SHould I adjust the speed of teh fan on my forced hot air system?

JoeG

I read that I can increase teh speed of the fan on my Hot Air furnace by rotating the pulley on the motor forward, is this a good idea? the two furthest vents dont have much air coming out and the pressure is weak and the air is cold.



Any tips on doing this? Pros?Cons?

icesailor

Fan Speed:

If this is a old system, and has worked properly in the past, like when it was new, I would look and make sure that all the take-off's and supply/returns are connected and not blowing into space. If you have a duct that is not connected, you will have low pressure.

I wouldn't consider trying to increase the fan speed until you determine that the duct system is tight and not leaking.

Tim McElwain

Often poor air flow

is the result of insufficient return air. You can quickly prove that by running the furnace with the blower door off and see if you have increased flow at the registers. If you do then you need more return air.



Typically a far as blower speed goes it is preferred for heating to run the blower at a lower speed to help maintain a steady flow of warm air. Warm air is less dense than cold air therefore it typically needs lower blower speed.

JoeG

ok

A 1/4 of my house has a crawl space the rest is a basement, tonight I wrapped most of the pipe under there with old insulation and the air now coming out of the vents is def warmer.



I hvae one pipe in my basement that used to be hooked up to a floor vent but that vent was removed due to remolding, I have it running into the basemen now, should I put a register on it or just turn the flapper vavle in the pip to like half shut?

billtwocase

fan speed

i would throttle down that basement takeoff, it is probably robbing you of forced air. Also if you do increase the blower speed by adjusting the pulley, you will need to adjust the tension. The belt will ride higher on the pulley, and make the belt too tight. The motor actually should slip some before it rotates the blower if adjusted properly. Too tight burns out motors and bearings.

JoeG

ok

How tight should belt be? Inch of deflection or so? this is a oneida furnace I have no idea how old, it runs smooth and quiet it does look old though. I just got the house over summer and just moved in theis week. Did A remodle

Tim McElwain

With fan shut off

the belt should be able to be depressed 1". You may find that when you speed it up that you are blowing cold air when it first starts and when it shuts off. So remember where it was before you moved it.



How many returns do you have on this furnace?

Ironman

Fan Speed

I wouldn't increase the blower speed unless you check the amp draw afterward and make sure it's within the FLA rating on the motor's data plate.



Also, if you have A/C on this blower, its ability to de-humidify will be reduced as you increase fan speed.

JoeG

No AC Yet.

I think there are only 2 returns taht I know Of and they are pretty big. ANd I think there are 9 or 10 vents. The upstairs is heated with electric.

JoeG

No AC Yet.

I think there are only 2 returns taht I know Of and they are pretty big. ANd I think there are 9 or 10 vents. The upstairs is heated with electric.

Big Ed_4

Watch the Delta T

If you increase it too far your flue gas can condense and too little your furnace can burn out.. On your furnace label there is a posted temperature difference ... After you adjust the fan speed, you will also need to take the temperature of the return air and the supply air ... The difference between them should be with in the posted range .. The supply air reading should be taken just after the first bend , not in the face of the heat exchanger where its radiant heat can throw off the correct readings..

JoeG

Where is the label?

Where is the label on the furnace. Also what is the correct settings for the honwell control that controls the on and off temps on the furnace? Thanks

Tim McElwain

I assume the Honeywell control

is the Fan & Limit Control such as L4064 if that is correct the high limit is set to 200 Degrees and the fan on setting to around 130 to 140, the fan off around 110.



The information on the furnace as to make model and serial number and temperature rise can be found in the burner area on one of the sides.