Heat Pump vs Efficient AC on Summer electricity usage

[Romer]

I have a Solar System with 32kWh LG Battery Backup. Right now I generate more Electricity than I use. Over the summer, I use more electricity than I generate but it is offset by Net Credits so I don't pay for any electricity.

My Home HVAC systems are 18 years old. I have two systems that divide the house. One of my AC's is a 10 SEER and the other is a 13 SEER. Last year the tech who repaired one of the furnaces said he didn't think the furnace would last much longer based on readings he took. Whether that is true or not, my systems are at or near the end of their life.

Both my HVAC systems are still working, so not in any hurry. I am going to wait until January for the new 2023 incentives come out to get quotes in case that impacts them.

I have been researching Heat Pumps and living in Colorado, I would need a Dual Fuel system if I went that route.

My Backup Battery system right now runs the furnace but not the AC in an outage. So I would have to make changes if I wanted a Heat pump for heat in a Dual Fuel system. That would depend on surge power for startup for the heat pumps. Maybe there is an option to just switch to the Furnace.

The Simplest change would be a new Furnace and more efficient AC.

Something I have been searching but can't find an answer to, Does a 20 SEER AC and a 20 SEER Heat pump use the same amount of electricity in the summer?

I believe I would see a significant reduction with a 20 SEER AC in electricity in the summer. These systems currently use 40-50 kWh's extra on a hot day compared to the spring

Using a Heat pump in a dual fuel system for heat would reduce Gas usage , but increase electricity usage in the fall and winter as I understand it

My overall goal is to reduce Electricity usage to help offset an EV when we eventually get one, likely 2024.

another question is I think I can run a Heat Pump as just an AC and have the option to change that later, but I don't know if that is true. Anyone know the answer to that?

I will of course discuss with contractors when I get several quotes in a few months. I am wanting to define what options I want quoted

I appreciate any insights into my two questions

 

[Spock]

when you get the EV, explore if it can be used as additional battery backup for the house.
surge power: can you put a "soft start" module on a heat pump to reduce the in rush current? (you can on an A/C so I don't know why you couldn't on a heat pump... its just an A/C going backwards).

 

[OldShooter]

... Does a 20 SEER AC and a 20 SEER Heat pump use the same amount of electricity in the summer? ...

I am not hampered by particular expertise here, but an AC is a heat pump, so my guess is that any differences will be equipment-specific and small, not generic and significant.

 

[euro]

"""""another question is I think I can run a Heat Pump as just an AC and have the option to change that later, but I don't know if that is true. Anyone know the answer to that?""""

I don't see why not. You physically flip a switch on your thermostat control panel from "cool" to "heat" when you want to use the heat pump for heating rather than cooling. You don't HAVE to flip the switch....

 

[Romer]

when you get the EV, explore if it can be used as additional battery backup for the house.
surge power: can you put a "soft start" module on a heat pump to reduce the in rush current? (you can on an A/C so I don't know why you couldn't on a heat pump... its just an A/C going backwards).

I know some EVs like the Ford Lightening can be used as a battery. My 32kWh can power for a couple of days in an outage. I agree, something to check on, but not currently a driving factor for me

I would definitely have to work the startup cycle relative to my system and a soft start would be an option.

I am not hampered by particular expertise here, but an AC is a heat pump, so my guess is that any differences will be equipment-specific and small, not generic and significant.

Good to know

"""""another question is I think I can run a Heat Pump as just an AC and have the option to change that later, but I don't know if that is true. Anyone know the answer to that?""""

I don't see why not. You physically flip a switch on your thermostat control panel from "cool" to "heat" when you want to use the heat pump for heating rather than cooling. You don't HAVE to flip the switch....

Thanks - that is very helpful

 

[Bamaman]

The deal with the dual fuel heat pump system is that the heat pump will provide heat down to a specific temperature where it suddenly gets inefficient. Then the Natural Gas or LP burner will kick in and the fan will push the heated forced air throughout the system.

My first thought of a 20 SEER HVAC system is how much is the initial cost? What's the breakeven point vs. a 15 SEER system?

