Household thermostats

[Jersey mike]

I believe I’m having an issue with my thermostat, it’s about 12 years old, maybe older. It’s a Honeywell basic heat/ac digital programmable.

I’m looking at new thermostats but most have been modernized ie WiFi enabled and auto switching from heat to a/c.

From what I’ve read the WiFi doesn’t need to be enabled for it to work, but what I’m very curious about is the auto switching.

Does anyone have such a thermostat and how does it work and can that be overridden?

I know when I need heat and I know when I need a/c. We keep our house warm in the winter, usually in the 73-75 range during the day and about 71-72 at night. I don’t need the computer in the thermostat deciding that’s too warm and it’s time for air conditioning.

Also, these new thermostats require a “C” wire which I don’t believe I have but I’ve read it’s not too big a deal because it can’t be bypassed, but doing that eliminates the option to run just on “Fan mode” which we do from time to time but not on a regular basis. The question on this is, the new thermostats do not have battery backup, so if there is a power outage does the thermostat have a memory or is it wiped out.

I ask that because if we are away, how does the thermostat know what to do or resume doing?

If anyone has some experience I’d appreciate some feedback.....thanks in advance.

There’s an error in this statement;

Also, these new thermostats require a “C” wire which I don’t believe I have but I’ve read it’s not too big a deal because it can’t be bypassed, but doing that eliminates the option to run just on “Fan mode” which we do from time to time but not on a regular basis. The question on this is, the new thermostats do not have battery backup, so if there is a power outage does the thermostat have a memory or is it wiped out.


The “C” wire CAN BE bypassed...not can’t be..that was a typo. My mistake of not proofreading.

[98valk]

have u changed the battery in the one u have?   lowes and homedepot still sell the honeywells non-wifi.  one that is programmable and one that is not.

[cookiedough]

take the plastic cover off the thermostat and make sure all the wires are securely connected to the unit.

My old 1993 honeywell chronotherm III has battery backup but we have a battery flasher light that is a digital readout in front of unit notifying us when batteries need changing.  It must not take much battery backup ever since I think in 27 years now we have replaced the AA batteries like 3-4x's is all. 

[Serk]

I have Sensi by Emerson thermostats, WiFi enabled, and use the WiFi enabled portion. I've not messed with them without the WiFi functionality enabled, but with it, I can "lock" the unit into cool or heat mode, or put it in auto mode and give it upper and lower temperature bounds and it will do what it needs to do to keep the temperature within those bounds.

(Here in Texas it's not uncommon to need heat and A/C in the same day)

I thought the WiFI was kinda a gimmick at first but wouldn't give it up for anything now. Wake up kinda warm, grab the phone, tappity tap tap and cool it off. Also easy to program it to set certain temperatures at certain times.

Edit to add:

This is my current upstairs thermostat. See the "System mode" area, that's where you can lock it to either cool, heat or let it choose:



Edit to add another thing:

Another nice thing, especially with kids, with the Wifi you can lock out the local controls entirely.

[scooperhsd]

We had a Honeywell Programmable Thermostat in our NC home, and it was wonderful. It had 4 settings per day,  The way it worked , 3 degrees F minimum change to go from AC to heat (or vice versa). You had to program what type of system you had (we had a single stage Heat pump w/ a propane furnace auxilary heat). Our setpoints was 75 for AC and 72 for heat (usually). Our thermostat was the Honeywell RTH7600 (maybe RTH7500). This thermostat could be set for practically anything on the equipment side - the heat pump could just as easily be set for AC, and tell the system you had a furnace only - it would handle it with zero issues. It did have builtin battery backup, and yes - it did use the C wire for power.

Using this, lets start with the house at 74. If the house warmed to 75, it would turn on the heat pump in AC mode. If the indoor temp dropped to 72, then it would engage the heatpump (by default). If it cool enough outside (around 20-25 F) After running long enough, it would turn on the furnace. Or, you could set the thermostat on EMERGENCY HEAT and instead of using the heat pump for heat, it would use the furnace only. We set it for using the heatpump because the cost of propane was more than the heatpump use rate.

SO  - if left set to defaults, and if the temp outside could change enough, you could see it changing modes from AC to heat to emergency heat in a single day. Or it could go from emergency heat to heat to AC . Mostly it would just change from AC to Heat or Vice versa, without us having to do anything, or even being in the house.

We liked this way because it kept us comfortable with no oversight required. we could change the thermostat equipment settings to compensate for problems until the HVAC service tech came to fix it (on the heat side, anyway). I've been considering changing the central thermostat of MIL's house to one similar to this, but....

[Wizzard]

I have 3 NEST thermostats and love them. Had them for 3 years now. I would buy them again if needed.

