Furnace Issues

[ExtraSlow]

OK, I'll type out the whole thing, which I should have done to start.
Furnace was running for shorter than normal periods, and house wasn't warming up, so I figured it was "short cycling". Noticed at the same time that the wireless thermostat was occasionally showing "no signal". none of this felt urgent, because the house was sort of close to the correct temperature most of the day, so the furnace must have been working most of the time.

LED on furnace board wasn't showing an error, but I followed the procedure in the manual to retrieve stored codes, and it did show a code for "flue limit switch error". Ok, that seems like a common airflow-related issue. Replaced the air filter, checked the combustion air intake, and that's nice and clear. I cannot check the furnace exhaust, as it's on my roof and the roof is covered in ice and snow in that area. I did get on a ladder to look at it, and there's no external blockage anyway. Couldn't be too badly blocked, since it's running fine most of the time.

So I'm sitting here, thinking that I have two things indicating issues, and I don't know which to troubleshoot. The wireless thermostat (Honeywell THM532R sending to Honeywell TH6320R) seems to be losing connectivity sometimes. AND the flue limit switch is showing an error occasionally. Could one problem cause the other? I don't see how, but .....

I have called Atco, and they plan to come out sometime next week.

What am I missing here?

[Waldi]

Had similar issue with my aunt furnace on Dec, 24, and brought ATCO tech to diagnose as they advised us to replace pressure switch which we did. Problem started again I went to diagnose led light and it was pointing to pressure switch. Call ATCO again and they came after testing indicated that igniter might be faulty and need to be replaced and they did not have one available they recommended ARPIs. Not having much choice called those guys and tech showed up fairly soon. He tested furnace and determined that control board is faulty. Replace it and furnace started to work. Lessons learned, the fault indicator was not working correctly as board was fried and tech even stated that most likely replacing of pressure sensor was not required. If you are troubleshooting furnace follow more advanced methodology using multimeter.

[speedog]

Draft inducer motor, do not have.
Furnace igniter, do not have.
Pressure switch, do not have.
Control board, do not have.

I think I am thankful for these do not have.

[Darell_n]

This quote is hidden because you are ignoring this member. Show Quote

Draft inducer motor, do not have.
Furnace igniter, do not have.
Pressure switch, do not have.
Control board, do not have.

I think I am thankful for these do not have.

Reliable heat is a luxury, and you sir, will have it. I myself have a unicorn, standing pilot and thermocouple with a control board and inducer motor. Made only during the glorious year of 1996.

[ThePenIsMightier]

This quote is hidden because you are ignoring this member. Show Quote

Reliable heat is a luxury, and you sir, will have it. I myself have a unicorn, standing pilot and thermocouple with a control board and inducer motor. Made only during the glorious year of 1996.

Nineteen! Ninety!! Six!!!
Nineteen!! Ninety!!! Six!!!!

[ExtraSlow]

So, I don't appear to be having connectivity issues between the furnace and the wireless thermostat any more. That's great! I also haven't noticed the furnace short cycling, but.....

The furnace is still showing the stored "3-3" code that indicates "flue limit switch error".

Thoughts anyone, but especially @Darell_n ?

[Darell_n]

This quote is hidden because you are ignoring this member. Show Quote

So, I don't appear to be having connectivity issues between the furnace and the wireless thermostat any more. That's great! I also haven't noticed the furnace short cycling, but.....

The furnace is still showing the stored "3-3" code that indicates "flue limit switch error".

Thoughts anyone, but especially @Darell_n ?

Sounds like a switch that needs to be manually reset. What is your make and model #?

[ExtraSlow]

Carrier 58STA110 Series 130

[Darell_n]

If it is just a stored code and the heat is working at the time, just cycle the power switch for the furnace to clear the saved code. I would measure the heat rise across the furnace while heating. If it is too high it will trip the '33' code and is likely caused by insufficient airflow. Dirty filter, filter with too high a MERV rating, use of return air filters in the house, too many vents closed off, or the furnace is just oversized for the ducts. Fortunately, you can simply use the next speed on your blower motor as it came wired to heat on the lowest speed. (page 34 in your manual).

