HVAC Talk

[jrref]

With all the recent heat we have been having here in central Florida, I thought it would be good to have a thread on general HVAC questions and learnings. There are so many misconceptions on HVAC and there are so many "experts" here on TOTV, maybe we can share some knowledge?

To start, I was reading about conventional vs smart thermostats and their potential effects on your HVAC system. We have to assume we are using a basic single or two stage system since newer variable speed systems generally use special thermostats or what they call Wall Units becasue they are small computers that control the different components in a communicating system.

So, which is better a conventional basic thermostat that came with your home or ones like you can get in the hardware store or Nest or Ecobee Smart thermostats? I've had all three and can tell you about my thoughts but can anyone share theirs?

For these types of thermostats:
Which one kept the temperature the most constant?
Which one kept the humidity the most constant?
Which one saved the most money and how do you think it did that?
Which one was the easiest to install and use?

Remember we are talking about basic HVAC systems that go full 100% On and full 100% OFF eventhough some many be two stange.

[retiredguy123]

I have the basic, single stage Carrier heat pump, with the original basic thermostat. It has been working fine for almost 10 years, and every room is within one degree of the thermostat setting. Once, about 6 years ago, my capacitor went bad, and Munn's came out and replaced it within a few hours. There was no charge because he system was still under warranty. The only change I ever made was that I use MERV 11 filters instead of the standard MERV 8 and I change it every 6 months. I found that these seem to make the house quieter and less dusty. I pour a gallon of hot tap water down the condensate drain every month, and I inspect the coils for dirt but I have never needed to clean them, although I have hosed down the outside unit. I have never paid any company for maintenance.

[jrref]

I have the basic, single stage Carrier heat pump, with the original basic thermostat. It has been working fine for almost 10 years, and every room is within one degree of the thermostat setting. Once, about 6 years ago, my capacitor went bad, and Munn's came out and replaced it within a few hours. There was no charge because he system was still under warranty. The only change I ever made was that I use MERV 11 filters instead of the standard MERV 8 and I change it every 6 months. I found that these seem to make the house quieter and less dusty. I pour a gallon of hot tap water down the condensate drain every month, and I inspect the coils for dirt but I have never needed to clean them, although I have hosed down the outside unit. I have never paid any company for maintenance.

I also feel MERV 11 is the best but I wouldn't go above that. With the 4 inch filters you can do this because of the better air flow than a 1 inch filter provides. Since you don't get your unit serviced, I would suggest once a year or whenever you change your filter, get one of these temperature probes and at your air handler measure the difference in temperature at the return and at the output of the air handler. These temperature probes usually have a sharp metal tip where you can easily pierce the duct board. You should measure about 18-20 degree difference. This is a good way to tell if the system is working properly without putting gauges and measureing the pressures, etc.. If it's alot less than you probably want to investigate what could be wrong. When you are done just take some blue tape and cover the two holes on the duct board for next time.

If you change the filter regularly, flush the condensate line once a month, keep the coils clean, If you can, change the start capacitor and contactor with a good American made one and not a cheap Chinese one that costs $12 on Amazon maybe every 5 years, and if you put a surge protector at the outside power disconnect, If you don't develop a leak, your system has a good chance of lasting 10-15 years if it's a heat pump.

If you have one of these installed which in addition to power surges protects against brown outs and over voltages, then you increase your chances even more. RectorSeal RSH-50 VRMDC KIT - AC Unit Surge Protector (https://rectorseal.com/rsh-50-vrmdc-kit/)

Also installing a soft start kit will help but they also can fail.

Although most have the single stage systems, every time they go On they can draw a huge amount of current. Given these Smart Thermostats cycle many times an hour to keep the temperature and humidity more constant, thats a lot of wear and tear. It's kind of like driving your car full throttle all the time then stopping. I don't understand why manufacturers don't install some sort of Soft Start system as part of the unit.

[Bilyclub]

I’m curious to see what most people here try to keep their humidity level at in the house.

[jrref]

I’m curious to see what most people here try to keep their humidity level at in the house.

