Who’s going to Tesla after their current TDI?

IndigoBlueWagon

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I used that data. Electricity is about $.23/kWh here. Oil fluctuates, averaging about $3.75/gallon this year, maybe a bit less.

If I was going to supplement the oil heat in my house I'd install a wood stove or a stove fired with propane. My house lends itself to a heat source at the fireplace (center chimney colonial).
 
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nwdiver

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I used that data. Electricity is about $.23/kWh here. Oil fluctuates, averaging about $3.75/gallon this year, maybe a bit less.
You get ~3kWh of heat per kWh from electricity from a heat pump. That's ~$0.077/kWh.

You get ~37kWh of heat per gallon of oil if your furnace is impossibly efficient. That's ~$0.10/kWh.
 

IndigoBlueWagon

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You get ~3kWh of heat per kWh from electricity from a heat pump. That's ~$0.077/kWh.
You get ~37kWh of heat per gallon of oil if your furnace is impossibly efficient. That's ~$0.10/kWh.
I don't understand this. Do you mean BTU? Therms?
 

Daemon64

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That number makes no sense. What do you pay for electricity? There's 37kWh in a gallon of heating oil. Even if your oil furnace is 100% efficient you're paying ~$0.10/kWh at $4 per gallon. The average COP of a heat pump is ~3. So electricity would have to be >$0.30/kWh before oil is cheaper.

Instead of using an online calculator (maybe accurate, maybe not).... divide your $/gallon by 37 vs your $/kWh divided by 3. Compare those two numbers. It's probably something like $4/37 = $0.11 VS $0.15/3 = $0.05. So oil is probably >2x the cost of a heat pump....

NWDiver,

We switched out entire house to heat pumps 2 Fujitsu Hyper heats 35k BTU Heating & 35K BTU cooling each. We have 8 heads. Our ACH50 when tested before redoing half my basement and sealing it completely... was 5ACH50. We do have an ERV that runs 120CFM all year, but in the end our electricity ended up being around $650 / $750 / mo. Normally around $250( 1000 kwh )( electric Tank heater uses 300 KwH/mo by itself )... usage was around 2500 - 3200 kwh all winter... keep the house 66. ( our kwh rate is .256 )

We're switching to wood heat w/ a Blaze King 40. 81% Efficient, 80lbs of firewood in the box will run up to 40hrs on low( 14k btu low ), or 12 - 16 on high( 47,800 btu high ). (https://www.blazeking.com/wp-content/uploads/2022/02/BK_King_Prin_Broch_2-2022_Web.pdf ) Estimated wood usage under 3 cords for the entire season. This is a Catalyst stove. Emissions 1.1g/hr, CO .6g / min. CO2 production 26,784grams / month if run for every second of the month, or 59lbs of CO2 per month... for reference CO2 in 1 Gallon of gas 20lbs, 1 Gallon of Diesel 22.38. Based on Massachusetts CO2 / electricity kwh of 961lbs / MWH.... that means that same month running the splits is 1,441.5 lbs of CO2 up to 1922lbs of CO2.... The trees and there are lots of them around my house will easily suck up that amount...
 

IndigoBlueWagon

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We switched out entire house to heat pumps 2 Fujitsu Hyper heats 35k BTU Heating & 35K BTU cooling each. We have 8 heads. Our ACH50 when tested before redoing half my basement and sealing it completely... was 5ACH50. We do have an ERV that runs 120CFM all year, but in the end our electricity ended up being around $650 / $750 / mo. Normally around $250( 1000 kwh )( electric Tank heater uses 300 KwH/mo by itself )... usage was around 2500 - 3200 kwh all winter... keep the house 66. ( our kwh rate is .256 )
This is interesting. How big is your house? I think it's somewhat colder where you are than here on the South Shore, but not by a lot.

I've been happy that our 6 kW solar array provides nearly 100% of our electrical needs, which isn't bad for a 3,300 square foot house with central air and a swimming pool. But it's fully utilized. I'd love to add more solar but don't have another ideal spot for it like the garage roof I sited specifically for solar.
 

nwdiver

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I don't understand this. Do you mean BTU? Therms?
Does it matter? A kWh is a kWh. Compare Apples to Apples. $0.077/kWh for a Heat pump vs $0.10/kWh for oil.

