Heat pump/ac using 4 kWh - how do I fix this?

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notmyhand
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Heat pump/ac using 4 kWh - how do I fix this?

Post by notmyhand » Sun Jun 28, 2020 4:20 pm

In an attempt to figure out why my electricity bills are so high, I went through and turned off breakers to determine how much electricity things were drawing. Turns out my heat pump is using 4 kilowatts an hour to cool my home. Which translates to about $10 a day! There has to be a better solution?

7% HSPF and 9 SEER heat pump, 4 years old. Keep the house at 72. Only have electricity available at the house.

How do I fix this large draw? Does this seem right? Is there another cooling/heating source available that I should upgrade too instead? I do not have natural gas available.

Thanks for insight!

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whodidntante
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by whodidntante » Sun Jun 28, 2020 4:30 pm

That's reasonable. Assuming proper function and unless you have a variable speed compressor or blower, you can't do anything to reduce energy consumption while it's running. But you can improve insulation, reduce air gaps, keep sunlight out, and other improvements so it does not run as often or as long. This will reduce your total energy consumption, which is what you pay for.

Chuck107
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Chuck107 » Sun Jun 28, 2020 4:33 pm

Are you sure it's only 9 seer and 4 yrs old? I'm thinking the min seer rating allowed 4 yrs ago is around 13 seer.

EDIT
Here is a calc I just pulled up comparing costs of different seer's per KW per hr.

https://kobiecomplete.com/cool-tips/see ... alculator/

EDIT again.

2015
In the United States, the lowest allowable SEER for a split-system air-source heat pump is 13. For a system to be granted the coveted Energy Star level, the SEER has to exceed 14.5. For ideal cooling efficiency at an affordable price, look for SEER ratings of 16-18. The minimum HSPF on the market for a split-system air-source heat pump is 7.7, with Energy Star models exceeding HSPF 8.2.
https://www.brennanshvac.com/blog/what- ... -selection

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4nursebee
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by 4nursebee » Sun Jun 28, 2020 4:44 pm

Chuck107 wrote:
Sun Jun 28, 2020 4:33 pm
Are you sure it's only 9 seer and 4 yrs old? I'm thinking the min seer rating allowed 4 yrs ago is around 13 seer.

EDIT
Here is a calc I just pulled up comparing costs of different seer's per KW per hr.

https://kobiecomplete.com/cool-tips/see ... alculator/

EDIT again.

2015
In the United States, the lowest allowable SEER for a split-system air-source heat pump is 13. For a system to be granted the coveted Energy Star level, the SEER has to exceed 14.5. For ideal cooling efficiency at an affordable price, look for SEER ratings of 16-18. The minimum HSPF on the market for a split-system air-source heat pump is 7.7, with Energy Star models exceeding HSPF 8.2.
https://www.brennanshvac.com/blog/what- ... -selection
I agree, cant even buy 9 SEER.
4kwh sounds right though.
How are you finding usage?
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by jebmke » Sun Jun 28, 2020 4:49 pm

Chuck107 wrote:
Sun Jun 28, 2020 4:33 pm
Are you sure it's only 9 seer and 4 yrs old? I'm thinking the min seer rating allowed 4 yrs ago is around 13 seer.
I was surprised by this as well.

I'd also have the house checked for air leaks. Before investing in a new system, make sure that the house is well sealed and adequately insulated.

72 seems on the low side but that's just me. We normally run ~76-77 and cut back to 74-75 at night.
When you discover that you are riding a dead horse, the best strategy is to dismount.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by tibbitts » Sun Jun 28, 2020 4:52 pm

notmyhand wrote:
Sun Jun 28, 2020 4:20 pm
In an attempt to figure out why my electricity bills are so high, I went through and turned off breakers to determine how much electricity things were drawing. Turns out my heat pump is using 4 kilowatts an hour to cool my home. Which translates to about $10 a day! There has to be a better solution?

7% HSPF and 9 SEER heat pump, 4 years old. Keep the house at 72. Only have electricity available at the house.

How do I fix this large draw? Does this seem right? Is there another cooling/heating source available that I should upgrade too instead? I do not have natural gas available.

Thanks for insight!
I have no idea why you think you have 9SEER, maybe you meant 19, but it doesn't matter, it costs money to cool your home and $10/day is completely reasonable for many homes. There is likely nothing to "fix." You don't even say what size your unit is. You don't say what your electric rate is. You can't expect help in identifying a better solution without providing more information.

