Heat pumps are extremely energy efficient. With the known tonnage (or BTUs), the SEER rating, and the HSPF rating, we can calculate almost exactly how much electricity a heat pump use (watts, kWh usage) per hour, per day, and even per month. Based on that, we can calculate how much it costs to run a heat pump per hour, per day, and per month.
Knowing how many watts, kWh a heat pump use is useful in a number of cases, including:
- How much does it cost to run a heat pump? (They are considered very energy-efficient)
- How big a generator do you need to run a heat pump? (Start-up wattage is key here; in the event of a power outage)
- Will a solar panel system be able to provide enough electricity to power a heat pump?
Naturally, we also want to know how much we will pay for running a heat pump.
This is quite a large spectrum of questions (we calculated both for cooling mode and heating mode individually, and created 4 calculators and 5 charts). In order to figure out your much electricity your heat pump uses (and how much it costs to run), you have to consider 4 main factors that the heat pump wattage depends on:
- Size or capacity (tonnage); primary factor. The bigger the heat pump, the more power it will need to run. Example: 4-ton heat pump will use more electricity than a 2-ton unit.
- Cooling energy efficiency (SEER rating); primary factor for cooling. The more efficient the heat pump, the fewer watts it will require to run. Example: 14 SEER 3-ton heat pumps draw 3,061 watts (max. wattage) and 1775 average wattage (58% of max wattage). 22 SEER 3-ton heat pump draws 2,406 max. watts and 1395 average running watts; that’s quite a big difference.
- Heating energy efficiency (HSPF rating); primary factor for heating. The higher the HSPF rating, the less wattage will a heat pump draw. Lower wattage also means lower electricity or kWh use per month, and lower heating costs.
- Type of heat pump; secondary factor. In general, the same size ground-source heat pump requires less electricity to run than an air-source heat pump (due to a higher SEER rating).
In order to fully calculate the electricity usage and running cost of a heat pump, we are going to take a structured approach here. First, we are going to look at the cooling mode (using the SEER rating). After that, we are going to look at the heating mode (using the HSPF rating). Here are the key resources you will get for both cooling and heating modes:
- Heat pump maximum wattage. This is relevant in the event of a power outage; you will be able to determine the size of the generator you need to run a heat pump.
- Heat pump electricity usage per hour, day, and per month. By using average running wattage (58% of the max. wattage), we will calculate the kWh usage. We have prepared several charts with wattage and kWh usage for 1-6 ton and 14-22 SEER and 8-14 HSPF heat pumps to help you out.
- Heat pump expenditure calculators and charts. You input the size of your heat pump (in tons), SEER rating for cooling mode or HSPF rating for heating mode, and the calculator will tell you how much electricity your heat pump use (kWh per hour, kWh per day, and kWh per month). Additionally, the heat pump running cost calculators will tell you how much does it cost to run a heat pump; you only need to specify the electricity price per kWh ($/kWh) in your area.
Sounds about right?
We will include a number of calculated charts with average heat pump electricity usage and costs in this article. Here is the quick outtake for 1-6 ton 14-22 SEER and 8-14 HSPF heat pumps:
- In cooling mode, a heat pump will use anywhere from 0.55 kWh to 5.14 kWh per hour, from 4.36 kWh to 41.14 kWh per day, and from 130.91 kWh to 1234.29 kWh per month. The corresponding running cost (based on $0.15/kWh electricity prices) is $0.08 to $0.77 per hour, $0.65 to $6.17 per day, and $19.64 to $185.14 per month.
- In heating mode, a heat pump will use anywhere from 0.86 kWh to 9.00 kWh per hour, from 6.86 kWh to 72 kWh per day, and from 205.71 kWh to 2160 kWh per month. The corresponding running cost (based on $0.15/kWh electricity prices) is $0.13 to $1.35 per hour, $1.03 to $10.80 per day, and $30.86 to $324 per month.
- According to EIA’s Residential Energy Consumption Survey (RECS) data, an average US household will use 3784 kWh annually for heating (costing $434 per year) and 3084 kWh annually for cooling (costing $262 per year).
Note: If you would like for us to calculate the kWh usage and running cost of your heat pump, you can give us some numbers (tonnage, SEER, HSPF, cost of electricity or location) in the comment section below, and we can help you with the calculations.
Alright, let’s start with the cooling mode in the 1st part (based on the SEER rating), and we will cover the heating mode in the 2nd part (based on the HSPF rating)
Cooling Mode Electricity Usage And Running Costs
Now, determining exactly how many watts does a heat pump require to run when cooling isn’t all that easy. If you crack open the specification sheet of a heat pump, you will rarely see something like “Max. Wattage = 3,000W”.
What you will always find in the specs sheet, however, is the SEER rating. We can use the SEER rating to determine how many watts and amps do you need to run such a heat pump. First of all, we will look at how to get to the wattage of any heat pump via SEER rating.
Further on, you will also find how many watts do 1-6 ton heat pumps use (summarized in a table).
How To Check How Many Watts Does A Heat Pumps Use When Cooling?
As you know, wattage is not labeled on the heat pump spec sheet. Fortunately, SEER rating (Seasonal Energy Efficiency Rating) is. We can calculate the total wattage heat pump uses from SEER rating using these two equations:
EER = −0.02 × SEER² + 1.12 × SEER (Equation 1)
Total Wattage = Capacity (In BTUs) ÷ EER (Equation 2)
In short, we convert SEER to EER (Equation 1), and we use the calculated EER to calculate the total wattage of a heat pump (Equation 2). It might sound a bit complex but it’s quite easy; you just insert the SEER rating in Equation 1 and go from there.
Here’s an example of what we get:
A 2-ton heat pump (24,000 BTU) has a 20 SEER rating. How many watts does it run on? Let’s calculate that:
EER at 20 SEER = −0.02 × 20² + 1.12 × 20 = 14.4
Total Wattage (2-ton, 20 SEER) = 24,000 BTU ÷ 14.4 = 1,667 Watts
Using these two equations, we can calculate how much power any heat pump use when in cooling mode. We did just that and summarized the results in this table:
How Many Watts Do Heat Pumps Use When Cooling (Max. Wattage)?
These results will help you determine the size of a generator in the event of a power outage. We are going to cover average heat pump electricity usage later on (as well as costs):
| Heat Pump Size: | Wattage (14 SEER): | Wattage (16 SEER): | Wattage (18 SEER): | Wattage (20 SEER): | Wattage (22 SEER): |
| 1 ton (12,000 BTU) | 1,020 W | 938 W | 877 W | 833 W | 802 W |
| 1.5 ton (18,000 BTU) | 1,531 W | 1,406 W | 1,316 W | 1,250 W | 1,203 W |
| 2 ton (24,000 BTU) | 2,041 W | 1,875 W | 1,754 W | 1,667 W | 1,604 W |
| 2.5 ton (30,000 BTU) | 2,551 W | 2,344 W | 2,193 W | 2,083 W | 2,005 W |
| 3 ton (36,000 BTU) | 3,061 W | 2,813 W | 2,632 W | 2,500 W | 2,406 W |
| 3.5 ton (42,000 BTU) | 3,571 W | 3,281 W | 3,070 W | 2,917 W | 2,807 W |
| 4 ton (48,000 BTU) | 4,082 W | 3,750 W | 3,509 W | 3,333 W | 3,209 W |
| 4.5 ton (54,000 BTU) | 4,592 W | 4,219 W | 3,947 W | 3,750 W | 3,610 W |
| 5 ton (60,000 BTU) | 5,102 W | 4,688 W | 4,386 W | 4,167 W | 4,011 W |
| 6 ton (72,000 BTU) | 5,102 W | 4,688 W | 4,386 W | 4,167 W | 4,011 W |
Using this table, you can answer pretty much any question regarding how many watts does your heat pump run on when cooling.