~3400BTU per kWh or 0.034 therm per kWh. Does it matter what units you use if you're comparing cost per unit of useful (thermal) energy? $0.077 < $0.10.

kWh, BTU and Therm are just different units all measuring the same thing... Energy.
 
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Daemon64

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This is interesting. How big is your house? I think it's somewhat colder where you are than here on the South Shore, but not by a lot.

I've been happy that our 6 kW solar array provides nearly 100% of our electrical needs, which isn't bad for a 3,300 square foot house with central air and a swimming pool. But it's fully utilized. I'd love to add more solar but don't have another ideal spot for it like the garage roof I sited specifically for solar.

The house is 2553sqft + 2car attached garage. The house in many places are still original. We switched the attic to R60 blown cellulose. The walls in 964 sqft now have R15 Mineral Wool & Intello Smart Vapour Barrier --- in that same area we have 14 New double hung double paned R3.8 windows, and a new fiberglass foam door. 1/2 of the 964 sqft basement now is 2" R10 GPS Foamboard 32" below grade, 1" R5 GPS foam board on the floor, and the above ground walls in those sections are R15 Mineral wool w/ intello air barrier. Mind you through half the winter all that concrete was completely un-insulated. The rim of the house has 2" of foam on it now as well. Any places I've added new stuff are completely air sealed. It also was WAY leakier when we got it, think like 25 - 30 ACH50. The walls were also originally R7 and the attic R19.

We do have a 13.2kwh array but with only 10kwh AC worth of micro inverters which is national grid net metering max. But they are not in the most ideal locations and were just turned on, on 3/24/22.

Between the wood stove and the solar we should have no more electric bill.

Clarification We moved in Feb 2021... Its been a BUSY year...
 
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IndigoBlueWagon

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That's a lot of sealing and insulating you did. If after all that you still had electric bills that high it points out how heat pumps aren't necessarily the most cost effective solution in this climate.
 

nwdiver

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That's a lot of sealing and insulating you did. If after all that you still had electric bills that high it points out how heat pumps aren't necessarily the most cost effective solution in this climate.
Would've been ~30% higher with oil. The numbers are the numbers....
 

Daemon64

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That's a lot of sealing and insulating you did. If after all that you still had electric bills that high it points out how heat pumps aren't necessarily the most cost effective solution in this climate.
It also points out that electricity rate is stupid high. There was an 2009 combi boiler natural gas that was at EOL of sure ( super scaled ) before that w/o any changes was using about $400 / mo in natural gas... heh Forced hot water.
 

IndigoBlueWagon

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Would've been ~30% higher with oil. The numbers are the numbers....
Don't think so. My monthly oil cost, recently adjusted for the oil price increases of late, is $349. That's for a 3,300 square foot house, larger than Daemon64s. And it's not nearly as well sealed. It also includes my 90 year old mother in a 730 square foot in-law apartment where she typically sets the heat at 78 degrees.
 

nwdiver

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Don't think so. My monthly oil cost, recently adjusted for the oil price increases of late, is $349. That's for a 3,300 square foot house, larger than Daemon64s. And it's not nearly as well sealed.
.... If you're paying $3.75 for a gallon of oil and $0.23/kWh for electricity you're paying ~30% more for a unit of heat (kWh,BTU or Therm) from oil than you would for a unit of energy from a heat pump. The math is straight forward. Where are you getting lost?

$3.75 for a gallon of oil buys you 37kWh or 125,000BTU or 1.3 Therms of heat from oil.

$3.75 in electricity would buy you 49kWh or 166,300BTU or 1.7 therms of heat from a heat pump.
 

IndigoBlueWagon

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It also points out that electricity rate is stupid high. There was an 2009 combi boiler natural gas that was at EOL of sure ( super scaled ) before that w/o any changes was using about $400 / mo in natural gas... heh Forced hot water.
I bet a properly sized condensing boiler set up to run in condensing mode most of the time would have cost half that to operate. When I replaced my boiler I did a size calculation based on actual therms used, and installed a new boiler only slightly bigger than half the size of the original. My oil consumption fell over 40% the first year, and I've been told a lot of that was because of reduced standby losses.
 

