Hello,

I have a couple questions about my furnace and more specifically my Fan & Limit control.

Riello 40 Oil Furnace
Honeywell L4064 Fan & Limit Control
Recently, at the time of the annual furnace inspection and cleaning, the technician who came to look at the furnace said that my furnace was "going up on limit" and that it was a problem. He said that I needed to clean the a-coil with an old toothbrush, and he figured that would fix the problem.

What I did. I took off an access panel to look at the a-coil, it seemed clean. I brushed it with the tooth brush, but no dirt came off. I replaced the access panel.

What I noticed since. The thermostat calls for heat, the burner turns on and heats up, then the fan starts and then after a short time (mins) the Honeywell L4064 goes up to the limit and the furnace shuts off, even though the thermostat has not reached the desired temperature. After a while the Honeywell L4064 Fan & Limit Control dial comes off the limit and the furnace will start again only to repeat what I have described above.

Is this normal behavior?

If not:
Can I take my Honeywell L4064 Fan & Limit Control out and clean it?
Will cleaning it make any difference or is something else going on?

Answers or any other advice is appreciated.
Thanks

Hello,

I have a couple questions about my furnace and more specifically my Fan & Limit control.

Riello 40 Oil Furnace
Honeywell L4064 Fan & Limit Control
Recently, at the time of the annual furnace inspection and cleaning, the technician who came to look at the furnace said that my furnace was "going up on limit" and that it was a problem. He said that I needed to clean the a-coil with an old toothbrush, and he figured that would fix the problem.

What I did. I took off an access panel to look at the a-coil, it seemed clean. I brushed it with the tooth brush, but no dirt came off. I replaced the access panel.

What I noticed since. The thermostat calls for heat, the burner turns on and heats up, then the fan starts and then after a short time (mins) the Honeywell L4064 goes up to the limit and the furnace shuts off, even though the thermostat has not reached the desired temperature. After a while the Honeywell L4064 Fan & Limit Control dial comes off the limit and the furnace will start again only to repeat what I have described above.

Is this normal behavior?

If not:
Can I take my Honeywell L4064 Fan & Limit Control out and clean it?
Will cleaning it make any difference or is something else going on?

Answers or any other advice is appreciated.
Thanks



Are both sides of the coil clean? Witch way is the air flowing and what side would get dirty?

Whatever,, the limit should not be reached unless there is a problem i.e. poor airflow. So look at all the ways air could be restricted

are both sides of the coil clean? witch way is the air flowing and what side would get dirty?

whatever,,,,, the limit should not be reached unless there is a problem ie poor airflow. so look at all the ways air could be restricted
I agree with juggallojed. The coil has two sides return and supply. Make sure you clean the return air side. Limits open for a reason, to keep from damaging the unit and from burning down the house.(limits do go bad, but make sure its bad. Never raise a limit just to make it work.)

T-Top and juggallojed,

Thanks for your replys. I will take another look at the A-Coil (both sides).

I will be sure not to adjust the limits.

Thanks again.