer 2020 compliant versions. (Osburn 2700i)

What I am thinking is that because we do not have a door on the stairs going downstairs, the heat upstairs pushes the cold air down and just makes the downstairs heat pump run harder. We do keep the temp set at 63 downstairs. A door may be in order to stabilize things.

Any thoughts on this theory?

FWIW- this last billing cycle we used 2500 kWh for a 2800 sq ft house. (1900 upstairs/ 900 downstairs) This same period last year it was closer to 2000 kWh.
Located in the Piedmont of NC. Seems really high to me.

 

[EbS-P]

Last year the only cold day or two happened right around chthonic it warmed back up. I’m looking at my wood stacks and be probably used 3 times as much this year as last. If you have Duke you can get your energy comparison and it shows the average temperature. I’m not saying that the temps are responsible for all of the difference but probably a lot of it.

How are of heating your water? When it get cold the incoming water get colder too.

The coldest air is going to sink anyway. So unless you have added new penetrations that weren’t sealed I don’t think your displacement idea would result in higher usage.

 

[Eric Minnis]

Agree- we have had colder weather this year for sure. I've run through much more wood this year than last. I do heat our water with an electric water heater that is under the house in a climate controlled crawl space though.

Maybe 2500 kWh is average for this size house in this area.

 

[EbS-P]

You just need to get your hm energy report.

Quick snapshot of mine 3000 sq ft(1000 is a basement which is super unusual here) 1948-73 construction. With electric heat In Wilmington.

2500 seems a bit high. I’m about as low as one can get. I even hang 90% of the laundry out. (5 kids worth) and charge and EV for 300-400 kWh a month.

Figure out if your heatpump is regularly using the resistance strips. Mine would anytime the room temp was 2 or more degrees from set point after 10 minutes of runtime. I got an ecobee thermostat and locked out the strips above 35 outside temp and will only run them if the room temperature is 4 or more degrees below set point.

 

[Eric Minnis]

Just updated my profile on the Duke Energy site. Interesting thing. . . . we are well below average and even below the "efficient home" rating in the AC months but well above average in the winter heating months. Very hard to believe since we heat so much with wood.

We do keep a little electric heater going in the garage. It is one of the oil radiator types just to keep it decent in there.

 

[Eric Minnis]

 

[30WCF]

Shorter days mean more lights running. Christmas lights and trees running around the clock. Shorter days also means more time spent indoors, so maybe more tv or games or whatever y’all do.

 

[vatmark]

Does your insert have an electric blower that runs? Maybe that contributes to some of it?

 

[Eric Minnis]

It does have a small electric blower and because it is an insert, it runs when the stove is working.

In hindsight- if we ever build again, I'll ditch the insert and do an alcove for a free standing Jotul or similar. We have one (F45) in the basement and it blows the much larger insert away in terms of performance. It also causes me to want a whiskey drink but then again, any fire does.

 

[EbS-P]

Your garage heater could be using 300kwh a month. Time to get a kill a watt meter and start finding out how much small appliances like that are using.

It’s clear to me this is a heating issue. Have you had your hvac systems serviced? If not have the technician walk you through how and when units use the backup resistive strips.

You can also get hourly use stats from Duke. They can be helpful but kinda limited trying to figure out what appliances are the biggest culprit

 

[mellow]

Check into Sense, it isn't perfect but will let you find phantom devices using more power than you think.

Sense.com – The Sense Home Energy Monitor

sense.com

 

[NHWS]

Check into Sense, it isn't perfect but will let you find phantom devices using more power than you think.

Be sure to read their privacy policy, and decide whether or not you are comfortable with Google, Facebook, etc., having highly detailed information about your use of the electrical devices in your home.

We may use information that we collect in the following ways :
...
– To link or combine your information with other personal information we get from third parties, to help understand your needs and provide you with better service.

– To provide you with personalized promotions, offers, and advertisements, which may include providing third party advertising vendors with data collected to target advertising based on the end users’ online activity.

Sense may store and process personal information in the United States and other countries which may have data protection rules that are different from those of your country.

We do not disclose your personal information with third parties other than as follows:
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– with third-party resellers, integrators, and program providers if applicable in your specific situation, who may use the data for purposes such as research, customer support, or in order to provide their respective services to you.

 

[brenndatomu]

We do keep a little electric heater going in the garage. It is one of the oil radiator types just to keep it decent in there.

Those use a ton of power!

It does have a small electric blower and because it is an insert, it runs when the stove is working.

Those use next to nothing.

So is it possible that the heat pump(s) are running some sort of internal heater, or defroster? Seems I recall that being a thing...

 

[kevin588127]

Are you sure that your heat pumps are operating and that you aren't going into emergency heat mode? I have an ecobee tstat and it lets me see which stages of heat or cool are kicking in and for how long. It also overlays it to the outside temp and humidity. I'm similar square footage but much colder climates. My heat pump locks out under 22f outside temps. I see numbers like yours in Sept and Oct. I've been on electric strips for the last month😭

 

[Bobbob]

I definitely think that there is a problem with your heat pumps. Possibly defrosting to frequently. I live in a much colder climate than you do and my house was built in the 60's with less insulation. I heat similar sized space as you and am also all electric. My last electric bill we used 1500 kw. That includes laundry and showers for four. We average about 1200 kw throughout the year. Last time I had an alarmingly high bill it was due to our heat pump defrosting too often. The control board malfunctioned and needed replaced. If that's not the problem than you have another appliance that is using excess electricity, such as a fridge, freezer or your hot water heater.

 

[begreen]

Just updated my profile on the Duke Energy site. Interesting thing. . . . we are well below average and even below the "efficient home" rating in the AC months but well above average in the winter heating months. Very hard to believe since we heat so much with wood.

We do keep a little electric heater going in the garage. It is one of the oil radiator types just to keep it decent in there.

Does the heatpump fan run concurently with the stove running for air circulation?

 

[BillBurns]

Its probably a combination of a few things. Anything that makes heat with electric is going to use a lot of juice. My light bill goes up in winter, and I heat 70% with wood. Oil for overnight. When its 5 degrees out, staying warm and not freezing the water pipes is worth the light bill.

 

[djlew]

You just need to get your hm energy report.

Quick snapshot of mine 3000 sq ft(1000 is a basement which is super unusual here) 1948-73 construction. With electric heat In Wilmington.

2500 seems a bit high. I’m about as low as one can get. I even hang 90% of the laundry out. (5 kids worth) and charge and EV for 300-400 kWh a month.

Figure out if your heatpump is regularly using the resistance strips. Mine would anytime the room temp was 2 or more degrees from set point after 10 minutes of runtime. I got an ecobee thermostat and locked out the strips above 35 outside temp and will only run them if the room temperature is 4 or more degrees below set point.

View attachment 323652

Had a similar issue here... Depending on what kind of thermostat and how it's set up, it could be kicking on an "aux" or "emergency" heat strip that will run your wallet dry if it's constantly running. I was putting out 700 dollar electric bills in the coldest months before my wood stove. The heat pump would defrost, blow cold air that just rendered the previously heated air useless, kick on the heat strip eventually, rinse and repeat. If there was a larger temperature differential compared to last year, that could be it. Looking at your graph, seems semi consistent, so maybe not. Did you change a thermostat to a smart thermostat or something? To me, seems like some sort of a change in configuration or addition of certain appliances.