IndigoBlueWagon

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.... If you're paying $3.75 for a gallon of oil and $0.23/kWh for electricity you're paying ~30% more for a unit of heat (kWh,BTU or Therm) from oil than you would for a unit of energy from a heat pump. The math is straight forward. Where are you getting lost?
Maybe your math does lie. Estimated cost calculations and Daemon64's real life example shows the heat pumps to be more expensive than oil or natural gas where we live. At least for houses like his or mine. Perhaps you can figure out why.
 

nwdiver

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Maybe your math does lie.
It's just physics. Is there not 37kWh in a gallon of oil? Does a heat pump not have an average COP of 3? If those numbers are correct then so is the math. There are other variables that can change how much you pay. Bottom line is you're paying more for a unit of energy from oil than from a heat pump because physics. And... that assumes your oil furnace is 100% efficient which is impossible.
 
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IndigoBlueWagon

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Boiler, not furnace. And it's about 86% efficient, which is pretty much state of the art for an oil fired boiler. Condensing gas boilers are in the low 90s.

I think you're missing something. Some people use heat pumps around here to supplement their existing systems, but I know some towns won't allow pumps as a primary heat source in a single family dwelling. And if it were as inexpensive as you say I'd expect much more of a trend towards conversions, which I'm not seeing. Like Daemon64 says, electric rates are stupid high here.
 

nwdiver

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Boiler, not furnace. And it's about 86% efficient, which is pretty much state of the art for an oil fired boiler. Condensing gas boilers are in the low 90s.

I think you're missing something. Some people use heat pumps around here to supplement their existing systems, but I know some towns won't allow pumps as a primary heat source in a single family dwelling. And if it were as inexpensive as you say I'd expect much more of a trend towards conversions, which I'm not seeing. Like Daemon64 says, electric rates are stupid high here.
Like I said... there's nothing wrong with using oil as a backup heat source. I'm not missing anything. You're just giving more credence to anecdotes than hard data. A heat pump provides ~3kWh of heat per kWh of electricity. @ $0.23/kWh that's ~$0.077/kWh of heat. Heat pumps aren't more popular for the same reason Ivermectin WAS 'popular'... misinformation.

Even here... where heat pumps are absolutely fantastic... I've heard several builders say they don't work. 'They just don't work'. It. Is. Insanity. 2+2 is 5 and that's the hill they're gonna die on...... If someone could find a way to harness 'mercan 'sturbborness' as an energy source we'd be set :/
 
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Daemon64

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Like I said... there's nothing wrong with using oil as a backup heat source. I'm not missing anything. You're just giving more credence to anecdotes than hard data. A heat pump provides ~3kWh of heat per kWh of electricity. @ $0.23/kWh that's ~$0.077/kWh of heat. Heat pumps aren't more popular for the same reason Ivermectin WAS 'popular'... misinformation.

Even here... where heat pumps are absolutely fantastic... I've heard several builders say they don't work. 'They just don't work'. It. Is. Insanity. 2+2 is 5 and that's the hill they're gonna die on......

Because it gets cold enough here that the COP gets well below 3 in the 2s and 1s. I had so many days this season 20 or below it wasn't even funny. Heat pumps are great in marginal climates... but when it's cold out they are not. Nearly as efficient.
 

nwdiver

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Because it gets cold enough here that the COP gets well below 3 in the 2s and 1s. I had so many days this season 20 or below it wasn't even funny. Heat pumps are great in marginal climates... but when it's cold out they are not. Nearly as efficient.
Yep.... if the COP approaches ~2 then use oil.

Like I said... there's nothing wrong with using oil as a backup heat source.
 

