Texas filter: replace Central AC with Heat Pump?
August 24, 2024 10:08 AM Subscribe
The kind folks who installed a new central AC system in my Austin home suggest it’s nearing the end of its life (10 years) and should be replaced soon. They discouraged me from replacing with a heat pump. A friend who oversees HVAC issues with a large school district said that I should stick with my existing gas furnace, as ‘heat pumps are more efficient than older electric furnaces but not gas.’ Should I consider installing a heat pump to replace the AC and continue using the gas furnace for heating?
The house was built in 1954 and has ducting through the attic, which has some insulation. The current system (AC and heat) works well. I was quoted ~$12,000 to replace the AC, which is showing signs of impending problems. Naturally I’m interested in tax credits for the heat pump as well as energy savings. Also interested in trusted local vendors who would give me an unbiased assessment. Thanks!
The house was built in 1954 and has ducting through the attic, which has some insulation. The current system (AC and heat) works well. I was quoted ~$12,000 to replace the AC, which is showing signs of impending problems. Naturally I’m interested in tax credits for the heat pump as well as energy savings. Also interested in trusted local vendors who would give me an unbiased assessment. Thanks!
Do you have to replace your gas furnace as well? I don't live in Texas, but here in Alberta (Canada's Texas) I know a few people who have replaced their AC with a heat pump, but definitely didn't replace their gas furnace. A heat pump would not be able to keep up with our winters, so it is mostly just acting as an AC and providing heat in the shoulder seasons. The logic for doing this was that the price of gas and electricity are moving targets and while it may be cheaper to heat ones home with natural gas one month, that can change. A heat pump gives you the flexibility to change with market conditions instead of being locked into whatever the situation happened to be when you replaced your AC.
I think it would really depend on the price difference between a heat pump and a regular AC (a regular air conditioner is just a heat pump that only goes in one direction). If it isn't much more expensive, and you keep your gas furnace, then you have kind of future-proofed yourself for the case where renewables get much cheaper and/or gas gets more expensive.
posted by selenized at 10:36 AM on August 24 [1 favorite]
I think it would really depend on the price difference between a heat pump and a regular AC (a regular air conditioner is just a heat pump that only goes in one direction). If it isn't much more expensive, and you keep your gas furnace, then you have kind of future-proofed yourself for the case where renewables get much cheaper and/or gas gets more expensive.
posted by selenized at 10:36 AM on August 24 [1 favorite]
'heat pumps are more efficient than older electric furnaces but not gas.'
It's really apples to oranges here and blanket statements like this don't really capture the reality.
The building trades tend to be very conservative with little education on newer technologies and a healthy dose of folk wisdom in place of fact. This unfortunately creates a strong tendency for people who we perceive as experts in a field to spout a lot of very outdated or incorrect information. This is a major barrier to the adoption of better building technologies and something to bear in mind as you navigate this.
posted by ssg at 11:05 AM on August 24 [21 favorites]
It's really apples to oranges here and blanket statements like this don't really capture the reality.
- On the basis of energy entering your house, of course a heat pump is much more efficient than a gas furnace (because a heat pump can be 300% or 400% efficient, while a gas furnace can never be more than 100% efficient).
- On the basis of cost, it depends on your gas and electricity prices and your specific climate and heating needs.
- On the basis of overall energy efficiency, taking into account the energy mix that goes into electrical generation in Texas (which is gas, followed by wind and coal), in your mild winter climate a good heat pump will be more efficient than burning gas directly for heat. This is also true of overall carbon emissions, which will be lower with a good heat pump.
The building trades tend to be very conservative with little education on newer technologies and a healthy dose of folk wisdom in place of fact. This unfortunately creates a strong tendency for people who we perceive as experts in a field to spout a lot of very outdated or incorrect information. This is a major barrier to the adoption of better building technologies and something to bear in mind as you navigate this.
posted by ssg at 11:05 AM on August 24 [21 favorites]
The newish hyperheat Mitsubishi heat pumps are rated at full efficiency down to 5 degrees F and will operate at lower efficiency down to -13 F. They can also be supplemented with additional air heaters if those extreme lower ranges are a concern, but an HVAC technician will be able to tell you what you need.
One thing we're running into while preparing for a heatpump installation is that heat pumps have pretty specific requirements for incoming air, and many old ducted systems don't have enough capacity in the air return ducting. We've got to increase a couple of our ducts in order to have enough incoming air for the system.
posted by msbrauer at 11:09 AM on August 24 [7 favorites]
One thing we're running into while preparing for a heatpump installation is that heat pumps have pretty specific requirements for incoming air, and many old ducted systems don't have enough capacity in the air return ducting. We've got to increase a couple of our ducts in order to have enough incoming air for the system.
posted by msbrauer at 11:09 AM on August 24 [7 favorites]
What you should look into is a dual fuel systems. It leverages both a traditional gas furnace and a heat pump.
