Central A/C question kinda long post
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Originally Posted By: DBMaster
Oh, and just a general tip. A tech instructor at my company told me that leaving the blower running continuously will actually lengthen the life of both it and its capacitor. I personally haven't noticed any significant change in the electric bill as the blower uses very little juice compared to the compressor. A nice side benefit is that you get less dust settling on things and the air is constantly circulating across filters.
I wouldn't recommend that, particularly in humid Tx. The rationale being that as soon as the compressor quits, and the evap. coil warms up, the still-running-blower now will pick up and distribute all the condensate from both the wet coil and drip pan back into your house, raising the humidity.
In our neck o' the woods, humidity removal is on par with cooling. When you leave the blower fan on 24/7, your e-bill will be higher and your indoor humidity level will rise & fall with the compressor running instead of remaining constant.
Indoor relative humidity for me is stable around 40%, even when it's much higher outside.
Further, all the A/C filter does is keep the coil clean, not your house, or clear your allergies, or your animals. It just keeps the coil clean.
Oh, and just a general tip. A tech instructor at my company told me that leaving the blower running continuously will actually lengthen the life of both it and its capacitor. I personally haven't noticed any significant change in the electric bill as the blower uses very little juice compared to the compressor. A nice side benefit is that you get less dust settling on things and the air is constantly circulating across filters.
I wouldn't recommend that, particularly in humid Tx. The rationale being that as soon as the compressor quits, and the evap. coil warms up, the still-running-blower now will pick up and distribute all the condensate from both the wet coil and drip pan back into your house, raising the humidity.
In our neck o' the woods, humidity removal is on par with cooling. When you leave the blower fan on 24/7, your e-bill will be higher and your indoor humidity level will rise & fall with the compressor running instead of remaining constant.
Indoor relative humidity for me is stable around 40%, even when it's much higher outside.
Further, all the A/C filter does is keep the coil clean, not your house, or clear your allergies, or your animals. It just keeps the coil clean.
Yeah leaving the blower running continuously does not sound like a good idea. I see zero benefit and a larger electric bill.
Those are good points, but the blower obviously doesn't use much power as I have not noticed anything significant on the bill. My humidity levels seem to rise and fall with ambient humidity and I have a meter in the house. The piece of advice came from one of the instructors here at Lennox with many years of A/C experience. I know that the filter's job is to keep the coil clean, but I have definitely noticed reduced dust on furniture purely because some of it is not being allowed to settle from the air.
Time will tell, I suppose.
Time will tell, I suppose.
We run the blower constantly in our home. Our unit uses a variable speed soft start blower motor which slows to a purr when the compressor/condenser is not active.
The advantages are continuous filtration of the air and more even temps throughout the home. Note that the air handler is the cheap portion of the system to run as it barely uses much at its 'idle' speed.
The advantages are continuous filtration of the air and more even temps throughout the home. Note that the air handler is the cheap portion of the system to run as it barely uses much at its 'idle' speed.
Originally Posted By: DBMaster
Those are good points, but the blower obviously doesn't use much power as I have not noticed anything significant on the bill. My humidity levels seem to rise and fall with ambient humidity and I have a meter in the house. The piece of advice came from one of the instructors here at Lennox with many years of A/C experience. I know that the filter's job is to keep the coil clean, but I have definitely noticed reduced dust on furniture purely because some of it is not being allowed to settle from the air.
Time will tell, I suppose.
If you have the old-style AC motor it'll add up more than you realize. Lets assume you do, it runs off of 110VAC and draws 5A. We'll ignore power factor to keep things simple.
110*5 = 550W*1hr = 550Whr which is also 0.55kWhr. So if you leave it running for 24hrs that adds up to 13.2kWhrs. Over a week it adds up to 92.4kWhrs. Over 4 weeks (month) we're now at 370kWhrs.
You mention using about 2000kWhrs during the Tx Summer, so this is about 19% of your bill. Roughly.
Then again your system may be running nearly full time to keep the temp @ 71°. All depends on too many factors to go into.
The varying humidity inside is due to the reason I explained above. It's the most immediate source of moisture and in Tx Summers we have a lot of moisture to deal with. That's why the evap coil sweats like crazy: our dew points are quite high.
Those are good points, but the blower obviously doesn't use much power as I have not noticed anything significant on the bill. My humidity levels seem to rise and fall with ambient humidity and I have a meter in the house. The piece of advice came from one of the instructors here at Lennox with many years of A/C experience. I know that the filter's job is to keep the coil clean, but I have definitely noticed reduced dust on furniture purely because some of it is not being allowed to settle from the air.
