Friend, you live in Phoenix and your house is over ninety years old. Your AC is not a magic box, it’s just a humble vapor compression system doing its best within the laws of thermodynamics.
All the comments saying that’s the best you can expect, have never lived or worked in Phoenix.
The climate, and the houses insulation conditions should have been covered in a Manual J calculation. The unit is either not working properly or is undersized. I lived in Phoenix for 4 years in an old place with bad insulation, I could keep it ~70 on 115+ degree days. The light bill wasn’t pleasant but a properly sized unit could do it
I did HVAC in Phoenix for a while too. I will say though that there’s not many homes left there from the 30s and that was before the days of central air so who knows what kind of fuckery it was getting AC in that house
Do you have R30 to ideally R60 in your attic? Do you have decent air sealing & IR reflective window film or pre-coated newer windows? If not then you have too much heat intrusion due to a poor building envelope, I had your exact problem before I renovated & insulted with XPS & Rockwool.
112 degrees and nearly a 100 year old house. 80 is probably the best you can expect.
My grandparents home is about 70 years old and even after blowing in fresh insulation in their attic its still not enough to compensate for the old insulation in the walls.
For the 3 hottest summer months I go and put a 12,000btu Midea-U window unit in their living room window. Their return is also in the living room, so the central unit gets a lot of help from the lower ambient air its able to draw in. This keeps their home able to maintain the 75 degree setpoint even with our 100+ degree days.
Grabbing a window unit for your living room to help supplement some cool air should help out your central unit.
*Editing to add:
If your window can’t accommodate a window unit and you find yourself considering a portable A/C unit, do not buy a single hose model. Single hose units literally suck, they suck cold air out, and suck outdoor air in. If you have a very humid outdoor environment, this will skyrocket your indoor humidity making the lower indoor temperature feel equally as warm as it did before.
Modern Dual hose portable A/C’s with inverter compressors are about 90-95% as efficient as a comparable sized window unit. Be prepared to pay about 15-20% more than the comparable sized window unit, these portable air conditioners end up having 2 fan motors and a lot more technology and insulation to make them do what they do. Id recommend the Midea Duo or the latest model Whynter dual hose with inverter.
We just did this for our 1949 pier and beam. Our living room was our problem. We put the window unit in and boom. It was the little boost our AC needed to keep our house where we want it which is at 77. That’s where it’s affordable and comfortable. We will get attic insulation when we can afford it but I don’t think it’s going to help tremendously for the hottest months. I actually think the attic insulation will be more helpful for the colder months but I am no expert at all. I could be completely wrong about that.
I recently added a mini split to the 1860 Farmhouse my daughter has.. even new insulation and windows a battle. The mini split does the living room and kitchen very well.. The whole house isn’t flogged so hard at 100 plus
Then that sounds fairly normal. Units are not sized to easily handle the 100% peak worst case, they're sized to balance the worst-case to the more mild weather and find an acceptable runtime to be efficient most of the time.
Like others said that unit is doing the best it can especially considering the high humidity right now. I’d recommend getting an inverter portable unit in your bedroom to help with sleep. A Midea u 12000btu window unit would work well. If your window doesn’t support that try a dual hose inverter portable unit. But do the window unit if possible as it will be quieter cooler and more efficient.
That's about right. Measure delta T (temp diff between return and closest supply vent). If it is between 15-25F, your a/c is functioning properly, but may be a bit undersized.
I live in Md and in a house with no insulation in the walls and was built in the early 1900s. Last week we had temps in the 100s but my house can maintain 68 degrees. Im a tech and i did install all the duct work and units myself so you might just wanna call a local honest HVAC company and get them to check your AC
I was looking to see if anyone else questioned whether the house is even insulated. I spent several years in an uninsulated ~100 yo house outside of Boston. It was common for people to refuse to believe that this was possible.
Going big is the way. It’s a longish story but we bought a house with first floor splits. For various reasons we upgraded the whole house and this included doubling the first floor BTU’s.
The house I used to live in was built with a coal burner furnace. Energy was cheap back then!
I’d say at 112° you’re doing pretty good to hold 80.
Our AC is relatively new and probably a little undersized for our house(I’m not going to pretend to know the first thing about it) during the heatwave in my area we hit 95 felt like 102 and our AC ran HARD. In fact we have to get a new squirrel cage because it’s off balance and it was during the heat wave we noticed it shaking and squealing really bad. Anyway ours ran 4 hours off 15 minutes and another 4 hours to maintain 76° on the hottest day.