[msb]

We have a Honeywell unit, about 8 years old. Has more settings than I care to learn. We usually keep it on Auto mode and it works well, switching between heat pump, backup furnace when it gets below  - 5°C, and A/C in the Summer. We often override it though  as temps can really vary day to day here and the Mrs and me have different comfort levels (she keeps turning the heat up in Winter, I keep turning it back down  ) The Auto settings remain programmed  after power outages and when overriding.

[Robert]

I have the Nest 3 also and I do like it. There are pros and a few cons.

Check the wiring because sometimes the wiring will not charge the battery in the thermostat unless you have a ground, power in addition to the wires needed to run the system. Had to install new wires from the ac/heater to the Nest to provide a good ground to keep the batteries to full charge. If the battery looses charge you loose WiFi.

Sometimes you fight the thermostat settings, Nest has an automatic away that sets the thermostat to a default away temp. When you take a nap weekends in the afternoon and it does not see any movement in the house things can get warm. You can disable it if you remember. But its a very good feature most of the time.

I love that I can turn on the ac or heat from wherever I am and have the house cool when I come home. When the wife was sick I was able to make sure she was comfortable while at work.

When I was away I set the thermostat at the default away temp and every couple of days would run the ac to keep the house fresh from halfway across the globe.

Some thermostats like the Nest you can buy remote temp sensors and install them in a room away from the thermostat.

I like this since at night it keeps the temp in the bedroom or whatever room I have the remote sensor in exactly where I want it. The living room tends to be a bit cooler than the bedroom so there is no guess when you set the thermostat in the living room hoping the bedroom is correct also. Just set the desired sensor and set the temp and it will maintain the temp in that room.Or if you are hot in the middle of the night and keep your phone by your bed you can reach over and change the temp. It keeps the air circulating and temp on trakc in the middle of the night when things could get a bit warm without a sensor in the bedroom.

The schedule is good for and it can be altered, changed or will automatically learn your movements to set temp from home and away.

All the rest I agree with others here and would not want to go back to the old thermostats.

The Nest is a bit easier than most to setup and run and the thermostat is pretty plain in turning up the temp. Just press the face you see the temp and turn it to the desired temp, its that easy. I did not want a complicated thermostat since the wife would complain about it.

ecobee Ive heard is good also and does have remote sensors.

I also did not get a thermostat with Alexa or any other form of AI to speak to, but it is available if you want.

[Wizzard]

I have the Nest 3 also and I do like it. There are pros and a few cons.

Check the wiring because sometimes the wiring will not charge the battery in the thermostat unless you have a ground, power in addition to the wires needed to run the system. Had to install new wires from the ac/heater to the Nest to provide a good ground to keep the batteries to full charge.

Sometimes you fight the thermostat settings, Nest has an automatic away that sets the thermostat to a default away temp. When you take a nap weekends in the afternoon and it does not see any movement in the house things can get warm. You can disable it if you remember. But its a very good feature most of the time.

I love that I can turn on the ac or heat from wherever I am and have the house cool when I come home. When the wife was sick I was able to make sure she was comfortable while at work.

When I was away I set the thermostat at the default away temp and every couple of days would run the ac to keep the house fresh from halfway across the globe.

Some thermostats like the Nest you can buy remote temp sensors and install them in a room away from the thermostat.

I like this since at night it keeps the temp in the bedroom or whatever room I have the remote sensor in exactly where I want it. The living room tends to be a bit cooler than the bedroom so there is no guess when you set the thermostat in the living room hoping the bedroom is correct also. Just set the desired sensor and set the temp and it will maintain the temp in that room.Or if you are hot in the middle of the night and keep your phone by your bed you can reach over and change the temp. It keeps the air circulating and temp on trakc in the middle of the night when things could get a bit warm without a sensor in the bedroom.

The schedule is good for and it can be altered, changed or will automatically learn your movements to set temp from home and away.

All the rest I agree with others here and would not want to go back to the old thermostats.

Do not need to run a new wire. There is a small module made that will use a pulse type signal for ground using another wire and it works fine and battery will stay charged. I know because I have installed several of these in older homes. Works great. You can also turn off the automatic away

https://smartthermostatguide.com/c-wire-venstar-add-a-wire-adapter-review/

[Robert]

Do not need to run a new wire. There is a small module made that will use a pulse type signal for ground using another wire and it works fine and battery will stay charged. I know because I have installed several of these in older homes. Works great. You can also turn off the automatic away

https://smartthermostatguide.com/c-wire-venstar-add-a-wire-adapter-review/

Thanks, that looks great but where were you a year ago  .

