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Using "fan only" mode

Posted by gardeningannie (My Page) on
Fri, Oct 12, 12 at 15:28

Sure could use your help ~ here are the facts:

120 year old building converted to apartments. Unit in question is 2nd floor, one large room, 400 sq. feet with 10' ceilings and own small hvac system in utility closet.

There are three 3'X6' windows on the 25' west wall (lots of sun) and an opposite wall of at least 3 air vents located about 2 feet from the ceiling.

Tenant is not much on using the A.c. due to cost, but in summer, would (besides keeping the shades drawn to reduce heat) like to run the 'fan only' mode to blow fresh air into the space while using one box window fan positioned to 'exhaust out' to help remove hot air from space and create a 'draw'.

My questions are these:

1. Does this sound like an effective way of creating air movement and accomplishing the same goal as window fans would at opposite ends of a house?

2. Is running the 'fan only' option on an hvac more expensive that just using regular room/window fans?

3. Would using this 'fan only' setting cause undo wear and tear on the hvac unit if used like this 5-6 months out of the year?

Always appreciate the help and opinions of my Gardenweb family. annie

Follow-Up Postings:

RE: Using "fan only" mode

It might not be very effective because you might be drawing air in from surrounding indoor space rather than outside. A fan in each of two windows, one in and out out would likely be more effective and leave the HVAC blower off. Don't forget that big motors make big heat.

RE: Using "fan only" mode

Thanks ~ Do you think he could actually create a significant difference in the whole room air movement when both 'in' and 'out' windows fans are 15' apart and on the same wall? Thought they would have to be opposite or adjacent walls.

Also surprised that the fan on the small hvac would produce counter productive heat. Would running it like this be hard on the unit?

RE: Using "fan only" mode

The fan motor in the blower will likely be much bigger than the fan motor of a window fan.

If you have one fan exhausting, the incoming air has to come from somewhere. Either around the fan or from leaks or another open window somewhere else. 15' apart is fine, but if it is hotter or more humid outside, you will not be doing yourself any favors.

The only 'advantage' to running the fan is that the air gets filtered. Personally, I wouldn't do it.

RE: Using "fan only" mode

"Thanks ~ Do you think he could actually create a significant difference in the whole room air movement when both 'in' and 'out' windows fans are 15' apart and on the same wall? "


"Also surprised that the fan on the small hvac would produce counter productive heat."

Put your hand on the motor after it has been running for an hour, you'll see.

"Would running it like this be hard on the unit?"

Not particularly. It is designed to run continuously.

RE: Using "fan only" mode

Thanks for all the thoughts on this. I feel the need to clarify that while this option of simply moving around a lot of hot air certainly isn't optimal for the majority of us, this guy has lived the past 10 years with no a.c. and survived 105 degree summers in a second floor apartment only using window fans.

The fact that this newer apartment has a central unit will be a seldom used 'perk' as far as the a.c. is concerned, but he has asked about the safety and expense of simply utilizing the hvac fan to produce a 'wind source' blowing from the higher wall vents and across the room to the lower, exhausting window fan on the opposite wall.

As well, he would probably have another window open, but at least there would be a draw from higher up and across the room to help remove hot air. To only count on creating air flow from window 1 to window 3 on the same wall wouldn't do much for the rest of the space, I'm afraid.

Does that make more sense? And is it still a 'no go' due to safety, expense or wear and tear on the hvac?

RE: Using "fan only" mode

There is no significant issue running the fan to create air movement. It is probably not particularly different in efficiency than a box fan. There is certainly no safety issue.

A box fan directed right on the person just makes more sense but if the fan on the HVAC does the job, it is fine.

RE: Using "fan only" mode

david cary,

Years ago we owned a beautiful home across Puget Sound from Seattle on the Kitsap Peninsula. The weather there is quite mild and the norm was not to have central air... and in three years there we saw no snow... except on the not too distant mountains.

Our furnace was an electric furnace designed for use in a mobile home. No gas, no oil, no propane - just inexpensive electricity from a combination of nuclear and hydro-electric.

I wired in a switch to allow a second higher speed fan operation without calling for heat. We ran the higher speed fan for weeks if not months on end and it kept our home more comfortable during the summer.

There was no downside that we could find and the heat from the fan motor was never noted.

RE: Using "fan only" mode

OP mentions nothing about the geographic location of this building, whether humidity is a factor, whether it's an area that cools down at night, etc.

Running the system could make the room warmer.

The cost to cool a 400 sq ft space can't be very much. This sounds like an elderly person who's fixed in his ways. If he'd rather sit in a stifling room with the AC off, that's his choice, and it's not a very smart one.

We have an elderly family member who lives where it gets uncomfortably hot. He complains about it but is unwilling to do anything differently (like using AC or moving). The result is that he's hot and that's that.

RE: Using "fan only" mode

snidely ~ Actually the guy is only in his hate 30's (not elderly), but just living on a very tight budget. The long, narrow, 2nd floor apartment has 3 windows on the south/west wall. One small tree that gives some shade to the middle window is the only natural sun shield. Humidity is always an issue here in summer. He plans to make good use of shades and fans most days/nights and A.C. only during the hottest weather.

Having shared all the comments regarding this post with him, I think he is going to see what kind of difference it makes having the hvac fan going to move air. Will be interesting to see how that goes. Thanks to all ~ annie

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