HVAC filters

[RyanY]

I'll try to answer a few of your questions.
A 3 ton is a 3 ton no matter the age or refrigerant used.
If there is any difference, you may not be running at full capacity due to its age.

The difference between your house and the neighbors is the second story.
You have part of the house with cooled space above.... you have less heat gain.
Units are sized by sq ft, insulation values and design temp. Maybe some other thing I have forgotten, I'm not an engineer.

A simple HVAC as described is either on or off.
It only works at one speed.
If it is hotter outside, the compressor will have higher pressures and pull more amps.
A HVAC does not "cool" the air, it removes heat. The hotter it is outside, the harder it is to get rid of the heat gathered.
Heat pups have to gather heat from outside and bring it in. That is why they are less effective in colder climates.
Temperature setpoint or humidity have no effect on how hard a HVAC works.....just how long it runs.
Your unit does not "know" what the temperature is...it is either on or off as controlled by the TStat.
Unless a humidistat has been added...humidity has no effect on run time.

A properly sized unit will run long enough to control humidity.
Some engineers will oversize the evaporator coils in humid areas by 1/2 ton just for the extra surface area.
Allows for more condensate to form and run off.

An oversized unit may not have enough runtime to allow enough condensate to form and run off the coil to the drain.
I have had buildings that had drastically oversized units. They did not run long enough for the condensate to run off the coil.
In those cases, the condensate just evaporated and re-entered the space.
The air exiting the evaporator coil is at 100% humidity.
When that air warms and expands the humidity lowers.

Undersized units or undercharged units do not form condensate well.
The evap coil is not getting cold enough.
As a simple rule of thumb, your suction line should have condensate on it all the way back to the compressor...but not on the compressor body.

The best way to run a system in cooling mode is fan on.
It keeps interior temperatures more even and prevents hot spots.
Acts like a ceiling fan. The extra run time us somewhat offset by the lack of starting amps from the start stop of "Auto" operation.
A utility company class I took long ago said it was cheaper to run the fan all the time.
That may have changed.

In Heat mode, fan on auto.

Thank you! That explanation makes a lot of sense, and helps me understand why the neighbor's unit is effective even though his house is a lot smaller than mine. Another point is that I have a lot of large trees, whereas he does not.

 

[hrv]

I have a portable dehumidifier and when we had some really bad humid days (inside the house, over 50% is noticeable), I ran it. It got it down to 42-45% humidity and it felt much better. I'd like to run it much more but it's a bit noisey.

I do the same here in Louisville as it gets hot and very humid at times..

 

[hrv]

Thank you! That explanation makes a lot of sense, and helps me understand why the neighbor's unit is effective even though his house is a lot smaller than mine. Another point is that I have a lot of large trees, whereas he does not.

You are so right. When my Carrier was installed in 2017 it is a 2 ton hvac with a 2.5 ton evaporator...Why??? It takes out more of the humidity...

 

[hrv]

Dehumidification takes time, and a unit that is oversized will short-cycle on and off more frequently (since thermostat set point is reached more quickly) instead of running longer to reach set point and therefore dehumidifying more effectively. You are also less comfortable with an oversized unit not only due to increased humidity but also due to increased temperature swings. Lastly, you have to keep in mind matching the air handler to the exterior unit...they have to be sized well to work together. In my case the furnace (air handler) is sized for heat needs and not cooling needs, but that's how it should be given my far north climate.

YUP in this case...Bigger is NOT better..

 

[hrv]

I'll try to answer a few of your questions.
A 3 ton is a 3 ton no matter the age or refrigerant used.
If there is any difference, you may not be running at full capacity due to its age.

The difference between your house and the neighbors is the second story.
You have part of the house with cooled space above.... you have less heat gain.
Units are sized by sq ft, insulation values and design temp. Maybe some other thing I have forgotten, I'm not an engineer.

A simple HVAC as described is either on or off.
It only works at one speed.
If it is hotter outside, the compressor will have higher pressures and pull more amps.
A HVAC does not "cool" the air, it removes heat. The hotter it is outside, the harder it is to get rid of the heat gathered.
Heat pups have to gather heat from outside and bring it in. That is why they are less effective in colder climates.
Temperature setpoint or humidity have no effect on how hard a HVAC works.....just how long it runs.
Your unit does not "know" what the temperature is...it is either on or off as controlled by the TStat.
Unless a humidistat has been added...humidity has no effect on run time.

