HVAC Fan "ON" Or "Auto"

MALCO.New.York

So says you!

http://en.wikipedia.org/wiki/Ceiling_fan#Uses

http://www.spyfu.com/Term.aspx?t=281866

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neolitic

I don't live in Wiki-adia.
What ever works for you, but
what I said seems to work well with
cathedral ceilings, which is the most
common habitat for ceiling fans hereabouts.

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MALCO.New.York

The objective is to "reverse" the Natural tendencies of the Conditioned Air.

Summer: Force the warmer air down so it can be Conditioned by the Cool air that is inherently "hugging the floor".

Winter: Draw the cooler air upward to be Conditioned by the Heated air that your furnace has created.

Ebb and Flow!

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delta l

Perhaps my wording needs some clarity.

I don't have a reference handy, but from my following of HVAC/R forums, it has been the contention of the PROs that following a call for cooling, continued air circulation will cause the coil to gain heat and re-evaporate some of the condensate, which has not completely drained, i.e., wet coil.

While running the fan in this situation will help to mitigate stratification, allowing some fan time off will lessen re-evaporation of condensate.

Delta

MALCO.New.York

Disagree on ALL fronts! Just speaking from limited but well absorbed experience.

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flashheatingand

Based on the local rates electrical rates: .07/kwh
most residential fans use about 500watts (120 volts * 4.0 watts=480)
that comes to $.084/day or just over $300/ year.

Thats $300 a year with the fan on 24/7. If left on auto you would consume about 1/3 the amount power. So, you are spending roughly 200/year to run the fan 24/7 Thats the economic side of the question.

As for comfort and "air cleaning" 24/ 7 is better, but, usually the fan runs at high speed while in the "on" mode. When the heat kicks in, the fan will run a a lower speed. It is hard on the motor to change speeds from high to low. If the furnace short cycles the fan changes speed several times an hour which can shorten the life of a blower.

I would just leave the fan at auto, but, there are applications which on 24/7 is better.

Brock

[quote=flashheatingand;541869]Based on the local rates electrical rates: .07/kwh
most residential fans use about 500watts (120 volts * 4.0 watts=480)
that comes to $.084/day or just over $300/ year.

Thats $300 a year with the fan on 24/7. If left on auto you would consume about 1/3 the amount power. So, you are spending roughly 200/year to run the fan 24/7 Thats the economic side of the question.

As for comfort and "air cleaning" 24/ 7 is better, but, usually the fan runs at high speed while in the "on" mode. When the heat kicks in, the fan will run a a lower speed. It is hard on the motor to change speeds from high to low. If the furnace short cycles the fan changes speed several times an hour which can shorten the life of a blower.


You mean $30.00 (thirty dollars) per year. .084 x 365 days equals $30.66

Compared to about $10.00 with the fan on auto cycle.

I would rethink it if I was handing out 200 bones extra per year. I'm not that much into health and comfort.

flashheatingand

Sorry, I was off with the decimal points, I meant 84 cents a day. Which comes out to be about three hundred dollars a year.

.07/kwh. Fan uses .5 kw/hr. Doing the math it would come out to .84/day. (.5*.07)*24=.84... We have some good electric rates compared to the rest of the country. You should do the math for your location. The bigger the air handler, the higher the wattage, but, with most residential furnaces, the fan draws about 1/2 a kw.

Just out of curiosity, how much do you pay for electricity in the mid-west?

Brock

I should know this, but I haven't looked at the paper bill in a long time. The average for my 3000 sq. ft home is about $100.00 per month. We heat with natural gas though and that bill runs about the same if averaged out over the year maybe a little less than $100.00 because the H/W tank is on gas.

Texwing

Welllll, i sense I should stay out of it but....the value of running the fan ON all the time would depend on many factors. Having done some advanced research on duct losses, it would be interesting to know, in Southern climes with 130 degree attics and shoddy flexible ducting systems, undersized returns, and leaks everywhere, does running the fan in the "on" position provide more harm than benefit? In other words, if you take in the reality of the typical southern attic duct system, increase its operation by 70%, and then figure out the increased duct losses, infiltration, humidity load, and so on, what you find? So, blanket statements as to whether "ON" is good or bad may need to be a little more specific to location, system, and home style.
Just my two cents worth.

Dr Heat

Now that two cents is worth 40 bucks well said. Other thoughts do you have oa intake are the ducts properly sized are you running an eac perhaps a true steam does your furnace have a constant fan tap? Ask your tech. when he comes to service your furnace.