Calculating the cost of heat?

[bank5]

My heat pump unit froze up so I've been using some emergency (electric) heat. I decided to monitor how much electricity I'm using with the emergency heat on and off. With it on for two hours, I used a total of 9 kWh. With it off for two hours I used a total of 2 kWh. I found the difference pretty astonishing.

Has anyone monitored/logged/calculated heating costs? What results did you find and how much were you able to save on electricity?

[FUEGO]

Nat gas is cheaper than electricity to produce heat. We spend roughly $300 a year on natural gas for heat (may be closer to $200 with the reduced nat gas rates). At 8.5 cents a kWh for electricity, that would allow us to run our small portable 1500 watt electric heater for 40 minutes every hour during a 150 day heating season from ~Oct 15-Mar 15. That would keep one room very very toasty but not the whole house very toasty at all.

[bank5]

Wow, only $300/year is incredible. This online calculator shows that a heat pump is much cheaper for a lot of scenarios - Dare to Compare -- Gas Furnace Vs. Electric Heat Pump However, I'm not so sure about the source or the numbers.

[FUEGO]

Quote:

Originally Posted by bank5 Wow, only $300/year is incredible. This online calculator shows that a heat pump is much cheaper for a lot of scenarios - Dare to Compare -- Gas Furnace Vs. Electric Heat Pump However, I'm not so sure about the source or the numbers.

1800 sf house. $300 for heat. $300 for water heater and the monthly nat gas connection charge. $700 for a/c. $500 remainder of electrical usage during the year. All those are +- $100 but annual energy expenses run right at $1800 consistently for the last few years.

[Zathras]

Heat pumps tend to be far more efficient than most forms of emergency electric heat.
In terms of efficiency it tends to be Heat Pumps > Natural Gas > electric floor boards and such.
That is real rough though and can change depending upon your heat pump/furnace/ratiator, etc.

[Walt34]

Some things it is better not to know. We have natural gas heat, we set it to where we are comfortable and damn the cost.

We will scrimp on a lot of things but heat in the winter is not one of them.

One of the guys at work used to tease me about that, saying that NASA used the IR signature from my house as a navigational beacon.

[samclem]

Quote:

Originally Posted by bank5 With it on for two hours, I used a total of 9 kWh. With it off for two hours I used a total of 2 kWh. I found the difference pretty astonishing.

Yes, that electric resistance heat (the emergency "strips" in your heat pump) require a lot of energy. Actually, they (technically) are nearly 100% efficient, which sounds great, except that electricity (per BTU) is a lot more expensive than natural gas or propane, and also that your heat pump, in normal operation, is more than 100% efficient.

But, in perspective: This is an emergency situation (your heat pump is essentially inoperative) and you are heating your whole house for 7kwh. At the average national rate, that is less than $1 per hour. And that's only when the strips are actually on, which I assume is not 100% of the time. Yes, it sounds like a lot if you looked at doing it for a whole month, but if it were 15 degrees F outside and 40 deg F inside and you are very cold and thinking your pipes might freeze when someone said that for $1 an hour your house could be heated to 68 deg F, I'll bet we'd all think it was money well spent.

[bank5]

I found this which has some good info in it - Ask Mr. Electricity: Saving money on heating

[W2R]

Quote:

Originally Posted by Walt34 Some things it is better not to know. We have natural gas heat, we set it to where we are comfortable and damn the cost. We will scrimp on a lot of things but heat in the winter is not one of them. One of the guys at work used to tease me about that, saying that NASA used the IR signature from my house as a navigational beacon.

If we are ever in West Virginia, we'll know how to find you!

I do the same, I suppose, but I put on warm clothes, wool socks, and if I am not moving around I snuggle in a thermal blanket before I decide whether or not I am comfortable.

I have gas heat, and my yearly gas bills (entire bills, not just heat) were $451 in 2008 and will probably be around $360 in 2009. But then, I live in New Orleans and this is not exactly the North Pole. The expense here comes from the electricity for A/C in the summer.

[bank5]

Thanks for the replies. I just mapped my energy usage for the last couple of years. I use a lot more on energy in the winter. February is by far my highest month. I'm sure a lot has to do with the inefficiency of heat pumps when the temperature gets below 40.

I think I'll be able to save a bunch during the winter by getting a programmable thermostat. I had previous read that heat pumps were less efficient with programmable thermostats but after reading a bit more about it, I now think that's only geothermal heat pumps.

[W2R]

If it is feasible with your heat pump, I think you will really like the programmable thermostat, bank5. They are well worth the money, in my opinion anyway.

[FUEGO]

Quote:

Originally Posted by FUEGO 1800 sf house. $300 for heat. $300 for water heater and the monthly nat gas connection charge. $700 for a/c. $500 remainder of electrical usage during the year. All those are +- $100 but annual energy expenses run right at $1800 consistently for the last few years.

Scratch that - $300 for heat was usage from a few years ago apparently when nat gas was much cheaper. Last year we spent $500 on heat and $300 on all other natural gas usage. $600 on heat the previous year. Guess you got to look at the actual numbers to get a correct answer, huh?

But our bills have dropped 20-45% year over year when looking at the last 5 months. So our heating costs may get back down to the $300 range this year with cheap nat gas.

[REWahoo]

Quote:

Originally Posted by bank5 I think I'll be able to save a bunch during the winter by getting a programmable thermostat. I had previous read that heat pumps were less efficient with programmable thermostats but after reading a bit more about it, I now think that's only geothermal heat pumps.

