Author Topic: Any tips for using whole-house fan?  (Read 8375 times)

jengod

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Any tips for using whole-house fan?
« on: July 07, 2016, 03:18:46 PM »
It has come to my attention that we do have a whole-house fan and that its use can be scheduled through our Nest thermostat.

We have made a lot of progress on temp-controlling our house in summer through double-pane windows, wooden shutters, leaving windows open for circulation at night and planting trees. But it still gets quite hot late afternoon when sun hits us directly.

Thoughts on how to reduce use of AC by increasing use of fan? TIA


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« Last Edit: July 07, 2016, 03:25:28 PM by jengod »

onlykelsey

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Re: Any tips for using whole-house fan?
« Reply #1 on: July 07, 2016, 03:22:36 PM »
Right before you open the windows at night, turn on the whole house fan (maybe 9 PM this time of year in my area).  It will increase suction so more cool air comes in through your windows and out through your attic.  Turn it off (and close the slats, if you can) in the morning when you shut the house back up.  if I stayed home all day I'd probably not close up windows until 10 AM, but I don't think the nest programmability is very helpful for a whole house fan, as you have to close the windows as well.  If you try to close the windows with the fan on, I've seen old windows actually bounce back up because of the pressure differential.

They are AMAZING.  If it's powerful, you may end up having to weight papers/curtains/etc to keep them from going crazy.

Rezdent

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Re: Any tips for using whole-house fan?
« Reply #2 on: July 07, 2016, 04:37:03 PM »
We run ours overnight too.
You can direct air flow by choosing which windows to open.  If my kitchen is hotter then I open only kitchen windows and turn on the fan.  Bedtime, I'll close kitchen windows and open the ones in the bedroom.

Syonyk

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Re: Any tips for using whole-house fan?
« Reply #3 on: July 07, 2016, 06:20:13 PM »
Whole house fan controlled through the Nest?  Can you clarify what you mean?

Are you referring to an attic fan/"huge exhaust fan" in the ceiling that sucks a few thousand CFM out, or are you referring to the Nest "fan on" mode in which the furnace fan runs circulating air throughout the house with the furnace/AC turned off?

The only thing I'm aware of the Nest can control is the second.  Which won't help much for cooling things down.  It just circulates air inside the house.

Stache it Away

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Re: Any tips for using whole-house fan?
« Reply #4 on: July 07, 2016, 06:37:54 PM »
We actually decided to cover and insulate over our house fan after reading a study that showed a significant amount of heat is lost through them which negates the savings offered by an attic fan (don't recall the actual study as this was years ago).  The best solution is probably to use it in the summer to drop the temp in the house down at night and then turn it off.  In the winter it is best to cover them up to stop convective heat loss which can be significant.  I think this is why most new homes don't have them anymore.

Syonyk

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Re: Any tips for using whole-house fan?
« Reply #5 on: July 07, 2016, 07:01:29 PM »
We actually decided to cover and insulate over our house fan after reading a study that showed a significant amount of heat is lost through them which negates the savings offered by an attic fan (don't recall the actual study as this was years ago).  The best solution is probably to use it in the summer to drop the temp in the house down at night and then turn it off.  In the winter it is best to cover them up to stop convective heat loss which can be significant.  I think this is why most new homes don't have them anymore.

... yeah... you cover it with insulation in the winter. :p

jengod

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Re: Any tips for using whole-house fan?
« Reply #6 on: July 07, 2016, 07:14:19 PM »
Whole house fan controlled through the Nest?  Can you clarify what you mean?

Are you referring to an attic fan/"huge exhaust fan" in the ceiling that sucks a few thousand CFM out, or are you referring to the Nest "fan on" mode in which the furnace fan runs circulating air throughout the house with the furnace/AC turned off?

The only thing I'm aware of the Nest can control is the second.  Which won't help much for cooling things down.  It just circulates air inside the house.

Damn. I bet it's just that furnace fan. Carry on with your informative chat while I investigate further.


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Paul | pdgessler

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Re: Any tips for using whole-house fan?
« Reply #7 on: July 07, 2016, 07:42:41 PM »
Whole house fan controlled through the Nest?  Can you clarify what you mean?

Are you referring to an attic fan/"huge exhaust fan" in the ceiling that sucks a few thousand CFM out, or are you referring to the Nest "fan on" mode in which the furnace fan runs circulating air throughout the house with the furnace/AC turned off?

The only thing I'm aware of the Nest can control is the second.  Which won't help much for cooling things down.  It just circulates air inside the house.

Damn. I bet it's just that furnace fan. Carry on with your informative chat while I investigate further.

That's correct. The Nest does have an auxiliary "star" terminal for certain extra devices, but whole house fans are not (at the time of writing, at least) supported.

Reference: https://nest.com/support/article/What-is-the-star-connector-on-the-2nd-generation-Nest-Learning-Thermostat#!

Syonyk

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Re: Any tips for using whole-house fan?
« Reply #8 on: July 07, 2016, 07:52:21 PM »
Press -> fan -> start now?

PGSD

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Re: Any tips for using whole-house fan?
« Reply #9 on: July 11, 2016, 02:00:41 PM »
We have a whole house fan and love it (bought used, installed myself :). One tool to get the most out of it is use an inside/outside thermometer (~$10 at WalMart). It has a sensor you put outside that wirelessly transmits the outside temp to the inside unit (inside unit also shows the inside temp).

When the outside temp gets several degrees cooler (or, warmer in the winter), the whole house fan goes on.

As mentioned, you can cool off certain areas of the house by opening or closing windows as needed. We open only the bedroom windows as night as we get a nice breeze when the fan is on.   

RyanAtTanagra

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Re: Any tips for using whole-house fan?
« Reply #10 on: July 12, 2016, 02:27:16 PM »
Right before you open the windows at night, turn on the whole house fan

Not relevant to OP anymore, but did want to say you might want to reverse those steps.  I've never seen it myself, but I have heard of whole house fans in a well-sealed house breaking windows if turned on with the house buttoned up.