A properly sized unit will run long enough to control humidity.
Some engineers will oversize the evaporator coils in humid areas by 1/2 ton just for the extra surface area.
Allows for more condensate to form and run off.

An oversized unit may not have enough runtime to allow enough condensate to form and run off the coil to the drain.
I have had buildings that had drastically oversized units. They did not run long enough for the condensate to run off the coil.
In those cases, the condensate just evaporated and re-entered the space.
The air exiting the evaporator coil is at 100% humidity.
When that air warms and expands the humidity lowers.

Undersized units or undercharged units do not form condensate well.
The evap coil is not getting cold enough.
As a simple rule of thumb, your suction line should have condensate on it all the way back to the compressor...but not on the compressor body.

The best way to run a system in cooling mode is fan on.
It keeps interior temperatures more even and prevents hot spots.
Acts like a ceiling fan. The extra run time us somewhat offset by the lack of starting amps from the start stop of "Auto" operation.
A utility company class I took long ago said it was cheaper to run the fan all the time.
That may have changed.

In Heat mode, fan on auto.

or dont fun the fan and run the ceiling fan...they tend to use less electricity..

 

[KJSmith]

or dont fun the fan and run the ceiling fan...they tend to use less electricity..

Ceiling fans typically are for a single room.

The reason to run the unit fan is to keep the air moving through the whole house.
Gets rid of of warm areas.
Brings air back by the TStat for better control.

Makes a bigger difference than you would think.
Try it.

 

[hrv]

Ceiling fans typically are for a single room.

The reason to run the unit fan is to keep the air moving through the whole house.
Gets rid of of warm areas.
Brings air back by the TStat for better control.

Makes a bigger difference than you would think.
Try it.

You are right but the ceiling fans will work maybe not as good but use less electricity..

 

[KevinMalone]

The best way to run a system in cooling mode is fan on.
It keeps interior temperatures more even and prevents hot spots.
Acts like a ceiling fan.

I've read that it was better to have the fan on only when cooling is called for. The rationale was that if the fan was always on, it would increase humidity as it would blow air across the condensation on the coils. This seems to be supported by data as well

https://www.americanheat.com/reason-to-not-run-your-ac-fan-during-summer/

 

[Hall]

I do the same here in Louisville as it gets hot and very humid at times..

I think a lot of people are surprised by how warm and humid we can get in the midwest. It's not Florida hot and humid by any stretch but we easily see 95º F and higher and 50% and higher humidity in the summer.

 

[KJSmith]

I've read that it was better to have the fan on only when cooling is called for. The rationale was that if the fan was always on, it would increase humidity as it would blow air across the condensation

If your unit is oversized and running in short cycles it can be a problem.

A properly sized unit will run long enough to allow condensate to drain off.
A dirty evaporator can slow the condensate from dripping off the coil.

The first couple of lines in that article said many techs and manufacturers recommend running the fan all the time.

It's recommended for overall comfort in cooling mode.

I have never seen anyone recommend running a fan full time in heating mode in a residential application.

In commercial buildings fans run all the time.

My suggestion is to try it for a week and see what you think.

 

[alarmguy]

I know it varies, but the old rule of thumb was 1 ton per 400 square feet.

I’m being told now it’s 600-700 sq ft depending on building materials and shade such as tree lines

This is a great thread, based on both your posts I found this. We have a 2 ton unit as factorytuned2012 does, its been very satisfactory for the last year but then two weeks ago I started to wonder, as posted after having company over, oven going, HOT Humid day (though we have lots of those) and the poor choice of having the thermostat set at 77 before the company arrived, after turning it down to 75 the the temperature did not go lower, it fact the unity ran constantly and went from 77 to 79. I was measuring input and output temperatures and thought I only had a spread of 12 degrees. FOR THAT DAY, thinking maybe I need a small amount of freon that was never properly filled.

However last night I measured the spread again and it was 14 degrees maybe 15. Now I am wondering if the probe on my state of the art meat thermometer is the correct instrument to use *LOL* When using my IR temperature gun last night pointed at the intake and output grills, we were a solid 20 degree spread. Yes, it was nighttime and just my wife and I, after dinner but I think this would suggest the freon charge is correct. Anyway I am going to keep a log, I want to mention again, a home inspector also had satisfactory results, I cant remember but think I remember him having probes in the intake and exhaust.

