Heat Pump economic balance point/variable electric rates

[dango10010]

Hello all. I recently upgraded my house with a comfortmaker 80,000 btu furnace and a 3 ton heat pump. I also air sealed and insulated my house right before (and still need to do more air sealing of the rim joists in the basement). Recently, I signed up for a program with Ameren IL that offers an hour by hour electricity rate, during high demands I pay more, currently about 6 or 7 cents per kwh and during low demands its considerably less maybe 3 cents per kwh. I haven't yet been switched over, but they install a new meter and can tell you how much you used and paid hour by hour the day before. The gas is about .71 per therm(?). I used to kick it down to a cooler temperature at night, but now I am thinking since the electricity will be cheaper in the night I might just keep it a constant temperature and maybe lower it slightly during peak times. The heat pump will keep the house a constant temperature down to about 15 F, I usually keep my house about 70F. Or I could let the temp fall at night, and during the morning then have the furnace kick on to bring the temp up and not pay the higher electric rates. Have I mentioned I am cheap?

[tipsrfine]

Did you do the air sealing yourself? Did you have a blower door test performed first to determine the size & location of the leaks? Did you have a worst case depressurization test of the combustion zone around your furnace & hot water heater (if gas)?

[dango10010]

I had someone come in and do a blower door test for Ameren before and after, this was needed to get some incentives back from Ameren, I sealed up most of the rim joists as instructed by the contractor, its very easy just messy and time consuming. and sealed the leaks in the basement that lead upstairs to stop the air from going up into the attic as the chimney effect. Still have a bit more to good in on the back part of the house that is a crawl space that was added onto. Its quite a bit better but not as good as a new properly sealed house, my house is almost 100 years old. We did do the combustion test as well, it passed but I may eventually run a pipe outside for combustion of the furnace and a chimney liner for the water heater or I might get an efficient hot water heater that can be vented like the furnace.

[pwg11386]

i don't recommend constantly changing your balance point temperature. The control is not designed to be adjusted so frequently. Also, i don't recommend that you drop the balance point any lower than 30 degrees; your heat pump can heat at lower temperatures, but it doesn't do it efficiently when its so cold outside which means wasted electricity. When it gets below 30 outside, youll get more bang for your buck using your furnace (providing its installed correctly and the gas pressures and blower is set up)

[SJProwler]

When it gets below 30 outside, youll get more bang for your buck using your furnace (providing its installed correctly and the gas pressures and blower is set up)

That is not necessarily true, I also have the on-peak/off-peak electrical rates.

Down to 17 degrees my HP (HSPF 8.7) provides heat during the off peak rate for less than half the price of my 97% AFUE Gas furnace.

100k btu of heat Off Peak $.41
100k btu of heat On Peak $1.49
100k btu of heat Nat Gas $.92

I force the emergency heat on only during On Peak electric periods, the rest of the time the Heat Pump runs and I have my balance point set at 20 deg. and get 90 degree air from the registers and the house is very comfortable.

[snewman24]

That is not necessarily true, I also have the on-peak/off-peak electrical rates.

Down to 17 degrees my HP (HSPF 8.7) provides heat during the off peak rate for less than half the price of my 97% AFUE Gas furnace.

100k btu of heat Off Peak $.41
100k btu of heat On Peak $1.49
100k btu of heat Nat Gas $.92

I force the emergency heat on only during On Peak electric periods, the rest of the time the Heat Pump runs and I have my balance point set at 20 deg. and get 90 degree air from the registers and the house is very comfortable.

What is the COP of your heat pump @ 17°F ?

[snewman24]

Also, what electrical utility in Michigan gives off-peak rates that are less than 1/3 of peak rates?

[SJProwler]

Here is the fuel cost comparison using the current rates in my area.

My heat pump has a COP of 3.59 at 47f and 2.18 at 17f
My furnace is rated at 97% AFUE
My off peak electric is .03918 delivered
My Nat Gas is .0085987 per cu ft delivered
Propane is currently $2.392 per gal
Heating Oil is currently $3.165

Cost per 100,000 btu of useable heat
Corn Pellets: $3.84
Electric baseboard: $1.05
Heat pump: $0.53
Oil: $2.80
Propane: $2.70
Natural gas: $0.86

My electric supplier is Indiana Michigan Electric, a division of American Electric Power.
Their current tariff is below,

(Tariff Code 032)
Service Charge ($)--7.90
Energy Charge (¢ per kWh):.....Power Supply.....Delivery....Total

For all on-peak kWh used.........12.348.............1.782......14.13
For all off-peak kWh used..........2.136.............1.782........3.918

So at current rates my previous statement was off a few cents when calculated at 17f.

[snewman24]

That's a great off-peak rate - too bad it's not around the clock. It would be great for charging an electric car all night.

[SJProwler]

Not attempting to hijack the OP's thread but I have 2200 amps of -48v batteries that I'm planning to charge off-peak and run on during on-peak as soon as I can afford the inverters. And eventually add a wind generator to supplement.