Teague
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Teague » Sun Jun 28, 2020 4:56 pm

I'm guessing you mean it uses 4KW when running, not 4KW per hour. 4KW per hour isn't really a way to measure this. Though it could certainly use 4KW hours per hour. Which brings us right back to 4KW when running.

Anyway, that sounds not unreasonable. I'd guess probably a 3 or maybe 4 ton unit?

On the 9 SEER I'd guess it's a 9 EER, not SEER? That's more in line with the unit's age. SEER and EER, they're not the same.
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iamlucky13
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by iamlucky13 » Sun Jun 28, 2020 5:00 pm

Are you assuming it is running continuously, or did you base that $10 per day on actual number of hours per day? While a heat pump should not be oversized, if it is running continously, something is wrong, and you would likely be experiencing almost daily instances when the AC can not keep the temperature at your set point.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by adamthesmythe » Sun Jun 28, 2020 5:01 pm

Everywhere I have lived AC was a substantial cost during the summer, a few hundred per month. How many "a few" is will depend on your electric rates, outside and inside temperatures.

Not clear what you have measured, the energy is in units of kW*hr and the power is kW. You pay for the energy, the energy is the kW consumed while running multiplied by the average fraction of an hour that the unit runs.

Insulation and indoor setpoint are the things you can address easily. Probably any recent unit has at least decent efficiency, good enough that pre-failure replacement would make no sense.

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notmyhand
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by notmyhand » Sun Jun 28, 2020 5:19 pm

Thanks so much everyone! You can see how much I know about the topic.

We used 2131 kWh last month which everyone says is super high.
So I spent two hours and turned all breakers off except for the essentials and after one hour, the meter read 2kW than the hour before. Then I turned the AC breaker back on and it went up 6.

My meter says kWh which is why I keep saying kWh.

Sounds like this is normal for the AC then. So I need to figure out what else is wrong.

As for the SEER, I'm just going by the energy audit we had last year and it says 9 SEER oddly enough. We walked through the house for the first time as they were installing it. It's Luxaire model number THJD60S41SA. I have no idea where to check what the SEER is or what tonnage it is.

Suggestions from the energy audit we had:
Attic insulation - go from R value 20 to R Value 38 - 4.2% energy savings
Wall/Ceiling insulation - none needed
Reduce air leakage by 25% (currently at 0.091 sq in/sq ft) - 3.6% energy savings
Replace windows from double pane to double pane with argon- 1.9% energy savings
Replace two doors from u-value of 0.46 to 0.21 - 0.9% savings
Replace heatpump from 7% HSPF and 9 SEER to 9% HSPF and 15 SEER - 21.5% savings
Replace water heater from 88% EF to 98% EF - 4.9% savings
No suggestions on lighting and appliances

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whodidntante
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by whodidntante » Sun Jun 28, 2020 5:20 pm

Here is a chart of energy consumption versus temperature for the whodidntante estate on a recent kinda hot day. So what you're seeing is reasonable. The estate was billed $5.27 for electricity that day.
Image

tibbitts
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by tibbitts » Sun Jun 28, 2020 5:26 pm

notmyhand wrote:
Sun Jun 28, 2020 5:19 pm
Thanks so much everyone! You can see how much I know about the topic.

We used 2131 kWh last month which everyone says is super high.
So I spent two hours and turned all breakers off except for the essentials and after one hour, the meter read 2kW than the hour before. Then I turned the AC breaker back on and it went up 6.

My meter says kWh which is why I keep saying kWh.

Sounds like this is normal for the AC then. So I need to figure out what else is wrong.

As for the SEER, I'm just going by the energy audit we had last year and it says 9 SEER oddly enough. We walked through the house for the first time as they were installing it. It's Luxaire model number THJD60S41SA. I have no idea where to check what the SEER is or what tonnage it is.

Suggestions from the energy audit we had:
Attic insulation - go from R value 20 to R Value 38 - 4.2% energy savings
Wall/Ceiling insulation - none needed
Reduce air leakage by 25% (currently at 0.091 sq in/sq ft) - 3.6% energy savings
Replace windows from double pane to double pane with argon- 1.9% energy savings
Replace two doors from u-value of 0.46 to 0.21 - 0.9% savings
Replace heatpump from 7% HSPF and 9 SEER to 9% HSPF and 15 SEER - 21.5% savings
Replace water heater from 88% EF to 98% EF - 4.9% savings
No suggestions on lighting and appliances
Nobody believes you have a 4yr old 9 SEER no matter what your audit says.

quantAndHold
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by quantAndHold » Sun Jun 28, 2020 5:36 pm

Adjust the thermostat. It doesn’t need to be at 72. 76-78 is probably adequate.