Example: Let’s say you have a 16 SEER 3-ton unit. How many watts does it require to run in cooling mode? Just check the table, and you will see that such a 3-ton unit runs on 2,813 W when operating at 100% output
This is quite valuable information if you’re looking at what wattage generator you need to run a 3-ton unit.
Now, most homeowners will like to know how much electricity a heat pump uses (we are still covering the cooling mode in this chapter) and how much it all costs. Here’s the next step:
Heat Pump Cooling kWh Usage Calculator And Chart
Obviously, we don’t run a heat pump at 100% all the time. In fact, the SEER rating presupposes that we run it at 100% output only 1% of the time. In the post about how the SEER rating is calculated here, we have used the SEER formula that looks like this:
SEER = (1 × EER100% + 42 × EER75% + 45 × EER50% + 12 × EER25%)/100
Basically, the SEER rating is a weighted average of an AC unit or heat pump in cooling mode running at 25%, 50%, 75%, and 100% output. The clever heads at the DOE that come up with the SEER rating presume that a heat pump runs at an average of 58% output (this is close to real-world usage).
That means that the SEER rating will help us calculate the average running wattage of any heat pump in cooling mode. Example: Let’s say we have a 5-ton 16 SEER heat pump in cooling mode. How much power does it run on? Here is how we can calculate that:
Running Wattage (5-Ton 18 SEER) = 60,000 BTU (This is equal to 5 tons) / 16 SEER = 3,750 Watts
Now that we have the running wattage, we can calculate the kWh usage. This unit – with 3,750 running watts – will use:
- 3.75 kWh per hour.
- 30.00 kWh per day (running 8 hours per day).
- 900.00 kWh per month (running 8 hours per day for 30 days).
If we multiply these kWh usages by electricity prices (let’s say $0.15/kWh), we see that a 5-ton 16 SEER heat pump will cost 900.00 kWh × $0.15/kWh = $135 per month (it’s quite a big unit). But we are getting ahead of ourselves.
Let’s first use the following heat pump cooling kWh usage calculator to see how many kWh your unit will use per hour, per day, and per month. Below the calculator, you will find a calculated chart for 1-6 ton and 14-22 SEER heat pumps. After that, we are going to use the same calculator + chart principle to calculate the cost of running a heat pump in cooling mode.
Here is the calculator, followed by the calculated kWh chart for the cooling mode:
As you can see, the calculator will automatically calculate the kWh usage in cooling mode. Example of how to use it: Let’s say that you have a 3.5-ton 20 SEER unit. You slide the 1st slider to ‘3.5’, the 2nd slider to ’20’, and you get the results: Such a heat pump will use 2.10 kWh per hour (running on 2,100 watts), 16.8 kWh per day, and 504 kWh per month.
Cooling kWh Usage Per Hour, Per Day, And Per Month (Chart)
Here is the promised chart for varying heat pump’s power usage per day, per hour, and per month in cooling mode:
| Heat Pump Size: | 14 SEER Electricity Usage: | 16 SEER Electricity Usage: | 18 SEER Electricity Usage: | 20 SEER Electricity Usage: | 22 SEER Electricity Usage: |
| 1 ton (12,000 BTU) | 0.86 kWh Per Hour 6.86 kWh Per Day 205.71 kWh Per Month |
0.75 kWh Per Hour 6.00 kWh Per Day 180.00 kWh Per Month |
0.67 kWh Per Hour 5.33 kWh Per Day 160.00 kWh Per Month |
0.60 kWh Per Hour 4.80 kWh Per Day 144.00 kWh Per Month |
0.55 kWh Per Hour 4.36 kWh Per Day 130.91 kWh Per Month |
| 1.5 ton (18,000 BTU) | 1.29 kWh Per Hour 10.29 kWh Per Day 308.57 kWh Per Month |
1.13 kWh Per Hour 9.00 kWh Per Day 270.00 kWh Per Month |
1.00 kWh Per Hour 8.00 kWh Per Day 240.00 kWh Per Month |
0.90 kWh Per Hour 7.20 kWh Per Day 216.00 kWh Per Month |
0.82 kWh Per Hour 6.55 kWh Per Day 196.36 kWh Per Month |
| 2 ton (24,000 BTU) | 1.71 kWh Per Hour 13.71 kWh Per Day 411.43 kWh Per Month |
1.50 kWh Per Hour 12.00 kWh Per Day 360.00 kWh Per Month |
1.33 kWh Per Hour 10.67 kWh Per Day 320.00 kWh Per Month |
1.20 kWh Per Hour 9.60 kWh Per Day 288.00 kWh Per Month |
1.09 kWh Per Hour 8.73 kWh Per Day 261.82 kWh Per Month |
| 2.5 ton (30,000 BTU) | 2.14 kWh Per Hour 17.14 kWh Per Day 514.29 kWh Per Month |
1.88 kWh Per Hour 15.00 kWh Per Day 450.00 kWh Per Month |
1.67 kWh Per Hour 13.33 kWh Per Day 400.00 kWh Per Month |
1.50 kWh Per Hour 12.00 kWh Per Day 360.00 kWh Per Month |
1.36 kWh Per Hour 10.91 kWh Per Day 327.27 kWh Per Month |
| 3 ton (36,000 BTU) | 2.57 kWh Per Hour 20.57 kWh Per Day 617.14 kWh Per Month |
2.25 kWh Per Hour 18.00 kWh Per Day 540.00 kWh Per Month |
2.00 kWh Per Hour 16.00 kWh Per Day 480.00 kWh Per Month |
1.80 kWh Per Hour 14.40 kWh Per Day 432.00 kWh Per Month |
1.64 kWh Per Hour 13.09 kWh Per Day 392.73 kWh Per Month |
| 3.5 ton (42,000 BTU) | 3.00 kWh Per Hour 24.00 kWh Per Day 720.00 kWh Per Month |
2.63 kWh Per Hour 21.00 kWh Per Day 630.00 kWh Per Month |
2.33 kWh Per Hour 18.67 kWh Per Day 560.00 kWh Per Month |
2.10 kWh Per Hour 16.80 kWh Per Day 504.00 kWh Per Month |
1.91 kWh Per Hour 15.27 kWh Per Day 458.18 kWh Per Month |
| 4 ton (48,000 BTU) | 3.43 kWh Per Hour 27.43 kWh Per Day 822.86 kWh Per Month |
3.00 kWh Per Hour 24.00 kWh Per Day 720.00 kWh Per Month |
2.67 kWh Per Hour 21.33 kWh Per Day 640.00 kWh Per Month |
2.40 kWh Per Hour 19.20 kWh Per Day 576.00 kWh Per Month |
2.18 kWh Per Hour 17.45 kWh Per Day 523.64 kWh Per Month |
