Mark, You have no idea what you are talking about so you should quit while you are ahead. Go buy a clamp on amp meter and watch the motor load on start up. Then watch one while you hold the motor from running while it is trying to start. Do that about 2 or 3 times and feel how hot the motor gets. You may then begin to understand. Bubba
Then i would suggest that you leave your car running all the time. You don't have a clue.
Mark & Bob, The blower motors are designed to be able to run constantly without damage to the bearings or windings. Just ask any motor manufacturer. I have been to many motor seminars & the main failure mode is HEAT. A motor with restricted air flow will run hot and die an early death. Starting causes some strain on motors but dirty or restricted filters cause overheating which will damage motors. A blower motor should last as long as the furnace if it has enough air flow to keep it cool. That is if it runs constantly OR cycles.
Running the fan set to on will increase humidity when cooling by as much as 15% in high humidity climates. This is because when the compressor shuts off the water left on the coil will re-evaporate into the air stream. Get a data logger to record humidity and try it both ways. I did. A Lennox manual titled "Equipment Selection in Humid Applications" came to the same conclusion.
My fan motor on my 2.5 ton heat pump indoor unit draws 2.2 amps at 240 volts. Just over 475 watts at 0.9 power factor. at my utility rates that is about 4 cents an hour. That is just under $30.00 per month when running 24/7.
I leave mine set to auto. If you have cheap electricity or a different climate or both, feel free to set it to ON.
The advantages are it will even out temperatures and filter the air better. The disadvantages are high summer humidity in many climates, high electric bills and drafty feeling in the winter. The best time to run the fan set to ON is spring & fall.
Stretch
Stretch,
Thanks for the input. I can see where setting the fan to 'on' in humid climates can increase humidity. My experience is limited to my particular climate. I wonder if Lennox was only talking about properly sized cooling systems when they say "as much as 15%".
I have hydronic baseboard heat with straight air in the attic. With the blower on, my heat is more even, because it pushes the heat back down to the floor.
Let''s look at it this way:
Ideally, 1hp = 746watts
If a motor delivers 1/2 hp, then its actual wattage will run over half of this, because the motor isn't 100% efficient at converting electrical energy into useful mechanical energy.
A half horse blower motor consumes about 400 watts.
On low speed, however, at 230 volt, the amperage draw can run down around the 1.2 amp region.
On many newer units continuous fan is defaulted to low speed, which is equivalent to about 1/2 the rate hp of the motor. IOW, on low speed a half horse motor will be running at closer to 1/4 hp, or thereabouts, or somewhere in the region of 200 watts, and the amp draw corresponding to this on 230 volts is down around the 1 amp mark. I've seen them running under 1 amp.
hvacrmedic
That I suppose would mean that the air in the house is cleaner.
But only a little bit
I always leave mine on auto. These are mattters of taste, and De gustibus, no est disputandum (or something like that: There is no disputing with regard to taste.) but I don't care if there are minor variations in temperature, and I like the silence when the fan is off altoghether. It would drive me crazy to have it on all the time.r.
Remove NOPSAM to email me. Please let me know if you have posted also.
A constant noise is less distracting than one that changes (on and off) unpredictably.
BTW, I remember spending the night with someone who left the fan on all the time, and the room I slept in was next to the furnace. I never noticed the fan after a few minutes except once. That time, it was a power failure.
non est disputandum.
To some people.
This is a matter of taste.
This I really can't spell: Chaque a sangue. Each to his own taste.
Remove NOPSAM to email me. Please let me know if you have posted also.
Chacon a son gout (there's an accent over the "a" that I'm incapable of placing).
The only times I've left mine on "ON" were during parties in the winter when I'd have many guests over. The body heat generated by each guest is enough to raise the temperature of the room a few degrees above normal, making the furnace not run at all. After 3-4 hours the main floor where all the guests are becomes 2-4 degrees hotter than the rest of the house, and the air starts getting a bit stuffy from all the people and the lack of air circulation. Often the windows will start to fog up from the extra humidity (from all the cooking, guests talking and drinking, etc.)
I leave the fan on ON to get better air circulation during those times. The whole house stays at a much more comfortable and constant temperature, the air is less humid and stuffy, and the windows don't fog up.
...and it's really important to do that if you're serving a bean dish like chili ;-)
Patrick
Is there something wrong with my furnace? If I leave the fan "ON" there's a big boom when the heat kicks on when the gas lights. I just assumed that the gas was being sucked up by the fan and torched when it lit.
If I leave it on "AUTO" it works just fine.
That does not sound normal to me.
Yeah. I better just leave it on "AUTO".
Yeah, that you can pretend that the heat exchanger isn't cracked.
hvacrmedic
Ignorance is bliss. What I don't know about can't hurt me.
What you don't know can certainly hurt you.
Uhh, chili isn't a bean dish, it is a green dish.
Thanks for the input. I can see where setting the fan to 'on' in humid climates can increase humidity. My experience is limited to my particular climate. I wonder if Lennox was only talking about properly sized cooling systems when they say "as much as 15%".
I have hydronic baseboard heat with straight air in the attic. With the
blower on, my heat is more even, because it pushes the heat back down to the floor.
Bob, Yhe 15% was what I measured with my data logger using my system. My unit is properly sized. Lennox does not give a percentage in their manual.
Stretch
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