I had an old furnace at my home and needed / wanted to add AC (thanks climate change :-/ ). I spent the extra $1k to swap out the AC unit for a heat pump version and then a bit more for the full communicating thermostat vs a normal "2H/2C" one. It did require me to make sure I had a furnace and heat pump from the same company so the entire system would work together well.
In the summer, the heat pump works like a standard AC unit. No changes there. But in the winter, the thermostat is smart enough look at the outside temperature and use either the heat pump or the gas furnace based on the current conditions. The heat pump is great when it is over 30° and I just need to raise the internal temp by a few degrees. If it is really cold outside or I need to do something like take the house from 60° to 68° quickly, the system just uses the gas furnace.
posted by SegFaultCoreDump at 11:36 AM on August 24 [1 favorite]
I had an old furnace at my home and needed / wanted to add AC (thanks climate change :-/ ). I spent the extra $1k to swap out the AC unit for a heat pump version and then a bit more for the full communicating thermostat vs a normal "2H/2C" one. It did require me to make sure I had a furnace and heat pump from the same company so the entire system would work together well.
In the summer, the heat pump works like a standard AC unit. No changes there. But in the winter, the thermostat is smart enough look at the outside temperature and use either the heat pump or the gas furnace based on the current conditions. The heat pump is great when it is over 30° and I just need to raise the internal temp by a few degrees. If it is really cold outside or I need to do something like take the house from 60° to 68° quickly, the system just uses the gas furnace.
posted by SegFaultCoreDump at 11:36 AM on August 24 [1 favorite]
Dual systems don’t have to be with gas. Our heat pump has an electric backup that works great for us and gets rid of the gas furnace which is a major source of indoor air pollution in your home that increases your risk (and especially any children’s risk) of many health issues.
Our minimum temps are typically about 6 degrees F and the system almost never switches over to the backup electric. The heat pump can handle almost all of our weather.
We got our heat pump installed by a commercial hvac company who specializes in heat pumps. All the standard residential contractors also did gas, and they were either incredibly ignorant or lying out their asses about what heat pumps were capable of and what was needed to comfortably heat and cool our home.
posted by congen at 12:30 PM on August 24 [3 favorites]
Our minimum temps are typically about 6 degrees F and the system almost never switches over to the backup electric. The heat pump can handle almost all of our weather.
We got our heat pump installed by a commercial hvac company who specializes in heat pumps. All the standard residential contractors also did gas, and they were either incredibly ignorant or lying out their asses about what heat pumps were capable of and what was needed to comfortably heat and cool our home.
posted by congen at 12:30 PM on August 24 [3 favorites]
While you do have to think about backup heat with a heat pump in a very cold climate, in Austin, where the lowest ever recorded temperature was -2F and typical lows are much higher, a good heat pump alone is definitely sufficient.
posted by ssg at 1:47 PM on August 24 [7 favorites]
posted by ssg at 1:47 PM on August 24 [7 favorites]
There is currently a federal tax credit available for 30% of the cost of eligible heat pump installations, up to $2000. For warm states like Texas, any Energy Star certified ducted heat pump qualifies.
posted by gueneverey at 2:13 PM on August 24 [2 favorites]
posted by gueneverey at 2:13 PM on August 24 [2 favorites]
The kind folks who installed a new central AC system in my Austin home suggest it’s nearing the end of its life (10 years) and should be replaced soon.
Ten years? Seems like a short lifespan to me. In my experience they should last double that or more.
posted by Jessica Savitch's Coke Spoon at 2:16 PM on August 24 [8 favorites]
Ten years? Seems like a short lifespan to me. In my experience they should last double that or more.
posted by Jessica Savitch's Coke Spoon at 2:16 PM on August 24 [8 favorites]
I think you need to find a new HVAC contractor. A heat pump installation is virtually guaranteed to be at least as efficient as a gas furnace, and quite probably vastly more efficient. The "new" (as in, several years old now) inverter-based heat pump models are darn near infinitely variable in speed and power, to always stay within the optimum efficiency band for the current heating or cooling demand. Even if you get an absolute lemon of a heat pump and it's "only" on par with gas for efficiency, at least you're off fossil fuels and aren't burning hydrocarbons inside your house anymore.
posted by xedrik at 6:15 PM on August 24 [3 favorites]
posted by xedrik at 6:15 PM on August 24 [3 favorites]
Heat pump systems that utilize existing ducting tend to be a little bit more expensive than the 'ductless' pop-a-hole in your wall type. They need a blower unit, and typically more labor to tie them into an existing system.