I set mine to 56%

[retiredguy123]

I’m curious to see what most people here try to keep their humidity level at in the house.
I don't use the optional humidity feature on the standard thermostat. This feature will overcool the house by about 3 degrees to reduce humidity when it exceeds the humidity setting. I always have the feature turned off and I have never had an issue with high humidity. Currently, the relative humidity in the house is 40 percent, and the range from the past 36 hours has been from 37 to 44 percent. My thermostat is set at 78 degrees. You can buy a humidity measuring device from Amazon for about 10 dollars, and it will track the humidity over the past 36 hour time period.

[Michael G.]

My 3 yr. old two stage Carrier installed by Munn's came with a Ecobee Premium Smart thermostat stalled.
I live alone, and home most of the time and have it set "on hold" at 77 degrees 24/7, no auto resets.
Set it and forget it.

Every household has to determine what temp is comfortable for them.
I sleep perfectly at those temps with a ceiling fan running on low in the bedroom.

If I would leave the house, for say a week, I would probably set it @ 80 degrees on hold.

When I lived up north, and my wife and I both worked, the reset thermostats really worked great,
set lower on heating during the day when nobody was home.

[Altavia]

60% on an Ecobee.

The humidity calibration was 8% high, adjusted via the settings.

I've been experimenting with adjusting the minimum on time from 5 min to 10 min to reduce start/up wear and tear on the system.

For the data junkies, there's information available via the reports tab.

[Topspinmo]

not a cheap Chinese One? So, new units come with Chinese ones. My recently installed carrier less than two years old. Will never be able to eliminate Chinese products.

[jrref]

60% on an Ecobee.

The humidity calibration was 8% high, adjusted via the settings.

I've been experimenting with adjusting the minimum on time from 5 min to 10 min to reduce start/up wear and tear on the system.

For the data junkies, there's information available via the reports tab.

I think it would be better adjusting the temperature "Swing". I believe it's set to 4 degrees on the Ecobee meaning 2 degrees above and below your setting. But you are correct, the better the thermostat keeps the temperature at the set point, the more it's running accelerating wear on the compressor.

A thermostat's swing setting, also known as temperature differential or maintenance band, determines how much the temperature fluctuates above or below the setpoint before the heating or cooling system engages. This setting affects how often your HVAC system cycles on and off. A smaller swing setting results in more frequent but shorter cycles, while a larger swing setting leads to fewer but longer cycles.

[jrref]

not a cheap Chinese One? So, new units come with Chinese ones. My recently installed carrier less than two years old. Will never be able to eliminate Chinese products.

Are you sure that capacitor was not changed? Because they never write on the capacitor from the factory. That's usually done by a repair tech, so the next tech knows the values if the description is worn off over time.

[jrref]

You can better find the temperature "sweet spot" that you like by adjusting the set temperature and humidity. In some cases you can set the temperature higher with a lower humidity setting giving your more comfort and efficiency.

On a single stage system it's going to be harder to set the humidity since the system only runs at 100% or Off. With a variable speed system or even a two stage system, you will have better control of the humidity because the system runs longer and slower. My variable speed system sometimes goes into Dehumidifing mode which is running at a very low speed specifically to lower the humidity.

[retiredguy123]

You can better find the temperature "sweet spot" that you like by adjusting the set temperature and humidity. In some cases you can set the temperature higher with a lower humidity setting giving your more comfort and efficiency.

On a single stage system it's going to be harder to set the humidity since the system only runs at 100% or Off. With a variable speed system or even a two stage system, you will have better control of the humidity because the system runs longer and slower. My variable speed system sometimes goes into Dehumidifing mode which is running at a very low speed specifically to lower the humidity.
To clarify, most HVAC systems in The Villages do not have the capability to "increase" the humidity in your house. This requires a humidifier that actually sprays water into your duct. What you do have is an optional humidity setting on your thermostat that can "reduce" the relative humidity by increasing the cooling time or by overcooling your house to a few degrees below the temperature setting. Even today, when it is raining, my thermostat is set on 79 degrees, the optional humidity feature is turned off, and the relative humidity in my house is a comfortable 43 percent. It seems to me that if you need to set your humidity setting to 55 or 60 percent, you must be leaving a door or window open, or you are adding outside air into your house. The relative humidity in my house never gets that high.