| 4.5 ton (54,000 BTU) | 3.86 kWh Per Hour 30.86 kWh Per Day 925.71 kWh Per Month |
3.38 kWh Per Hour 27.00 kWh Per Day 810.00 kWh Per Month |
3.00 kWh Per Hour 24.00 kWh Per Day 720.00 kWh Per Month |
2.70 kWh Per Hour 21.60 kWh Per Day 648.00 kWh Per Month |
2.45 kWh Per Hour 19.64 kWh Per Day 589.09 kWh Per Month |
| 5 ton (60,000 BTU) | 4.29 kWh Per Hour 34.29 kWh Per Day 1028.57 kWh Per Month |
3.75 kWh Per Hour 30.00 kWh Per Day 900.00 kWh Per Month |
3.33 kWh Per Hour 26.67 kWh Per Day 800.00 kWh Per Month |
3.00 kWh Per Hour 24.00 kWh Per Day 720.00 kWh Per Month |
2.73 kWh Per Hour 21.82 kWh Per Day 654.55 kWh Per Month |
| 6 ton (72,000 BTU) | 5.14 kWh Per Hour 41.14 kWh Per Day 1234.29 kWh Per Month |
4.50 kWh Per Hour 36.00 kWh Per Day 1080.00 kWh Per Month |
4.00 kWh Per Hour 32.00 kWh Per Day 960.00 kWh Per Month |
3.60 kWh Per Hour 28.80 kWh Per Day 864.00 kWh Per Month |
3.27 kWh Per Hour 26.18 kWh Per Day 785.45 kWh Per Month |
Alright, this was a lot of calculating, but now we have the numbers:
As we can see from the chart, heat pumps in cooling mode use:
- Anywhere from 0.55 kWh to 5.14 kWh per hour.
- Anywhere from 4.36 kWh to 41.14 kWh per day.
- Anywhere from 130.91 kWh to 1234.29 kWh per month.
How much do all of these kWh cost?
To get to the heat pump cooling mode running cost, we basically have to multiply all these kWh by the price of electricity ($/kWh).
To help you out, we have created a heat pump cooling mode cost calculator, complete with the cost chart for 1-6 ton 14-22 SEER heat pumps. Here is the cost calculator:
Alright, same deal here, you can insert the price of electricity. If you don’t know how much electricity costs in your area, you can consult this EIA electricity price state-by-state chart. We see that the electricity prices in October 2022 (last available data) range from $0.10/kWh (Washinton state) to over $0.30/kWh (Rhode Island).
In order to calculate the average heat pump running cost in cooling mode, we are going to use a roughly average state-by-state electricity price of $0.15/kWh. Here are the calculated running costs per hour, per day, and per month for 1-6 ton 14-22 SEER heat pumps, based on $0.15/kWh residential electricity prices:
Cooling Running Cost Per Hour, Per Day, And Per Month (Chart)
| Heat Pump Size: | 14 SEER Running Cost: | 16 SEER Running Cost: | 18 SEER Running Cost: | 20 SEER Running Cost: | 22 SEER Running Cost: |
| 1 ton (12,000 BTU) | $0.13 Per Hour $1.03 Per Day $30.86 Per Month |
$0.11 Per Hour $0.90 Per Day $27.00 Per Month |
$0.10 Per Hour $0.80 Per Day $24.00 Per Month |
$0.09 Per Hour $0.72 Per Day $21.60 Per Month |
$0.08 Per Hour $0.65 Per Day $19.64 Per Month |
| 1.5 ton (18,000 BTU) | $0.19 Per Hour $1.54 Per Day $46.29 Per Month |
$0.17 Per Hour $1.35 Per Day $40.50 Per Month |
$0.15 Per Hour $1.20 Per Day $36.00 Per Month |
$0.13 Per Hour $1.08 Per Day $32.40 Per Month |
$0.12 Per Hour $0.98 Per Day $29.45 Per Month |
| 2 ton (24,000 BTU) | $0.26 Per Hour $2.06 Per Day $61.71 Per Month |
$0.22 Per Hour $1.80 Per Day $54.00 Per Month |
$0.20 Per Hour $1.60 Per Day $48.00 Per Month |
$0.18 Per Hour $1.44 Per Day $43.20 Per Month |
$0.16 Per Hour $1.31 Per Day $39.27 Per Month |
| 2.5 ton (30,000 BTU) | $0.32 Per Hour $2.57 Per Day $77.14 Per Month |
$0.28 Per Hour $2.25 Per Day $67.50 Per Month |
$0.25 Per Hour $2.00 Per Day $60.00 Per Month |
$0.23 Per Hour $1.80 Per Day $54.00 Per Month |
$0.20 Per Hour $1.64 Per Day $49.09 Per Month |
| 3 ton (36,000 BTU) | $0.39 Per Hour $3.09 Per Day $92.57 Per Month |
$0.34 Per Hour $2.70 Per Day $81.00 Per Month |
$0.30 Per Hour $2.40 Per Day $72.00 Per Month |
$0.27 Per Hour $2.16 Per Day $64.80 Per Month |
$0.25 Per Hour $1.96 Per Day $58.91 Per Month |
| 3.5 ton (42,000 BTU) | $0.45 Per Hour $3.60 Per Day $108.00 Per Month |
$0.39 Per Hour $3.15 Per Day $94.50 Per Month |
$0.35 Per Hour $2.80 Per Day $84.00 Per Month |
$0.31 Per Hour $2.52 Per Day $75.60 Per Month |
$0.29 Per Hour $2.29 Per Day $68.73 Per Month |
| 4 ton (48,000 BTU) | $0.51 Per Hour $4.11 Per Day $123.43 Per Month |
$0.45 Per Hour $3.60 Per Day $108.00 Per Month |
$0.40 Per Hour $3.20 Per Day $96.00 Per Month |
$0.36 Per Hour $2.88 Per Day $86.40 Per Month |
$0.33 Per Hour $2.62 Per Day $78.55 Per Month |
| 4.5 ton (54,000 BTU) | $0.58 Per Hour $4.64 Per Day $138.86 Per Month |
$0.51 Per Hour $4.05 Per Day $121.50 Per Month |
$0.45 Per Hour $3.60 Per Day $108.00 Per Month |
$0.41 Per Hour $3.24 Per Day $97.20 Per Month |
$0.37 Per Hour $2.95 Per Day $88.36 Per Month |
| 5 ton (60,000 BTU) | $0.64 Per Hour $5.14 Per Day $154.29 Per Month |
$0.56 Per Hour $4.50 Per Day $135.00 Per Month |
$0.50 Per Hour $4.00 Per Day $120.00 Per Month |
$0.45 Per Hour $3.60 Per Day $108.00 Per Month |
$0.41 Per Hour $3.27 Per Day $98.18 Per Month |
| 6 ton (72,000 BTU) | $0.77 Per Hour $6.17 Per Day $185.14 Per Month |
$0.68 Per Hour $5.40 Per Day $162.00 Per Month |
$0.60 Per Hour $4.80 Per Day $144.00 Per Month |
$0.54 Per Hour $4.32 Per Day $129.60 Per Month |
$0.49 Per Hour $3.93 Per Day $117.82 Per Month |
As we can see, the heat pump running cost increases with the size of the heat pump (6-ton units use more electricity than 1-ton units) and with the decrease in the SEER rating for cooling mode (14 SEER units use more electricity than 22 SEER units).