Close off rooms that aren’t being used. Most of us in big homes have a couple of rooms we really don’t need to heat or air condition. Look at your house from the perspective of what you would do if you didn’t have AC. Close shades on the sunny side of the house, put up awnings, plant trees, etc.

If your AC unit isn’t in the shade, put a shade up over it. It will run more efficiently if it’s not being blasted by the hot sun all day.

Take action on some of the home energy audit action items. In particular, the insulation and air sealing are probably cheap fixes that will pay for themselves within the year.

If you’re planning on staying in the house for awhile, get a more efficient heat pump. Also consider solar.
Yes, I’m really that pedantic.

Chuck107
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Chuck107 » Sun Jun 28, 2020 5:37 pm

Luxaire model number THJD60S41SA aprox 13 seer

http://www.upgnet.com/PdfFileRedirect/8 ... C-1112.PDF

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by adamthesmythe » Sun Jun 28, 2020 5:39 pm

notmyhand wrote:
Sun Jun 28, 2020 5:19 pm
My meter says kWh which is why I keep saying kWh.
Us engineering types are very particular about units.

kW AN hr would be interpreted as kW/hr which makes no sense. kWh = kW*hr which does make sense. IF what your meter is doing is measuring the instantaneous power consumed and converting it into an energy assuming everything runs continuously.

However- your meter probably doesn't perform averaging and since the AC cycles on and off your energy use is less than the peak kWh reading.

In any case- what your audit shows is that most of the things have pretty marginal benefit. EXCEPT, maybe, for the efficiency of the AC, IF the numbers quoted are correct.

Even so- replacing the unit- IF it does have poor efficiency- will cost thousands of dollars so you can see the payoff time on that investment would be several years.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Teague » Sun Jun 28, 2020 5:40 pm

Chuck107 wrote:
Sun Jun 28, 2020 5:37 pm
Luxaire model number THJD60S41SA aprox 13 seer

http://www.upgnet.com/PdfFileRedirect/8 ... C-1112.PDF
Hmm, was that audit done by the utility company, or a contractor that sells HVAC units? If utility company they messed up. If a contractor, well then, hmm.
Semper Augustus

Topic Author
notmyhand
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by notmyhand » Sun Jun 28, 2020 5:43 pm

Teague wrote:
Sun Jun 28, 2020 5:40 pm
Chuck107 wrote:
Sun Jun 28, 2020 5:37 pm
Luxaire model number THJD60S41SA aprox 13 seer

http://www.upgnet.com/PdfFileRedirect/8 ... C-1112.PDF
Hmm, was that audit done by the utility company, or a contractor that sells HVAC units? If utility company they messed up. If a contractor, well then, hmm.
3rd party service contracted by the utility company. Good to know that it's 13 SEER!

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by jebmke » Sun Jun 28, 2020 5:43 pm

Also, when was the last time the system was checked? A normal check will examine the air handling unit and compressor to make sure they are functioning properly and that the discharge air temperature is adequate for the season.
When you discover that you are riding a dead horse, the best strategy is to dismount.

Chuck107
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Chuck107 » Sun Jun 28, 2020 5:44 pm

quantAndHold wrote:
Sun Jun 28, 2020 5:36 pm
Adjust the thermostat. It doesn’t need to be at 72. 76-78 is probably adequate.

Close off rooms that aren’t being used. Most of us in big homes have a couple of rooms we really don’t need to heat or air condition. Look at your house from the perspective of what you would do if you didn’t have AC. Close shades on the sunny side of the house, put up awnings, plant trees, etc.

If your AC unit isn’t in the shade, put a shade up over it. It will run more efficiently if it’s not being blasted by the hot sun all day.

Take action on some of the home energy audit action items. In particular, the insulation and air sealing are probably cheap fixes that will pay for themselves within the year.

If you’re planning on staying in the house for awhile, get a more efficient heat pump. Also consider solar.
I agree with all except for shading the outside a/c unit, as long as you don't block air flow it wont hurt but it won't help either.
The amount of air moving thru the unit will exhaust the usable cooler shaded air around the unit too quickly to matter.
I can't recall where I read a study on it, but it said it does not matter due to the mentioned reason.

Teague
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Teague » Sun Jun 28, 2020 5:46 pm

Chuck107 wrote:
Sun Jun 28, 2020 5:44 pm
quantAndHold wrote:
Sun Jun 28, 2020 5:36 pm
Adjust the thermostat. It doesn’t need to be at 72. 76-78 is probably adequate.

