I bought a Honeywell Model RTH7600 programmable thermostat.

On the thermostat, I've set the "Set to:" (i.e., "desired") temperature at 82 degrees.

When the furnace's blower comes on, the burners cycle on and off for less than a minute several times but the current room temperature doesn't go higher than 70 to 73 degrees. What might be the reason for this condition?

Note: The owner's manual says "This thermostat works on 24 volt or 750 mV systems. It will NOT work on 120/240 volt systems". Should I be using a NON-programmable thermostat?

Most furnaces have a high limit safety switch that shuts
The burner off if the temperature inside the furnace gets too high.
That might be your problem.
The temperature inside the furnace can get too high if the blower
Is not moving enough air because of a clogged filter
Or a number of other reasons.
Is this a gas or oil furnace?
M

I have a Lennox MERIT® SERIES Model G40UH-36A-070X 03 gas furnace.

The filter is clean.

I can see two green LED lights (Diag#1 and Diag#2) through a "port-hole" on the front of the furnace.

Above the "porthole" is a "SureLight Diagnostic Code/Status of Furnace" chart.

When the fan is running and the burners are lit, the LEDs have a simultaneous fast flash (which means "Normal Operation").

But, when the fan is NOT running and the burners are NOT lit, the LEDs have an alternating slow flash which means:

a. Burner failed to ignite
b. Limit open more than 3 minutes
c. Lost flame sense 5 times in 1 heat cycle
d. Pressure switch opened 5 times in one heat cycle.

On Friday, December 15, 2017 at 9:45:59 PM UTC-5, condo owner wrote:
I bought a Honeywell Model RTH7600 programmable thermostat.

On the thermostat, I've set the "Set to:" (i.e., "desired") temperature at 82 degrees.

When the furnace's blower comes on, the burners cycle on and off for less than a minute several times but the current room temperature doesn't go higher than 70 to 73 degrees. What might be the reason for this condition?

Note: The owner's manual says "This thermostat works on 24 volt or 750 mV systems. It will NOT work on 120/240 volt systems". Should I be using a NON-programmable thermostat?


Here we go again. A few days ago you had a similar thread where you
had all kinds of issues with a Totaline thermostat not being able to
raise the temp over 76 when set to 82. So,
now you come in here and start a whole new thread, as if starting from
fresh, with a different thermostat, not mentioning the previous history?

If two thermostats didn't work and you are having the above problems, I think
it's time for a service call. Also, I suggested in the other thread that
you connect the two wires for heat together and see if the furnace would
run continuously. Had you done that, you'd have known it wasn't the
thermostat long ago. Or maybe you're just trolling.

On Friday, December 15, 2017 at 10:49:33 PM UTC-6, condo owner wrote:
I have a Lennox MERIT® SERIES Model G40UH-36A-070X 03 gas furnace.

The filter is clean.

I can see two green LED lights (Diag#1 and Diag#2) through a "port-hole" on the front of the furnace.

Above the "porthole" is a "SureLight Diagnostic Code/Status of Furnace" chart.

When the fan is running and the burners are lit, the LEDs have a simultaneous fast flash (which means "Normal Operation").

But, when the fan is NOT running and the burners are NOT lit, the LEDs have an alternating slow flash which means:

a. Burner failed to ignite
b. Limit open more than 3 minutes
c. Lost flame sense 5 times in 1 heat cycle
d. Pressure switch opened 5 times in one heat cycle.


I replaced a lot of pressure switches when I worked on HVAC systems. The first thing I would do was run a wire through the tube where it connects to the combustion chamber to make sure it was clear. Sometimes it would clog with rust or other debris. You can pull the red silicone tubing off the nipple where it connects to the combustion chamber and blow in it to see if the pressure switch clicks. The switches will often lose sensativty and need to be replaced. ^_^

[8~{} Uncle Switch Monster

On 12/15/2017 10:49 PM, condo owner wrote:
I have a Lennox MERIT® SERIES Model G40UH-36A-070X 03 gas furnace.

The filter is clean.

I can see two green LED lights (Diag#1 and Diag#2) through a "port-hole" on the front of the furnace.

Above the "porthole" is a "SureLight Diagnostic Code/Status of Furnace" chart.

When the fan is running and the burners are lit, the LEDs have a simultaneous fast flash (which means "Normal Operation").

But, when the fan is NOT running and the burners are NOT lit, the LEDs have an alternating slow flash which means:

a. Burner failed to ignite
b. Limit open more than 3 minutes
c. Lost flame sense 5 times in 1 heat cycle
d. Pressure switch opened 5 times in one heat cycle.

It might be the flame sensor. It might be possible to fix
it by cleaning it, or it might need replacement. A service
tech can probably figure it out right away. That's what
fixed it when I was having what sounds like a similar problem.

Bill

On 12/16/2017 12:08 AM, trader_4 wrote:
On Friday, December 15, 2017 at 9:45:59 PM UTC-5, condo owner wrote:
I bought a Honeywell Model RTH7600 programmable thermostat.

On the thermostat, I've set the "Set to:" (i.e., "desired") temperature at 82 degrees.

When the furnace's blower comes on, the burners cycle on and off for less than a minute several times but the current room temperature doesn't go higher than 70 to 73 degrees. What might be the reason for this condition?

Note: The owner's manual says "This thermostat works on 24 volt or 750 mV systems. It will NOT work on 120/240 volt systems". Should I be using a NON-programmable thermostat?


