We moved into a house with a 12 year old goodman (Xenon brand but I was told goodman parts) and two end bells on the furnace fan motor have burned out now (I know from the old owners receipts it happened before). The folks who repaired can't tell me why…that I seem to have a lemon. I use MERV 11 filters, have the furnace cleaned annually and vents cleaned last year. Any thoughts on what might cause this and anything I could look into so we don't have this happen again. @chris mentions airflow potentially…how do I know if Adjustments are needed?
Also, I read that the newer furnace filters MERV 11 and under have good airflow…is there a way to test my system for airflow and how the filter way to affecting this? I can easily change air filters if that is this is the consensus though.
I don't know if this means anything or not, but we also have water dripping out of the air return during the air conditioning season…I thought I heard repairman say that fan speed could be adjusted to fix this…any ideas?
Furnace end bell burned out twice in 4 years
furnacerepair
Best Answer
It sounds like you have an ECM "constant flow" blower that ramps up output as high as necessary to maintain the set airflow (aka an ECM constant torque motor). A MERV 11 filter is too restrictive for most residential systems. In this case, the motor would compensate for the restrictive filter by running harder and hotter to maintain the airflow. Switch to a MERV 8 filter (it's still a pretty good filter). If your system delivers more airflow than you need, then also set the airflow selector switches in the furnace to a lower setting. Obviously the air filter should also be changed regularly before it becomes plugged or the blower will again ramp up to a very high level to compensate.
EDIT; Specifics related to OP's situation:
It turns out OP has a very high performance MERV 11 filter which if correctly matched to the system might be OK. The stamp on the side of the filter states "Airflow Capacity up to 1400 CFM." In reality I would expect this to mean this filter might be successfully employed on a system with a 3 ton cooling capacity (3 tons / 1200 cfm). It would not work for a larger system.
I found more detailed information on an air cleaner that uses OP's media here:
http://www.cleancomfort.com/assets/Brochures_SpecSheets/Filtration/SS-AM11-3225.pdf
The referenced unit above uses two (2) AMP-M1-1056 filters and therefore handles twice the airflow of OP's setup. In my experience a pleated filter is near its end of life when the static pressure drop reaches about 0.2" WC. Looking at the "AM11-3225-5 Pressure Drop vs. Air Flow Rate" chart on page 2, one sees 0.2" static pressure loss corresponds to 2600 CFM for two filter cartridges when new. So according to this chart, 1300 CFM would be the max airflow through OP's one cartridge when new and if one were to run the filter at that high a flow it would need to be changed very frequently (at least monthly?) because it would become more restrictive as it filled with particles.
My conclusion: If OP's system does not exceed 3 tons / 1200 CFM and OP changes the filters monthly (normal intervals of 3-6 months are plausible if the system is 2 tons / 800 CFM or smaller) then the existing setup is probably OK. Otherwise switch to something less restrictive.