Most gas furnaces that heat through ductwork don't work in a power outage; electricity still runs the blowers that actually move the heat through your home. Unless you currently have a generator or like a gas insert in your fireplace, the calculus for 'what to do when the power is out' is identical between (again, most) gas and electric systems.
We just had a ducted heat pump system installed to replace our gas furnace because our system was aging out of it's useful, most efficient life, and we really wanted an AC system for warm(ing) summers. We were quoted about what you were for just an AC system; going heat pump only made sense with those numbers. Our house was built in the same decade, but our heat system is in the crawlspace under the house. All in, it was only a couple thousand extra bucks to get the whole heat pump installed. This puts us firmly on the roadmap to be able to eventually run the whole system off solar when we're able.
Part of this depends on the prices of gas and electricity in your area. I can't find super recent comparisons, but back in 2021, electricity in TX was just a little higher than in my area (but still almost half as much as power up in several NE states). Our HVAC folks had a calculator that would take your gas usage over a year, and show how much electricity you would need to consume to get the same BTU output. I asked for the inputs they used, and they checked out, more or less for what we were estimating and the published information on the unit we ordered. Gas was marginally cheaper (like, less than $100/year) than electricity, but locks us out of producing our own power eventually for the biggest electrical consumption in our home. And gas does not give us AC in the summer, which is becoming increasingly necessary. A heat pump system is good, and fine; a heat pump system with any amount of solar is excellent over the span of decades.
But also, rolled into the conversation about which is 'better' is a moral dimension. Gas can be cheaper than electric heating, but is it better? More moral? In every case, an electrified system can be powered emission free. Gas does not have that potential.
posted by furnace.heart at 7:30 PM on August 24 [4 favorites]
Most gas furnaces that heat through ductwork don't work in a power outage; electricity still runs the blowers that actually move the heat through your home. Unless you currently have a generator or like a gas insert in your fireplace, the calculus for 'what to do when the power is out' is identical between (again, most) gas and electric systems.
We just had a ducted heat pump system installed to replace our gas furnace because our system was aging out of it's useful, most efficient life, and we really wanted an AC system for warm(ing) summers. We were quoted about what you were for just an AC system; going heat pump only made sense with those numbers. Our house was built in the same decade, but our heat system is in the crawlspace under the house. All in, it was only a couple thousand extra bucks to get the whole heat pump installed. This puts us firmly on the roadmap to be able to eventually run the whole system off solar when we're able.
Part of this depends on the prices of gas and electricity in your area. I can't find super recent comparisons, but back in 2021, electricity in TX was just a little higher than in my area (but still almost half as much as power up in several NE states). Our HVAC folks had a calculator that would take your gas usage over a year, and show how much electricity you would need to consume to get the same BTU output. I asked for the inputs they used, and they checked out, more or less for what we were estimating and the published information on the unit we ordered. Gas was marginally cheaper (like, less than $100/year) than electricity, but locks us out of producing our own power eventually for the biggest electrical consumption in our home. And gas does not give us AC in the summer, which is becoming increasingly necessary. A heat pump system is good, and fine; a heat pump system with any amount of solar is excellent over the span of decades.
But also, rolled into the conversation about which is 'better' is a moral dimension. Gas can be cheaper than electric heating, but is it better? More moral? In every case, an electrified system can be powered emission free. Gas does not have that potential.
posted by furnace.heart at 7:30 PM on August 24 [4 favorites]
Speaking as a heatpump owner in a far more frigid area (Indiana) I’d say Texas is a fantastic climate to have a heatpump. That HVAC guy is nuts.
posted by Thorzdad at 4:18 AM on August 25 [4 favorites]
posted by Thorzdad at 4:18 AM on August 25 [4 favorites]
It's 2024. Heat pumps definitely work fantastically well in the South, even during cold snaps. My guess is they have selfish reasons for discouraging heat pumps -- less margin (profit), more hassle because they are a little more complicated than dumb furnaces, who knows. Remove that HVAC installer from future consideration.
However, using a heat pump makes you more reliant on your electricity feed. If you have a gas furnace, and the power goes out, you can get your heat going again with only a small generator to run the blower (and brains) of the gas furnace -- I've done exactly this during a multi-day power outage. But a heat pump requires far more power (same as an air conditioner) than just the blower, and your average generator won't support it. So if you made it through the last few winters (in Texas!) without power problems, I think you are good to go with a heat pump.