Anyway, purpose of my posts are I just want to make sure the system is charged fully and was disappointed even though out of warranty by 4 months, they wanted $85 to come to the house and check. Rubs me the wrong way in a new community that they are in almost every day to check a system they installed that is supposed to give 10 to 20 years worth of service. Thanks to factory tuned that I have learned I have a 2 ton unit which is marginal and I am ok with that in this particular house because it has been very good until that ill-fated day *LOL* Granted now I wish it was 2.5 tons.

One other note, past house built new, 3000 sq ft some areas 16 ft ceilings, a LOT of west windows with only tinted glass, lived there 16 years, two builder supplied Heil units never an issue except one. Main floor unit always seemed a little too warm. Had a few people look at it and one of the biggest scams was a company that wanted to put a whole new main floor unit in, when all I wanted was some freon.
Anyway, (I forgot, think it was r22) Livied like that for a while, I mean it was ok cooling just not great and second floor unit would pick up the slack. Turns out, I FIGURE THIS OUT MYSELF. Our units at the time, were made to handle to the new freon and could be converted, therefore the system could handle the higher pressures. I dont know but whatever, I bought a big tank of R22 and gauges on eBay for a bargain and I filled the unit to the same pressures I measured on the second floor unit that the one scam company would not do. System ran perfect and still does over a decade later.

You may find this interesting - "Sizing an HVAC system by square footage is a very crude general rule of thumb. It sounds like the contractors built an efficient house and sized the hvac system appropriate for your home."
https://learnmetrics.com/ac-tonnage-calculator/

 

[alarmguy]

The best way to run a system in cooling mode is fan on.
It keeps interior temperatures more even and prevents hot spots.
Acts like a ceiling fan. The extra run time us somewhat offset by the lack of starting amps from the start stop of "Auto" operation.
A utility company class I took long ago said it was cheaper to run the fan all the time.
That may have changed.

In Heat mode, fan on auto.

This is the one thing I cant agree with, one size in my opinion doesn't fit all.
IF I run the fan all the time, first I am adding wear and tear to the blower motor and constantly using energy powering it, but second, with the evaporator and ductwork in the attic its like I am taking the hot air from the attic as it heats and distributing it to the house with the fan running all the time when cooling is not required.

At night if temps are low in the 50s time of year. Honeywell thermostats have a neat fan feature. It has 3 settings, "AUTO" - "ON" - "CIR"
I love the "CIR" circulate feature as the cool attic temps will cool down the ductwork and the CIR feature turns the fan on 20 minutes per hour even if cooling isnt required and will circulate the air in and out of the bedrooms.
This is also VERY handy in the summer when guests are here. AS most sleep with doors closed the CIR feature will stabilize the temperature in the bedrooms without the fan constantly blowing. I wouldnt own any other thermostat for this reason.
https://thermostating.com/what-does-circ-mean-on-the-thermostat/#google_vignette

 

[hrv]

This is the one thing I cant agree with, one size in my opinion doesn't fit all.
IF I run the fan all the time, first I am adding wear and tear to the blower motor and constantly using energy powering it, but second, with the evaporator and ductwork in the attic its like I am taking the hot air from the attic as it heats and distributing it to the house with the fan running when cooling is not required.

At night if temps are low in the 50s time of year. Honeywell thermostats have a neat fan feature. It has 3 settings, "AUTO" - "ON" - "CIR"
I love the "CIR" circulate feature as the cool attic temps will cool down the ductwork and the CIR feature turns the fan on 20 minutes per hour even if cooling isnt required and will circulate the air in and out of the bedrooms.
This is also VERY handy in the summer when guests are here. AS most sleep with doors closed the CIR feature will stabilize the temperature in the bedrooms. I wouldnt own any other thermostat for this reason.
https://thermostating.com/what-does-circ-mean-on-the-thermostat/#google_vignette

I have the same and like that feature too...

 

[BrainThicknessVariation]

The 3M purple filters are the only way to go. They go on sale from time to time on Amazon and Costco.

 

[I<3oil]

I think a lot of people are surprised by how warm and humid we can get in the midwest. It's not Florida hot and humid by any stretch but we easily see 95º F and higher and 50% and higher humidity in the summer.