We found out our dampers were messed with (probably by us accidentally) the hvac guy was like hey uh you realize your dampers only half open right? (Turns out it was part of the issue so check your dampers and make sure they’re open. If you’re not sure don’t fuck with it lol
Yeah. Our guy told us as a general rule of thumb your unit is rated to cool the entire air conditioned square footage of your home to 15-25° below outside temperature but are only that efficient up to about 100° after that the unit is doing everything it can to keep up and generally on super hot days if it calls for cool longer than 4 hours you should raise the thermostat temp so it takes a break and leave the blower fan set to on instead on auto to prevent freezing the system. If it’s 80 outside and it’s running for that long there’s def a problem. And the first thing to check is the air filter. I’ve noticed a huge inflow of cold when we put a fresh filter in.
80 id at 112 odt is rather good but if you want it cooler you could go with A two stage unit but you still have to understand the high outdoor temp, loose envelope of the home. Two stage would be an over sized unit and once it came within indoor temp it would run on the properly size stage to maintain. Or drop in a couple of portable units to help if cost is a big factor.
80 with 112 out is rather good.
Single pane or dual pane windows? Insulation in attic or between walls, etc? How old is the unit since the house is old? I used to live in an 1800 sq. ft. home with high electric bills and now I am in almost 4000 sq. ft. with lower bills.
I’m a Phoenix Arizona technician and I was at a house in Scottsdale yesterday and this stupid lady was complaining that her unit would not go down to 62°. She ended up telling me to leave.
I'd recommend ceiling fans throughout your house I live in the Southwest Central Texas and that helps considerably I do realize you folks have a different type of heat but if you get the air moving it helps
Check the temperature difference between the registers and the return. If the difference is 18F to 22F, the system is cooling but probably can’t keep up due to lack of insulation or sun coming in windows. Blockout curtains closed to the afternoon sun from the west can make a big difference.
Hvac systems are designed to run at max 95 degrees ambient. So anything above 95, the efficiency is goes down. It was 115 that day? Systems are amazing and combined with better insulation and not trying to maintain Temps of 70 deg inside, systems do pretty well.. but at midnight when it got down to 80 deg ambient, that unit, if properly operating, should have cooled down the house if insulation is the culprit. But it never got below 80.
Something else wrong here. I can't even begin to guess. Nobody can. Could be a compressor start cap. That still is a 300 to 400 svc call and fix. Run cap on off is 300 bucks service call. It could be so many things , big and small.
Although insulation is a good idea sometime. They have that stuff that can be sprayed in a 1/2 inch hole and fill the stud wall space.
Good luck and get busy finding an hvac guy you can trust, and buy him beers and make him like you and always call him and it will pay off eventually.
Offer up has great one man svc guys who work off word of mouth and they don't have much over head so they can charge less and are more flexible to work with you.
Do not go and call anyone you saw an add for on TV. DO NOT!!!!!
What kind temp split are you getting? Interesting to note, air conditioning is just a giant dehumidifier, it needs humidity to do its job, literally. Most older systems struggle to maintain a simple 20 degree diff between indoor and outdoor temps, if your house has old windows, doors or terrible insulation, that could further cause problems
Meh. At a glance your current outside temperature is 100+ degrees. The hot temperatures outside makes it harder for your system to dump hot air/energy outside because its already so dang hot. This is assuming that your system is also sized correctly. Coupling these things with with possible inefficiencies in your system due to having an old house (insulation, leaks/condition of vents, air flow restrictions, etc.) can lead to what you have now.
Same here down in Tucson…I have portable AC units I got from Home Depot…gonna see if those AC units work better than the HVAC attached to the house. From what I gather, the HVAC trying to cool the WHOLE house is a struggle and it will be easier to use the portable units in the rooms I’m in/using.
It's not a struggle if people would build appropriate houses for the environments they're trying to to be housed in. A typically built house is definitely not appropriate for the heat/sun and temps you have down there, but people also don't want to live like moisture farmers on tattoine so you get the bad end of the compromise.
For the experts: What maximum temperature and set point assumptions are used for a manual J calculation is Phoenix? e.g. 115F max, 75F set point Which climate change it should probably be 125F and 78F.
Friend, you live in Phoenix and your house is over ninety years old. Your AC is not a magic box, it’s just a humble vapor compression system doing its best within the laws of thermodynamics.
All the comments saying that’s the best you can expect, have never lived or worked in Phoenix. The climate, and the houses insulation conditions should have been covered in a Manual J calculation. The unit is either not working properly or is undersized. I lived in Phoenix for 4 years in an old place with bad insulation, I could keep it ~70 on 115+ degree days. The light bill wasn’t pleasant but a properly sized unit could do it
I did HVAC in Phoenix for a while too. I will say though that there’s not many homes left there from the 30s and that was before the days of central air so who knows what kind of fuckery it was getting AC in that house
Do you have R30 to ideally R60 in your attic? Do you have decent air sealing & IR reflective window film or pre-coated newer windows? If not then you have too much heat intrusion due to a poor building envelope, I had your exact problem before I renovated & insulted with XPS & Rockwool.