As we can see, using $0.15/kWh electricity prices for 1-6 ton 14-22 SEER units, the cost of running a heat pump in cooling mode ranges between:
- $0.08 to $0.77 per hour.
- $0.65 to $6.17 per day.
- $19.64 to $185.14 per month.
Alright, this has been the cooling more. Let’s look at the same electricity expenditure and cost of heat pumps in heating mode:
Heating Mode Electricity Usage And Running Costs
If we used the SEER rating for heat pump energy efficiency in cooling mode, we have to use the HSPF rating in much the same way for heating.
Namely, the HSPF rating is based on the heat pump COP rating (Coefficient of Performance). The COP rating will decrease with decreasing outdoor temperature; the HSPF rating presumes that the heat pump will run at 47°F outdoor temperature.
We can calculate the heat pump wattage in heating mode using this HSPF-based equation:
Average Running Wattage (Heating Mode) = Heat Pump BTUs / HSPF rating
Here is one example. Let’s say that we have a 3-ton heat pump (that is 36,000 BTU heat pump since 1 ton = 12,000 BTU) with a 10 HSPF rating. How much electricity does it run on? Here is how we use this equation:
Average Running Wattage (3 Ton, 10 HSPF) = 36,000 BTU / 10 HSPF = 3,600 Watts
As we can see, such a heat pump will have an operating wattage of 3,600W. It will use:
- 3.6 kWh of electricity per hour. At $0.15/kWh, the running cost is $0.54 per hour.
- 28.8 kWh per day. At $0.15/kWh, the running cost is $4.32 per day.
- 864 kWh per day. At $0.15/kWh, the running cost is $129.60 per month.
To help out with everybody’s heat pump in heating mode, we are going to calculate electricity expenditure (kWh per hour, day, month) for 1-6 ton 8-14 HSPF heat pumps. We will also give you calculators you can use yourself.
In the 1st segment, you have the heat pump heating mode calculator and the corresponding chart for 1-6 ton 8-14 HSPF heat pumps. In the 2nd segment, you will find a calculator that calculates how much it costs to run a heat pump in heating mode, and the corresponding chart.
Let’s start with the heat pump heating mode kWh usage:
Heat Pump Heating kWh Usage Calculator And Chart (Per Hour, Day, Month)
Alright, we see that heat pumps in heating mode use more kWh than in cooling mode. That’s because the SEER ratings (cooling) are usually quite higher than the HSPF ratings (heating).
You can use this calculator to figure out how many kWh does a heat pump in heating mode use per hour, per day, and per month. We have used this calculator to calculate these average kWh usage for 1-6 ton 8-14 HSPF heat pumps, and gathered the results in this chart:
| Heat Pump Size: | 8 HSPF Electricity Usage: | 9 HSPF Electricity Usage: | 10 HSPF Electricity Usage: | 12 HSPF Electricity Usage: | 14 HSPF Electricity Usage: |
| 1 ton (12,000 BTU) | 1.50 kWh Per Hour 12 kWh Per Day 360 kWh Per Month |
1.33 kWh Per Hour 10.67 kWh Per Day 320 kWh Per Month |
1.20 kWh Per Hour 9.60 kWh Per Day 288 kWh Per Month |
1.00 kWh Per Hour 8 kWh Per Day 240 kWh Per Month |
0.86 kWh Per Hour 6.86 kWh Per Day 205.71 kWh Per Month |
| 1.5 ton (18,000 BTU) | 2.25 kWh Per Hour 18 kWh Per Day 540 kWh Per Month |
2.00 kWh Per Hour 16 kWh Per Day 480 kWh Per Month |
1.80 kWh Per Hour 14.40 kWh Per Day 432 kWh Per Month |
1.50 kWh Per Hour 12 kWh Per Day 360 kWh Per Month |
1.29 kWh Per Hour 10.29 kWh Per Day 308.57 kWh Per Month |
| 2 ton (24,000 BTU) | 3.00 kWh Per Hour 24 kWh Per Day 720 kWh Per Month |
2.67 kWh Per Hour 21.33 kWh Per Day 640 kWh Per Month |
2.40 kWh Per Hour 19.20 kWh Per Day 576 kWh Per Month |
2.00 kWh Per Hour 16 kWh Per Day 480 kWh Per Month |
1.71 kWh Per Hour 13.71 kWh Per Day 411.43 kWh Per Month |
| 2.5 ton (30,000 BTU) | 3.75 kWh Per Hour 30 kWh Per Day 900 kWh Per Month |
3.33 kWh Per Hour 26.67 kWh Per Day 800 kWh Per Month |
3.00 kWh Per Hour 24 kWh Per Day 720 kWh Per Month |
2.50 kWh Per Hour 20 kWh Per Day 600 kWh Per Month |
2.14 kWh Per Hour 17.14 kWh Per Day 514.29 kWh Per Month |
| 3 ton (36,000 BTU) | 4.50 Per Hour 36 kWh Per Day 1080 kWh Per Month |
4.00 kWh Per Hour 32 kWh Per Day 960 kWh Per Month |
3.60 kWh Per Hour 28.80 kWh Per Day 864 kWh Per Month |
3.00 kWh Per Hour 24 kWh Per Day 720 kWh Per Month |
2.57 Per Hour 20.57 kWh Per Day 617.14 kWh Per Month |
| 3.5 ton (42,000 BTU) | 5.25 kWh Per Hour 42 kWh Per Day 1260 kWh Per Month |
4.67 kWh Per Hour 37.33 kWh Per Day 1120 kWh Per Month |
4.20 kWh Per Hour 33.60 kWh Per Day 1008 kWh Per Month |
3.50 kWh Per Hour 28 kWh Per Day 840 kWh Per Month |
3.00 kWh Per Hour 24.00 kWh Per Day 720.00 kWh Per Month |
| 4 ton (48,000 BTU) | 6.00 kWh Per Hour 48 kWh Per Day 1440 kWh Per Month |
5.33 kWh Per Hour 42.67 kWh Per Day 1280 kWh Per Month |
4.80 kWh Per Hour 38.40 kWh Per Day 1152 kWh Per Month |
4.00 kWh Per Hour 32 kWh Per Day 960 kWh Per Month |
3.43 kWh Per Hour 27.43 kWh Per Day 822.86 kWh Per Month |
| 4.5 ton (54,000 BTU) | 6.75 kWh Per Hour 54 kWh Per Day 1620 kWh Per Month |
6.00 kWh Per Hour 48 kWh Per Day 1440 kWh Per Month |
5.40 kWh Per Hour 43.20 kWh Per Day 1296 kWh Per Month |
4.50 kWh Per Hour 36 kWh Per Day 1080 kWh Per Month |
3.86 kWh Per Hour 30.86 kWh Per Day 925.71 kWh Per Month |
| 5 ton (60,000 BTU) | 7.50 kWh Per Hour 60 kWh Per Day 1800 kWh Per Month |
6.67 kWh Per Hour 53.33 kWh Per Day 1600 kWh Per Month |
6.00 kWh Per Hour 48 kWh Per Day 1440 kWh Per Month |
5.00 kWh Per Hour 40 kWh Per Day 1200 kWh Per Month |
4.29 kWh Per Hour 34.29 kWh Per Day 1028.57 kWh Per Month |
| 6 ton (72,000 BTU) | 9.00 kWh Per Hour 72 kWh Per Day 2160 kWh Per Month |
8.00 kWh Per Hour 64 kWh Per Day 1920 kWh Per Month |
7.20 kWh Per Hour 57.60 kWh Per Day 1728 kWh Per Month |
6.00 kWh Per Hour 48 kWh Per Day 1440 kWh Per Month |
5.14 kWh Per Hour 41.14 kWh Per Day 1234.29 kWh Per Month |
Alright, we can see that a heat pump in heating mode will (depending on the tonnage and HSPF rating) use:
- Anywhere from 0.86 kWh to 9.00 kWh per hour.
