Blower operation

[bobthebuilder]

My furnace is a low effic, probably around 14-15 yrs old.

The heating cycle works good (as best as expected). The problem is that when the heat/blower shut down (as expected) all is good, until the blower (by itself) turns on about 3-5min after the heating is done, and is only on for about 5 - 10secs.

Any thoughts out there?

Thanks
R[?]

[LazyPup]

Bob,

That is not a problem. During the heat cycle the blower is controlled by a thermostat in the heat plenum. Sometimes when the blower turns off there is enough residual heat in the burner and plenum section to raise the plenum temp enough to restart the fan till it blows the hot air out.

[bobthebuilder]

Thank you for the reply...that was one of my thoughts, but this issue has only started within the last couple of months.

The blower would come on once after the house reached temperature, but now it is coming on twice.

It's not a huge issue, but the blower motor is experiencing unnecessary wear and tear. A lot of current is drawn during the inital start up of the motor, which is really a waste. Not to mention that it gets annoying, since I am specifically listening and counting the number of times it comes on.

Anything that I can check / clean / repair to solve this problem. Like I said, it normally wasn't an issue until recently.

Thanks

[imeduc]

Is your filter clean ???? The AC coil clean .The blower wheel blades clean so it can blow like it should??? This all help.

ED

My mistakes dont define me they inform me.

[bobthebuilder]

quote:Originally posted by imeduc

Is your filter clean ???? The AC coil clean .The blower wheel blades clean so it can blow like it should??? This all help.

ED

My mistakes dont define me they inform me.

The furnace is in relatively good shape and is also clean.

Is there anything beyond what you have mentioned, that would be of interest to check into too???

Thanks
R

[imeduc]

They all do this as it gets warmer out side. If you want you could get a new Fan Limit control if that is what you have make sure the element is the same length. Or push up the on setting?????

My mistakes dont define me they inform me.

[bobthebuilder]

It happens during the dead of winter as well!

It seams to be getting more frequent.

What do I look for when trying to find the fan control?

(I'm a newbie, wannabe, don't want to pay the $100 service call fee)

Any useful info would be appreciated .

[imeduc]

What kind of furnace make do you have there? amy small silver like box on the plenum or in th uper right corner of the furnace

My mistakes dont define me they inform me.

[LazyPup]

Let me set your at ease on one point of your concern. You stated that a lot of current is consumed during motor start which you feel is a waste.

When we purchase electrical utility we are charged by the number of Kw/Hr we consume. One Kilowatt hour is the amount of energy consumed by a load that draws 1000 watts continuously for a period of one hour.

To illustrate, it would be the amount of energy drawn by having ten 100 watt lightbulbs on continuously for an hour.

Typically the blower motors used for inside fan motors are 1/4 horse power motors.

One horsepower equals 746 watts of electrical energy therefore a 1/4 horsepower motor consumes 746/4= 186.5 watts

One of Sir Issac Newtons laws postulates that when a body is at rest it tends to remain at rest, or when a body is in motion, it tends to remain in motion until acted upon by an outside force. That is the law of inertia.

When a motor is stopped (a body at rest) inertia trys to keep it at rest, therefor at startup a motor draws a extra force of electrical current to overcome inertia and begin the rotation. It is true that if we were to measure the actual start current it would prove to be approximate three times the run current, but the duration of that current is only the time required to start the motors armature in rotation, which is typically a very small fraction of a second. If one were to watch the current on an analog (needle type) amp meter the needle moves like the windshield wiper of a car, zoom to the top and instantly drops back to the normal run current for the motor.

In fact, if you have to go to the basement to watch the motor run, and if you have three 60watt lightbulbs in your basement you are actually wasting more energy to the basement lights than what is being consumed by the motor.

[heatmon]

bobthebuilder,
You state that the furnace is clean after being asked if the filter(s) is clean. But your problem sounds like a dirty filter (getting worse as time goes by). So- for the record- can you tell us what condition you found your filters in? Are they clean? Thanks.

This is just my opinion, and with it and a dollar, you can get a cup of coffee in most places.