Your best bet is to find a really experienced and honest HVAC outfit. I like owner/operator a/c men who have low cost of doing business--2 to 3 helpers. Those large HVAC just have too much overhead, and they're often owned by the equipment manufacturers. There are just too many fast talking HVAC salesmen trying to maximize profits by taking advantage of customers. You may have already met one of those fast talking Solar salesman when you went on solar.

 

[ncbill]

I did what the OP is considering back in 2009...replaced a gas furnace/central AC setup with a heat pump with gas furnace backup.

Mainly because retail gas prices per therm had nearly doubled from one month to next the previous winter (wholesale price had soared to nearly $15/MMBtu from around $3/MMBtu)

However, as soon as I had installed it, gas prices dropped back down to around $3/MMBtu.

The first few winters I used the heat pump but found the cooler air temperature and noise it would make to defrost seriously annoying.

Plus the additional wear & tear on the system from running the compressor year-round.

So I stopped using the heat pump at all for heating and have used the gas furnace since.

A a 20 SEER AC and a 20 SEER Heat pump will the same amount of electricity in the summer to cool.

But, finding a company that knows how to properly install a traditional split system so that you actually get that 20 SEER?

Good luck.

Since I only pay 10 cents/kWh year-round I'd buy a lower SEER dual-fuel HVAC (SEER 15 is currently what I have) instead.

 

[ERD50]

...The first few winters I used the heat pump but found the cooler air temperature and noise it would make to defrost seriously annoying. ...

Right, this would be a near deal breaker for me, unless the cost delta became a really big deal.

I like the very warm air coming out of a gas furnace duct. It's one of the reasons I am pretty aggressive at turning the heat down when we go out, and overnight. It can be cold in the house, but as soon as that very warm air is circulating, you feel warmer. I also like to raise the temp a few degrees before taking a shower on a cold day - nice warm air circulating through the bathroom.

The output of the heat pumps is just sort of lukewarm. I know people who have complained about this.

https://www.coolray.com/help-guides/help-my-heat-pump-is-blowing-cold-air-in-heat-mode

Gas furnaces produce air that is 130-140°F range. So 85-92°F feels cold to new heat pump owners.

 

[folivier]

I'm curious as to what readings the guy took to determine that "he didn't think the furnace would last much longer based on readings he took."

 

[Romer]

I'm curious as to what readings the guy took to determine that "he didn't think the furnace would last much longer based on readings he took."

Here is his summary from the Invoice 18 months ago. He did not try to sell me anything or even suggest I talk to his company. Verbally it was something he suggested I keep an eye on and consider going forward.

 

[ERD50]

Here is his summary from the Invoice 18 months ago. He did not try to sell me anything or even suggest I talk to his company. Verbally it was something he suggested I keep an eye on and consider going forward.

I'm not sure what the draft inducer fan amps are supposed to be, but if they are on the high side, that could indicate the bearings starting to get tight.

I lubed mine on my old furnace, and got a few more years out of it. IIRC, I did need to replace it eventually.

Check the cost of a new fan assembly for your model. Probably ~ $120, and most are fairly easy DIY job. But that would give you some handle on a service call cost if you pay to have it done. Typically a 100% markup, maybe $85 for the call, and an hour of labor? That adds up, but they need to make a buck, and it shouldn't be too bad if you aren't a DIY type.

-ERD50

 

[folivier]

Also if the fan motors use capacitors for starting that is an easy and cheap replacement.

 

[Romer]

I'm not sure what the draft inducer fan amps are supposed to be, but if they are on the high side, that could indicate the bearings starting to get tight.

I lubed mine on my old furnace, and got a few more years out of it. IIRC, I did need to replace it eventually.

Check the cost of a new fan assembly for your model. Probably ~ $120, and most are fairly easy DIY job. But that would give you some handle on a service call cost if you pay to have it done. Typically a 100% markup, maybe $85 for the call, and an hour of labor? That adds up, but they need to make a buck, and it shouldn't be too bad if you aren't a DIY type.

