Electricity Savings of Operating Wood Stove vs Forced Air Electric/Heat Pump

[dobias]

Are we talking about face cords or full cords? I'm too damned old to chop my own & pay $60 per face cord (16" long) delivered & stacked.
It's still cheaper than heating with LP.
Frank

 

[pgmr]

A heat pump generally doesn't work well in setback situations using a programmable thermostat. Because the recovery time is so long, most systems are setup to kick on the backup stage if the temp isn't rising fast enough or set point temp is X # of degrees above the actual temp. Using resistance coils, NG/propane furnace or oil to recover the temp is probably a wash with the $ saved during the setback period.

For those w/resistance coils, the COP for those is always 1 (100% eff - theoretically). The COP of a heat pump is always greater than 1 (it's not "making" heat, simply moving it from outside to inside). You should never set your system up to bypass the hp and only run the coils (unless the hp isn't working). Let the hp run, the coils are meant to supplement the hp and also to temper the air during a defrost cycle.

So I should let my HP run even when it's way below 30F?
Only need back up if I'm gone a few days...then it's the heat pump and resistance forced air furnace.
In order for my coils to come on I have to actually lose temp when the HP is on..double mercury thermostat.

I would leave it on if I had resistance coil auxiliary heaters. They can both be running at the same time, but even in really cold temps, the HP will be the cheaper of the two / btu delivered.

 

[HotCoals]

A heat pump generally doesn't work well in setback situations using a programmable thermostat. Because the recovery time is so long, most systems are setup to kick on the backup stage if the temp isn't rising fast enough or set point temp is X # of degrees above the actual temp. Using resistance coils, NG/propane furnace or oil to recover the temp is probably a wash with the $ saved during the setback period.

For those w/resistance coils, the COP for those is always 1 (100% eff - theoretically). The COP of a heat pump is always greater than 1 (it's not "making" heat, simply moving it from outside to inside). You should never set your system up to bypass the hp and only run the coils (unless the hp isn't working). Let the hp run, the coils are meant to supplement the hp and also to temper the air during a defrost cycle.

So I should let my HP run even when it's way below 30F?
Only need back up if I'm gone a few days...then it's the heat pump and resistance forced air furnace.
In order for my coils to come on I have to actually lose temp when the HP is on..double mercury thermostat.

I would leave it on if I had resistance coil auxiliary heaters. They can both be running at the same time, but even in really cold temps, the HP will be the cheaper of the two / btu delivered.

10-4..thanks.

 

[mrfjsf]

A heat pump generally doesn't work well in setback situations using a programmable thermostat. Because the recovery time is so long, most systems are setup to kick on the backup stage if the temp isn't rising fast enough or set point temp is X # of degrees above the actual temp. Using resistance coils, NG/propane furnace or oil to recover the temp is probably a wash with the $ saved during the setback period.

For those w/resistance coils, the COP for those is always 1 (100% eff - theoretically). The COP of a heat pump is always greater than 1 (it's not "making" heat, simply moving it from outside to inside). You should never set your system up to bypass the hp and only run the coils (unless the hp isn't working). Let the hp run, the coils are meant to supplement the hp and also to temper the air during a defrost cycle.

So I should let my HP run even when it's way below 30F?
Only need back up if I'm gone a few days...then it's the heat pump and resistance forced air furnace.
In order for my coils to come on I have to actually lose temp when the HP is on..double mercury thermostat.

I would leave it on if I had resistance coil auxiliary heaters. They can both be running at the same time, but even in really cold temps, the HP will be the cheaper of the two / btu delivered.

10-4..thanks.

On a side note, you may want to seriously consider ditching that old mercury stat, ESPECIALLY if you are running a HP. They are just not accurate enough, can be troublesome at times and IMHO cannot properly control a HP to peak efficiency. Mercury stats do not have the "Intelligence" to allow for a deadband, they can only sense that the temp has dropped below the set swing value and they kick on your heat strips. Also, do not do a setback with a heatpump. They are not designed to quickly recover from a setback. They are designed to produce a constant, low temperature heat and keep the house at a given setpoint, not swing from cold to hot and vice versa.