Close off rooms that aren’t being used. Most of us in big homes have a couple of rooms we really don’t need to heat or air condition. Look at your house from the perspective of what you would do if you didn’t have AC. Close shades on the sunny side of the house, put up awnings, plant trees, etc.

If your AC unit isn’t in the shade, put a shade up over it. It will run more efficiently if it’s not being blasted by the hot sun all day.

Take action on some of the home energy audit action items. In particular, the insulation and air sealing are probably cheap fixes that will pay for themselves within the year.

If you’re planning on staying in the house for awhile, get a more efficient heat pump. Also consider solar.
I agree with all except for shading the outside a/c unit, as long as you don't block air flow it wont hurt but it won't help either.
The amount of air moving thru the unit will exhaust the usable cooler shaded air around the unit too quickly to matter.
I can't recall where I read a study on it, but it said it does not matter due to the mentioned reason.
I read the same study, or at least a summary of something similar. Not immediately intuitive but made sense to me after a bit of intracranial processing. Basically the amount of solar energy per unit time absorbed by the condenser fins through insolation is much much less than the amount of energy radiated from the condenser fins and carried away by the blown air from the fan, to the point that the insolation doesn't matter.

Or something like that.
Last edited by Teague on Sun Jun 28, 2020 5:55 pm, edited 4 times in total.
Semper Augustus

Glenn
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Glenn » Sun Jun 28, 2020 5:50 pm

Three suggestions:

1. Turn the thermostat up. We keep ours at 78 (but, then, I live in Arizona and am acclimated to heat).

2. Consider installing ceiling fans - they can make a big difference.

3. Add insulation.

Chuck107
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Chuck107 » Sun Jun 28, 2020 5:52 pm

notmyhand wrote:
Sun Jun 28, 2020 5:19 pm


We used 2131 kWh last month which everyone says is super high.
Nothing is apples to apples, Here in Tn, 1600 sq ft home 41 yrs old sounds like the same loose construction home (leaks, insulation).
.10 per kwh 27 seer geothermal HP, Heat pump for Hot water. Me the Wife and a Parakeet.
Last month $138.14 for elec. 8 bucks is for a meter charge I think, something like that.
1300 kw used.
We keep the a/c at 72 during the day and 66 at night.

Teague
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Teague » Sun Jun 28, 2020 5:58 pm

Chuck107 wrote:
Sun Jun 28, 2020 5:52 pm
notmyhand wrote:
Sun Jun 28, 2020 5:19 pm


We used 2131 kWh last month which everyone says is super high.
Nothing is apples to apples, Here in Tn, 1600 sq ft home 41 yrs old sounds like the same loose construction home (leaks, insulation).
.10 per kwh 27 seer geothermal HP, Heat pump for Hot water. Me the Wife and a Parakeet.
Last month $138.14 for elec. 8 bucks is for a meter charge I think, something like that.
1300 kw used.
We keep the a/c at 72 during the day and 66 at night.
Another variable is where the thermostat is located. Ours is in the middle of hall deep in the bowels of the house. We set it at 73 to keep the most used living areas at 76-77F.
Semper Augustus

Chuck107
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Chuck107 » Sun Jun 28, 2020 6:02 pm

Teague wrote:
Sun Jun 28, 2020 5:58 pm
Chuck107 wrote:
Sun Jun 28, 2020 5:52 pm
notmyhand wrote:
Sun Jun 28, 2020 5:19 pm


We used 2131 kWh last month which everyone says is super high.
Nothing is apples to apples, Here in Tn, 1600 sq ft home 41 yrs old sounds like the same loose construction home (leaks, insulation).
.10 per kwh 27 seer geothermal HP, Heat pump for Hot water. Me the Wife and a Parakeet.
Last month $138.14 for elec. 8 bucks is for a meter charge I think, something like that.
1300 kw used.
We keep the a/c at 72 during the day and 66 at night.
Another variable is where the thermostat is located. Ours is in the middle of hall deep in the bowels of the house. We set it at 73 to keep the most used living areas at 76-77F.
True our t-stat is centrally located as well, another thing is the OP does not say what state he's in, could make a huge difference either way.

Edit...
A bit of sleuthing on my part finds the OP in Pa. (Previous postings) nothing sinister :happy

Chuck107
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Chuck107 » Sun Jun 28, 2020 6:21 pm

https://www.climatemaster.com/residenti ... r/sc01.php

Using the above calc I compared my system to the OP's 13 seer unit in my home.
My Home with geothermal and hw heat pump should be 36% savings over a 13 seer with electric HW.