Ten years is pretty short, so that's another reason I don't trust that HVAC company. I'd try to get it to 20 years with repairs, either using that same HVAC company and flatly ignoring their replacement pressure, or moving to a new servicer. The unit we just replaced lasted 30-35 years! (age mix in the parts)
posted by intermod at 2:10 PM on August 25 [1 favorite]
However, using a heat pump makes you more reliant on your electricity feed. If you have a gas furnace, and the power goes out, you can get your heat going again with only a small generator to run the blower (and brains) of the gas furnace -- I've done exactly this during a multi-day power outage. But a heat pump requires far more power (same as an air conditioner) than just the blower, and your average generator won't support it. So if you made it through the last few winters (in Texas!) without power problems, I think you are good to go with a heat pump.
Ten years is pretty short, so that's another reason I don't trust that HVAC company. I'd try to get it to 20 years with repairs, either using that same HVAC company and flatly ignoring their replacement pressure, or moving to a new servicer. The unit we just replaced lasted 30-35 years! (age mix in the parts)
posted by intermod at 2:10 PM on August 25 [1 favorite]
I would not replace a ten year old AC unit that isn't actively and repeatedly breaking, myself.
I did replace a much older one with a heat pump. Ductwork was in good shape so it was an easy switch. Price was in the same ballpark as your quote. The argument for keeping the gas furnace was that it's cheap and my house was already set up for it.
Given the power grid issues, I do think it's a good idea to have a second energy source, either gas or solar. I favor solar for environmental reasons, but know people who have installed generators that tie into the house gas line.
If you're in Austin proper, you may qualify for a city rebate program on a new heat pump. There's a list of installers that work with the program, which is a good starting point. (I looked for ones on the list that were local and specialized in HVAC work - they aren't all primarily HVAC companies .)
posted by mersen at 9:41 PM on August 25 [1 favorite]
I did replace a much older one with a heat pump. Ductwork was in good shape so it was an easy switch. Price was in the same ballpark as your quote. The argument for keeping the gas furnace was that it's cheap and my house was already set up for it.
Given the power grid issues, I do think it's a good idea to have a second energy source, either gas or solar. I favor solar for environmental reasons, but know people who have installed generators that tie into the house gas line.
If you're in Austin proper, you may qualify for a city rebate program on a new heat pump. There's a list of installers that work with the program, which is a good starting point. (I looked for ones on the list that were local and specialized in HVAC work - they aren't all primarily HVAC companies .)
posted by mersen at 9:41 PM on August 25 [1 favorite]
Response by poster: So much good information, thanks. In case anyone is still watching this post, let me underscore:
1) The AC is already failing- there’s a slow leak that can’t be found or fixed; I think it’s 10-13 years old
2) The gas furnace is newish and works fine. I would continue to use it assuming it’s cheaper than using the heat pump (for heating)
3) The questions are: will replacing my ducted central air with a heat pump (using the existing ceiling- mounted ducts) function well at cooling the house (in Texas!)? Would existing tax credits and local incentives make the cost similar to or cheaper than the cost of new AC? Am I right in assuming summer electric costs for a heat pump would be lower than for a convenentional AC?
THANKS
posted by carterk at 9:17 AM on August 26
1) The AC is already failing- there’s a slow leak that can’t be found or fixed; I think it’s 10-13 years old
2) The gas furnace is newish and works fine. I would continue to use it assuming it’s cheaper than using the heat pump (for heating)
3) The questions are: will replacing my ducted central air with a heat pump (using the existing ceiling- mounted ducts) function well at cooling the house (in Texas!)? Would existing tax credits and local incentives make the cost similar to or cheaper than the cost of new AC? Am I right in assuming summer electric costs for a heat pump would be lower than for a convenentional AC?
THANKS
posted by carterk at 9:17 AM on August 26
will replacing my ducted central air with a heat pump (using the existing ceiling- mounted ducts) function well at cooling the house (in Texas!)?
A heat pump is just an air conditioner that can also be run in reverse to heat. There would be no difference in cooling function.
Am I right in assuming summer electric costs for a heat pump would be lower than for a convenentional AC?
Heat pumps are usually a little bit more efficient than standard ACs (though you can get better ACs that are just as efficient). It won't make a major difference but you can easily check the cooling efficiency ratings of potential heat pumps and ACs (and your current AC).
posted by ssg at 3:07 PM on August 26
A heat pump is just an air conditioner that can also be run in reverse to heat. There would be no difference in cooling function.
Am I right in assuming summer electric costs for a heat pump would be lower than for a convenentional AC?
Heat pumps are usually a little bit more efficient than standard ACs (though you can get better ACs that are just as efficient). It won't make a major difference but you can easily check the cooling efficiency ratings of potential heat pumps and ACs (and your current AC).
posted by ssg at 3:07 PM on August 26
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posted by aramaic at 10:30 AM on August 24