- Anywhere from 6.86 kWh to 72 kWh per day.
- Anywhere from 205.71 kWh to 2160 kWh per month.
Based on the kWh usage, we can calculate the heat pump heating mode heating cost by multiplying the kWh usage with the electricity prices (we take $0.15/kWh average electricity price for the calculations).
This next heat pump operating cost calculator does just that; below the calculator, we have summarized the results for 1-6 ton 8-14 HSPF heat pumps in a neat chart as well:
Heat Pump Heating Running Cost Calculator And Chart (Per Hour, Day, Month)
As you can see, we have 3 inputs here (tonnage, HSPF rating, and electricity price). The calculator will automatically estimate how much it cost to run a heat pump in heating mode per hour, per day, and per month.
Here are the summarized results for heating costs for 1-6 ton and 8-14 HSPF heat pumps:
| Heat Pump Size: | 8 HSPF Running Cost: | 9 HSPF Running Cost: | 10 HSPF Running Cost: | 12 HSPF Running Cost: | 14 HSPF Running Cost: |
| 1 ton (12,000 BTU) | $0.22 Per Hour $1.80 Per Day $54 Per Month |
$0.20 Per Hour $1.60 Per Day $48 Per Month |
$0.18 Per Hour $1.44 Per Day $43.20 Per Month |
$0.15 Per Hour $1.20 Per Day $36 Per Month |
$0.13 Per Hour $1.03 Per Day $30.86 Per Month |
| 1.5 ton (18,000 BTU) | $0.34 Per Hour $2.70 Per Day $81 Per Month |
$0.30 Per Hour $2.40 Per Day $72 Per Month |
$0.27 Per Hour $2.16 Per Day $64.80 Per Month |
$0.22 Per Hour $1.80 Per Day $54 Per Month |
$0.19 Per Hour $1.54 Per Day $46.29 Per Month |
| 2 ton (24,000 BTU) | $0.45 Per Hour $3.60 Per Day $108 Per Month |
$0.40 Per Hour $3.20 Per Day $96 Per Month |
$0.36 Per Hour $2.88 Per Day $86.40 Per Month |
$0.30 Per Hour $2.40 Per Day $72 Per Month |
$0.26 Per Hour $2.06 Per Day $61.71 Per Month |
| 2.5 ton (30,000 BTU) | $0.56 Per Hour $4.50 Per Day $135 Per Month |
$0.50 Per Hour $4 Per Day $120 Per Month |
$0.45 Per Hour $3.60 Per Day $108 Per Month |
$0.38 Per Hour $3 Per Day $90 Per Month |
$0.32 Per Hour $2.57 Per Day $77.14 Per Month |
| 3 ton (36,000 BTU) | $0.68 Per Hour $5.40 Per Day $162 Per Month |
$0.60 Per Hour $4.80 Per Day $144 Per Month |
$0.54 Per Hour $4.32 Per Day $129.60 Per Month |
$0.45 Per Hour $3.60 Per Day $108 Per Month |
$0.39 Per Hour $3.09 Per Day $92.57 Per Month |
| 3.5 ton (42,000 BTU) | $0.79 Per Hour $6.30 Per Day $189 Per Month |
$0.70 Per Hour $5.60 Per Day $168 Per Month |
$0.63 Per Hour $5.04 Per Day $151.20 Per Month |
$0.52 Per Hour $4.20 Per Day $126 Per Month |
$0.45 Per Hour $3.60 Per Day $108.00 Per Month |
| 4 ton (48,000 BTU) | $0.90 Per Hour $7.20 Per Day $216 Per Month |
$0.80 Per Hour $6.40 Per Day $192 Per Month |
$0.72 Per Hour $5.76 Per Day $172.80 Per Month |
$0.60 Per Hour $4.80 Per Day $144 Per Month |
$0.51 Per Hour $4.11 Per Day $123.43 Per Month |
| 4.5 ton (54,000 BTU) | $1.01 Per Hour $8.10 Per Day $243 Per Month |
$0.90 Per Hour $7.20 Per Day $216 Per Month |
$0.81 Per Hour $6.48 Per Day $194.40 Per Month |
$0.68 Per Hour $5.40 Per Day $162 Per Month |
$0.58 Per Hour $4.64 Per Day $138.86 Per Month |
| 5 ton (60,000 BTU) | $1.13 Per Hour $9 Per Day $270 Per Month |
$1.00 Per Hour $8 Per Day $240 Per Month |
$0.90 Per Hour $7.20 Per Day $216 Per Month |
$0.75 Per Hour $6 Per Day $180 Per Month |
$0.64 Per Hour $5.14 Per Day $154.29 Per Month |
| 6 ton (72,000 BTU) | $1.35 Per Hour $10.80 Per Day $324 Per Month |
$1.20 Per Hour $9.60 Per Day $288 Per Month |
$1.08 Per Hour $8.64 Per Day $259.20 Per Month |
$0.90 Per Hour $7.20 Per Day $216 Per Month |
$0.77 Per Hour $6.17 Per Day $185.14 Per Month |
Here are the ranges for 1-6 ton 8-14 HSPF heat pump heating costs:
- $0.13 to $1.35 per hour.
- $1.03 to $10.80 per day.
- $30.86 to $324 per month.
Now that we have all the numbers, we hope that you have a better insight into how much electricity heat pumps use (for both cooling and heating mode) and how much it costs to run them.