Op's electric usage last month 2131
My usage 1300

2131 - 36% = 1363

Looks like the OP's current unit is functioning properly based on my off handed comparison.

Edit...
OOPS my mistake I said my unit was a 27 "SEER" It's EER not SEER. above calc is the same however.
Last edited by Chuck107 on Sun Jun 28, 2020 6:29 pm, edited 1 time in total.

Housedoc
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Housedoc » Sun Jun 28, 2020 6:28 pm

72 is too comfortable for a Boglehead. Crank it up to 78 during the day or higher if everyone leaves the house during the day. 76 in evening and 75 to sleep. Ceiling fàns or room pedestal fan that oscillates is great.

Starfish
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Starfish » Sun Jun 28, 2020 6:31 pm

notmyhand wrote:
Sun Jun 28, 2020 4:20 pm
In an attempt to figure out why my electricity bills are so high, I went through and turned off breakers to determine how much electricity things were drawing. Turns out my heat pump is using 4 kilowatts an hour to cool my home. Which translates to about $10 a day! There has to be a better solution?

7% HSPF and 9 SEER heat pump, 4 years old. Keep the house at 72. Only have electricity available at the house.

How do I fix this large draw? Does this seem right? Is there another cooling/heating source available that I should upgrade too instead? I do not have natural gas available.

Thanks for insight!

There are better ways.
1. Set the temperature higher (72F is too low for summer, probably even unhealthy, I would go with at least 75).
2. Have better insulation, better widows (triple).
3. Make sure you have a well ventilated attic.
4. Install reflective foil on the south/west windows.
5. Use fan instead.

Starfish
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Starfish » Sun Jun 28, 2020 6:37 pm

Housedoc wrote:
Sun Jun 28, 2020 6:28 pm
72 is too comfortable for a Boglehead. Crank it up to 78 during the day or higher if everyone leaves the house during the day. 76 in evening and 75 to sleep. Ceiling fàns or room pedestal fan that oscillates is great.
I would even call it comfortable. The temperature shock between outside and inside and the constant air blow is very annoying. If you are adapted for outdoor temperatures, 72 is too cold for tshirt and shorts. If you can live in shorts at 72 you will have a serious problem for outside activities.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by suemarkp » Sun Jun 28, 2020 6:45 pm

Another sanity check is to look at the AC unit nameplate. There should be a number for "MCA". The current it draws while running will be a bit less than this. If the MCA value is 20 amps, and since most central AC/heat pumps are 240 Volt, the running watts are 240 * 20. That is 4800 watts. If it runs continuously for an hour, that will be 4.8 KW-Hr. Your AC unit may run most of the day on hot days. But it should definitely cycle off at night. So if it had a total of 10 hours of runtime in a full day, 4.8 KW-hr would be 48 KW-Hr per day. If power costs 10 cents per kw-hr, this would be $4.80 per day.
Mark | Kent, WA

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by adamthesmythe » Sun Jun 28, 2020 7:02 pm

Housedoc wrote:
Sun Jun 28, 2020 6:28 pm
72 is too comfortable for a Boglehead. Crank it up to 78 during the day or higher if everyone leaves the house during the day. 76 in evening and 75 to sleep. Ceiling fàns or room pedestal fan that oscillates is great.
Time for another calculation to show how much more money you have at retirement by just setting the thermostat one degree higher. Or the immense amount if you forego air conditioning entirely.

illumination
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by illumination » Sun Jun 28, 2020 7:03 pm

I have a newish AC unit and it was closer to 5kwh when I measured it on my smart meter on like a 3 ton unit, so 4kwh sounds normal to me.

You might though want to check the refrigerant level, if the unit takes too long to cool the place down, it can just run all day trying to hit the set temperature. A quick and dirty test would be taking the temp where in the home the intake is and what the output temperature at the vent is, there should be around a 20 degree difference. So if it's 75 going in, around 55 should be coming out. If it's only like 10 degrees difference, you may have a low charge or another issue going on.