I'm not sure the setback program is a problem limited only to geothermal.

As I understand it, a heat pump uses 'emergency heat' to supplement the heat put out by the compressor if the difference between the current temperature and the temperature selected on the thermostat differs by more than a couple of degrees (I'm speaking of temps in the house, not outside). Using a programmable thermostat to drop the temp to 60 at 10 PM then kick it back up to 68 at 6 AM would see the emergency heat kick in to assist in getting the temp to the higher setting. As I understand it, the added cost of the less-efficient emergency heat to get the temp back up more than offsets the savings from the lower setting during the previous eight hours.

If you can find information the above thinking is incorrect I would love to see it. We have a heat pump and I would really like to get a programmable thermostat but always believed it would be more costly than maintaining a constant setting.

[ziggy29]

If the emergency heat is electric resistance, yeah, it's very expensive. Our heat pump system has an emergency resistance heating element. If the heat pump fails, I guess it would come on; otherwise it only comes on rarely when the heat pump needs a little more help (usually when the temperature is below about 25º, and even then not always).

I'm not sure a programmable thermostat will save all that much for a heat pump system. If you suddenly increase the temperature by 5º, for example, most thermostats will trigger the expensive emergency heat. I just keep our thermostat at a constant 68 for heating and 78 for cooling.

[NW-Bound]

The heat pump of my house in Phoenix has no resistance heating elements due to the moderate climate. The heat pump of my other house at 7,000 ft where the record low is -26degF has a two-stage resistance heater. If the 1st heater fails to keep the temperature up, the thermostat would kick it up another notch with the 2nd stage. Yikes!

[Letj]

Quote:

Originally Posted by FUEGO Nat gas is cheaper than electricity to produce heat. We spend roughly $300 a year on natural gas for heat (may be closer to $200 with the reduced nat gas rates). At 8.5 cents a kWh for electricity, that would allow us to run our small portable 1500 watt electric heater for 40 minutes every hour during a 150 day heating season from ~Oct 15-Mar 15. That would keep one room very very toasty but not the whole house very toasty at all.

Wow Fuego! Did you mean $300/yr or a month? I spend that a month in the winter. I use gas to heat this house and the hotwater tank. Which part of the country is that? Is this just for cooking?

[bank5]

Quote:

Originally Posted by REWahoo As I understand it, a heat pump uses 'emergency heat' to supplement the heat put out by the compressor if the difference between the current temperature and the temperature selected on the thermostat differs by more than a couple of degrees (I'm speaking of temps in the house, not outside). Using a programmable thermostat to drop the temp to 60 at 10 PM then kick it back up to 68 at 6 AM would see the emergency heat kick in to assist in getting the temp to the higher setting. As I understand it, the added cost of the less-efficient emergency heat to get the temp back up more than offsets the savings from the lower setting during the previous eight hours.

This is what I've thought in the past but I'm not sure now, especially after reading this - Ask Mr. Electricity: Saving money on heating

It seems like there is a lot of variables involved so it's tough to find concrete data. I'm going to track it myself and see if I notice any sort of a difference for my own circumstances.

I think most of the programmable heat pump thermostats are programmed so they don't use the emergency heat. So if you set it for 60 degrees over night and 68 degrees at 6am, it will gradually increase the heat well before 6am so the emergency heat isn't used.

[mickeyd]

I've only turned the heat on a few times this winter (mostly @ night) so I don't know how much it cost me.

[bank5]

Quote:

Originally Posted by ziggy29 If the emergency heat is electric resistance, yeah, it's very expensive. Our heat pump system has an emergency resistance heating element. If the heat pump fails, I guess it would come on; otherwise it only comes on rarely when the heat pump needs a little more help (usually when the temperature is below about 25º, and even then not always). I'm not sure a programmable thermostat will save all that much for a heat pump system. If you suddenly increase the temperature by 5º, for example, most thermostats will trigger the expensive emergency heat. I just keep our thermostat at a constant 68 for heating and 78 for cooling.

I'm not sure at which temperature my auxiliary heat kicks in at but I think that's why January and February are by far my highest months. I'm guessing it requires a lot of emergency heat during those months, especially when the temperature drops at night.

I think the programmable heat pump thermostats are programmed to increase the heat gradually so they don't use the emergency heat. I'll probably go ahead and get one. It should help save electricity in the summer and hopefully also in the winter.

[ziggy29]

Quote:

Originally Posted by bank5 I'm not sure at which temperature my auxiliary heat kicks in at but I think that's why January and February are by far my highest months. I'm guessing it requires a lot of emergency heat during those months, especially when the temperature drops at night. I think the programmable heat pump thermostats are programmed to increase the heat gradually so they don't use the emergency heat. I'll probably go ahead and get one. It should help save electricity in the summer and hopefully also in the winter.

There's no fixed temp at which the emergency heat kicks in, but when the thermostat senses that the heat pump "needs help" it kicks in. Usually that's when the outdoor temperature drops low enough that the heat pump has trouble getting enough heat out of the air or when the thermostat is set several degrees above the current ambient temperature.

I would think there might be some thermostats designed for heat pumps which may not kick in the emergency heat just because you increased the temperature setting, and if there are then it would probably be a good investment. It's really not an issue for summer cooling, but only for winter heating.