If you haven’t found the answer in the article above, you can give it as a comment below, and we’ll try to help you out with the calculation.
Thanks for your help.
I’m getting solar panels that will cover some 120% of my current consumption 16K kw/h year. This means 19000 kw/h. I’m looking into a 4 ton 17 seer heat pump around 10 hspf as a way of switching from my current oil heat system. I’m having a hard time figuring out how much extra electricity this heat pump will consume and if it would be mostly covered by the solar panel production. I live in Connecticut so I expect around 2300 hours of heating need per year. Can you help? Thanks so much.
Hello Joseph, good idea about solar panels. A 4 ton 17 SEER HVAC unit running at 100% output should have a running wattage of about 3,600W. Running such a unit for 8 hours per day at 100% output will burn through 28.8 kWh. Now, in most cases, you are running it much below 100%. Given how the SEER rating is calculated, it’s presumed that you run it, on average, at 58% output. That reduces running it for 8 hours to 16.13 kWh per day. Similar numbers are for heating (10 HSPF rating).
If you run it for 2300 hours per year, that would be 6.3 hours per average day, yielding 12.7 kWh per day. But you will probably use it in the winter much more than in the summer months. This is a way how you can theoretically try to evaluate is the solar panels will be sufficient. Hope it helps a bit in understanding how to do these calculations.
Hello LM- I have 5T Geothermal heat pump with a scroll compressor.
The compressor mfr. says it has a 10.4 EER (approx. 12 SEER).
Compressor RLA 26.0, LRA 118.0, Total FLA 32.8. Min amps 39.3, Max Fuse
Breaker 65. My question: How many starting watts of power or amps do I need? I’m trying to figure out what size(KW) whole house generator are needed. Thank-you
Hello Mel, you can consult our article about what size whole house generator you need here. Basically, heat pumps can have quite high starting watts; about 2x or 3x of running wattage. A 5-ton unit should have about 5,000W running wattage. That means you need anywhere from 10,000W to 15,000W start wattage.
The starting wattage should be labeled on the unit itself. Alternatively, you can also check the specs sheet. Hope this helps a bit.
Just a note on start up surge. I have monitored my new dual inverter heatpumps and there is no more surge. The inverters ramp up slowly over approximately 1 to 2 minutes when starting. This would make it much easier to start with a generator.
Hi Paul, yes, no surge is a literal blessing. You need a lot smaller generator to run a heat pump if the heat pump doesn’t have a start up wattage much higher than the running wattage.
How did you derive the 58% on average. Thanks—
Hello Henry, that’s quite an interesting question. Namely, we use a formula for SEER rating to derive that number. SEER rating tries to capture the real-life outputs of AC units. It presumes that the unit will run 1% of the time at 100% output, 42% of the time at 75% output, 45% at 50% output, and 12% at 25% output. If you calculate the weighted average of the average output, you get that a unit will run at the equivalent of 58% output. Hope this makes sense.
Got it. Thanks. This is very helpful in calculating hourly energy and then cost.
I am having a tough time considering a heat pump more efficient and less costly to use. My Daikin 16 seer says an avg of 4.75 kw a day and yet I am finding pellet stoves of 1 kw or less per day for my 1200 sq foot home.
Hi Richarda, well, to adequately compare the two, you have to put all the numbers on a sheet of paper and calculate from that. In many cases, heat pumps are a better solution since they cost less to run and offer air conditioning in the summer as well.
I am trying to determine if my electrical feed can handle a heat pump. I have calculated the wattage of the heat pump by using your formula from the SEER rating and have determined that the heat pump will run at 2,907 watts. Do I have to add anything to this to account for startup wattage when calculating the total load for my supply feed or do I just use the running wattage as the amount. I have calculated my spare capacity wattage as 4,600 watts. Do I simply subtract 2,907 from 4,600 (~1,700 remaining spare capacity) to confirm that I have the capacity to install the heat pump without worry of overloading the circuit? Or do I have to calculate the startup wattage (3 times as per you article above or ~8,700 watts) and subtract this amount?
Hi Bernie, thanks for all these numbers. Now, SEER is calculated with the presumption that the heat pump runs at 58% of the max. wattage. The start-up wattage is always hard to find; the 3 times the running wattage is the rule of thumb for air conditioning. You do have to add quite a lot on top on 2,907 watts for start up wattage.
Namely, with 4600W capacity, you will definitely be able to run the heat pump. However, starting is the key question (AC and heat pumps are notoriously hungry as far as start up watts are concerned). I’m afraid you will need close to 8,700 watts for starting the unit. Hope this clears things a bit.
Hello, I am trying to compute total kWH per year for the ASHP for heat only. Two units 3 ton and 4 ton at 19 SEER. Currently use 925 gallons of oil for heat only, boiler at 85% (I have subtracted 125 gallons from oil use for hot water). The system would have supplement from oil fired boiler, coil in air handler.
How much would I save on AC? Current AC units are 12 SEER and ASHP at 19 SEER, assume 3000kWH for AC only from June through Sept (most in July and August(?
My new solar panel system will produce 15,500 kWH annually. My current baseline electric consumption with current 12 SEER AC units is 11,500. I am trying to see whether the ASHP will be within 15,500 total use, taking into account lower summer AC use perhaps lowering baseline by 1,000kWh, leaving about 5,000kWh for heat ASHP electric.
Thank you.
Hi Jack, sorry for the late reply. With the air-source heat pump heating, you have to use the HSPF rating. The SEER rating is used for cooling efficiency, while the HSPF rating is used for heating efficiency. If you can provide us with the HSPF ratings for all these units, we can do some calculations on as far as heating is concerned.
Alright, we can do some calculations for the AC unit for cooling. The current baseline consumption with the 12 SEER AC is 11,500 kWh. If you upgrade to 19 SEER AC (same tonnage), you are looking at 12/19 = 0.63; that’s a 37% reduction. Effectively, you will now only have to use 7,245 kWh to produce the same cooling output; that’s a 4,255 kWh per year savings just by switching from 12 SEER to 19 SEER AC unit.
Hope this helps a bit with your calculations.
if I use on average 1,200 gallons of heating oil per year to heat my home and provide hot water, how much electricity will I use to generate the same number of BTU (168M) with a geothermal/ground source? I live here in New England. thanks
Hi Rick, according to Wikipedia, the COP of ground source heat pump ranges between 3 and 6 (300% to 600% efficiency). 1 kWh of electricity at 100% efficiency is equal to 3,412 BTU. With a geothermal heat pump, we are talking 300% to 600% efficiency, or 10,236 BTU to 20,472 BTU per kWh, respectively.
Alright, you need to generate 168M or 168,000,000 BTU. If we divide this amount of BTU by 10,236 BTU per kWh and 20,472 BTU per kWh, we get: 8,206 to 16414 kWh. This is how much electricity you will use for the same BTUs as burning 1,200 gallons of heating oil.