72 though is pretty cold, you can get used to a higher temperature, so much of being comfortable with climate control is just psychological and what you're used to. So just creep it up a degree or two a day and see how you do. I would be extremely uncomfortable with that cold a temp in my house.
Ceiling fans are a game changer, at a low setting you don't know they are on and really make the place feel cooler.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Ping Pong » Sun Jun 28, 2020 7:19 pm

OP said they turned the A/C off for 2 hours while they were testing the load of other parts of the house. They then turned the A/C on, so it had to spend a lot of energy bringing the temperature back.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by whodidntante » Sun Jun 28, 2020 7:24 pm

Ping Pong wrote:
Sun Jun 28, 2020 7:19 pm
OP said they turned the A/C off for 2 hours while they were testing the load of other parts of the house. They then turned the A/C on, so it had to spend a lot of energy bringing the temperature back.
Yeah, but a cheap air conditioning unit is either on or off. It doesn't go to warp 9 just because the house is warm.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by tomd37 » Sun Jun 28, 2020 7:30 pm

Notmyhand

Sounds like you might have a "SMART" meter. If you are looking at and reading the numbers directly off the the face of the electric meter I suspect you are getting the one-time high reading for usage upon start up. Google the subject of reading electric meters (for the type of meter you have) and I bet you are reading what the highest one time demand was at a given time, and that would be right when the a/c starts up. I looked into this myself recently and I saw a one-time peak demand reading of 7.167 kW on my SMART meter.

My highest monthly usage last year (2019) here in middle Tennessee when we had 99 days of 90 degrees or over last summer was 1103 kWh for July 2019 and the total electric bill for that month was $154.08 for the 1103 kWh usage.
Last edited by tomd37 on Mon Jun 29, 2020 3:22 pm, edited 2 times in total.
Tom D.

WS1
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by WS1 » Sun Jun 28, 2020 7:41 pm

Time for the weekly reminder that comfort is not just about temperature; it’s about humidity, air movement, evenness of temp, etc

http://www.natethehousewhisperer.com/

teCh0010
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by teCh0010 » Sun Jun 28, 2020 10:14 pm

tomd37 wrote:
Sun Jun 28, 2020 7:30 pm
Notmyhand

Sounds like you might have a "SMART" meter. If you are looking at and reading the numbers directly off the the face of the electric meter I suspect you are getting the one-time high reading for usage upon start up. Google the subject of reading electric meters (for the type of meter you have) and I bet you are reading what the highest one time demand was at a given time, and that would be right when the a/c starts up. I looked into this myself recently and I saw a one-time high demand of 7.167 kWh on my smart meter.

My highest monthly usage last year (2019) here in middle Tennessee when we had 99 days of 90 degrees or over last summer was 1103 kWh for July 2019 and the total electric bill for that month was $154.08 for the 1103 kWh usage.
That really depends on what you have consuming electricity. I have a 5 ton AC, a 4 ton ac, a pool pump, and a heat pump pool heater. In the humid and hot deep south, my highest usage was 4100 KWH. That's almost all AC and effectively zero pool heat.

There are a couple of weeks in may where it can be bad. Hot enough during the day to keep the AC running, and cool enough at night to keep the pool heat pump running.

ralph124cf
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by ralph124cf » Sun Jun 28, 2020 10:44 pm

Check to see if your cooling fins are dirty. They can be hosed off with a garden hose.

Ralph

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Starfish » Sun Jun 28, 2020 11:19 pm

teCh0010 wrote:
Sun Jun 28, 2020 10:14 pm
tomd37 wrote:
Sun Jun 28, 2020 7:30 pm
Notmyhand

Sounds like you might have a "SMART" meter. If you are looking at and reading the numbers directly off the the face of the electric meter I suspect you are getting the one-time high reading for usage upon start up. Google the subject of reading electric meters (for the type of meter you have) and I bet you are reading what the highest one time demand was at a given time, and that would be right when the a/c starts up. I looked into this myself recently and I saw a one-time high demand of 7.167 kWh on my smart meter.

My highest monthly usage last year (2019) here in middle Tennessee when we had 99 days of 90 degrees or over last summer was 1103 kWh for July 2019 and the total electric bill for that month was $154.08 for the 1103 kWh usage.
That really depends on what you have consuming electricity. I have a 5 ton AC, a 4 ton ac, a pool pump, and a heat pump pool heater. In the humid and hot deep south, my highest usage was 4100 KWH. That's almost all AC and effectively zero pool heat.

There are a couple of weeks in may where it can be bad. Hot enough during the day to keep the AC running, and cool enough at night to keep the pool heat pump running.
That's about my yearly consumption. No pool or AC though. It was pretty chilly today.

FishTaco
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by FishTaco » Sun Jun 28, 2020 11:39 pm

If you're in a deregulated power market, you should see if the teaser rate you received when you signed up for power has expired. 2131 kWh where I am in Texas will run a little over 200/month. I have a few bills like that every summer. If the bill seems higher than last year, you should also account for people being at the house more bc of covid and using more power.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by bikesandbeers » Mon Jun 29, 2020 12:01 am

My 16 seer, 4 year old system pulls around 5kw when running at full tilt.