Couldn't really find a solution at the time and that is the exact problem me and my son had. I had to snake a wire from the ac/heat to the thermostat and it was not to fun, but got done and then had no problems whatsoever. Running a wire through an attic through a header and in plaster walls is a unique challenge.

Thanks again, That goes into the important information file 

[Wizzard]

Do not need to run a new wire. There is a small module made that will use a pulse type signal for ground using another wire and it works fine and battery will stay charged. I know because I have installed several of these in older homes. Works great. You can also turn off the automatic away

https://smartthermostatguide.com/c-wire-venstar-add-a-wire-adapter-review/

Thanks, that looks great but where were you a year ago  .

Couldn't really find a solution at the time and that is the exact problem me and my son had. I had to snake a wire from the ac/heat to the thermostat and it was not to fun, but got done and then had no problems whatsoever. Running a wire through an attic through a header and in plaster walls is a unique challenge.

Thanks again, That goes into the important information file 

You are welcome. I always look for the easiest route as I hate snaking wires. Especially in old houses.

[Jess from VA]

I have this ancient one, maybe original to the house.  It works well, and I've learned how to tweak it just right to tweak temps.  If I leave home for days, I just set the heat or cool way down or up from normal to save money.  Year round, I tend to have daytime and night time settings; it's right outside my bedroom, so I tweak it before and after sleeping.  Easy.

When I had to get a new HVAC system for $8K two months ago, they offered to give me a new computerized thermostat.  I said hell no... I don't need no new thing in my life that is smarter than I am, and that will take weeks or months to master and cause me no end of irritation (like my new truck). They laughed a lot.

I don't own a cell phone, and my cordless phone has no effect whatsoever on this thermostat.  I wouldn't call it anyway, since the conversation would be pretty one sided.


When I go to visit my 91yo mom, I have to get her to change the modern electronic thermostat, because I'm afraid to touch it.  She grumbles about it all the time, but since my brother put it in for her, she won't ask him to change it back to simple for her. 

[scooperhsd]

I've thrown out those type of Thermostats before. One possible hazard to them - that is MERCURY in the little glass tube that completes the circuit....

[t-man403]

I don’t have time now as I have to get to work. I will PM you later as this is what I do for a living and maybe I can advise or help somehow.

[F6Dave]

I have this ancient one, maybe original to the house.  It works well, and I've learned how to tweak it just right to tweak temps.  If I leave home for days, I just set the heat or cool way down or up from normal to save money.  Year round, I tend to have daytime and night time settings; it's right outside my bedroom, so I tweak it before and after sleeping.  Easy.

When I had to get a new HVAC system for $8K two months ago, they offered to give me a new computerized thermostat.  I said hell no... I don't need no new thing in my life that is smarter than I am, and that will take weeks or months to master and cause me no end of irritation (like my new truck). They laughed a lot.

I don't own a cell phone, and my cordless phone has no effect whatsoever on this thermostat.  I wouldn't call it anyway, since the conversation would be pretty one sided.


When I go to visit my 91yo mom, I have to get her to change the modern electronic thermostat, because I'm afraid to touch it.  She grumbles about it all the time, but since my brother put it in for her, she won't ask him to change it back to simple for her. 

Mine is even more ancient than that!  If it's too cold I turn it up, too hot and I turn it down.  Nice and simple like a Valkyrie!

[Wizzard]

Also, these new thermostats require a “C” wire which I don’t believe I have but I’ve read it’s not too big a deal because it can’t be bypassed, but doing that eliminates the option to run just on “Fan mode” which we do from time to time but not on a regular basis. The question on this is, the new thermostats do not have battery backup, so if there is a power outage does the thermostat have a memory or is it wiped out.

The nest will work without wifi but you need wifi to put in the options. Why would you have a wifi thermostat without wifi? I have posted here on what to do about the battery C or charge wire. You can use the fan wire and it still works the fan if you use the module I have posted a link to. And you can still run the fan on. Memory is not wiped out in a power failure. There is a NVram that backs up your settings  and they will be there when the power is back on. I have installed many of these.

[msb]

I have this ancient one, maybe original to the house.  It works well, and I've learned how to tweak it just right to tweak temps.  If I leave home for days, I just set the heat or cool way down or up from normal to save money.  Year round, I tend to have daytime and night time settings; it's right outside my bedroom, so I tweak it before and after sleeping.  Easy.

When I had to get a new HVAC system for $8K two months ago, they offered to give me a new computerized thermostat.  I said hell no... I don't need no new thing in my life that is smarter than I am, and that will take weeks or months to master and cause me no end of irritation (like my new truck). They laughed a lot.

