I'm a homeowner concerned about frequent errors on a Bryant Evolution 97% 987MB66120C24 modulating furnace. Most common error is 33 Limit Fault. This occurs 20 to 40 minutes into a long/hot run, such as morning recovery from nighttime setback. Furnace appears to continue to run normally (including modulating up or down as warranted) despite that error. Nonetheless I don't like to see the error in the log, and would like to get to the bottom of it.
Furnace was installed in January 2020 by an installer who has seriously disappointed me. (The most remarkable example: Initially instaleld 2" for this 120K BTU furnace, when manual clearly calls for 2.5" a the smallest and for any reasonable PVC run, 3". Ripped out and done right at my insistence. Plenty more disappointments including them pulling a <100k BTU permit for a 120k BTU furnace, splattering purple PVC primer on my patio, miswiring the fresh air system, and more.) I'm within their 1 year labor warranty but don't want to blindly follow their diagnosis or recommendation; prefer to have my own informed opinion based on, I hope, guidance from experts here.
Furnace serves ~5200 sqft home in greater Seattle. Home built in 2003; this was an early replacement of a noisy 80% furnace, seeking greater comfort, noise reduction, and efficiency. Supply ducts are 2 12", one 8", one 6". Two 10" return ducts. I suspect inadequate return ducts. New filters just installed. Registers open. Exhaust and intake pipe lengths are within spec, accounting for fittings.
Thermostat gives Airflow Verification Test results as follows:
System CFM 1400
Static pressure 0.51
Blower RPM 938
Min CFM 364
Today I happened to be in the Furnace Status screen during when a 33 Limit Fault occurred. Took a photo to preserve. Here's what it said:
gas heat 100%
indoor airflow CFM 1457
blower RPM 1024
static pressure 0.61 in
inducer RPM 3315
leaving air temperature N/A
lockout time left ---
INFO 33 LIMIT FAULT
Last 10 System Events screen confirms 17 Limit Faults in the last 11 days.
I'd value and appreciate any suggestions. Not a small project for installer to provide another return duct given the location and angles, but I don't mind paying for that work (and doing the inevitable cleanup, sheetrock, painting, etc. afterwards -- ugh) for a significant improvement in performance or equipment life. I would also like to understand more about what is going on. I was surprised to see the Furnace Status reporting a CFM greater than what the Airflow Verification Test reported, but admittedly not a big difference. More surprised by the greater static pressure -- I gather 0.51 (per the Airflow Verification Test screen) is fine, versus 0.61 (per Furnace Status when running at 100%) is noticeably higher.
Furnace was installed in January 2020 by an installer who has seriously disappointed me. (The most remarkable example: Initially instaleld 2" for this 120K BTU furnace, when manual clearly calls for 2.5" a the smallest and for any reasonable PVC run, 3". Ripped out and done right at my insistence. Plenty more disappointments including them pulling a <100k BTU permit for a 120k BTU furnace, splattering purple PVC primer on my patio, miswiring the fresh air system, and more.) I'm within their 1 year labor warranty but don't want to blindly follow their diagnosis or recommendation; prefer to have my own informed opinion based on, I hope, guidance from experts here.
Furnace serves ~5200 sqft home in greater Seattle. Home built in 2003; this was an early replacement of a noisy 80% furnace, seeking greater comfort, noise reduction, and efficiency. Supply ducts are 2 12", one 8", one 6". Two 10" return ducts. I suspect inadequate return ducts. New filters just installed. Registers open. Exhaust and intake pipe lengths are within spec, accounting for fittings.
Thermostat gives Airflow Verification Test results as follows:
System CFM 1400
Static pressure 0.51
Blower RPM 938
Min CFM 364
Today I happened to be in the Furnace Status screen during when a 33 Limit Fault occurred. Took a photo to preserve. Here's what it said:
gas heat 100%
indoor airflow CFM 1457
blower RPM 1024
static pressure 0.61 in
inducer RPM 3315
leaving air temperature N/A
lockout time left ---
INFO 33 LIMIT FAULT
Last 10 System Events screen confirms 17 Limit Faults in the last 11 days.
I'd value and appreciate any suggestions. Not a small project for installer to provide another return duct given the location and angles, but I don't mind paying for that work (and doing the inevitable cleanup, sheetrock, painting, etc. afterwards -- ugh) for a significant improvement in performance or equipment life. I would also like to understand more about what is going on. I was surprised to see the Furnace Status reporting a CFM greater than what the Airflow Verification Test reported, but admittedly not a big difference. More surprised by the greater static pressure -- I gather 0.51 (per the Airflow Verification Test screen) is fine, versus 0.61 (per Furnace Status when running at 100%) is noticeably higher.
source https://hvac-talk.com/vbb/showthread.php?2223324-Bryant-Infinity-furnace-frequent-33-Limit-Faults-on-a-recent-install&goto=newpost
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