 

[wjb111]

I only have 1 full month to compare. I used 8.9 units less of natural gas for December 2011 vs December 2010. This past December was quite mild for this area in Michigan. Doing the math I saved about $75 in natural gas but used close to 2 face cords of wood at $60 per cord. We burn 24/7 maybe 90% of the time. I have to shut down the T5 for a day to cool off & clean the ashes out every 4-5 days. With this very small sampling it is costing me more to heat with the new T5. I suppose if I had a truck, chainsaw & a source to cut wood I might have a ROI. At least we are staying nice & warm. The family room typically run 75-80 degrees with the rest of the 1800 sq ft house a little cooler. I'm curious out the next 2 winter months compare.....

 

[Rhone]

What is going on with the $0.05/kW? My electric is $0.11/kWh with a $0.12 upcharge per killowatt for delivery, green, renewable, taxes so I pay $0.23/kWh on average. Take your total electric bill, divided by the used, and you'll have a more accurate representation of what you actually pay. The electric bill reminds me of paying for college, if you take one class tuition is only around $275 but you'll be hit with a $900+ bill because it's everything else.

I used to heat with oil, and I'd go through 750 gallons/year. After my wood insert it dropped to 230 gallons for just hot water. It worked out I was saving $1000/year minus $480 on wood or about $520/year. Now oil is $3.70 so I'm saving $2000/year minus $630 for wood = $1,300/year. That's worst case, I can usually scrounge a cord or two/year and each cord saves $210.

I was using 230 gallons/oil for hot water @ $3.70/gal = $850/year on hot water. I installed a solar hot water system for $2,500 (after rebates) with 3 panels and now I go through 11 gallons/year for savings of $810.30/year from solar.

I actually hate burning wood, it's time consuming and I'm not as young as I used to be. I rate my solar investment higher than my wood stove. Could I go back I'd have installed 6 solar panels, that would've given me almost all my hot water year round, and all but probably 2 months of heating. Maybe the next person who buys my house will do it... I sure hate when it's 40F and clear and sunny and I'm spending my time lighting a fire when... had I 3 more panels I'd be able to sit and relax. I'll take free easy heating over laborous cheap heating anyday

 

[Jags]

Rhonemas - where the heck have you been??

 

[kiltedpiper98]

We have had a warm winter here, and I just installed the fireplace in December, so I don't have any good numbers to put in. I did want to mention with the heat pump, many have an outside thermostat/switch that will turn off the heat pump and just use the back-up / aux heat once the temperature drops below a preset level. The best way to determine what that is would be looking at the COP and the charts as mentioned before, but the other way would be seeing what the temps coming out of the registers is compared with the outside temps. That will give you your Delta T, which will let you know at what outdoor temp you will not be happy/comfortable. For my heat pump (about 8 years old - standard grade) it is maxed at about 35 to 40 degrees. So if it is 35 degrees outside, the register will be 75 degrees, which means the room temp will feel cool, and the unit probably can't keep up with the heat loss from a moderately insulated home.

+1 to those who say wood heat is a quality of life/comfort thing. Inside temps at 75 degrees in the winter is great. I would not want to pay for that with gas back up and the heat pump below 40 degrees.

 

[Rhone]

Rhonemas - where the heck have you been??

Surprised you remember me, then again it's nice to still see the same members here it's such a great community. An accident happened some years ago (I got my wife pregnant) and I've been nothing but busy since! I don't remember what free time is anymore

 

[tcassavaugh]

wonder what the savings would be if you left the air handler off and let convection do its work.

cass

 

[Jags]

Rhonemas - where the heck have you been??

Surprised you remember me, then again it's nice to still see the same members here it's such a great community. An accident happened some years ago (I got my wife pregnant) and I've been nothing but busy since! I don't remember what free time is anymore

Glad to have you back.

Now back to the regularly scheduled show.

 

[begreen]

Welcome back Rhonemas! And congratulations on the new addition.

 

[dafattkidd]

I am always in awe of how low other people pay for utilities in other parts of the country. I love burning wood but would have a hard time justifying the time and energy for $100/month for winter months. By installing my insert I save about 700-800 gallons of oil. If i heated with electric my electric bill would be through the roof. I mean over $1000/month.