I don't own a cell phone, and my cordless phone has no effect whatsoever on this thermostat.  I wouldn't call it anyway, since the conversation would be pretty one sided.


When I go to visit my 91yo mom, I have to get her to change the modern electronic thermostat, because I'm afraid to touch it.  She grumbles about it all the time, but since my brother put it in for her, she won't ask him to change it back to simple for her. 

"I have this ancient one"
Why doesn't this surprise me, Jess?   I haven't had one of those in my house since the early 80's

[98valk]

I have this ancient one, maybe original to the house.  It works well, and I've learned how to tweak it just right to tweak temps.  If I leave home for days, I just set the heat or cool way down or up from normal to save money.  Year round, I tend to have daytime and night time settings; it's right outside my bedroom, so I tweak it before and after sleeping.  Easy.

When I had to get a new HVAC system for $8K two months ago, they offered to give me a new computerized thermostat.  I said hell no... I don't need no new thing in my life that is smarter than I am, and that will take weeks or months to master and cause me no end of irritation (like my new truck). They laughed a lot.

I don't own a cell phone, and my cordless phone has no effect whatsoever on this thermostat.  I wouldn't call it anyway, since the conversation would be pretty one sided.


When I go to visit my 91yo mom, I have to get her to change the modern electronic thermostat, because I'm afraid to touch it.  She grumbles about it all the time, but since my brother put it in for her, she won't ask him to change it back to simple for her. 

I have an org Dayton in my house built in '59 that looks just like that one.  still works great. I've compared a digital thermometer I have and both register the same temps.  Built to last with the mercury bulb.

[Jersey mike]

have u changed the battery in the one u have?   lowes and homedepot still sell the honeywells non-wifi.  one that is programmable and one that is not.

Yes I change the batteries about every 2 years. I just changed them last week when I was checking it.

I also used some canned air to blow out any dust and got some dust bunnies out.

I’ve been looking online at the non-WiFi models, most seem to have screens with a smaller readout. I was hoping to avoid needing my glasses to read the thermostat.

[Jersey mike]

I have the Nest 3 also and I do like it. There are pros and a few cons.

Check the wiring because sometimes the wiring will not charge the battery in the thermostat unless you have a ground, power in addition to the wires needed to run the system. Had to install new wires from the ac/heater to the Nest to provide a good ground to keep the batteries to full charge.

Sometimes you fight the thermostat settings, Nest has an automatic away that sets the thermostat to a default away temp. When you take a nap weekends in the afternoon and it does not see any movement in the house things can get warm. You can disable it if you remember. But its a very good feature most of the time.

I love that I can turn on the ac or heat from wherever I am and have the house cool when I come home. When the wife was sick I was able to make sure she was comfortable while at work.

When I was away I set the thermostat at the default away temp and every couple of days would run the ac to keep the house fresh from halfway across the globe.

Some thermostats like the Nest you can buy remote temp sensors and install them in a room away from the thermostat.

I like this since at night it keeps the temp in the bedroom or whatever room I have the remote sensor in exactly where I want it. The living room tends to be a bit cooler than the bedroom so there is no guess when you set the thermostat in the living room hoping the bedroom is correct also. Just set the desired sensor and set the temp and it will maintain the temp in that room.Or if you are hot in the middle of the night and keep your phone by your bed you can reach over and change the temp. It keeps the air circulating and temp on trakc in the middle of the night when things could get a bit warm without a sensor in the bedroom.

The schedule is good for and it can be altered, changed or will automatically learn your movements to set temp from home and away.

All the rest I agree with others here and would not want to go back to the old thermostats.

Do not need to run a new wire. There is a small module made that will use a pulse type signal for ground using another wire and it works fine and battery will stay charged. I know because I have installed several of these in older homes. Works great. You can also turn off the automatic away

https://smartthermostatguide.com/c-wire-venstar-add-a-wire-adapter-review/

Thank you, cool little gizmo. 

[Jess from VA]

"I have this ancient one"
Why doesn't this surprise me, Jess? Grin  I haven't had one of those in my house since the early 80's

It should surprise no one Mike.

I think it's humorous that in the 70s and 80s, I was up on all cutting edge stuff out at the time.

But at some point I was too busy working and taking care of my house, cars, bikes and wife to keep up with everything since.  And frankly, I don't feel like I'm missing out on much.

But when someone loans you their smartphone to make a local call, they look at you funny when you tell them you have no idea how one of those things works.  For instance, why in tarnation do they put buttons on the outside edges of them, so when you just hold onto one, you screw everything up?

I have become my grandfather (with the ranting about new fangled contraptions).

My mom says I look just like her dad too (long gone).... and lord he was an old man as I remember him.    

