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# Cost of oil vs electricity to raise heat 6 degrees

Member Posts: 23
edited January 2023
I have my oil thermostat set at 58 degrees during the day. My goal is to heat the space I'm in to 64 degrees. So I want to raise the temperature by 6 degrees, 16 hours a day. I have two choices: turn the oil boiler up to 64 degrees, or use a space heater in the room I'm in. (Thermostat is set at 50 at night.)
My electricity cost is 26 cents per kWh (supply + delivery charge). I've calculated that the 1500-watt space heater would cost \$94 a month, or \$58 if I use the 900-watt setting.
QUESTION: How can I calculate the cost to raise the oil boiler from 58 to 64 degrees 16 hours a day?
My cost of oil: \$4.15 a gallon. The boiler motor uses 2500 watts.
I found this information for turning the temperature down: "The Department of Energy estimates savings of about 1 percent for each degree of thermostat adjustment per 8 hours.” Does that mean 2% for 16 hours, and 12% for 6 degrees for 16 hours? Is that the monthly cost?
Or is it a simple matter of comparing BTUs for electricity and oil? My state's dept. of energy shows an \$/MBTU cost of oil as \$40 and electricity \$90. That may not be helpful because I'm comparing a whole-house oil boiler to a space heater for one room.
Using the oil burner has the advantage of heating the whole house for increased comfort as you move from room to room, offset by the disadvantage of the cost of heating spaces I'm not using.

Single zone house
1200 square-foot house

• Member Posts: 4,696
Using straight electric over the oil no brainer. Electric will cost more every time. Now a heat pump is a different story, but they don't like large setbacks. 64° is cold, 58° even worse. Why?
• Member Posts: 22,937
It's almost just straight BTU to BTU. But not quite. The ringer in the deck is what other space the oil boiler is being asked to heat at the same time. If the oil boiler is just being asked to raise that one space -- perhaps it's the only space, or it's on its own zone -- then it's BTU to BTU and, as @pecmsg says, it's a no brainer. If the oil boiler is also heating the rest of the place, a possibility you mention, then it gets much more complicated -- but then there are other considerations involved as well, such as the rest of the space becoming more comfortable.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 23
edited January 2023
My calculation based on additional 12% per month (see above):
4 gal/day = 120 gal/mo x \$4.15/gal = \$498/mo
An additional 12% would be \$60. Does that calculation make sense?
If yes, it would seem to make more sense to raise the thermostat rather than paying the same amount to heat a small space with an electric heater.
House is 1200 square feet on two floors. I realize that there are many variables that enter into the answer to my question. I'm hoping for a rough estimated comparison.
• Member Posts: 22,937
The calculation does make sense -- so far as it goes. Too many variables, though, to be much more than a more or less educated guess.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 4,696
https://coalpail.com/fuel-comparison-calculator-home-heating

Electric @ \$0.26 Kw \$7600 per 1 mil BTU's
Oil @ \$4.14 gal \$3900 per 1 mil BTU's
• Member Posts: 23
pecmsg said:

https://coalpail.com/fuel-comparison-calculator-home-heating

Electric @ \$0.26 Kw \$7600 per 1 mil BTU's
Oil @ \$4.14 gal \$3900 per 1 mil BTU's

How is that chart useful for comparing a boiler that heats the whole house with a small space heater that heats only the immediate space around the user?

• Member Posts: 23

The calculation does make sense -- so far as it goes. Too many variables, though, to be much more than a more or less educated guess.

A more or less educated guess would be enough to help me choose between the two alternatives.