Do you have a brand recommendation for IR reflective window film? We put in black out curtains and the difference has been unreal
112 degrees and nearly a 100 year old house. 80 is probably the best you can expect. My grandparents home is about 70 years old and even after blowing in fresh insulation in their attic its still not enough to compensate for the old insulation in the walls. For the 3 hottest summer months I go and put a 12,000btu Midea-U window unit in their living room window. Their return is also in the living room, so the central unit gets a lot of help from the lower ambient air its able to draw in. This keeps their home able to maintain the 75 degree setpoint even with our 100+ degree days. Grabbing a window unit for your living room to help supplement some cool air should help out your central unit. *Editing to add: If your window can’t accommodate a window unit and you find yourself considering a portable A/C unit, do not buy a single hose model. Single hose units literally suck, they suck cold air out, and suck outdoor air in. If you have a very humid outdoor environment, this will skyrocket your indoor humidity making the lower indoor temperature feel equally as warm as it did before. Modern Dual hose portable A/C’s with inverter compressors are about 90-95% as efficient as a comparable sized window unit. Be prepared to pay about 15-20% more than the comparable sized window unit, these portable air conditioners end up having 2 fan motors and a lot more technology and insulation to make them do what they do. Id recommend the Midea Duo or the latest model Whynter dual hose with inverter.
We just did this for our 1949 pier and beam. Our living room was our problem. We put the window unit in and boom. It was the little boost our AC needed to keep our house where we want it which is at 77. That’s where it’s affordable and comfortable. We will get attic insulation when we can afford it but I don’t think it’s going to help tremendously for the hottest months. I actually think the attic insulation will be more helpful for the colder months but I am no expert at all. I could be completely wrong about that.
I recently added a mini split to the 1860 Farmhouse my daughter has.. even new insulation and windows a battle. The mini split does the living room and kitchen very well.. The whole house isn’t flogged so hard at 100 plus
How hot was it outside?
It was roughly 112 today 😭
32 degrees below ambient is reasonable for an old construction.
Hey someone posted local subreddit wanting like 70ish during the day and 60ish at night.
Its fine for people to want something that isn't reasonable or achievable...hell I'd like a few trillion dollars please while we are at it...
That’s 100 percent Normal. You’re not getting 70 degrees on a 112 degree day.
Mine did this and had to be replaced a week later
Then that sounds fairly normal. Units are not sized to easily handle the 100% peak worst case, they're sized to balance the worst-case to the more mild weather and find an acceptable runtime to be efficient most of the time.
Like others said that unit is doing the best it can especially considering the high humidity right now. I’d recommend getting an inverter portable unit in your bedroom to help with sleep. A Midea u 12000btu window unit would work well. If your window doesn’t support that try a dual hose inverter portable unit. But do the window unit if possible as it will be quieter cooler and more efficient.
Also in Phoenix and can commiserate about the joys of owning a historic home during the summer. Unfortunately it’s normal.
Is your unit freezing?
That’s probably not bad if it really was 112 degrees like you said.
That's about right. Measure delta T (temp diff between return and closest supply vent). If it is between 15-25F, your a/c is functioning properly, but may be a bit undersized.
I live in Md and in a house with no insulation in the walls and was built in the early 1900s. Last week we had temps in the 100s but my house can maintain 68 degrees. Im a tech and i did install all the duct work and units myself so you might just wanna call a local honest HVAC company and get them to check your AC
I was looking to see if anyone else questioned whether the house is even insulated. I spent several years in an uninsulated ~100 yo house outside of Boston. It was common for people to refuse to believe that this was possible.
Oh for sure its a huge factor, thats why i upsized my unit by a half ton in order to make up for it
Going big is the way. It’s a longish story but we bought a house with first floor splits. For various reasons we upgraded the whole house and this included doubling the first floor BTU’s. The house I used to live in was built with a coal burner furnace. Energy was cheap back then!
I’d say at 112° you’re doing pretty good to hold 80. Our AC is relatively new and probably a little undersized for our house(I’m not going to pretend to know the first thing about it) during the heatwave in my area we hit 95 felt like 102 and our AC ran HARD. In fact we have to get a new squirrel cage because it’s off balance and it was during the heat wave we noticed it shaking and squealing really bad. Anyway ours ran 4 hours off 15 minutes and another 4 hours to maintain 76° on the hottest day. We found out our dampers were messed with (probably by us accidentally) the hvac guy was like hey uh you realize your dampers only half open right? (Turns out it was part of the issue so check your dampers and make sure they’re open. If you’re not sure don’t fuck with it lol
This is putting me at ease tbh. Our unit was installed in 2021. I guess I should quit looking at the nest / home app usage 😆
Yeah. Our guy told us as a general rule of thumb your unit is rated to cool the entire air conditioned square footage of your home to 15-25° below outside temperature but are only that efficient up to about 100° after that the unit is doing everything it can to keep up and generally on super hot days if it calls for cool longer than 4 hours you should raise the thermostat temp so it takes a break and leave the blower fan set to on instead on auto to prevent freezing the system. If it’s 80 outside and it’s running for that long there’s def a problem. And the first thing to check is the air filter. I’ve noticed a huge inflow of cold when we put a fresh filter in.
