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Hi all,
I'm trying to determine if there is an issue with my new furnace or if I'm just expecting too much from it. I have a 3004 sq ft house not including the basement though the basement is not heated. We've had a Bryant furnace for 23 yrs and never had any issues with heating comfort. Just over a year ago we replaced the HVAC system and installed a Bryant 2 stage 110K BTU In/89K BTU out furnace (not a heat pump) and a 2-4 stage Bryant Housewise thermostat. Cooling has not been a problem. We never had a heating comfort problem with our old single stage furnace/thermostat which had exactly the same BTU ratings as the new furnace. Problem: the new furnace rarely heats the house above 67 degrees when the outside temperatures are at/below 20-25 degrees F and house temp often goes as low as 64-65 degrees when outside temperatures are in the single digits. This is when the set temperature is between 70-74 (I've tried multiple set temp). Often the furnace (and thermostat) will just shut down for an hour or more well below the set temperature before it kicks back in again. I can turn off the power to reset it and get it going again but this is not a solution and I still cannot get it to set point (70) when it's really cold out. I have had the heating and cooling company that installed it out 3x already and they have tried lowering the gas pressure and turning up the fan (they've also checked/cleaned the heat sensor (?) but I've only seen an incremental improvement. My question is whether I have a case for replacing the furnace or some component of it before I call them again.  Additional question, is it possible that they wired my multistage thermostat to just operate in single stage mode and are relying on the furnace to operate the two-stage capability and would that even matter (both stages do come on synchronously as they should)? I do not recall them doing any significant rewiring when they installed the new thermostat though I may be wrong about that.

Something is not right.  Are there any error codes? Even if it's just a lockout code.

110 BTU is kinda high for a 3k house. But it can still work if the airflow, ductwork, etc is correct.

Could be a number of things, but it seems the techs are in process of figuring it out. If they are correcting manifold pressure, etc.  Too many variables to give you a good diagnosis online.

That's the problem with a problem that only happens after a long time of operation. Or only when it's snowy, or windy outside. It'll get figured out. Too many variables to give you a good advice without typing out a small essay.  Overheating, draining, pipe slope, furnace slope, dip switch settings. All could be culprits. And that's without knowing the exact error code.

Like Sergroum mentioned try to retrieve the error codes on the control board.  It should mention how on the back of the door or in the manual.

I wonder if they messed up the staging.  Are you certain the furnace kicks into high fire or is it stuck running on low fire?  There should be something on the control board to indicate what stage is running.

Thanks for the feedback folks! I had reached a point where I was going to insist that my service provider simply replace the furnace or at least whatever key components might be faulty but un-diagnosable but maybe there's' still some tweaking that can be done (?). I also was beginning to think maybe I just needed a bigger furnace but maybe it would be better if it was smaller (?). I keep coming back to the fact that my previous single stage furnace was the same size but I didn't have this problem with it. I guess this is what I get for going more hi-tech! RE has it been cycling Lo->Hi?  It definitely has, though the Hi cycle only stays on for about 15 minutes at a time (maybe normal). I've been paying attention to the cycling to try and glean what's happening but it seems idiosyncratic and problems only occur when the outside temperatures are low which makes it frustrating. Everything seemed fine yesterday when the temperature was above freezing. This morning I woke up at 4:30 AM and it was 67 degrees in the house (had it set for 72) and the furnace was off. I shut the power off and on then went back to bed. Not sure of it came back on but probably did. Woke up at 8 AM and it was still 67 in the house (18 outside) and it was off again. It's 11 AM now and the thermostat is still saying its' 67 in the house (now 24 outside) and the furnace still hasn't come on since 8 this morning. It also say's "heating" in red but actually nothing is happening. I'm not going to restart it this time. I'm actually hoping it doesn't come on then I can call in for emergency service and maybe get a better diagnosis of the problem. Re error codes. Don't know where to find those. Nothing about this in the manual, nothing I can see behind the furnace cover, and nothing comes up on the thermostat display (by control panel do you mean the thermostat display?). I did get an email alert from the thermostat last week when we were out of town saying the thermostat was calling for heat but the furnace was not responding. Scared the heck out of me since we were out of town but I was able to turn off the furnace from my phone and turn it back on and it kicked in again. Something ain't right! OK, here we go, it's 11:03 AM and it finally has come back on.  It feels like the service guys keep doing the same fixes over and over again expecting a different result. However, I'm going to call them and give them another shot. I'm not the unreasonable-ranting type but this is getting a bit ridiculous.

What is the model number of the furnace?  Usually there is a little round window on the bottom door you can look through to see the LED error codes.

What you describe is definitely an error code lockout.  It will be fixable once we figure out what the error is.

Or maybe a bad thermostat.

Thanks for the reply. My unit is Bryant product # 820TA66110V21A-B, model number 820TA66110V21 . I took a closer look inside the unit. There is an inner panel with a window that just has an amber light that's on so I took off the inner panel. I also found the sticker with a list of status codes. Per the description given on the panel sticker, the amber light (LED1) will flash short or long the number of times corresponding to the code number. The thing is it is currently just solid amber (on) so I presume there no error code is being indicated. A solid LED light according to the instructions on the panel simply means "Control has 24VAC power". There is also a green bulb (LED2) that is off. Not sure what that is for. Instructions also note that the codes will be erased after 72 HR so I may have missed something.  A code can be recalled following a number of steps that I'm not comfortable following. I greatly appreciate your help. I'm not expecting you to solve my problem but certainly interested in any insights.  At this point I'm just waiting to hear back from my service provider.