Here the cost-wise calculation: Let’s say that electricity in New England costs about $0.20/kWh. So we are talking anywhere from $1641.20 to $3282.40 per year. How much do you par for 1,200 gallons of heating oil? If we take an average of $5 per gallon, that’s $6,000 per year for heating oil. So, you are looking for at least about 50% in cost. Hope these calculations help.
Great article, I am looking at going solar and have just installed a heat pump but have no time running it. I need to estimate my addition KWH needs to size my solar appropriately. Its a 18.5seer, 11eer 11hspf 5 ton heap pump. Can you help me estimate my additional needs. I am located near 95926 zip code and use the heat about 4 months a year.
Hi Dustin, estimating the additional kWh usage is the smart move. Alright, for most of these estimates, we use the presumption that a heat pump is being used for 3 months 8 hours per day for heating, and the same for cooling (DOE uses that for EnergyGuide labels as well). 3 months 8 hours per day = 720 hours. We use heat pumps more than 1000 hours per season, but, hey, let’s start with the 720h per season since DOE uses this metric.
Heating: 5 ton heat pump delivers 60,000 BTU of heating output. At 11 HSPF, the average cooling wattage is 60,000 BTU / 11 HSPF = 5455 watts. That’s 5.455 kWh per hour. Multiply that by 720 hours, and you get 3928 kWh/year for heating. If you intent to use longer, just add the heating hours. For example, 4 months 8 hour per day cooling would yield 5224 kWh.
Cooling: 5 ton heat pump delivers 60,000 BTU of cooling output. At 18.5 SEER, the average cooling wattage is 60,000 BTU / 18.5 SEER = 3243 watts. That’s 3.423 kWh per hour. Multiply that by 720 hours, and you get 2335 kWh/year for cooling. If you intent to use longer, just add the hours. For example, 4 months 8 hour per day cooling would yield 3106 kWh.
Hope these calculations make sense. You can follow the calculation and estimate the kWh usage for solar based on how much time you intent to use the heap pump. Btw, cool setup, the solar power heat pump, very eco-friendly.
Thanks for all this great information and helpful answers! Is there a way to calculate the EER from the HSPF rating?
Hi Jack, EER rating is used for cooling efficiency while HSPF rating is used for heating efficiency. So, the HSPF to EER conversion is not possible because this would be comparing apples to oranges.
Is there a way to calculate likely electricity usage from the HSPF?
Hi Jack, absolutely. That is a good idea; we should include it in the article. Alright, here is how this calculation goes: HSPF is a ratio between heating BTU output and electric input (wattage). It is calculated like this: HSPF = BTU / Max. Wattage. We can express max. wattage (when heat pump is running at 100% heating output) like this: Max. Wattage = BTU / HSPF.
Example: Let’s say we have a 24,000 BTU 10 HSPF heat pump. How many watts does it use? When running at 100% output, it uses 24,000 BTU / 10 = 2,400 Watts. That’s 2.4 kWh per hour.
Obviously, we don’t run the heat pump heating mode at 100% heating output all the time. Let’s say we run it at an average 58% output (similar to cooling and SEER rating). That would bring the heat pump heating electricity usage from our 24,000 BTU 10 HSPF example down to 1392 running watts or 1.392 kWh usage per hour.
Does this help? If you have a heat pump, share the BTUs and HSPF rating, and we can calculate the likely electricity usage of your heat pump.
Thanks–very helpful!
Very helpful calculator! Thank you. Working on figuring out if I can borrow the money to install heat pump and end up spending the same amount of money on heat as I do now with a kerosene burning furnace. IF so I can do itt.
Hi Annamarie, thank you. Yes, that’s quite a hard calculation; you have to include the interest rates, your location for heat pump COP vs. outdoor temperature, and so on. Fun calculations, hope you get a good estimate to make a financially viable decision here.
This is some great info, but we’re still a bit stuck & hoping you can help.
1st, would these figures change much with an inverted air heat pump? We’re told they’re more efficient, but they run all the time as opposed to the 8 hours a day the heat calculator suggests. We’re considering a 3 ton 10 HSPF inverted.
2nd, we wanted to try comparing the calculator values with our actual usage now. For heating, we burn an average of 1000 gallons of fuel oil per season = 138,690,000 BTU, so we divided by 36,000 to calculate that a 3 ton heat pump would run for 3853 hours to achieve those BTU throughout the season. But that’s 2.68 x the calculator’s assumption of 8 hours a day over a 6 month season (1440 hours). Obviously, this made our calculations for seasonal kWh usage for heat many times higher than when we used the calculator above. Can you tell us what we’re getting wrong with this conversion?
Hi Kathy, alright, let’s look at both of these questions:
1st) Inverter air heat pumps are more efficient, yes. However, the efficiency of the whole heat pump is expressed as the HSPF rating (heating) and the SEER rating (cooling). The efficiency that inverter adds to the heat pump is already accounted for in the HSPF rating. At lower temperatures, the inverter does have a higher COP coefficient, on average. In most cases, the inverter pays off.
2nd) Alright, here it might be useful to use kWh per hour usage (kWh per month presumes 8 hours/day usage). A 3-ton 10 HSPF heat pump will produce 36,000 BTU of heating output and use 3.60 kWh per hour to do so. Now, if you want to match the furnace heating output, you have correctly calculated that the heat pump should run for 3853 hours. We know that each running hour uses 3.60 kWh, so that’s 3853h × 3.60kWh/h = 13,870.80 kWh seasonal usage.
If you have an electricity rate of let’s say $0.15/kWh, this comes to $2080.62 per season. Yeah, that’s quite a lot.
However, we need to compare this to heating oil. How much does 1000 gallons of heating oil cost? If heating oil is $4 per gallon, that would be $4,000 in total. Hm. I hope all of this answers your question. If not, just give us heads up here.
Hello,
Thank you for your website and responses to these posts, very interesting and informative, much appreciated. Jack C here posting again, this time providing the HSPF rating that you needed, and providing more context for my question.
I have solar panel system that will produce about 5,000 kWh annually above our current use. I am trying to determine how much electricity an ASHP will consume to heat annually, will it exceed that 5,000 kWh surplus solar production and if so by how much. The heating contractor projects about 14,000 kWh per year for heating by ASHP, and the solar panel representative says he would expect annual electric use for ASHP for heating to be about 4,000-6,000 kWh for a house our size. The solar panel representative adds that he has never seen a house use 14,000 kWh annually (unless it is a huge mansion, not a 2800 sq ft home) having reviewed dozens of electric invoices. I am trying to determine which is most accurate. The anecdotal evidence from the solar panel representative is compelling, but am uncomfortable relying upon that where it is so dramatically different than the heating contractor’s projection, and that’s what brought me to your website.
In this context, and having looked at this for several weeks, I see two methods to project annual ASHP electric use for heating. Please let me know if you agree with this understanding and your thoughts.