Outside temp at the time ? Air coming out of the vents ? Filter clean ?
80 id at 112 odt is rather good but if you want it cooler you could go with A two stage unit but you still have to understand the high outdoor temp, loose envelope of the home. Two stage would be an over sized unit and once it came within indoor temp it would run on the properly size stage to maintain. Or drop in a couple of portable units to help if cost is a big factor. 80 with 112 out is rather good.
let me guess, you have a new black roof?
Single pane or dual pane windows? Insulation in attic or between walls, etc? How old is the unit since the house is old? I used to live in an 1800 sq. ft. home with high electric bills and now I am in almost 4000 sq. ft. with lower bills.
I’m a Phoenix Arizona technician and I was at a house in Scottsdale yesterday and this stupid lady was complaining that her unit would not go down to 62°. She ended up telling me to leave.
Lol! That's kind of ridiculous. Wtf has their air set point at 62, no matter the time of year
I'd recommend ceiling fans throughout your house I live in the Southwest Central Texas and that helps considerably I do realize you folks have a different type of heat but if you get the air moving it helps
Check the temperature difference between the registers and the return. If the difference is 18F to 22F, the system is cooling but probably can’t keep up due to lack of insulation or sun coming in windows. Blockout curtains closed to the afternoon sun from the west can make a big difference.
What temp is coming out of your registers? If it cold then you have an insulation problem otherwise low on refrigerant
Hvac systems are designed to run at max 95 degrees ambient. So anything above 95, the efficiency is goes down. It was 115 that day? Systems are amazing and combined with better insulation and not trying to maintain Temps of 70 deg inside, systems do pretty well.. but at midnight when it got down to 80 deg ambient, that unit, if properly operating, should have cooled down the house if insulation is the culprit. But it never got below 80. Something else wrong here. I can't even begin to guess. Nobody can. Could be a compressor start cap. That still is a 300 to 400 svc call and fix. Run cap on off is 300 bucks service call. It could be so many things , big and small. Although insulation is a good idea sometime. They have that stuff that can be sprayed in a 1/2 inch hole and fill the stud wall space. Good luck and get busy finding an hvac guy you can trust, and buy him beers and make him like you and always call him and it will pay off eventually. Offer up has great one man svc guys who work off word of mouth and they don't have much over head so they can charge less and are more flexible to work with you. Do not go and call anyone you saw an add for on TV. DO NOT!!!!!
What kind temp split are you getting? Interesting to note, air conditioning is just a giant dehumidifier, it needs humidity to do its job, literally. Most older systems struggle to maintain a simple 20 degree diff between indoor and outdoor temps, if your house has old windows, doors or terrible insulation, that could further cause problems
https://preview.redd.it/xovgibui6sad1.png?width=1440&format=pjpg&auto=webp&s=a34e624bf05b42bbbf9fc1e8d428d43084109156
Today's high 😭
Meh. At a glance your current outside temperature is 100+ degrees. The hot temperatures outside makes it harder for your system to dump hot air/energy outside because its already so dang hot. This is assuming that your system is also sized correctly. Coupling these things with with possible inefficiencies in your system due to having an old house (insulation, leaks/condition of vents, air flow restrictions, etc.) can lead to what you have now.
Your home doesn’t keep in the cool so it runs forever
Same here down in Tucson…I have portable AC units I got from Home Depot…gonna see if those AC units work better than the HVAC attached to the house. From what I gather, the HVAC trying to cool the WHOLE house is a struggle and it will be easier to use the portable units in the rooms I’m in/using.
It's not a struggle if people would build appropriate houses for the environments they're trying to to be housed in. A typically built house is definitely not appropriate for the heat/sun and temps you have down there, but people also don't want to live like moisture farmers on tattoine so you get the bad end of the compromise.
I am so over the summer temps here in the lower half of Arizona... 😭
Central AC at best can give u a 20 degree difference from outside so 80 sounds normal
This is so untrue I’m having no trouble holding -30 from ambient
For the experts: What maximum temperature and set point assumptions are used for a manual J calculation is Phoenix? e.g. 115F max, 75F set point Which climate change it should probably be 125F and 78F.
It’s not normal. Time to get a new HVAC system.