Here we go again. A few days ago you had a similar thread where you
had all kinds of issues with a Totaline thermostat not being able to
raise the temp over 76 when set to 82. So,
now you come in here and start a whole new thread, as if starting from
fresh, with a different thermostat, not mentioning the previous history?

If two thermostats didn't work and you are having the above problems, I think
it's time for a service call. Also, I suggested in the other thread that
you connect the two wires for heat together and see if the furnace would
run continuously. Had you done that, you'd have known it wasn't the
thermostat long ago. Or maybe you're just trolling.




Yes. My question would be:


Was the furnace not working with the old thermostat? Replacing it, to
solve the problem was the wrong choice...the problem is with the furnace.


OTOH: If the furnace was working fine with the old thermostat, then is
it wired wrong? two wire vs three wire for example

On 12/15/2017 9:45 PM, condo owner wrote:
I bought a Honeywell Model RTH7600 programmable thermostat.

On the thermostat, I've set the "Set to:" (i.e., "desired") temperature at 82 degrees.

When the furnace's blower comes on, the burners cycle on and off for less than a minute several times but the current room temperature doesn't go higher than 70 to 73 degrees. What might be the reason for this condition?

Note: The owner's manual says "This thermostat works on 24 volt or 750 mV systems. It will NOT work on 120/240 volt systems". Should I be using a NON-programmable thermostat?


You really need a good pro to help you. We've told you what to do a few
times. In particular I told you to get one of the round Honeywell or
similar thermostats. It could also be the furnace does not have the
power to raise the temperature as high as desired.

I cleaned the "flame sense" rod and it resolved my furnace problem. Now our furnace is again working correctly (i.e., the room temp is now above freezing!).

The price of a pad of steel wool was much cheaper than calling in a HVAC technician who would try to sell me a new furnace for a gazillion bucks.

On Sat, 16 Dec 2017 12:42:49 -0800 (PST), condo owner
wrote:

I cleaned the "flame sense" rod and it resolved my furnace problem. Now our furnace is again working correctly (i.e., the room temp is now above freezing!).

The price of a pad of steel wool was much cheaper than calling in a HVAC technician who would try to sell me a new furnace for a gazillion bucks.


No ****. Ain't it a hoot.

condo owner posted for all of us...



I bought a Honeywell Model RTH7600 programmable thermostat.

On the thermostat, I've set the "Set to:" (i.e., "desired") temperature at 82 degrees.

When the furnace's blower comes on, the burners cycle on and off for less than a minute several times but the current room temperature doesn't go higher than 70 to 73 degrees. What might be the reason for this condition?

Note: The owner's manual says "This thermostat works on 24 volt or 750 mV systems. It will NOT work on 120/240 volt systems". Should I be using a NON-programmable thermostat?

This is a repeat post from the poster whom didn't pay attention the first
time.

--
Tekkie

trader_4 posted for all of us...



On Friday, December 15, 2017 at 9:45:59 PM UTC-5, condo owner wrote:
I bought a Honeywell Model RTH7600 programmable thermostat.

On the thermostat, I've set the "Set to:" (i.e., "desired") temperature at 82 degrees.

When the furnace's blower comes on, the burners cycle on and off for less than a minute several times but the current room temperature doesn't go higher than 70 to 73 degrees. What might be the reason for this condition?

Note: The owner's manual says "This thermostat works on 24 volt or 750 mV systems. It will NOT work on 120/240 volt systems". Should I be using a NON-programmable thermostat?


Here we go again. A few days ago you had a similar thread where you
had all kinds of issues with a Totaline thermostat not being able to
raise the temp over 76 when set to 82. So,
now you come in here and start a whole new thread, as if starting from
fresh, with a different thermostat, not mentioning the previous history?

If two thermostats didn't work and you are having the above problems, I think
it's time for a service call. Also, I suggested in the other thread that
you connect the two wires for heat together and see if the furnace would
run continuously. Had you done that, you'd have known it wasn't the
thermostat long ago. Or maybe you're just trolling.

+100 REPEAT ALERT...

--
Tekkie

Oren posted for all of us...



On Sat, 16 Dec 2017 12:42:49 -0800 (PST), condo owner
wrote:

I cleaned the "flame sense" rod and it resolved my furnace problem. Now our furnace is again working correctly (i.e., the room temp is now above freezing!).

The price of a pad of steel wool was much cheaper than calling in a HVAC technician who would try to sell me a new furnace for a gazillion bucks.


No ****. Ain't it a hoot.

He should snuff out any flame or sparks he sees because everyone knows gaz
blows up!

--
Tekkie

My first post was about a Totaline thermostat.
This post is about a Honeywell thermostat.

Two different subjects = two different posts.

OK. From now on, I will add all NEW topics to my ORIGINAL post.

But that means that thread will contain many disjointed topics.

On Sunday, December 17, 2017 at 10:12:49 PM UTC-5, condo owner wrote:
OK. From now on, I will add all NEW topics to my ORIGINAL post.

But that means that thread will contain many disjointed topics.

The thing is there was just one overall problem, that you could not get
the heat in the house over 76. So, starting a new thread about your new
thermostat that you bought as part of trying to solve that, without the
context of what went before, just wastes a lot of time for anyone who
hasn't followed the other threads, doesn't realize you're the same poster,
etc. Additionally, if you had followed some of the simple advice given
in the first thread, ie just connect the two heat wires and see if the furnace
runs continuously, you'd have avoided a lot more screwing around, purchase
of a new thermostat, etc. Some people we just can't help from themselves.