I wanted to replace my 38 year old electric furnace with something newer. The two companies I talked to told me that a newer electric furnace won't be any more efficient than the one I have now. They both wanted to do heat pumps. I understand that these would be more efficient but I have trouble believing that in the last 40 years electric furnaces haven't improved at least somewhat. Am I wrong in thinking this? Gas in not available on my street.
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Home Furnace Experts needed
- Thread starter studlyrs
- Start date
danielzig
Well-known member
When using electric heat, 100% of the energy used goes towards heating the space. I would think the energy efficiency improvement you may see with a new furnace only comes in the form of a more efficient blower motor.
Falcon67
Well-known member
You were told the truth. Electric heat is 100% efficient. Hard to improve on that. Heat pump is the way to go if you want to stay on electric only.
X2 - electric is 100% efficient and usually the most expensive way to heat a house out of all the available options. You can't improve on wires burning kilowatt hours. They just burn a LOT of kilowatts. If we could afford to upgrade to a new Goodman heat pump system, our 10 yr old electric furnace would be on the scrap pile in a minute.
Gas is not available? How about propane? If not take a look at how long the payoff is. Cost to replace with new electric furnace + cost per year to run it, then cost of new heat pump + cost to operate per year, how many years before the heat pump is cheaper then the electric. An added benefit to the new heat pump is it also is a new ac.
ddawg16
Well-known member
While it is 'technically correct' that electric heat is 100% effecient.....i.e., 100% of the engergy going into the heater is converted to heat, it is far from accurate.
A more accurate way of looking at it is coefficient of performance (COP).
A resistive heater has a COP of 1.0. However, a heat pump will have a COP of say 3-4at 50 deg F...which means, for the same amount of KW, it will provide 3-4x more heat.
Obviously, as it gets colder, the COP goes down....typically heat pumps hit a COP of 1 around 0 deg F...in other words, below 0 resitive heating is more effieient....
So....while a resitive heater might be cheaper to buy....it cost a lot more to operate.
Side note....most heat pumps are typically more effecient than your average AC compressor and function quite was as an AC unit....just operates in reverse....pumps heat out instead in.
A more accurate way of looking at it is coefficient of performance (COP).
A resistive heater has a COP of 1.0. However, a heat pump will have a COP of say 3-4at 50 deg F...which means, for the same amount of KW, it will provide 3-4x more heat.
Obviously, as it gets colder, the COP goes down....typically heat pumps hit a COP of 1 around 0 deg F...in other words, below 0 resitive heating is more effieient....
So....while a resitive heater might be cheaper to buy....it cost a lot more to operate.
Side note....most heat pumps are typically more effecient than your average AC compressor and function quite was as an AC unit....just operates in reverse....pumps heat out instead in.
Falcon67
Well-known member
Gas is not available? How about propane?
Lots of cities don't allow propane tanks in town. Also, if your electric rate is below about .10/kWh, propane is likely not going to be economical at current pricing.
Gas in available on my street but not close enough for them to get it to my house. I guess I have been schooled. I am turning my house into a rental in the next few years and it wouldn't be worth it to invest in a heat pump. It would take about 7 years to pay for itself and it wouldn't get me enough extra rent to offset it.
i would also like to point out that just because something is old doesnt mean replacing it is more efficient. i was reading an article about the oldest refrigerator still running being submitted recently. The owner had owned it since new in like 1932 and while yes 1932 electronics and what not were way behind our times now think about the average life span of our appliances now 5-15yrs. if the person had replaced his refrigerator every 15yrs until now that would be 5 ish refrigerators each costing him say $500-1000 or about $2500-5000 for the last 80 or so years. the cost of the electricity that "inefficent" fridge used in no way could add up to the cost of replacing it every 15yrs imho.
imho if that heater isnt giving you problems and is still supplying the correct btu's etc. dont change it out, especially if its a rental save the money for when it does break then replace it.
this is just my opinion, im all for changing things out if they are broken or have problems etc. but if its working just fine i dont think the "energy savings" is there to just replace it.
also keep in mind as a rental you will have things break that are more wear items like hot water heaters, faucets etc....basically anything a renter can beat on will get beat on. The heater just sits there comes on when told to and shuts off.
imho if that heater isnt giving you problems and is still supplying the correct btu's etc. dont change it out, especially if its a rental save the money for when it does break then replace it.
this is just my opinion, im all for changing things out if they are broken or have problems etc. but if its working just fine i dont think the "energy savings" is there to just replace it.
also keep in mind as a rental you will have things break that are more wear items like hot water heaters, faucets etc....basically anything a renter can beat on will get beat on. The heater just sits there comes on when told to and shuts off.
VHF
Well-known member
I think a heat pump would work very well in your climate and cost only about 1/3 to operate than an electric furnace using resistance heating.
Highbeam
Well-known member
While it is 'technically correct' that electric heat is 100% effecient.....i.e., 100% of the engergy going into the heater is converted to heat, it is far from accurate.
Wrong. It is 100% accurate to say that electric resistance heat is 100% efficient. It's not our fault that you can't read a dictionary.
What you mean to say is that, "you can do better than 100% efficient if you use a heat pump." right?
Electric resistance heat is not 100% efficient. That's impossible and so is more then 100% that would be more energy out then in. Electric resistance is about as close as you can get to 100% though. That doesn't mean that its the cheapest and usually its the most expensive per BTU, and that's what really matters http://www.hearth.com/econtent/index.php/articles/fuel_cost_comparison_calculator/
pseudorealityx
Well-known member
Electric resistance heat is not 100% efficient. That's impossible and so is more then 100% that would be more energy out then in. Electric resistance is about as close as you can get to 100% though. That doesn't mean that its the cheapest and usually its the most expensive per BTU, and that's what really matters http://www.hearth.com/econtent/index.php/articles/fuel_cost_comparison_calculator/
Electric heat is 100% efficient.* There are some internal work stresses within the wire element as it will expand and whatnot while heated, but its awfully damn close to 100%.
Refrigeration equipment (like a heat pump) can have COP's higher than 1.0 because they aren't making the heat themselves. They are transferring heat from one location to another. They don't have to 'make' that heat themselves. The electricity you put into a heat pump runs a compressor (pump), which moves refrigerant around. The phase changes of said refrigerant by the use of pressure and temperature differentials gives you the (relatively) large heat transfer numbers. There's also typically 2 fans for the system that also must run to allow airflow.
That's why the COP for a heat pump changes with temperatures. It gets harder to pull heat FROM the outside as it gets colder. For the exact same reason that an A/C loses capacity as the outside temperature gets hotter.