Time will tell, I suppose.
If you have the old-style AC motor it'll add up more than you realize. Lets assume you do, it runs off of 110VAC and draws 5A. We'll ignore power factor to keep things simple.
110*5 = 550W*1hr = 550Whr which is also 0.55kWhr. So if you leave it running for 24hrs that adds up to 13.2kWhrs. Over a week it adds up to 92.4kWhrs. Over 4 weeks (month) we're now at 370kWhrs.
You mention using about 2000kWhrs during the Tx Summer, so this is about 19% of your bill. Roughly.
Then again your system may be running nearly full time to keep the temp @ 71°. All depends on too many factors to go into.
The varying humidity inside is due to the reason I explained above. It's the most immediate source of moisture and in Tx Summers we have a lot of moisture to deal with. That's why the evap coil sweats like crazy: our dew points are quite high.
Originally Posted By: SteveSRT8
We run the blower constantly in our home. Our unit uses a variable speed soft start blower motor which slows to a purr when the compressor/condenser is not active.
The advantages are continuous filtration of the air and more even temps throughout the home. Note that the air handler is the cheap portion of the system to run as it barely uses much at its 'idle' speed.
You have a different animal to deal with. Your blower motor is probably DC and may be frequency controlled. These are much more efficient than the type mentioned above.
Note if the air handler is an AC motor, it's not as cheap to run as you think as the math shows.
We run the blower constantly in our home. Our unit uses a variable speed soft start blower motor which slows to a purr when the compressor/condenser is not active.
The advantages are continuous filtration of the air and more even temps throughout the home. Note that the air handler is the cheap portion of the system to run as it barely uses much at its 'idle' speed.
You have a different animal to deal with. Your blower motor is probably DC and may be frequency controlled. These are much more efficient than the type mentioned above.
Note if the air handler is an AC motor, it's not as cheap to run as you think as the math shows.
Found this article quite interesting given our discussion.
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If you live in a humid climate (for example, in Florida), you need an air conditioner that does a good job of dehumidification. But if you live in a dry climate (for example, in Nevada), dehumidification is almost irrelevant, because the outdoor air is so dry. In Nevada, all you need is an air conditioner that lowers the temperature of the air in an energy-efficient way
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most air conditioner controls turn the air handler fan off when the compressor shuts down, or shortly thereafter. Even though the compressor is off, the indoor coil is still cold at that point. The coil is usually damp and dripping, and moisture has accumulated on the drip pan.
In a humid climate, you want the fan to be off at that point, so that all of the water droplets on the coil can drip down to the pan and find their way down the drain. If the fan continued to run after the compressor turned off, the water would re-evaporate and stay in the house — which would be bad, at least in a humid climate.
However, in a dry climate, you really don’t need any dehumidification, so you don’t really care if the moisture on the coil re-evaporates. “Since air conditioners were not designed for dry climates, they wring more water out of the air than they need to, wasting energy and costing you extra on your cooling bill,”
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...advice for homeowners in humid states like Florida. “Number one: do not run your fan all the time,” he answered. “Running your fan all the time is always a bad idea, but it is even worse if Florida than it is in a dry climate, because it totally eliminates your dehumidification.
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If you live in a humid climate (for example, in Florida), you need an air conditioner that does a good job of dehumidification. But if you live in a dry climate (for example, in Nevada), dehumidification is almost irrelevant, because the outdoor air is so dry. In Nevada, all you need is an air conditioner that lowers the temperature of the air in an energy-efficient way
Quote:
most air conditioner controls turn the air handler fan off when the compressor shuts down, or shortly thereafter. Even though the compressor is off, the indoor coil is still cold at that point. The coil is usually damp and dripping, and moisture has accumulated on the drip pan.
In a humid climate, you want the fan to be off at that point, so that all of the water droplets on the coil can drip down to the pan and find their way down the drain. If the fan continued to run after the compressor turned off, the water would re-evaporate and stay in the house — which would be bad, at least in a humid climate.
However, in a dry climate, you really don’t need any dehumidification, so you don’t really care if the moisture on the coil re-evaporates. “Since air conditioners were not designed for dry climates, they wring more water out of the air than they need to, wasting energy and costing you extra on your cooling bill,”
Quote:
...advice for homeowners in humid states like Florida. “Number one: do not run your fan all the time,” he answered. “Running your fan all the time is always a bad idea, but it is even worse if Florida than it is in a dry climate, because it totally eliminates your dehumidification.