-ERD50

They are about $160. I have repaired a lot of appliances, installed a Hot Water heater and work on my cars so I should be able to replace it if need be.

However, that isn't what this thread is about. I am more concerned about the AC units due to age and evaluating just upgrading the entire system to be more energy efficient while I do that.

I am in no hurry and researching so I can make an educated non panicked decision at a time of my choosing. I find the optimum solution takes time due to manufacturing or install delays. For Example, I preferred the new LG Chem 16 kW batteries to the Tesla Powerballs due to their better load capacity (Run more stuff). I waited an extra 4 months for my system because of that.

When my Hot water heater was 14 years old, I bought the model I wanted on sale and kept it in the garage for a year and when it died, I swapped it myself the same day. I don't have the skill though to swap an HVAC unit so would like to define what I want, how much and how long it takes to get it along with 2023 Fed Tax credits and local utility rebates.

I am an engineer (retired) and research the crap out of stuff before I execute. This thread is about making a pro-active rather than reactive decision. The comment about the Furnace is a data point showing reaching near the end of life on my current system.

I appreciate the suggestions and may go ahead and swap the motors, but that doesn't change that eventually I will want to make a pro-active decision to ensure I get what I want vs what they have. I hope that makes sense

 

[ncbill]

They are about $160. I have repaired a lot of appliances, installed a Hot Water heater and work on my cars so I should be able to replace it if need be.

However, that isn't what this thread is about. I am more concerned about the AC units due to age and evaluating just upgrading the entire system to be more energy efficient while I do that.

I am in no hurry and researching so I can make an educated non panicked decision at a time of my choosing. I find the optimum solution takes time due to manufacturing or install delays. For Example, I preferred the new LG Chem 16 kW batteries to the Tesla Powerballs due to their better load capacity (Run more stuff). I waited an extra 4 months for my system because of that.

When my Hot water heater was 14 years old, I bought the model I wanted on sale and kept it in the garage for a year and when it died, I swapped it myself the same day. I don't have the skill though to swap an HVAC unit so would like to define what I want, how much and how long it takes to get it along with 2023 Fed Tax credits and local utility rebates.

I am an engineer (retired) and research the crap out of stuff before I execute. This thread is about making a pro-active rather than reactive decision. The comment about the Furnace is a data point showing reaching near the end of life on my current system.

I appreciate the suggestions and may go ahead and swap the motors, but that doesn't change that eventually I will want to make a pro-active decision to ensure I get what I want vs what they have. I hope that makes sense

The gas furnace is what has the air hander, with the A-coil from the A/C or heat pump usually sitting above the air handler.

So there's no requirement to replace the furnace when replacing the cooling part of your HVAC.

And with the change in refrigerants I would not want to get stuck with a system that uses the soon-to-be-obsolete R-410A.

Because plenty of residential HVAC companies are charging $400/lb for the old R-22 refrigerant...wouldn't want to get stuck paying that for R-410A!

Plus I'd want to wait to make sure any kinks in systems using the new refrigerants are worked out before I bought one.

 

[Romer]

I have moved forward in my evaluation and received quotes from 3 companies. Still asking them questions about them

I have Heat Pump options (Dual Fuel) in all 3 quotes. The 2023 Tax incentives make the Heat Pump in one the same end cost as a 17 SEER AC. The Heat Pump is also listed as a 17 SEER

As stated earlier, I have Solar with Batteries and currently the Furnace stays on in a Grid Outage, but the AC (future Heat Pump) goes off. I asked the 3 contractors if you could switch the furnace on and they said it’s a set point that can’t be adjusted by the Homeowner. I have asked them to dig into that more

I am hoping to create additional margin to my solar production so we can charge an EV for essentially free in a year or two. Not sure if that should be a goal here as I can always add another string if that becomes a driver, but that is a lot more $$$

Digging deeper into the heat pump, it looks like it takes more power to heat the home than cool it. I was wondering those with Dual Fuel systems how their total electric usage over a year changed with the Heat Pump (Dual Fuel)? Did the savings in the summer offset the extra usage in the winter? Is it a net Electricity gain or loss? I know Gas usage would go down reducing the time the furnace is on

The best Heat Pump quote has a Daikin 96% 100K BTU Furnace and a Daikin 3 ton 17 SEER Heat Pump
The AC quote I think is the best is an American Standard 80% Gold series 100K BTU with and American Standard Gold Series 17 SEER AC 3 Ton. I know the furnace is not as efficient on gas. Getting a 96% furnace with a 17 SEER AC is $3K more. The Daikin Heat Pump system quote is essentially the same price as this when you consider state and federal tax incentives in 2023.