[Jersey mike]

The reason for this thread is because I’m trying to narrow down a recurring issue with my gas furnace.

Last winter I began having multiple failures.

Some of which are; ignitor not lighting, going out too soon, taking too long to turn on and I’m probably missing another.

Flame sensor; would cut out flame too soon, system would short cycle or fail to run for several cycles.

Other times the furnace would run as it was suppose to for days and weeks on end then poof out of nowhere failures.

This past spring we replaced motherboard thinking that’s the issue.

Why I believe thermostat is involved in some matter is because now the furnace does not like to run properly after more than 2 consecutive cycles. Thermostat will read “73”....call for heat, pre-fan turns on and igniter fails..once, twice or igniter lights and flame turns on and flame sensor shuts it down.

I’ve opened the furnace many times while the failures are going on and whether it’s coincidence I’m not sure but if I tickle the wires leading from the wiring plug for the igniter it will usually light and if there is a flameout a tap or two on the leads to the thermocouple will take care of that.

I’ve been at each lead and tried tightening or lightly squeezing all electric connections but no joy as something is still failing.

There are times when it seems the sensitivity or margin of error of the thermostat have changed. The Thermostat will suddenly shut off the call for heat. I usually have the HOLD set while we’re home and adjust manually during the day. If I adjust thermostat 2 degrees above a setting that failed it will usually fire up no problem but there are times when the recurring igniter or flame sensor are still there.

I have to add, running the A/C all summer was never an issue.

My furnace guy is on vacation until the end of the month so I’m troubleshooting this on the fly but have been doing it since the end of last winter.

System is only 6 yrs old. But it’s not a top of the line system.

[98valk]

The reason for this thread is because I’m trying to narrow down a recurring issue with my gas furnace.

Last winter I began having multiple failures.

Some of which are; ignitor not lighting, going out too soon, taking too long to turn on and I’m probably missing another.

Flame sensor; would cut out flame too soon, system would short cycle or fail to run for several cycles.

Other times the furnace would run as it was suppose to for days and weeks on end then poof out of nowhere failures.

This past spring we replaced motherboard thinking that’s the issue.

Why I believe thermostat is involved in some matter is because now the furnace does not like to run properly after more than 2 consecutive cycles. Thermostat will read “73”....call for heat, pre-fan turns on and igniter fails..once, twice or igniter lights and flame turns on and flame sensor shuts it down.

I’ve opened the furnace many times while the failures are going on and whether it’s coincidence I’m not sure but if I tickle the wires leading from the wiring plug for the igniter it will usually light and if there is a flameout a tap or two on the leads to the thermocouple will take care of that.

I’ve been at each lead and tried tightening or lightly squeezing all electric connections but no joy as something is still failing.

There are times when it seems the sensitivity or margin of error of the thermostat have changed. The Thermostat will suddenly shut off the call for heat. I usually have the HOLD set while we’re home and adjust manually during the day. If I adjust thermostat 2 degrees above a setting that failed it will usually fire up no problem but there are times when the recurring igniter or flame sensor are still there.

I have to add, running the A/C all summer was never an issue.

My furnace guy is on vacation until the end of the month so I’m troubleshooting this on the fly but have been doing it since the end of last winter.

System is only 6 yrs old. But it’s not a top of the line system.

"Some of which are; ignitor not lighting, going out too soon, taking too long to turn on and I’m probably missing another."

I've been told that is a sensor which causes that.
I don't believe it is the thermostat, more like the furnace from what your stating.

[Wizzard]

Is this a high efficiency furnace? Does it have a forced air flue?
I had these exact problems and all it was is one of the return rubber flex tubes on the efficiency blower was plugged.
Also could be one of the limit switches but these are easy to ck with an ohmeter.
Pretty sure its not  your thermostat

[msb]

"I have this ancient one"
Why doesn't this surprise me, Jess? Grin  I haven't had one of those in my house since the early 80's

It should surprise no one Mike.

I think it's humorous that in the 70s and 80s, I was up on all cutting edge stuff out at the time.

But at some point I was too busy working and taking care of my house, cars, bikes and wife to keep up with everything since.  And frankly, I don't feel like I'm missing out on much.

But when someone loans you their smartphone to make a local call, they look at you funny when you tell them you have no idea how one of those things works.  For instance, why in tarnation do they put buttons on the outside edges of them, so when you just hold onto one, you screw everything up?

I have become my grandfather (with the ranting about new fangled contraptions).