[jrref]

To clarify, most HVAC systems in The Villages do not have the capability to "increase" the humidity in your house. This requires a humidifier that actually sprays water into your duct. What you do have is an optional humidity setting on your thermostat that can "reduce" the relative humidity by increasing the cooling time or by overcooling your house to a few degrees below the temperature setting. Even today, when it is raining, my thermostat is set on 79 degrees, the optional humidity feature is turned off, and the relative humidity in my house is a comfortable 43 percent. It seems to me that if you need to set your humidity setting to 55 or 60 percent, you must be leaving a door or window open, or you are adding outside air into your house. The relative humidity in my house never gets that high.

OK I'm not challenging what you are saying but let's take a look at this. So, it's raining which means it's 100% humidity outside. But, in your home it's 43% and you have the temperature set at 79 degrees!

This can only mean a couple of things. 1) you have a very tightly sealed home or 2) your A/C is undersized and it's running a lot. You didn't mention a dehumidifier so I'm assuming you don't have one.

That said, you may have told us before but what type of home do you have? Block or Frame?
How many sq ft and what is the tonnage on your outside condenser? How many people living in the home?

Your home should have some natural but very small air flow between the inside and outside air. But your home might be very tight. Did you ever turn off your A/C and checked to see if the humidity rises? 43% seems unusually low for the summer months when it's very humid outside.

You are correct the A/C will only lower the humidity and can't increase it so when we talk about "setting the humidity" we are referencing how much the A/C can lower it while maintaining the set temperature.

[retiredguy123]

OK I'm not challenging what you are saying but let's take a look at this. So, it's raining which means it's 100% humidity outside. But, in your home it's 43% and you have the temperature set at 79 degrees!

This can only mean a couple of things. 1) you have a very tightly sealed home or 2) your A/C is undersized and it's running a lot. You didn't mention a dehumidifier so I'm assuming you don't have one.

That said, you may have told us before but what type of home do you have? Block or Frame?
How many sq ft and what is the tonnage on your outside condenser? How many people living in the home?

Your home should have some natural but very small air flow between the inside and outside air. But your home might be very tight. Did you ever turn off your A/C and checked to see if the humidity rises? 43% seems unusually low for the summer months when it's very humid outside.

You are correct the A/C will only lower the humidity and can't increase it so when we talk about "setting the humidity" we are referencing how much the A/C can lower it while maintaining the set temperature.
I have a 2BR, 1150SF, courtyard villa with a 2-ton heat pump. It is not undersized and it does not run a lot. I have poured-in-place concrete walls, and I never open the windows. I have 3 devices that measure the humidity and it is almost always less than 50 percent, usually around 40 to 45 percent in the summer. The current range recorded on my humidity devices is from 39 to 47 percent during the past 36 hours, even though I have experienced a lot of rain the past two days. I never use any humidity control, except the normal air conditioning, which is always set at 79 degrees, day and night. Those are the facts.

[jrref]

I have a 2BR, 1150SF, courtyard villa with a 2-ton heat pump. It is not undersized and it does not run a lot. I have poured-in-place concrete walls, and I never open the windows. I have 3 devices that measure the humidity and it is almost always less than 50 percent, usually around 40 to 45 percent in the summer. The current range recorded on my humidity devices is from 39 to 47 percent during the past 36 hours, even though I have experienced a lot of rain the past two days. I never use any humidity control, except the normal air conditioning, which is always set at 79 degrees, day and night. Those are the facts.

OK, Everything sounds good but it's still strange to see how the humidity can stay so low without the A/C running a lot in the summer. Maybe some other's can comment.

[Altavia]

I think it would be better adjusting the temperature "Swing". I believe it's set to 4 degrees on the Ecobee meaning 2 degrees above and below your setting. But you are correct, the better the thermostat keeps the temperature at the set point, the more it's running accelerating wear on the compressor.

