Fan Limit Switch Settings Q&A

Fan Limit Control Setting Adjustment Numbers FAQs

Fan Limit Control Switch Settings Q&A

What are normal settings for limit switch to be set on a Honeywell gas furnace?

What are normal settings for limit switch to be set on a Honeywell gas furnace? (Jan 1, 2016) nick

Reply:

Nick

The fan limit switch temperature settings (shown on the dial sketch) are discussed in detail

at FAN LIMIT CONTROL SETTINGS.

Using the Honeywell L4064B fan limit control as an example

From the factory the FAN OFF finger is usually set to about 90 °F.

From the factory the FAN ON is usually set to about 130 °F.

From the factory, the LIMIT OFF is set to 200 °F.

How do I match the fan limit control to the fan off temperature?

Hi Sir, I would like to know what is reference point to decide temperature. I mean to say how do you know at which temperature fan stops so I can set fan off switch to that temparature? (Nov 10, 2014) Anonymous said:

Please feel free to contact me at wachobank7@gmail.com. Thank you very much for your time.

Reply:

Anon

I think you've got it wrong. It is the limit switch that will stop the fan.

The recommended temperature settings, designed to protect the heat exchanger from dangerous cracks due to overheating, are pre-set on the control by the manufacturer and should not be changed without consulting with the manufacturer of your furnace.

Watch out: messing with the limit switch dial while trying to change its settings can bend internal parts, taking the switch out of calibration and making it DANGEROUS!

Details are at FAN LIMIT CONTROL SETTINGS 

How do I set the fan limit switches on my electric / wood furnace?

I have a wood/electric furnace with 2 high/low limit switches, the fan limit switch is set at factory settings, but where do I set the wood thermostat/ damper motor at? - On 2021-12-16 by Alfie ,-

Reply by Inspectapedia Com Moderator - set the damper according to the manual for your wood stove

@Alfie,

If I understand correctly, since your alternate heat mode is electric with no concern about needing two different draft settings depending on which it source is in use.

You would set the damper according to the manual for your wood stove and that's probably model specific.

Can you tell us the brand and model of the stove so that we can look at its manual?

My guess is that your wood burner thermostat has to be set low enough to avoid dangerously overheating the furnace and cracking its heat exchanger, but just what that temperature is will depend on the brand and model heater.

What if there is no FAN-ON white button to push or pull on the fan limit switch

My fan limit control says push man and an arrow, no white button, only an empty hole. What should I do?

I set the numbers at their correct positions but the blower still remains on for a while and then comes back on after going off. I was lucky enough to replace my blower motor on my own after ordering it online.

The least of my worries was the fan limiter. Now after a month of heat I need help! Thank you (Jan 31, 2014) marie

Reply: not all fan limit switches include a manual FAN-ON switch or button

If your limit control has no actual operable push-pull button or switch, then it's a model that omitted that feature. The switch will still work automatically. The manual switch is an extra, not mandatory.

Watch out: Be careful not to mess with, force, or bend the switch parts - doing so could make it unsafe.

Can the fan limit switch plenum temperature be changed?

Can the plenum fan limit switch temperature be changed. its not adjustable just mounts inside the plenum approx 3 inches.

i have found some that range from 200/180, 180/150 and so on. what is the maximum heat exchanger temperature for a force air oil furnace. and would using a higher temp limit switch solve the cold air from the fan running so long after the burner shuts down. somebody mounted furnace in a half basement and has a through floor heat supply with floor grate.

it doesn't have a return duct returning from inside the house. it draws the return air from under house via floor vents in each room its what i call a half ass installed furnace put in by budweiser consumers in a old house in the mountains.

forced air oil furnace runs and heats but during shut down the air is extremely cold before the fan limit shuts off the fan. On 2017-12-18 by william

by (mod) - not with the type of fan limit control shown here

Some fan limit controls have temperature adjustments but you are describing a non-adjustable limit control like the one I show in the photo above.

See the types of fan limit and temperature controls and their adjustments at FAN LIMIT SWITCH GUIDE

A higher upper limit setting in your furnace would not solve the problem that you describe and it risks damaging the heat exchanger which in turn would make the system unsafe, risking fatal carbon monoxide poisoning. It would be better to correct the return air supply to the furnace.