Right now it's only 75* but 84% humidity. High for today is 98*. It's gonna be 105-110* heat index.

Blech

 

[hrv]

Right now it's only 75* but 84% humidity. High for today is 98*. It's gonna be 105-110* heat index.

Blech

I have placed a 3 gallon bucket where the HVAC drains and some times I will set it out in the evening and when I wake up in the morning the bucket is full and sometimes overflowing on very humid days and night...HVAC is doing its job...

 

[KJSmith]

This is the one thing I cant agree with, one size in my opinion doesn't fit all.

I should add that my opinions are based on where I live and work..... well, used to work....Texas.
Currently SE Texas.
High humidity and temperatures that are staying above 80f at night.

 

[factorytuned2012]

This is a great thread, based on both your posts I found this. We have a 2 ton unit as factorytuned2012 does, its been very satisfactory for the last year but then two weeks ago I started to wonder, as posted after having company over, oven going, HOT Humid day (though we have lots of those) and the poor choice of having the thermostat set at 77 before the company arrived, after turning it down to 75 the the temperature did not go lower, it fact the unity ran constantly and went from 77 to 79. I was measuring input and output temperatures and thought I only had a spread of 12 degrees. FOR THAT DAY, thinking maybe I need a small amount of freon that was never properly filled.

However last night I measured the spread again and it was 14 degrees maybe 15. Now I am wondering if the probe on my state of the art meat thermometer is the correct instrument to use *LOL* When using my IR temperature gun last night pointed at the intake and output grills, we were a solid 20 degree spread. Yes, it was nighttime and just my wife and I, after dinner but I think this would suggest the freon charge is correct. Anyway I am going to keep a log, I want to mention again, a home inspector also had satisfactory results, I cant remember but think I remember him having probes in the intake and exhaust.

Anyway, purpose of my posts are I just want to make sure the system is charged fully and was disappointed even though out of warranty by 4 months, they wanted $85 to come to the house and check. Rubs me the wrong way in a new community that they are in almost every day to check a system they installed that is supposed to give 10 to 20 years worth of service. Thanks to factory tuned that I have learned I have a 2 ton unit which is marginal and I am ok with that in this particular house because it has been very good until that ill-fated day *LOL* Granted now I wish it was 2.5 tons.

One other note, past house built new, 3000 sq ft some areas 16 ft ceilings, a LOT of west windows with only tinted glass, lived there 16 years, two builder supplied Heil units never an issue except one. Main floor unit always seemed a little too warm. Had a few people look at it and one of the biggest scams was a company that wanted to put a whole new main floor unit in, when all I wanted was some freon.
Anyway, (I forgot, think it was r22) Livied like that for a while, I mean it was ok cooling just not great and second floor unit would pick up the slack. Turns out, I FIGURE THIS OUT MYSELF. Our units at the time, were made to handle to the new freon and could be converted, therefore the system could handle the higher pressures. I dont know but whatever, I bought a big tank of R22 and gauges on eBay for a bargain and I filled the unit to the same pressures I measured on the second floor unit that the one scam company would not do. System ran perfect and still does over a decade later.

You may find this interesting - "Sizing an HVAC system by square footage is a very crude general rule of thumb. It sounds like the contractors built an efficient house and sized the hvac system appropriate for your home."
https://learnmetrics.com/ac-tonnage-calculator/

Yes indeed good content here all sparked by filters.

 

[alarmguy]

I should add that my opinions are based on where I live and work..... well, used to work....Texas.
Currently SE Texas.
High humidity and temperatures that are staying above 80f at night.

Yeah, agree, same here now on the coast, past home was the midlands 2 hours from the coast, much dryer but hotter.
Im happy with our new home and AC but I think like factorytuned posted another .5 ton might have been nice and at the same time, our house is nice and dry all the time, so I dont know. I would be concerned with moisture for sure.

I might actually buy two remote thermometers and place one inside the intake and another at an output.

 

[KJSmith]

our house is nice and dry all the time,

You can spend a lot of money trying to get just a little bit better.
Probably not worth it.

Your circulation feature may actually cost more than running the fan full time.
A lot of energy is used starting the motor 2-3 times an hour.
But we are discussing comfort...not energy savings.... and probably not enough to really matter.
Wear and tear are a moot point.
Indoor fan motors are very robust...they last forever.
In commercial settings you run them 24/7/365 and they still last forever.