A thermostat's swing setting, also known as temperature differential or maintenance band, determines how much the temperature fluctuates above or below the setpoint before the heating or cooling system engages. This setting affects how often your HVAC system cycles on and off. A smaller swing setting results in more frequent but shorter cycles, while a larger swing setting leads to fewer but longer cycles.

Thanks - found the automatic staging needs to be changed to manual to set the swing.

From there, you can adjust the heat/cool differential temperature.

The default swing value is ±0.50°F, changed it to ±1.5°F.

[Altavia]

OK, Everything sounds good but it's still strange to see how the humidity can stay so low without the A/C running a lot in the summer. Maybe some other's can comment.

Maybe the poured in place homes have lower air infiltration?

[Teed_Off]

I have a 2BR, 1150SF, courtyard villa with a 2-ton heat pump. It is not undersized and it does not run a lot. I have poured-in-place concrete walls, and I never open the windows. I have 3 devices that measure the humidity and it is almost always less than 50 percent, usually around 40 to 45 percent in the summer. The current range recorded on my humidity devices is from 39 to 47 percent during the past 36 hours, even though I have experienced a lot of rain the past two days. I never use any humidity control, except the normal air conditioning, which is always set at 79 degrees, day and night. Those are the facts.

Maintaining your relative humidity level between 39 and 47% is somewhat out of range for residential a/c systems in central Florida. Probably need to recalibrate your hygrometers. I needed to do so every six months or so when I felt the need to track RH for my satisfaction. Now I can read it on my programmable t-stat app, but I’m not convinced that it’s accurate.
I also keep my house at 79 degrees F during the day and 77 at night, but my RH is between 58 and 62% when I disable the humidity control feature.

[Topspinmo]

Are you sure that capacitor was not changed? Because they never write on the capacitor from the factory. That's usually done by a repair tech, so the next tech knows the values if the description is worn off over time.

No they are factory, I wrote on capacitor so I knew what size to to buy have extra one to fit like factory one.

[Topspinmo]

OK, Everything sounds good but it's still strange to see how the humidity can stay so low without the A/C running a lot in the summer. Maybe some other's can comment.


I have same CYV size, run time same, humidity around same. Just got my electric bill yesterday 144. dollars. Temp setting 78 degrees.

[retiredguy123]

Maintaining your relative humidity level between 39 and 47% is somewhat out of range for residential a/c systems in central Florida. Probably need to recalibrate your hygrometers. I needed to do so every six months or so when I felt the need to track RH for my satisfaction. Now I can read it on my programmable t-stat app, but I’m not convinced that it’s accurate.
I also keep my house at 79 degrees F during the day and 77 at night, but my RH is between 58 and 62% when I disable the humidity control feature.
I actually have 4 hygrometers spread around the house. One is part of a weather station that tracks the outdoor and indoor conditions. Two of them I have had for 8 years that are strictly measuring indoor conditions. Recently, I added another indoor unit. I am very certain that my humidity measurements are accurate, as they have never deviated more than about 2 percent from the others. If you are measuring indoor humidity, I recommend using at least two hygrometers because they are not as accurate as a thermometer.

[wikolia]

I'm house sitting and last Saturday's storm affected the thermostat for the a/c unit. it's 65 degrees in the house....the thermostat is set @ 85!...Munn's will not come out because I'm not listed on the homeowners account...any suggestions please?....

[Altavia]

I'm house sitting and last Saturday's storm affected the thermostat for the a/c unit. it's 65 degrees in the house....the thermostat is set @ 85!...Munn's will not come out because I'm not listed on the homeowners account...any suggestions please?....


I would try turning off the HVAC breaker, wait a minute, and turn it back on to see if the system resets.

The homeowner needs to get someone there if that doesn't work.

[retiredguy123]

I'm house sitting and last Saturday's storm affected the thermostat for the a/c unit. it's 65 degrees in the house....the thermostat is set @ 85!...Munn's will not come out because I'm not listed on the homeowners account...any suggestions please?....
The homeowner should be able to authorize Munn's to repair the system. They may need to provide a credit card number.