My mom says I look just like her dad too (long gone).... and lord he was an old man as I remember him.    

lol Jess. You, me, and many others on here are all in the same boat...we've become these guys

https://www.youtube.com/watch?v=kLYAK1_r0Zg

[F6Dave]

Years ago I read that flame sensors will get a build up of carbon that acts as insulation. As a result they can't detect the heat quickly enough to signal that the furnace is lit, so it shuts down to keep your house from blowing up. The fix is simple. Clean the black stuff off the sensor with steel wool.

[Wizzard]

Years ago I read that flame sensors will get a build up of carbon that acts as insulation. As a result they can't detect the heat quickly enough to signal that the furnace is lit, so it shuts down to keep your house from blowing up. The fix is simple. Clean the black stuff off the sensor with steel wool.

Flame sensors are pretty cheap,, just get one and keep on hand for future use.

[scooperhsd]

I'd have to agree it is not your thermostat, but rather something in your furnace, the carboned over flame sensor could cause this - at least it is worth checking. But this is really what you pay an HVAC guy for...

[F6Dave]

Years ago I read that flame sensors will get a build up of carbon that acts as insulation. As a result they can't detect the heat quickly enough to signal that the furnace is lit, so it shuts down to keep your house from blowing up. The fix is simple. Clean the black stuff off the sensor with steel wool.

Flame sensors are pretty cheap,, just get one and keep on hand for future use.

Agreed. I have a spare. But the connector is so hard to get to that I just clean it every year.

[Wizzard]

Lots of furnaces since the late 80's have led lights that flash codes to let you know what it could be.

[Jersey mike]

Is this a high efficiency furnace? Does it have a forced air flue?
I had these exact problems and all it was is one of the return rubber flex tubes on the efficiency blower was plugged.
Also could be one of the limit switches but these are easy to ck with an ohmeter.
Pretty sure its not  your thermostat

I believe it’s a 90% efficient furnace, vents out a concrete block flue.


The rubber tube has been checked, it flows air freely and the one end has been “checked and unclogged “ but there was never a blockage. No spiders in there.

[Jersey mike]

Years ago I read that flame sensors will get a build up of carbon that acts as insulation. As a result they can't detect the heat quickly enough to signal that the furnace is lit, so it shuts down to keep your house from blowing up. The fix is simple. Clean the black stuff off the sensor with steel wool.

Flame sensor is bright and shiny. It’s been cleaned and cleaned again. Flame is a nice blue.

I think my furnace is a lemon.

[sheets]

Had AC added to my system a couple years ago (bryant). Included a new modern thermostat that had a WiFi signal so I could adjust the house temps remotely. Two summers in a row the AC would not come on at the preprogrammed temp. The second service call the owner of the business called the Mfg. The end result was my thermostat was reading (and displaying) the weather from the coast - 40 miles away - in a different zip code and climate zone. The thermostat would not automatically turn on based on "its" interpretation of the weather. I'm in a different zip code and climate zone. The thermostat was thinking it was on a wall in a different location based on the WiFi signal weather conditions. After the second service call we skipped the automagic WiFi function and just simply programmed the thermostat to suit our desires. Has worked fine ever since. My location is in the boondocks. Your results will likely vary. Just a heads up on my experience. 

[F6Dave]

Had AC added to my system a couple years ago (bryant). Included a new modern thermostat that had a WiFi signal so I could adjust the house temps remotely. Two summers in a row the AC would not come on at the preprogrammed temp. The second service call the owner of the business called the Mfg. The end result was my thermostat was reading (and displaying) the weather from the coast - 40 miles away - in a different zip code and climate zone. The thermostat would not automatically turn on based on "its" interpretation of the weather. I'm in a different zip code and climate zone. The thermostat was thinking it was on a wall in a different location based on the WiFi signal weather conditions. After the second service call we skipped the automagic WiFi function and just simply programmed the thermostat to suit our desires. Has worked fine ever since. My location is in the boondocks. Your results will likely vary. Just a heads up on my experience. 

You're making those ancient thermostats like mine sound better!

[t-man403]

The reason for this thread is because I’m trying to narrow down a recurring issue with my gas furnace.

Last winter I began having multiple failures.

Some of which are; ignitor not lighting, going out too soon, taking too long to turn on and I’m probably missing another.

Flame sensor; would cut out flame too soon, system would short cycle or fail to run for several cycles.

Other times the furnace would run as it was suppose to for days and weeks on end then poof out of nowhere failures.

This past spring we replaced motherboard thinking that’s the issue.

Why I believe thermostat is involved in some matter is because now the furnace does not like to run properly after more than 2 consecutive cycles. Thermostat will read “73”....call for heat, pre-fan turns on and igniter fails..once, twice or igniter lights and flame turns on and flame sensor shuts it down.