• Member Posts: 7,590
edited January 2023
pecmsg said:

https://coalpail.com/fuel-comparison-calculator-home-heating

Electric @ \$0.26 Kw \$7600 per 1 mil BTU's
Oil @ \$4.14 gal \$3900 per 1 mil BTU's

So if you heat 20% of the space to 64° with electricity then you would only need 20 % of the 1 mil BTUs. That is about \$1500.00. 50% of the space is \$3800.00. with Oil heat you will always heat 100% of the space at \$3900.00 per

We could always redesign the oil heater for \$\$\$\$\$.00 to just do the same space as the space heater, Then we would be comparing like for like. But then you would have to amortize the cost of the project over the life of the equipment or the time you have left on earth. How old are you? Do we need to use your life expectancy or the equipment life expectancy. In all fairness if @Hemlock is 70 years old, then we need to use different numbers. And if @Hemlock's wife is feeding him Hemlock, then that reduces the time calculation even more.

Like @pecmsg, I luv to do the math. But we need to use real numbers!
Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
• Member Posts: 23

It's almost just straight BTU to BTU. But not quite. The ringer in the deck is what other space the oil boiler is being asked to heat at the same time. If the oil boiler is just being asked to raise that one space -- perhaps it's the only space, or it's on its own zone -- then it's BTU to BTU and, as @pecmsg says, it's a no brainer. If the oil boiler is also heating the rest of the place, a possibility you mention, then it gets much more complicated -- but then there are other considerations involved as well, such as the rest of the space becoming more comfortable.

Since I have old-fashioned water-filled radiators and a single zone, I have to heat the whole house. So the comparison is not between a space heater and oil boiler heating the same-sized space.

• Member Posts: 4,696
edited January 2023
Hemlock said:

The calculation does make sense -- so far as it goes. Too many variables, though, to be much more than a more or less educated guess.

A more or less educated guess would be enough to help me choose between the two alternatives.

By Comparing apples to grapes?

So WHY so cold?

Why such a setback?
• Member Posts: 7,590
edited January 2023
Hemlock said:

Since I have old-fashioned water-filled radiators and a single zone, I have to heat the whole house. So the comparison is not between a space heater and oil boiler heating the same-sized space.

So you would need to do a major redesign of the oil boiler system with zone valves and thermostats for each radiator. That might result in the need for a different circulator pump... so we need to know if this project is feasible in order to compare @pecmsg's grapes to your electric space heater. So, How old are you and why do you call yourself Hemlock? Is there a scheming future widow involved with this plot? Enquiring minds want to know?

from previous post
We could always redesign the oil heater for \$\$\$\$\$.00 to just do the same space as the space heater, Then we would be comparing like for like. But then you would have to amortize the cost of the project over the life of the equipment or the time you have left on earth. How old are you? Do we need to use your life expectancy or the equipment life expectancy. In all fairness if @Hemlock is 70 years old, then we need to use different numbers. And if @Hemlock's wife is feeding him Hemlock, then that reduces the time calculation even more.

Like @pecmsg, I luv to do the math. But we need to use real numbers!
Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
• Member Posts: 23

But we need to use real numbers!

The main missing number is the cost for the oil boiler to raise 1200 square feet one degree for 16 hours. If I know that, the rest is simple math.

• Member Posts: 23
edited January 2023
An easier calculation:
Cost to raise temp 1 degree: 3% of annual heating bill according to several sources
Cost to raise temp 6 degrees: 18%
Annual oil cost based on past experience: \$2000 (500 gal at \$4/gal)
18% of \$2000 = \$360
Annual comparison:
Space heater: \$94/mo x 7 mos \$658
Oil \$360
Oil seems to be the clear winner: a lot more heat for about half the cost.
Make sense?
• Member Posts: 7,590
Makes sense... Agreed
But we still want to know about the Hemlock. Where does she hide it? or are you hiding it from her?

I love a good Agatha Christie mystery...
"Hemlock and The Heater" or "Did it get all burned up?"
Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
• Member Posts: 23
edited January 2023
Thanks for checking my logic. I didn't think this was a no brainer. I wanted to see the numbers. It's amazing how inefficient small space heaters are. I have a 600-watt air conditioner that cools the whole downstairs (800 sq feet). The 1500-watt space heat only heats one corner of a room. Sorry I've been using space heaters for years, while staying cold.

You know, sometimes a hemlock is just a pretty tree.