METHOD #1
I believe you use this method in some of your responses and it is the method used by the heating contractors. This approach is based upon converting known gallons of oil used per year for heating, in my case 1000 gallons per year for heating only. From that approach the projection is about 13,000 kWh per year—computed as follows:
• 1000 gallons of oil to heat 2800 square foot home in Boston, MA area converts to 138.69M BTU;
• multiply by 0.2930710702 to convert BTU to kWh of heat equals 40,646 kWh of heat;
• take 85% of 40,646 kWh of heat to account for 85% efficiency oil boiler equals 34,549 kWh of heat;
• divide 34,549 kWh of heat by 2.7 average COP to account for more efficient ASHP equals 12,796 kWh projected annual electric consumed by ASHP.
METHOD #2
The second approach which I believe you have also used in the alternative, is based upon assumptions as to hours of heating per day, per season, applying the 58% factor you describe, for the specific region. For this, in your response to my prior post you said you needed the HSPF rating. Here is that information and hopefully this helps:
• First Floor Unit: 3.5 ton ASHP at 10.0 HSPF, click here for data sheet (https://www.mitsubishitechinfo.ca/sites/default/files/SB_PVA-A42AA7_PUZ-HA42NKA1_202201.pdf)
• Second Floor Unit: 3 ton ASHP at 11.2 HSPF, click here for data sheet (https://www.mitsubishitechinfo.ca/sites/default/files/SB_PVA-A36AA7_PUZ-HA36NKA_202103.pdf)
Thank you again for your assistance, much appreciated!
Jack
Hi Jack, thank you for the extensive info here. Let’s break this down one by one:
Never seen a house that uses 14,000 kWh of electricity per year? Well, according to EIA, they have all the information and do statistical analysis, the average household electricity consumption in 2021 was 10,632 kWh. Louisiana households use the most; their average is 14,302 kWh annually (here is the EIA source). So, 14,000 kWh is just a bit over average, and it is quite likely that you will uses that. Here, the heating guy has the correct idea, and the solar guy has wrong numbers.
Alright, let’s check the #1 Method math. It’s pretty sound, good job on calculation. The result is 12,796 kWh. Let’s see if we get about the same result with the #2 Method.
Basically, you have a net 6.5 ton ASHP with a weighted-average HSPF rating of 10.55. That means that running both heat pumps will use 6.5 tons × 12,000 BTU / 10.55 = 7,393W. If you run both of them for 1000 hours per season, you use 7,393 kWh. Now, we usually run a heat pump more than 1000 hours per year; closer to 1,500 hours. If we calculate for 1,500 running hours, that’s 11,090 kWh per year. That’s quite close to what you have correctly calculated with the #1 Method.
In short, the heating guy is right. You’re looking at close to 14,000 kWh electricity expenditure. I really can’t figure out where that 4,000 kWh to 6,000 kWh annually estimate from the solar guy came from. Maybe because he or she was selling 5,000 kWh annual solar panels? It might be a selling technic like “Hey, this solar system will run both of your heat pumps for free”.
Hope this gives you a little bit more insight into the expected electricity consumption. This was quite fun to calculate, if you have any more questions, just say and we’ll solve it together.
Thanks very much! The solar panel person’s comment was about 14,000 kWh for heat only; not a household using that for all purposes. Also, I already was under contract with the solar company and then had that discussion, so it was not a selling point. Any way, again, thanks for your response and it makes total sense and I appreciate it.
Glad to be of help, Jack. 🙂
I have a natural gas forced air system with 3.5 ton and 5 ton 16 SEER condensers for downstairs and upstairs heating/cooling.
My natural gas consumption in therms this year (which was much colder than usual) for heating was about 145 therms per month for November thru March. is there any way to calculate how many kWh a reasonably efficient heat pump (say 12 HSPF) would consume for heating based on my natural gas therms usage? I’ve looked but not found any way to convert from therms to heat pump kWh for heating.
Note: I’ve accounted for the gas use of our gas range, water heater, and barbeque so those therm numbers are just for heating.
thanks
Don
Hi Don, alright, here is how we can estimate this. Let’s presume that your current natural gas heating has 80% efficiency. That means that you burn 145 therms per month, but only about 116 therms are fully converted to heat (that’s 80%). Since 1 therm = 100,000 BTU, you are currently using 11,600,000 BTU per month to heat your home.
Now, the heat pump should also add the same amount of heat to your house; 11,600,000 BTU per month. A 12 HSPF heat pump can turn 1 kWh of electricity into 12,000 BTU of heat. That’s when it runs at very good conditions. In cold weather, heat pump will be less efficient; we can take an about 8,000 BTU per 1 kWh as a monthly average.
How many kWh do we use if 1 kWh produces 8,000 BTU and we have to produce 11,600,000 BTU per month? Let’s calculate: 11,600,000 BTU / 8,000 BTU per kWh = 1,450 kWh. This is the rough estimate. You can also make a cost analysis here if you know how much one therms cost and how much kWh costs in your area. Hope this helps.
It is always appropriate when talking about the cost of a heat pump HVAC to include a discussion of the expected maintenance costs that run approximately $100 more per month than oil-burner or gas-burner maintenance.
Hi there, that’s a valuable addition. We usually omit it in our calculations since it doesn’t represent a significant addition to the overall cost (since upfront cost and running costs are in the $1000s), but it is good to keep in mind that the maintenance costs are still there.
Two ton. 24,000. Seer 20. EER 12.5, HSPF4: 12 HSPF5: 10.
Halifax, Nova Scotia. Coldish winter, short cooling season (two months). Four bedroom house, not that big.
I like all the charts above, but how do you account for the different weather patterns? Florida would be way different from New YOrk.
Hi Susan, it is almost impossible to account for all the factors. The different weather patterns would be one, setting the thermostat to 68F, 70F, 72F would be another, insulation R-values would be the third, and so on.
The best the DOE came up with is these SEER and HSPF ratings that presume you run the HVAC unit at an average of 58% output. In reality, you would run it, let’s say, at 45% in Florida (warmer weather) and 65% in New York (colder weather). It’s just very hard to put all these factors into a model without overcomplicating them. Hope this helps.
Need help with the calculations for heat-pump operating costs. Data follows:
1.5 ton unit (Lennox)
Outside heat pump unit: Lennox Merit series, model 14HPX-018-230-11
Air-handler blower: series ECB29
Inside air handler: Lennox Elite series, model CBX27UH-018-230-6-02
HSPF: 8.5
Seer: 15
Location = south of Savannah, GA (very hot and humid)
Power cost: 0.11$/kwh
Thanks in advance, –Hal
Hi Hal, alright, we can calculate this quite easily. Let’s first check the cooling costs and then the heating costs:
– Cooling. The running wattage for a 1.5 ton 15 SEER unit is 18,000/15 = 1,200W. That means you are using 1.2 kWh of electricity per hour. At a $0.11/kWh, that’s $0.132 per hour. That would be $1.06 per 8 hours, and if you run it for a month 8 hours per day, that’s $31.68 per month for cooling.
– Heating. The running wattage for 1.5 ton 8.5 SEER unit is 18,000/8.5 = 2,118W; that’s 2.118 kWh per hour. The cost will be $0.233 per hour, and $1.86 per 8 hours. If you run it for a month 8 hours per day, that’s $55.92 per month for heating.
Hope this helps. 🙂