I live in Denver Colorado where the winters alternate been cold (18 deg F now) and mild 61 deg F last week. It can stay below zero for several days at a time

If both the AC and Heat Pump are 17 SEER with variable speeds, wouldn’t they use the same electricity in the summer? Whereas, the AC would use no Electricity in the off summer, while the Heat Pump would use more in the winter.

One uses less gas (Heat Pump) and the other (AC) would create more Electricity production margin. I have to decide if that margin means more to me than the gas savings. To do that I need to know if the Heat Pump overall will use more or less electricity than my current 18 y furnace and 10 SEER AC over 12 months.

Probably a few questions I am not smart enough to even ask about so looking for some insights

 

[SnowballCamper]

If you own a big enough yard, try some earth tubes. Then you're just running a fan, and not the compressor.

https://www.permaculturenews.org/2017/07/10/earth-tubes-natural-way-air-condition-home/

 

[Romer]

If you own a big enough yard, try some earth tubes. Then you're just running a fan, and not the compressor.

https://www.permaculturenews.org/2017/07/10/earth-tubes-natural-way-air-condition-home/

Thanks, I read about that and I do have a big enough yard, just more than I want to spend

My big question from what I posted above is deciding between a 17 SEER Heat Pump or 17 SEER AC considering full season gas and elec usage

 

[ncbill]

I have moved forward in my evaluation and received quotes from 3 companies. Still asking them questions about them

I have Heat Pump options (Dual Fuel) in all 3 quotes. The 2023 Tax incentives make the Heat Pump in one the same end cost as a 17 SEER AC. The Heat Pump is also listed as a 17 SEER

As stated earlier, I have Solar with Batteries and currently the Furnace stays on in a Grid Outage, but the AC (future Heat Pump) goes off. I asked the 3 contractors if you could switch the furnace on and they said it’s a set point that can’t be adjusted by the Homeowner. I have asked them to dig into that more

I am hoping to create additional margin to my solar production so we can charge an EV for essentially free in a year or two. Not sure if that should be a goal here as I can always add another string if that becomes a driver, but that is a lot more $$$

Digging deeper into the heat pump, it looks like it takes more power to heat the home than cool it. I was wondering those with Dual Fuel systems how their total electric usage over a year changed with the Heat Pump (Dual Fuel)? Did the savings in the summer offset the extra usage in the winter? Is it a net Electricity gain or loss? I know Gas usage would go down reducing the time the furnace is on

The best Heat Pump quote has a Daikin 96% 100K BTU Furnace and a Daikin 3 ton 17 SEER Heat Pump
The AC quote I think is the best is an American Standard 80% Gold series 100K BTU with and American Standard Gold Series 17 SEER AC 3 Ton. I know the furnace is not as efficient on gas. Getting a 96% furnace with a 17 SEER AC is $3K more. The Daikin Heat Pump system quote is essentially the same price as this when you consider state and federal tax incentives in 2023.

I live in Denver Colorado where the winters alternate been cold (18 deg F now) and mild 61 deg F last week. It can stay below zero for several days at a time

If both the AC and Heat Pump are 17 SEER with variable speeds, wouldn’t they use the same electricity in the summer? Whereas, the AC would use no Electricity in the off summer, while the Heat Pump would use more in the winter.

One uses less gas (Heat Pump) and the other (AC) would create more Electricity production margin. I have to decide if that margin means more to me than the gas savings. To do that I need to know if the Heat Pump overall will use more or less electricity than my current 18 y furnace and 10 SEER AC over 12 months.