I’ve opened the furnace many times while the failures are going on and whether it’s coincidence I’m not sure but if I tickle the wires leading from the wiring plug for the igniter it will usually light and if there is a flameout a tap or two on the leads to the thermocouple will take care of that.

I’ve been at each lead and tried tightening or lightly squeezing all electric connections but no joy as something is still failing.

There are times when it seems the sensitivity or margin of error of the thermostat have changed. The Thermostat will suddenly shut off the call for heat. I usually have the HOLD set while we’re home and adjust manually during the day. If I adjust thermostat 2 degrees above a setting that failed it will usually fire up no problem but there are times when the recurring igniter or flame sensor are still there.

I have to add, running the A/C all summer was never an issue.

My furnace guy is on vacation until the end of the month so I’m troubleshooting this on the fly but have been doing it since the end of last winter.

System is only 6 yrs old. But it’s not a top of the line system.

First off, your furnace doesn't have a thermo-couple and I highly doubt it's a t-stat problem. From your description of the problem, I'd be looking at the pressure switches. They will cause the furnace not to fire or fire and shut it down when the flue gases meet the inducer fan simulating a flame sensor problem. I have never replaced a flame sensor.....just clean it and put it back in. You could have blockage in the condensate system. Make sure it's draining properly and that the furnace is tilted forward slightly to help it drain. Be a shame to waste dollars on parts you don't need. Let your HVAC guy trouble shoot it when he's back if you not sure   of anything I just suggested. Hard to diagnose from here.  ???  

What Brand is the Furnace?

[Jersey mike]

The reason for this thread is because I’m trying to narrow down a recurring issue with my gas furnace.

Last winter I began having multiple failures.

Some of which are; ignitor not lighting, going out too soon, taking too long to turn on and I’m probably missing another.

Flame sensor; would cut out flame too soon, system would short cycle or fail to run for several cycles.

Other times the furnace would run as it was suppose to for days and weeks on end then poof out of nowhere failures.

This past spring we replaced motherboard thinking that’s the issue.

Why I believe thermostat is involved in some matter is because now the furnace does not like to run properly after more than 2 consecutive cycles. Thermostat will read “73”....call for heat, pre-fan turns on and igniter fails..once, twice or igniter lights and flame turns on and flame sensor shuts it down.

I’ve opened the furnace many times while the failures are going on and whether it’s coincidence I’m not sure but if I tickle the wires leading from the wiring plug for the igniter it will usually light and if there is a flameout a tap or two on the leads to the thermocouple will take care of that.

I’ve been at each lead and tried tightening or lightly squeezing all electric connections but no joy as something is still failing.

There are times when it seems the sensitivity or margin of error of the thermostat have changed. The Thermostat will suddenly shut off the call for heat. I usually have the HOLD set while we’re home and adjust manually during the day. If I adjust thermostat 2 degrees above a setting that failed it will usually fire up no problem but there are times when the recurring igniter or flame sensor are still there.

I have to add, running the A/C all summer was never an issue.

My furnace guy is on vacation until the end of the month so I’m troubleshooting this on the fly but have been doing it since the end of last winter.

System is only 6 yrs old. But it’s not a top of the line system.

First off, your furnace doesn't have a thermo-couple and I highly doubt it's a t-stat problem. From your description of the problem, I'd be looking at the pressure switches. They will cause the furnace not to fire or fire and shut it down when the flue gases meet the inducer fan simulating a flame sensor problem. I have never replaced a flame sensor.....just clean it and put it back in. You could have blockage in the condensate system. Make sure it's draining properly and that the furnace is tilted forward slightly to help it drain. Be a shame to waste dollars on parts you don't need. Let your HVAC guy trouble shoot it when he's back if you not sure   of anything I just suggested. Hard to diagnose from here.  ???  

What Brand is the Furnace?

I forgot it’s not thermocouple anymore, it’s flame sensor.

Brand of furnace (American Standard) is embarrassing to mention because if found (possible rumor maybe) out it’s made from parts that didn’t pass QC of a more well known (Lenox) company.

[Jersey mike]

Hey thanks everyone for taking time to read and give some feedback, it’s really appreciated.

