I joined a discussion with another member who's looking to replace a boiler, and didn't want to hijack that discussion with a furnace story. But seeing as this might apply to some here, I thought I'd share this. For posterity if nothing else.
Here's the other thread.
www.smokingmeatforums.com
Long story as short as I can, bought a fixer upper house that needed massive work on the heating system. From day one, electric bills were way more and I could never figure out what was in the house using so much electric, having brought most appliances from the previous house. I was perplexed.
One half of the living space is heated with a gas furnace (forced air). I did a bunch of duct work, and finally decided to replace the furnace itself, but retained the inefficient and over sized central air unit. Saw the expected gas savings, but was totally blown away by the electric savings.
For full disclosure, I have 7 refrigeration appliances in the house (fridges and freezers), 5 of which are 21-26 cu ft. Both for beer storage (homebrewer) and food storage (as everyone else). 2 are freezers with inkbird controllers so I can keep kegs of brew cold, but still set to 32f. There's an AC unit in the garage (2.5ton) and an AC for the kitchen (1.25 Ton), as well as a 5 Ton central air for the west side of the house.
Check out these graphs of the electric. Can you guess what day I ran electric heaters for the house and replaced the furnace? Who would have guessed that installing a furnace with a variable speed fan (DC electronically commutated variable speed motor, not an AC motor), could move the same air and do so for virtually no electric? Or better yet, who could have guessed that the blower motor in the old 2007 vintage high efficiency gas air handler would use almost as much electricity as all 7 fridges and freezers and all the AC units combined?
That image shows 90 days of this year vs last. Dates shown. Furnace was fired up on 3/10. The yellow line shows the degree days for that day, and you can see the colder it was with the old furnace, electric ran right along with it. Now, those values are totally disconnected as shown in the next chart. This is this past winter, 9.87 average degrees colder for that 30 days vs the previous year, but the electric use was cut off at the knees. (edit to add),I should also note the 29kwh on 3/23/2025 was a dinner party for my sister with 12 hrs cooking, etc.
That chart above shows 30 days 2026 vs 2025, where 2026 was 9.87 degrees colder on average, and yet used 39.3% less electricity. And that's for the entire house, not just the furnace.
To see what the hourly data looks like, I also have graphs showing the demand every 15 minutes, this year vs last. Check this out just as an example.
There, the peaks on the first chart are the clothes dryer or cooking, so ignore those. There's cooking shown in the lower chart too. But the thing to take in is, all that noise is the furnace blower fan. It's pretty profound... Who would have guessed that a furnace could use $700 in electric, more than another, while doing the same thing?
Here's the other thread.
New natural gas heating system
Sooo, last week my neighbors tree fell and cut my neutral line, leaving both hot lines coming into the house. One older tube TV went up in smoke and 10 days later I have a dead hot tub and a heating system needing parts. The system is from 2010 (I know not that old to me). It is a Burnham...
www.smokingmeatforums.com
Long story as short as I can, bought a fixer upper house that needed massive work on the heating system. From day one, electric bills were way more and I could never figure out what was in the house using so much electric, having brought most appliances from the previous house. I was perplexed.
One half of the living space is heated with a gas furnace (forced air). I did a bunch of duct work, and finally decided to replace the furnace itself, but retained the inefficient and over sized central air unit. Saw the expected gas savings, but was totally blown away by the electric savings.
For full disclosure, I have 7 refrigeration appliances in the house (fridges and freezers), 5 of which are 21-26 cu ft. Both for beer storage (homebrewer) and food storage (as everyone else). 2 are freezers with inkbird controllers so I can keep kegs of brew cold, but still set to 32f. There's an AC unit in the garage (2.5ton) and an AC for the kitchen (1.25 Ton), as well as a 5 Ton central air for the west side of the house.
Check out these graphs of the electric. Can you guess what day I ran electric heaters for the house and replaced the furnace? Who would have guessed that installing a furnace with a variable speed fan (DC electronically commutated variable speed motor, not an AC motor), could move the same air and do so for virtually no electric? Or better yet, who could have guessed that the blower motor in the old 2007 vintage high efficiency gas air handler would use almost as much electricity as all 7 fridges and freezers and all the AC units combined?
That image shows 90 days of this year vs last. Dates shown. Furnace was fired up on 3/10. The yellow line shows the degree days for that day, and you can see the colder it was with the old furnace, electric ran right along with it. Now, those values are totally disconnected as shown in the next chart. This is this past winter, 9.87 average degrees colder for that 30 days vs the previous year, but the electric use was cut off at the knees. (edit to add),I should also note the 29kwh on 3/23/2025 was a dinner party for my sister with 12 hrs cooking, etc.
That chart above shows 30 days 2026 vs 2025, where 2026 was 9.87 degrees colder on average, and yet used 39.3% less electricity. And that's for the entire house, not just the furnace.
To see what the hourly data looks like, I also have graphs showing the demand every 15 minutes, this year vs last. Check this out just as an example.
There, the peaks on the first chart are the clothes dryer or cooking, so ignore those. There's cooking shown in the lower chart too. But the thing to take in is, all that noise is the furnace blower fan. It's pretty profound... Who would have guessed that a furnace could use $700 in electric, more than another, while doing the same thing?
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