I am slighty jealous how low some of your price kwh is, however i live in coastal area an only need to use it for 2 months of the year.

Solar is getting really cheap though. Even if your utility doesn't offer net metering, you could see a decent payback you are using thousands of kwh per month, and get a system to offset half of that.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by BrandonBogle » Mon Jun 29, 2020 12:02 am

adamthesmythe wrote:
Sun Jun 28, 2020 5:01 pm
Everywhere I have lived AC was a substantial cost during the summer, a few hundred per month. How many "a few" is will depend on your electric rates, outside and inside temperatures.
:shock:

I keep my ac between 68 and 76, depending on time of day. It’s only a 1.5 ton unit (I think) servicing 2000+ sq ft across two floors. The house is all-electric. Electric stove, electric water heater, electric clothes dryer. I drive an electric car. My monthly average electric bill is around $140-$180/mo depending on how much I drive, and higher in the winter with Christmas lights and auxiliary heat on the really cold days.

I just looked. May 2020 was 42 kWh per day for 1,213 kWh for the month and $102.26 of energy use charge before the other fees and taxes added on. May 2019 was 40 kWh per day for 1,231 kWh for the month (29 days in 2020 cycle vs. 31 days in 2019 cycle). July 2019 was 1,321 kWh/mo and 46 kWh/day, 29 day cycle and $4.63/day.

A few hundred would be a shock to me!

Image
Last edited by BrandonBogle on Mon Jun 29, 2020 12:29 am, edited 1 time in total.

RetiredAL
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by RetiredAL » Mon Jun 29, 2020 12:27 am

notmyhand wrote:
Sun Jun 28, 2020 4:20 pm
In an attempt to figure out why my electricity bills are so high, I went through and turned off breakers to determine how much electricity things were drawing. Turns out my heat pump is using 4 kilowatts an hour to cool my home. Which translates to about $10 a day! There has to be a better solution?

How do I fix this large draw? Does this seem right? Is there another cooling/heating source available that I should upgrade too instead? I do not have natural gas available.

Thanks for insight!
Per your description of all electric, then you have missed a big item. Your hot water. Solutions - use less hot water, install solar water heater, install heat-pump water heater.

For example: A 4gpm shower for 10 minutes will consume 5.3kw to heat the water.

So how many showers are taken a day? For how long?

Changing from a high flow head to low flow 1.5 gpm head will save you proportionally. Reducing the time in the shower will save you proportionally.

Example Calcs:
4 gpm x 10 mintues = 40 gallons
40 gallons x 8.3 lbs/gal = 332 lbs of water.
332lbs X 50 degrees rise = 16,600 btu ( that's 50 degree water being raised to 100 degrees )
16,600 btu / 3140 btu/kw = 5.3KW just to heat the water

How do I know? We have an all-electric mountain cabin and we can definitely tell the difference between a 2 person weekend and a 6 person weekend.

Chuck107
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Chuck107 » Mon Jun 29, 2020 6:53 am

As a side note Nyle water heating systems, is bringing back their add on heat pump for water heaters.

https://www.nyle.com/water-heating-syst ... dential-2/

I have one thats almost 10 yrs old, still works perfectly.
I don't even have my water heater breakers turned on.
Instead of costing 500+ per yr for HW I pay about 150, as per my kill o watt meter.

Plus it dehumidifies my unheated basement saving me the cost of a separate dehumidifier and it's electric costs.
And it just plugs into 110v

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by teCh0010 » Mon Jun 29, 2020 7:23 am

BrandonBogle wrote:
Mon Jun 29, 2020 12:02 am
adamthesmythe wrote:
Sun Jun 28, 2020 5:01 pm
Everywhere I have lived AC was a substantial cost during the summer, a few hundred per month. How many "a few" is will depend on your electric rates, outside and inside temperatures.
:shock:

I keep my ac between 68 and 76, depending on time of day. It’s only a 1.5 ton unit (I think) servicing 2000+ sq ft across two floors. The house is all-electric. Electric stove, electric water heater, electric clothes dryer. I drive an electric car. My monthly average electric bill is around $140-$180/mo depending on how much I drive, and higher in the winter with Christmas lights and auxiliary heat on the really cold days.