The next morning the furnace seems to be off you should be able to count how many times each light flashes before pausing.

Yes, I see now that I'll want to pay closer attention to the error status LED. Unfortunately, the problem only occurs when it gets down into the teens and looking at the weather prediction it may be a long time before it gets that cold for an extended period which puts me in a real pickle. Also, I'm thinking there may never be an error message. The service guys didn't mention they found one the last 3 times they were out. Based on what I've observed it seems the furnace will cycle 3-4 times to try and reach the set point when it's really cold out then just shut down possibly because of the overheating safety mechanism (?). When it shuts down the thermostat goes dark then resets itself but the furnace doesn't come back on for an hour or more so the set point is never reached and the inside temp doesn't get above 67 unless the outside temp gets above ~ 25. So, I'm wondering whether this safety shut down mechanism would even generate an error message or is just part of the normal operation of the furnace? This is why I was beginning to think I was just expecting too much from the furnace. However, if that's the case, I'd say this is a pretty wimpy system and I got screwed when purchased it, especially since my old (23 yr old) furnace was working fine. I purchased the new HVAC system because of the age of my old system and the fact that the AC unit died and wasn't cost-effective to repair.

I still haven't heard back from my service provider. They probably think I'm crazy!

It sounds like a safety tripped for sure, so there will be an error code if it happens again.  You're not crazy, something is not working properly.

I'm going with they didn't install a double return air and/or the duct work is undersized and it's going off on limit. I've been hearing more and more of these situations. Those Bryant's/carriers are picky as f when it comes to air flow

What size/btu was the old furnace they pulled out?

OMG! Hvacpimp, you may have solved the mystery...I hope. Your comment about air return prompted me to take a look at the main return vent in our dinning room. We recently got a new dining room table and so I disassemble the old one and haven't gotten rid of it yet. One of the large glass top sections was laying against the wall...in front of the intake vent. It wasn't completely blocking it but maybe enough to prevent good air flow. I've moved it and now I just need to wait for some cold weather to see if it makes a difference. Looks like the temps are going to be in the teens this weekend. Keeping my fingers crossed and will post the results.

Well, unblocking the partially blocked intake vent was wishful thinking. Woke up to 18 degrees outside/67 degrees inside this morning. Furnace was off and displaying error code 13 (with reference to error code 33). Apparently, it had to quit after cycling too many times during the night. Error 13 says it would be off for 3 hr before resetting which was in fact the case. So, assuming the service guys already checked the integrity of all the components during their last 3 visits it seems I may have an air flow problem (?). All the vents in the upstairs and downstairs have been fully open. I also opened the 2 in the basement which I normally keep closed (we have fireplace down there so rarely need them) to try and improve airflow. Finally, I re-cleaned the furnace filters even though they weren't really dirty. The furnace utility room in the basement is well vented, but I have been leaving the door to the room open as well to maximize external air flow.  None of this should really be necessary.  I'm once again wondering if this just isn't the right furnace for our house and/or of poorer quality than our previous single stage Bryant furnace (old furnace was model #383KAV048111 series G 110/89K BTU). Would I be better off with a single stage furnace? I still have not gotten a return call from my service provider but will be getting back with them next week for sure, especially now that I have the error code. I should add that this is supposed to be the best rated company in our area and I paid top dollar for this HVAC system. They haven't charged me for the service visits even though my 1 yr service warranty has run out so there's that.

Wait. The new furnace is a year + old?  I was under impression it was just recently installed.

Installed August 2020. I probably shouldn't have referred to it as "new' but it's too new to be having this probable in my view. I in fact had the same problem in Dec 2020 and they came out and turned up the fan and reduced the gas pressure. Couldn't really tell if this did anything because they came out well after the fact and it never got that cold again until now. This morning it was off again with the same error code 13. 18 degrees out and 65 in the house. My wife has resorted to using a space heater in her office (works from home much of the time) which I'm not happy about.

Trying to follow along with this... with the model number you provided it would seem you had an 80% furnace installed in 2020?  How did this installation take place when mid efficient equipment has not be available in the residential market for many years now?  Serial number for the this appliance ?  Curious of the error code if it is indeed 13 or 31. 

Actually checking out the model that the OP put up.  It's single stagers too.  I think something here is off .



Reminds me of an episode of House M.D.

To recap, my Bryant furnace model 820TA66110V21 (2-stage) was installed in August 2020 and has been shutting down prematurely with error code 13. Re "mid efficient equipment has not be available in the residential market for many years now", my read on that is there was an attempted phase out years ago but perhaps unsuccessful or regionally incomplete (?) as all the Heating and Air Conditioning companies in Indianapolis are selling them. Update: two guys were out again to check my system and were able to reproduce the error 13 code after about 4 hours of working on it. They determined that while the manufacture install instructions did not call for it when they installed the system in 2020, the only way to keep the sensor furthest from the return air intake (apparently there are 2 sensors) from overheating would be to install an intake duct on both sides of the burners. Apparently, they learned that one of their colleagues has used this fix successfully once before on the model I have. I think Hvacpimp suggested this earlier as well. Since they consider this a manufacturer's defect (?), they are going to do the install at no charge. Stay tuned, scheduling this for next week. Interestingly, the guys set the furnace to run only in the first stage mode in the meantime and it has been doing just fine even when it has been very cold and is actually much quieter. Wondering why I went with the two-stage in the first place! I know this is supposed to save in heating costs in the long run but I haven't checked this yet.

Re: "Reminds me of an episode of House M.D." Good one but actually Dr. Ni, Ph.D.