Complete baloney. The air handler in almost any modern AC has variable speeds, sometimes infinitely variable. The coil drys out in seconds after shutdown, I've seen this with my own eyes. And even 20% penalty still seems a very small part of the total bill, only one fifth. Ours is considerably less than that, more like 5-10% or so.
I have a real hygrometer that tells the actual humidity in a room. Running the fan constantly in our system means it ramps down to a very low speed when the condenser shuts off. The result of the continuous air movement is more even numbers (temp and humidity) throughout the home, not to mention continuous air filtration. The dehumidification is most definitely NOT eliminated. That is ridiculously broad and not true in all cases.
If the system is operated in pure automatic mode and shuts the circulating fan off completely at correct temps both temp and humidity spike in very remote rooms and other areas due to windows, activity, etc. Having some air motion allows the Tstat to use the system in a variable amount as needed to maintain precise levels. This is where the real energy savings come from, as our very large condenser can simmer down to a bare minimum and just purr when the demands are low.
Since AC is a critical comfort feature here we choose to run our fan constantly, and others will simply have to decide for themselves what they want.
I have a real hygrometer that tells the actual humidity in a room. Running the fan constantly in our system means it ramps down to a very low speed when the condenser shuts off. The result of the continuous air movement is more even numbers (temp and humidity) throughout the home, not to mention continuous air filtration. The dehumidification is most definitely NOT eliminated. That is ridiculously broad and not true in all cases.
If the system is operated in pure automatic mode and shuts the circulating fan off completely at correct temps both temp and humidity spike in very remote rooms and other areas due to windows, activity, etc. Having some air motion allows the Tstat to use the system in a variable amount as needed to maintain precise levels. This is where the real energy savings come from, as our very large condenser can simmer down to a bare minimum and just purr when the demands are low.
Since AC is a critical comfort feature here we choose to run our fan constantly, and others will simply have to decide for themselves what they want.
My system is 1996 vintage and the blower motor is not variable speed. I still find it improves comfort to run it continuously. Slower air movement across the evaporator when the system is on will pull somewhat more humidity from the air than what I have, but I have not noticed an overall humidity increase (as measured by a Radio Shack hygrometer - cheap). I like the air movement and, believe it or not, the "white noise" produced by the blower. I did not see noticeable increases in my winter bills, either. Since I have gas heat changes in the winter bills would, presumably, be due to the blower running. However much it is, it's not much.
I've noticed an interesting effect in more-than-a-few houses down here in the humid South that the indoor air feels damp (stuffy) upon entering. Even though the temp control might be set at 72°, it feels warmer. About 5 min. after the air handler stops, you can feel the presence of heat...far off heat, but still. I later realized it's long-wave heat coming through the ceiling. Either not enough ceiling insulation, uneven insulation, poor attic ventilation, no radiant barrier, etc. Very interesting effect.
I have to disagree with you Steve that the evap coil would dry out in 'seconds' in an area with a high latent heat load such as Florida or the rest of the very humid South. Doesn't make sense that the dew point could be that low indoors in your area. Your nasal passages would be cracked. Nevada yes. Utah yes. Arizona yes. Florida? Texas? No way. Care to share your indoor relative humidity readings from your hygrometer? Mine is at 40% and the evap coil still sweats. Current outdoor Rh is 91% and outdoor dew point is 77°. It did rain last night...in central Tx....in July...amazing.
I do appreciate the movement of air: most all rooms have ceiling fans. Definitely makes a difference.
Temp & humidity shouldn't 'spike' in any room with the indoor blower off. Something else is going on and your a/c is having to constantly deal with it. Perhaps the same issue mentioned above? Perhaps air flow is insufficient to those areas? Or they have windows where the Sun hits the glass? Face South? Or West? Even East? Doing a cooling load calculation (Man. J) on your house might yield surprising results.
The last bill I paid amounted to $110 for 970kWH's for a small house (~1,500sqr. ft). And that's with a recent price increase....and on a now 23yr old system.
Not wanting to start an argument here, just adding in my two cents.
I have to disagree with you Steve that the evap coil would dry out in 'seconds' in an area with a high latent heat load such as Florida or the rest of the very humid South. Doesn't make sense that the dew point could be that low indoors in your area. Your nasal passages would be cracked. Nevada yes. Utah yes. Arizona yes. Florida? Texas? No way. Care to share your indoor relative humidity readings from your hygrometer? Mine is at 40% and the evap coil still sweats. Current outdoor Rh is 91% and outdoor dew point is 77°. It did rain last night...in central Tx....in July...amazing.