Probably a few questions I am not smart enough to even ask about so looking for some insights

When I needed a new HVAC I purchased a heat pump w/ gas furnace backup.

However, given dirt-cheap natural gas prices I soon switched to just using the 80% gas furnace for heat to save wear & tear on the compressor since I live in a hot climate where cooling is more important.

Just choose "auxiliary" or "emergency" heat on your thermostat to bypass the heat pump in favor of the gas furnace.

I'm assuming you don't also have electric heat strips...not common with gas backup.

The temperature that the heat pump hands off to gas furnace should be adjustable on your thermostat...you might have to go into a 'secret' menu...check online for your thermostat's manual.

 

[Romer]

When I needed a new HVAC I purchased a heat pump w/ gas furnace backup.

However, given dirt-cheap natural gas prices I soon switched to just using the 80% gas furnace for heat to save wear & tear on the compressor since I live in a hot climate where cooling is more important.

Just choose "auxiliary" or "emergency" heat on your thermostat to bypass the heat pump in favor of the gas furnace.

I'm assuming you don't also have electric heat strips...not common with gas backup.

The temperature that the heat pump hands off to gas furnace should be adjustable on your thermostat...you might have to go into a 'secret' menu...check online for your thermostat's manual.

Thank you, that is very helpful. My Niece and nephew live close by and have a Heat Pump and shared the Gas and elec usage with me to help. Normalizing for size of homes and the average temp per month for when the heat pump would be on vs off, it looks like with the High rates we just got hit with I would save about $500 a year on gas, but if rates go back down to what they were a few months ago, that is likely under $200. Just some quick calculations based on rough comparison. Don't ask to see my math

That is comparing total systems and I have two systems so replacing only 1 right now would be half of that

I like the option of being able to decide how and when to run the heat pump. The contractors really were not able to answer questions about that

 

[Romer]

As Paul Harvey use to say, and now for the rest of the story ( My adult children look at me going what when I say that)

I studied the Tax Rebates, reviewed Gas and Electric costs best I could and made my decision

I am getting the Daikin 96% Furnace and Daikin Fit + 17 SEER Heat Pump

I live in Colorado and in January there is a 10% Income State Tax Credit for Heat Pump Installs. That and the $2K Federal Tax Credit that any income can qualify for gives me $3800 in Tax Credits when I file taxes for the year. I pointed out to the company Colorado also eliminates Sales Tax on Heat Pumps starting January 1st. They don't charge me sales tax so they said they would take it off the price I pay. The Price after Xcel Energy and Sales Tax incentives is $18.26K. Total Cost after Tax Credits $13.8K.

I calculated roughly using My historical Xcel Energy usage (Gas and Elec) and the Heat Pump Gas usage at my Niece's house along with a 96% vs 80% furnace a gas savings of approx 400 THERMs a year. After the 50% price increase in Colorado to $1.51 a THERM (nov bill) that is $600 a year in Gas savings. That's a rough guess and I will have real data in the same setup next year.

The Heat Pump will use less electricity in the summer and more in the winter, but looking like still within the capabilities of my Solar System

My house has two systems, so replacing 1 in January to get the Tax credits/incentives and will do the 2nd one sometime between 2024-2026.

The one I am replacing has an 18 year old Furnace and AC and the remaining one has an 9 year old AC with a 18 year old furnace. I plan to take parts out of the furnace being removed to help the remaining one last another year or two.

The future data showing system performance will help me decided if it is 2024 or close to 2026. That and how well the furnace keeps on working.

 

[mpeirce]

I’ve owned dual fuel systems for some time and it’s frustrating that they always have a single temp where they switch from heat pump to gas for heat. To change it you have to use the service menu , usually behind a password, or just manually use “emergency heat.”

You’d think someone would build a thermostat that looked at gas cost, electricity costs, and the efficiency of the gas and heat pump system at various temps, then use the low cost option for those particular conditions.

You could even have it look at your solar/battery system to take that into consideration.

Has anyone seen such a thing?