IndigoBlueWagon

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So he numbers aren't that clear. And it explains why we don't see a wholesale shift to heat pumps here. Sure, it's fine as a backup heat source, as long as you're willing to pay for a second heat source. I made the choice to heat solely with oil, no heat pump, no wood stove, because it's comfortable and requires no attention. I have Nest thermostats that manage the night time setbacks, so I can literally forget about it. I seriously considered installing a wood stove last year. I had one for years in my antique home and liked it. But I honestly don't have time to tend a stove these days. And purchase and install would have cost about $4K. I wouldn't see a payback from that for a long, long time, depending on where the wood came from. I'm more interested in reducing the house's heating load through better sealing and insulation. I'd love to upgrade my windows, but I went a little crazy when we built the house, the main house has 34 windows. Most experts say that replacing windows is an expense you'll probably never recover in saved energy costs, unless they are in really bad condition.
 

nwdiver

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you're willing to pay for a second heat source.
??? You're not.... you're using your Air Conditioner to provide heat in the winter. If you didn't need or have A/C that would be a different story but you do.

The bigger question should be does it make sense to have separate systems that heat and cool or just a single system that can do both. We have some days here that a heat pump probably isn't the best option... but does it really make sense to have a separate system just for those few days?
 

IndigoBlueWagon

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I had my A/C unit replaced two years ago. Not going to throw that out. At end of life, maybe.

Sometimes the picture is bigger than just energy use. I talked to my heating company about replacing my oil fired hot water loop and storage tank with a heat pump water heater. They thought it was a good idea, except they see accelerated deterioration of boilers if they sit idle for months in the summer. It's better for them to run. So some energy savings may mean a shorter life for a major appliance.
 

turbobrick240

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So he numbers aren't that clear. And it explains why we don't see a wholesale shift to heat pumps here. Sure, it's fine as a backup heat source, as long as you're willing to pay for a second heat source. I made the choice to heat solely with oil, no heat pump, no wood stove, because it's comfortable and requires no attention. I have Nest thermostats that manage the night time setbacks, so I can literally forget about it. I seriously considered installing a wood stove last year. I had one for years in my antique home and liked it. But I honestly don't have time to tend a stove these days. And purchase and install would have cost about $4K. I wouldn't see a payback from that for a long, long time, depending on where the wood came from. I'm more interested in reducing the house's heating load through better sealing and insulation. I'd love to upgrade my windows, but I went a little crazy when we built the house, the main house has 34 windows. Most experts say that replacing windows is an expense you'll probably never recover in saved energy costs, unless they are in really bad condition.
If you were to install some ground source heat loops where your pool is currently located you could get a heat pump COP of 4.5 regardless of how cold it gets outside. That really shifts the numbers in favor of a heat pump.
 

IndigoBlueWagon

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If you were to install some ground source heat loops where your pool is currently located you could get a heat pump COP of 4.5 regardless of how cold it gets outside. That really shifts the numbers in favor of a heat pump.
As posted above, I like that idea a lot.
 

turbobrick240

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Mass. offers some pretty generous rebates on heat pump installations- up to $10k on air source, and $15k on ground source.

 

vandermic07

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They don't have to be. You just sign up with your utility, enjoy your ~75% discount and let the grid operator worry about when your car should charge :)

"As proposed, the program would run for 12 months and enroll up to 200 drivers. Customers of Duke Energy Carolinas would get the $19.99 monthly flat fee deal. The Duke Energy Progress customers would pay a bit more, at $24.99.

The flat rate covers up to 800 kwH per month, which works out to about 2,000 miles per month. Doing the math, that is a pretty good deal compared to the price of gas these days."

Yay! another subscription! I would go over the 800kwh/mo too. I wonder what it costs then? What is it going to cost on the 13th month? Like every other proposal. it doesnt stay cheap for long.


I know my utility doesn't offer this. I did get offered a free electric water heater when I built my house. They also do Net Metering for solar. nothing for EVs. We are part of a rural coop. not much EV activity here.
 

turbobrick240

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As long as we're venturing slightly off topic, I'll just go completely of topic with this link to a great video about an incredible, light Porsche 911. Looking good without a grille.

 

IndigoBlueWagon

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Air cooled Porsche prices are crazy. Saw this today:
 

turbobrick240

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My uncle had a '67 912 that he sold dirt cheap in the mid 70's when he had a young family to support and the steel industry in Ohio was circling the drain. He's still kicking himself for letting it go.
 
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