[cookiedough]

Is this a high efficiency furnace? Does it have a forced air flue?
I had these exact problems and all it was is one of the return rubber flex tubes on the efficiency blower was plugged.
Also could be one of the limit switches but these are easy to ck with an ohmeter.
Pretty sure its not  your thermostat

try replacing flame sensor rod (metal rod with porcelain bottom) as well as the ignition coil (made of graphite or something like that but doubt it is that since if broken, burners would not ignite).  Just had to to clean with fine sandpaper that flame senor rod last night furnance kept going out 2 to 3 seconds after gas ignited.  One hard to reach screw over one of the 3 burners is a metal rod in front and it was dirty.  20 seconds cleaning that rod and put 1 screw back in and good to go.  I go thru about 1 flame sensor rod every 5-8 years or so.  It is suppose to be done yearly but i let it go 4 years now since furnance was brand new.  I looked around and even already the middle burner housing is rusting slightly in 4 years.  That was my issue on my 23 year old furnance 4 years ago the burners and flute openings were so rusted and no parts on it being burners/flutes, that I needed a new furnance 4 years ago. 

[Wizzard]

Is this a high efficiency furnace? Does it have a forced air flue?
I had these exact problems and all it was is one of the return rubber flex tubes on the efficiency blower was plugged.
Also could be one of the limit switches but these are easy to ck with an ohmeter.
Pretty sure its not  your thermostat

I believe it’s a 90% efficient furnace, vents out a concrete block flue.


The rubber tube has been checked, it flows air freely and the one end has been “checked and unclogged “ but there was never a blockage. No spiders in there.

Does the main board have led lights? If so they flash a code. What model and brand do you have?

[t-man403]

The reason for this thread is because I’m trying to narrow down a recurring issue with my gas furnace.

Last winter I began having multiple failures.

Some of which are; ignitor not lighting, going out too soon, taking too long to turn on and I’m probably missing another.

Flame sensor; would cut out flame too soon, system would short cycle or fail to run for several cycles.

Other times the furnace would run as it was suppose to for days and weeks on end then poof out of nowhere failures.

This past spring we replaced motherboard thinking that’s the issue.

Why I believe thermostat is involved in some matter is because now the furnace does not like to run properly after more than 2 consecutive cycles. Thermostat will read “73”....call for heat, pre-fan turns on and igniter fails..once, twice or igniter lights and flame turns on and flame sensor shuts it down.

I’ve opened the furnace many times while the failures are going on and whether it’s coincidence I’m not sure but if I tickle the wires leading from the wiring plug for the igniter it will usually light and if there is a flameout a tap or two on the leads to the thermocouple will take care of that.

I’ve been at each lead and tried tightening or lightly squeezing all electric connections but no joy as something is still failing.

There are times when it seems the sensitivity or margin of error of the thermostat have changed. The Thermostat will suddenly shut off the call for heat. I usually have the HOLD set while we’re home and adjust manually during the day. If I adjust thermostat 2 degrees above a setting that failed it will usually fire up no problem but there are times when the recurring igniter or flame sensor are still there.

I have to add, running the A/C all summer was never an issue.

My furnace guy is on vacation until the end of the month so I’m troubleshooting this on the fly but have been doing it since the end of last winter.

System is only 6 yrs old. But it’s not a top of the line system.

First off, your furnace doesn't have a thermo-couple and I highly doubt it's a t-stat problem. From your description of the problem, I'd be looking at the pressure switches. They will cause the furnace not to fire or fire and shut it down when the flue gases meet the inducer fan simulating a flame sensor problem. I have never replaced a flame sensor.....just clean it and put it back in. You could have blockage in the condensate system. Make sure it's draining properly and that the furnace is tilted forward slightly to help it drain. Be a shame to waste dollars on parts you don't need. Let your HVAC guy trouble shoot it when he's back if you not sure   of anything I just suggested. Hard to diagnose from here.  ???  

What Brand is the Furnace?

I forgot it’s not thermocouple anymore, it’s flame sensor.

Brand of furnace (American Standard) is embarrassing to mention because if found (possible rumor maybe) out it’s made from parts that didn’t pass QC of a more well known (Lenox) company.

American Standard......lucky you! 

Probably the most reliable furnace made and no it's not made out of low quality parts. Manufactured by Trane and part for part identical. The Label on the door is the only difference. Be assured, you own a high quality product!

Now, the other thing to check is blockage in the vent system. The venting and condensate are all connected internally and effect whether it will run or not. Lift the intake (combustion air) pipe off the top of the furnace. You'll see within the collar, a baffle full of holes to let the air in but to keep contaminates out like Bee's, leaves and the like. If there is anything laying there, remove it. if there is nothing there, leave the pipe disconnected and run the furnace that way for a few day to see if it operates properly. If it does run properly, there may be something in the pipe or the venting is to long and the pressure switches (two stage) are not liking it. They are designed for only so long of a venting system and the elbows have to be taken into account.

Again I will say, I have never replace a flame sensor. I don't even carry them in my service van. Emery cloth cleans them perfectly! No different than having to clean your battery posts on your car. You don't change the battery because the posts are corroded!