The tech that checks your furnace should be measuring the heat rise and gas pressure before making any changes.

[ExtraSlow]

This quote is hidden because you are ignoring this member. Show Quote

I have called Atco, and they plan to come out sometime next week.

Hilarious. Atco has declined to do an equipment inspection. According to their email, they are too busy to do this. I'm no longer having issues, so maybe I don't care.

[Darell_n]

Well, winter hasn’t even arrived yet. There will be -30s very soon.

[ExtraSlow]

This quote is hidden because you are ignoring this member. Show Quote

Well, winter hasn’t even arrived yet. There will be -30s very soon.

Negative, I now live here:

[JDMMAN]

Wow interesting with all these people having furnace issues! My grandparent's H.E. Lennox was having issues starting up this past week. It was diagnosed to be a high-level switch; usually a pretty inexpensive part and easily self replaced. For those having this issue, try looking up your furnace model and find the high-level switch. For the Lennox unit they had, it was a $20 part.

[triplep]

I recently had an issue where the furnace would shut off and then cut power to the thermostat and turn it off completely and then the thermostat would reboot (Aprilaire WIFI model). One of the issues with the wireless is that they sometimes they aren't wired properly and after some time, draw more power then they need to and they trip the furnace to turn off. I think what I ended up checking was to make sure the common was wired in so the thermostat would have constant 24V. Wasn't the issue as it was connected. Ended up being a dirty air filter (my fault for not checking it first since I thought I had replaced it about a month ago and it looked pretty clean). Crazy what a dirty air filter will do to the furnace!

[ExtraSlow]

This quote is hidden because you are ignoring this member. Show Quote

If it is just a stored code and the heat is working at the time, just cycle the power switch for the furnace to clear the saved code.

Can you clarify how to clear the codes?
Turning off and back on at the wall switch doesn't seem to.

[ExtraSlow]

Reset my flame rollout switches and wasn't showing the error code after. Was showing the 1-1 all clear. Will check it in a bit when it's run a few cycles.

[ExtraSlow]

So I'm closing the book on my furnace issues. After a manual reset of the flame rollout switches a couple of days ago, the stored code has not returned. I have no idea when or why that rollout switch tripped. It hasn't happened again.

I think there must have also been a loose wire on the thermostat transmitter, which I accidentally fixed while checking things.

Weird that two unrelated things seemed to be happening over the Christmas break. I'll keep an eye on things through the next cold snap.

[Darell_n]

This quote is hidden because you are ignoring this member. Show Quote

So I'm closing the book on my furnace issues. After a manual reset of the flame rollout switches a couple of days ago, the stored code has not returned. I have no idea when or why that rollout switch tripped. It hasn't happened again.

I think there must have also been a loose wire on the thermostat transmitter, which I accidentally fixed while checking things.

Weird that two unrelated things seemed to be happening over the Christmas break. I'll keep an eye on things through the next cold snap.

I would be most concerned on why the heat worked at all with a tripped roll-out switch.

[ZenOps]

Just finished minor tune up of my finicky 93% Lennox. Cleaned off flame sensor - check. Vacuumed out that weird nipple at the back of the unit - check. Cleared all air intakes and outlets - check. Thwacked the condensate line with my finger a few times - check.

Getting ready for this weekends blast.

[Darell_n]

This quote is hidden because you are ignoring this member. Show Quote

Just finished minor tune up of my finicky 93% Lennox. Cleaned off flame sensor - check. Vacuumed out that weird nipple at the back of the unit - check. Cleared all air intakes and outlets - check. Thwacked the condensate line with my finger a few times - check.

Getting ready for this weekends blast.

We are going to need to see a photo of your weird nipple.