I do appreciate the movement of air: most all rooms have ceiling fans. Definitely makes a difference.
Temp & humidity shouldn't 'spike' in any room with the indoor blower off. Something else is going on and your a/c is having to constantly deal with it. Perhaps the same issue mentioned above? Perhaps air flow is insufficient to those areas? Or they have windows where the Sun hits the glass? Face South? Or West? Even East? Doing a cooling load calculation (Man. J) on your house might yield surprising results.
The last bill I paid amounted to $110 for 970kWH's for a small house (~1,500sqr. ft). And that's with a recent price increase....and on a now 23yr old system.
Not wanting to start an argument here, just adding in my two cents.
If your central ac is 19 years old I highly doubt it is a 13 seer. Older air conditioners lasted a lot longer than newer ones , at 19 years old I think that system is ready to retire.
I install comfort maker heat pumps and straight cool units down In FL (very few gas furnaces ) , the lowest seer rating they make now is 13, and you can go as high as 20 or more but those can get tricky in some applications due to undersized ducts etc.
As far as cost they can range from 3-4k to 10 or more depending on tonnage and seer.
Warranty is ten years on parts, labor depends on the company.
On average the systems we pull out are 15 years old, you can try to bend aid them if its worth the cost but a lot of people have been taking advantage of rebates the gov has offered the last few years to upgrade to more efficient air conditioners.
It is better to have matching units, in fact u can't mix match if you have a permit, but changing the condenser and evap coil is a very common practice here in Fl due to the gas furnaces being underworked.
I install comfort maker heat pumps and straight cool units down In FL (very few gas furnaces ) , the lowest seer rating they make now is 13, and you can go as high as 20 or more but those can get tricky in some applications due to undersized ducts etc.
As far as cost they can range from 3-4k to 10 or more depending on tonnage and seer.
Warranty is ten years on parts, labor depends on the company.
On average the systems we pull out are 15 years old, you can try to bend aid them if its worth the cost but a lot of people have been taking advantage of rebates the gov has offered the last few years to upgrade to more efficient air conditioners.
It is better to have matching units, in fact u can't mix match if you have a permit, but changing the condenser and evap coil is a very common practice here in Fl due to the gas furnaces being underworked.
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My system from 1996 is 10 seer. The condenser unit was replaced in 2005 due to the compressor failing ($1,500). I disagree about replacing. Depending upon what is wrong with the system it is FAR cheaper to fix it than replace. If the compressor goes bad, MAYBE, but the rebates and electricity savings will take YEARS to pay for a new system. When you go from 10 seer to the current minimum you have to replace everything, including the lines. That also means tacking the lines to the outside of the house rather than having them run inside the brick facade.
If anyone ever tries to sell me a system rather than repairing mine I would need to crunch some numbers, but from the sample cases I have checked, the payback period can be measured in DECADES.
If anyone ever tries to sell me a system rather than repairing mine I would need to crunch some numbers, but from the sample cases I have checked, the payback period can be measured in DECADES.
+1 And, he has a scroll compressor which is already efficient and can last a long time. Cleanliness and proper refrigerant levels are the keys to long life. In the OP's case, I think repair is the best option and then, at his leisure, start budgeting and investigating replacement options for the future.
FWIW, my system was installed in 1992 when the house was built.....new condensor fan motor & capacitor in 2010 and still cools great. We keep our house cool....72'F daytime and 69'F nightime and our electric bill rarely exceeds $130 per month in July/August and we are cooling 3500 sq ft plus I run two 6k BTU window units in my 1800 sq ft detached garage when I'm out there.
FWIW, my system was installed in 1992 when the house was built.....new condensor fan motor & capacitor in 2010 and still cools great. We keep our house cool....72'F daytime and 69'F nightime and our electric bill rarely exceeds $130 per month in July/August and we are cooling 3500 sq ft plus I run two 6k BTU window units in my 1800 sq ft detached garage when I'm out there.
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I partially disassemble my condenser unit annually to spray cleaner and hose the coil from the inside. I did created access to the evaporator in the attic and once vacuumed it in the winter when it was dry, but the pleated filters I use, plus the weather stripping I added around the filter frame keeps the air going across the evap pretty clean.
Replacing the condenser fan motor and cap would be an easy job for me, if ever needed.
Replacing the condenser fan motor and cap would be an easy job for me, if ever needed.
Depends on where you live and the system/house you're talking about.
