How does a combination fan and limit control work?

The fan limit switch controls when the furnace blower fan turns on and off. This control also provides a safety limit that turns off the burner or furnace if temperatures at the furnace get too high.

How does a fan limit switch work?

To put it very simply, the furnace fan limit switch is a control that tells your furnace’s fan when to turn on and off. So, when the furnace isn’t on, it tells the blower not to operate (and send cold air into your home) and when the furnace is on, it tells the blower to turn on and start circulating the warm air.

Should furnace fan be on auto or on?

“auto” is the best setting for your furnace fan in the winter. It will aid in saving energy and money while also working to keep your home at an optimal temperature. However, for summer, “on” is the best setting for your furnace fan.

What should my fan limit switch be set at?

For a general guide, set the two lowest ones (from the furthest left) to 100 and 130 degrees to control when the fan comes on and goes off. The third marker should be set around 200 degrees as a safety shut-off for the burner.

Do all furnaces have a fan limit switch?

Fan/Limit switches are used on all types of building heating furnaces. CLICK HERE to see a CLOSE-UP [image] of the FAN OFF, ON, and HIGH LIMIT OFF factory settings on this fan limit control. 1- FAN OFF: the low temperature at which the furnace blower fan will STOP to prevent blowing cool air onto room occupants.

Should I run my furnace fan all the time?

Running your furnace fan all the time isn’t exactly a bad thing. In fact, there’s no need to worry about the fan wearing out or breaking down because it’s designed to run continuously, and there’s an array of benefits connected to this. Here are some of them: Better circulation of heated and cooled air.

How many limit switches are in a furnace?

Identifying the Limit Switch

The mounting plate usually contains two or more terminals that receive control wires for the blower fan and the furnace’s gas valve. It’s possible that your furnace will have two or even three limit switches that check temperatures at different parts of the furnace.

Where is the limit switch located on a furnace?

The limit switch is a safety control switch located on the furnace just below the plenum. If the plenum gets too hot, the limit switch shuts off the burner. It also shuts off the blower when the temperature drops to a certain level after the burner has shut off.

Where is my fan limit switch on furnace?

Your fan limit switch is located inside the furnace panel cover, usually near the upper right corner. The fan limit switch is responsible for turning the blower on and off at the appropriate times.

What is the purpose of a limit switch in a warm air furnace?

A furnace limit switch is a component of a forced-air furnace that is responsible for turning on the furnace blower once the desired heat has been met inside the furnace. Without a functioning furnace limit switch, a furnace would not be able to regulate the temperature in conjunction with a thermostat.

How do I adjust my furnace fan?

When increasing the blower speed, loosen the setscrew a little bit. This is the part that holds the pulley to the furnace’s driveshaft. Turn the pulley one rotation clockwise on the shaft. If you want even more speed, do two rotations.

How do I adjust the fan control on my furnace?

Furnace FAN ON Setting

The FAN ON setting is the metal finger second from left-most, protruding through the round silver plate of the fan limit control. This finger is set to a temperature range from a minimum of 20 °F above the FAN OFF set point, to a maximum f 30 °F below the LIMIT OFF set point.

What kind of switch is the fan switch?

A single wall switch controls the power to the fan and light together, whereas a dual wall switch has two separate switches – one for the fan and the other for the light.

What effect does slowing down the blower speed have on a heating unit?

In heating, higher speed = (usually)more flow/lower temperature; lower speed = less flow, higher temperature. Depending on your local conditions, it is possible that heating and a/c can utilize the same blower speed. Too low a speed will cause freezing (no good)in a/c.

Can furnace fan speed be adjusted?

Quote from the video:
Quote from Youtube video: And that would end up lowering your fan speed. So you could do that at the at the blower motor here if you have these types of terminals. But if you have a plug here instead you need to make that

Does fan speed affect heat?

The volume near the fan will be hotter if you choose a lower fan speed while a higher fan speed spreads the heat better over a larger volume. Regarding no heating elements, I would think that the movement of unheated air would have a minuscule effect on the room air temperature.

Can you turn down blower on furnace?

Quote from the video:
Quote from Youtube video: Started you don't really want to slow down the speed of your blower unless you've consulted with a hvac installer or specialist.

How do I control the fan speed on my blower?

You can increase or decrease the blower speed by slightly adjusting the pulley on the blower drive motor. To increase blower speed, slightly loosen the setscrew that holds the pulley to the driveshaft. Move or turn the pulley clockwise on the shaft one turn, then tighten setscrew.

Is variable speed furnace worth it?

The best news … a variable speed furnace motor is 80–85% more efficient than a standard furnace motor. So, if you are going to upgrade from a 90% to a 96% efficient furnace make sure it has a variable speed furnace motor, and you could enjoy energy savings of up to $400 a year. Otherwise it’s not worth the investment.