I just looked. May 2020 was 42 kWh per day for 1,213 kWh for the month and $102.26 of energy use charge before the other fees and taxes added on. May 2019 was 40 kWh per day for 1,231 kWh for the month (29 days in 2020 cycle vs. 31 days in 2019 cycle). July 2019 was 1,321 kWh/mo and 46 kWh/day, 29 day cycle and $4.63/day.

A few hundred would be a shock to me!

Image
What is your climate zone, and how tight is your construction?

My house currently has 9 tons of cooling, we will drop to 8 when the 5 ton dies. It originally had 10 tons, we did a big air sealing and insulation job to cut the demand. Home built in 1998.

If we built our house new with tight construction (house wrap, sealed floor plate, sealed window frames, tight low e windows, Sealed rim joist, foam in the walls, all vertical penetration sealed, cellulose in the attic) we could probably run on a single 4 or 5 ton.

The guy who did my air sealing built a 5600 Sq ft house running a single 5 ton heat pump, but the majority of that air infiltration work has to be done at construction.

We are in the hot and humid deep south.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by BrandonBogle » Mon Jun 29, 2020 7:56 am

teCh0010 wrote:
Mon Jun 29, 2020 7:23 am
What is your climate zone, and how tight is your construction?

...

We are in the hot and humid deep south.
Unknown. NC in a home built in 1982 that I’ve done no energy-efficiency work on (besides replacing appliances). Grew up in Miami though, so people here wonder why I barely ever sweat lol. My usual response is “go to Miami and you’ll see I have no reason to swear here”. My humidity outdoors averages 90% in the summer.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by Valuethinker » Mon Jun 29, 2020 9:01 am

notmyhand wrote:
Sun Jun 28, 2020 4:20 pm
In an attempt to figure out why my electricity bills are so high, I went through and turned off breakers to determine how much electricity things were drawing. Turns out my heat pump is using 4 kilowatts an hour to cool my home. Which translates to about $10 a day! There has to be a better solution?

7% HSPF and 9 SEER heat pump, 4 years old. Keep the house at 72. Only have electricity available at the house.

How do I fix this large draw? Does this seem right? Is there another cooling/heating source available that I should upgrade too instead? I do not have natural gas available.

Thanks for insight!
4 kw x 24 hours = 96 kwhr at 10 cents/ kwhr? The problem there is the system should not be running full out more than a few hours a day. The fan would run more. If you live in some place very hot and humid you might be running a lot more hours than that.

Conversely if temperatures go below 32F and your system is not set right the electric bar heating will go on, and that is quite expensive.

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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by ncbill » Mon Jun 29, 2020 9:53 am

BrandonBogle wrote:
Mon Jun 29, 2020 7:56 am
teCh0010 wrote:
Mon Jun 29, 2020 7:23 am
What is your climate zone, and how tight is your construction?

...

We are in the hot and humid deep south.
Unknown. NC in a home built in 1982 that I’ve done no energy-efficiency work on (besides replacing appliances). Grew up in Miami though, so people here wonder why I barely ever sweat lol. My usual response is “go to Miami and you’ll see I have no reason to swear here”. My humidity outdoors averages 90% in the summer.
NC rates are also cheap...around $0.11/kWh for residential on Duke Energy.

I've only got one 3-ton unit for 2 floors, ~3,000 sqft. but I use natural gas for heating in the winter to save wear & tear on the heat pump's compressor.

And I agree the OP needs to get used to 76-78ºF indoors in the summer...add ceiling fan(s) or freestanding floor fan(s) if needed.

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BrandonBogle
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by BrandonBogle » Mon Jun 29, 2020 10:09 am

ncbill wrote:
Mon Jun 29, 2020 9:53 am
NC rates are also cheap...around $0.11/kWh for residential on Duke Energy.
Absolutely! I’m $0.086 per kWh or thereabouts.

fleetwdl
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by fleetwdl » Mon Jun 29, 2020 1:44 pm

We set thermostat at 77 F during the day and 76 F at night. Try that and your costs will plummet. If you don't have ceiling fans, install them. My all electric home bill for last month was $119. North Central Florida builder grade home 2020 of sq. ft. My unit's compressor would never kick off during the day if set for 72 F. If you have to have that, you will have to pay for it. All the engineering discussion doesn't really matter if you must have 72 F.

swengineer
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Re: Heat pump/ac using 4 kWh - how do I fix this?

Post by swengineer » Mon Jun 29, 2020 2:18 pm

Surprised I haven't seen this comment yet. Check if the coils in the compressor outside are clean, or are they partially blocked with dust, lint, spiderwebs, etc.

Cleaning the coils if they are very dirty can reduce your electricity costs.

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