My house has dual zone 13 SEER condensers. Single speed fans. When I first bought the place I was told in the Summer to set the thermostats and leave it. That worked until I got the first bill. Never made any sense to begin with. But it's simple advice.
Started experimenting. Cut a long story short I installed two digital/programmable thermostats. Programmed them to raise the temp just before I leave in the morning to 79 degrees. 20 minutes before I usually get home down to 75 degrees. In the winter I do something similar. cut a nice chunk out of my utility bill with just a bit of setup time.
My house has dual zone 13 SEER condensers. Single speed fans. When I first bought the place I was told in the Summer to set the thermostats and leave it. That worked until I got the first bill. Never made any sense to begin with. But it's simple advice.
Started experimenting. Cut a long story short I installed two digital/programmable thermostats. Programmed them to raise the temp just before I leave in the morning to 79 degrees. 20 minutes before I usually get home down to 75 degrees. In the winter I do something similar. cut a nice chunk out of my utility bill with just a bit of setup time.
^Yes, I also use a programmable stat. I let mine go up to 77 when I'm not there and drop to 72 by the time I get home. An A/C contractor I worked with a long time ago told me that five degrees is about all the setback you should allow. Any more than that and, when it's 100 outside, you won't get your house to the temp you want while the sun's still up. And, the system has to work extra hard to bring the temp back down. Heat energy is stored in everything - walls, furniture, floors, etc. I know people who set theirs up to 85 when they are not there and their houses are always hot - to me.
When I was unemployed in the summer of 2008 I pretty much left it set at 72 all the time and, honestly, I didn't notice any big difference in the bill. But, summer heat does vary. The number of triple digit days can change as much as 100% from year to year. I contract my electric service every year in the spring, but it has been pretty steady at between eight and nine cents per kWh for several years now. With a total annual usage of about 12,000 kWh fractional cents don't make a massive difference.
When I was unemployed in the summer of 2008 I pretty much left it set at 72 all the time and, honestly, I didn't notice any big difference in the bill. But, summer heat does vary. The number of triple digit days can change as much as 100% from year to year. I contract my electric service every year in the spring, but it has been pretty steady at between eight and nine cents per kWh for several years now. With a total annual usage of about 12,000 kWh fractional cents don't make a massive difference.
Originally Posted By: DBMaster
I partially disassemble my condenser unit annually to spray cleaner and hose the coil from the inside. I did created access to the evaporator in the attic and once vacuumed it in the winter when it was dry, but the pleated filters I use, plus the weather stripping I added around the filter frame keeps the air going across the evap pretty clean.
Replacing the condenser fan motor and cap would be an easy job for me, if ever needed.
A thorough yearly cleaning, both condensor & evaporator coils, is key to going the distance. Over the years I learned a lot about A/C from a textbook and poking around, as I didn't even know enough to ask intelligent questions. Otherwise it's far too easy to get taken advantage of or scared (your freon is now BANNED!) into taking an unwise action against your own best interests...if you knew them.
Letting someone else do your thinking for you rarely works in your favor.
I partially disassemble my condenser unit annually to spray cleaner and hose the coil from the inside. I did created access to the evaporator in the attic and once vacuumed it in the winter when it was dry, but the pleated filters I use, plus the weather stripping I added around the filter frame keeps the air going across the evap pretty clean.
Replacing the condenser fan motor and cap would be an easy job for me, if ever needed.
A thorough yearly cleaning, both condensor & evaporator coils, is key to going the distance. Over the years I learned a lot about A/C from a textbook and poking around, as I didn't even know enough to ask intelligent questions. Otherwise it's far too easy to get taken advantage of or scared (your freon is now BANNED!) into taking an unwise action against your own best interests...if you knew them.
Letting someone else do your thinking for you rarely works in your favor.
Ha! I know that R-22 is not banned. In fact, after several price increases last year it has actually come down in price several dollars per pound. I buy all the refrigerant for Lennox in the U.S. The manufacture is curtailed by the Montreal Protocol, but there is PLENTY of it out there - more than enough to keep your systems running for years. I would not even let that worry enter your minds. In addition to that, there are a number of replacement blends that will work just fine.
In short, don't let anyone sell you a new system just because R-22 is being replaced by R-410A. R410-A has actually been on worldwide backorder a few times already due the shortages of the R-125 that is half of the blend.
Do your research. Don't fall for the hype.
In short, don't let anyone sell you a new system just because R-22 is being replaced by R-410A. R410-A has actually been on worldwide backorder a few times already due the shortages of the R-125 that is half of the blend.
Do your research. Don't fall for the hype.
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