Whole house fan will only run on high speed

Reply

  #1  
Old 06-24-17, 09:46 PM
Member
Thread Starter
Join Date: Jun 2017
Location: usa
Posts: 7
Received 0 Votes on 0 Posts
Question Whole house fan will only run on high speed

I have a whole house fan. For years (since we bought the house 10 years ago), when we turned the fan on low, it turned on high first before settling on low (within a matter of a second or two). More and more frequently, it has been staying on high but if we keep turning it off and retrying it, eventually it will settle on low. Not anymore. Now it will only remain on high, regardless of whether or not the switch has been set to low or high. We've tried turning it on with a lot of windows open and with very few windows open - it doesn't work in either case.

My completely ignorant untrained mind thinks that this is something very basically mechanical, like something needs to lubricated, as opposed to something electrical. Does anyone have any guesses as to what might be going on?

Thanks in advance.
 
Sponsored Links
  #2  
Old 06-25-17, 08:14 AM
Banned. Rule And/Or Policy Violation
Join Date: Jun 2017
Location: USA
Posts: 785
Received 0 Votes on 0 Posts
If it's similar to an auto heater fan, it's electrical. I'm drawing a blank on what it's called, maybe a resistor mounted near the motor.
 
  #3  
Old 06-26-17, 07:35 PM
Member
Thread Starter
Join Date: Jun 2017
Location: usa
Posts: 7
Received 0 Votes on 0 Posts
I'm so ignorant (and the feminist in me is embarrassed to say I'll need to ask my husband) but would this be the sort of thing we (read: he) could do? We've installed ceiling fans and other minor stuff like that so we're not totally inept.

And thank you for the response.
 
  #4  
Old 06-26-17, 07:57 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
We need to know the make and model number of the motor. Also tell us about the wiring at the switch.

Moving to Electrical Forum.
 
  #5  
Old 06-26-17, 10:25 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,540
Received 508 Votes on 478 Posts
Most of those attic fan motors have two motor windings.... high speed and low speed. You select which speed it runs at based on the switch position.

I've never heard of one that starts on high and switches to low.
As Ray mentioned... some info on the motor is needed.
 
  #6  
Old 06-26-17, 10:46 PM
Member
Thread Starter
Join Date: Jun 2017
Location: usa
Posts: 7
Received 0 Votes on 0 Posts
I'm going to work on getting the make and model. It's a toggle switch and when you turn it on low, it makes the noise it makes when it starts up (I'm pretty sure that's normal because it has always done that). But it revs all the way up to high. Up until recently, it would do the same thing, rev up to high and then there would be a very audible noise as it dropped into low. I don't know how else to describe it other than that it's like it over shot and then fell back to the proper place. Now it doesn't do that at all. High or low on the switch = high speed.

Thank you all.
 
  #7  
Old 06-26-17, 10:57 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
Please post a clear and readable picture of the nameplate on the motor. Please open the switch box and post pictures of the wiring and the switch. http://www.doityourself.com/forum/li...rt-images.html
 
  #8  
Old 06-26-17, 11:51 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 21,119
Received 2 Votes on 2 Posts
Just an off the wall thought...do you have some sort of vent in the attic that is supposed to open when the fan is running, but otherwise stays closed? Normally they are mounted in a gable end I believe. They aren't electrical, they're purely mechanical and open from the air pressure in the attic.
 
  #9  
Old 06-27-17, 12:13 AM
Member
Thread Starter
Join Date: Jun 2017
Location: usa
Posts: 7
Received 0 Votes on 0 Posts
I'll take a picture of the vents in our hallway which open when we run the fan (now we have the AC going and it's 90 outside). But, in general, I think our works like you are describing. We flip the switch, there's that whooshing noise fans make when they start, and the slats of the vent in our hallway open.
 
  #10  
Old 06-27-17, 08:50 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,996
Received 39 Votes on 34 Posts
The fan is going to pull hot humid air from outside and exhaust the air conditioned air outside.
 
  #11  
Old 06-27-17, 12:32 PM
Member
Thread Starter
Join Date: Jun 2017
Location: usa
Posts: 7
Received 0 Votes on 0 Posts
Lol. I was explaining why I wasn't going to take a pic last night. Here's a pic and a link to a video so you can hear/see it in motion. For perspective, that opening is probably 6'x4'. Also, it's probably obvious to those who know how these work but there is a big fan in the dark foreground.

I'll see if I can get a pic of the motor with model info tonight.



https://youtu.be/aW8CpycjFGk
 
  #12  
Old 06-27-17, 01:37 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 21,119
Received 2 Votes on 2 Posts
I didn't mean in the hallway...I meant up in the attic. You either need an active vent like I described, or a lot of passive ventilation that is open to the exterior all the time.

Looking through the picture you posted, it appears you have an attic vent fan as well?
 
  #13  
Old 06-27-17, 02:41 PM
Member
Thread Starter
Join Date: Jun 2017
Location: usa
Posts: 7
Received 0 Votes on 0 Posts
Yes, two fans. One at the ceiling and one in the roof.
 
  #14  
Old 06-27-17, 03:06 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
To get back on track though the original question was about it no longer working on low speed. That is not likely to be vent related. It is either the switch, wire connection, or the motor. We need to the the switch opened and pulled out so we can clearly see the wires and switch..
 
  #15  
Old 06-27-17, 06:36 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 21,119
Received 2 Votes on 2 Posts
Yeah, the only reason I brought it up is that they were basing it on sound change (or not changing). If you are blowing air in to a open container and then close the exhaust...it can sound like the fan is speeding up.

Seems odd that there would be a multi-speed motor with a 2 speed switch and it would EVER have started in high.

As said...gotta have the pic's and info.
 
  #16  
Old 06-28-17, 12:14 PM
Member
Thread Starter
Join Date: Jun 2017
Location: usa
Posts: 7
Received 0 Votes on 0 Posts
That was sort of my train of thought.

I called a handyman and by my description he was fairly certain that it was the switch (as it sounds like some of you suspect). Because it's hot as hell in that miserable, difficult to access crawl space and because it's inexpensive and easy, I think, I'm going to replace the switch and see what happens. If that doesn't fix it, I'm sending my husband up to that yucky place to take photos.
 
  #17  
Old 06-28-17, 02:10 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
But being two speed it won't be just a simple light switch. Finding the right one may be the trick.
 
  #18  
Old 06-28-17, 02:49 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,540
Received 508 Votes on 478 Posts
A two speed attic fan should just need a basic toggle switch. SPDT.
It selects one fan winding for slow or the other for high.

Does the speed switch look like the silver handle coming out of the plate?

Name:  switch.jpg
Views: 1146
Size:  2.7 KB
 
  #19  
Old 06-28-17, 04:52 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
If no second on/off switch (or timer) it would be a SPDT center off. Or is it a rotary not toggle switch?
 
  #20  
Old 06-29-17, 12:42 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 10,274
Received 43 Votes on 35 Posts
I think I'd just replace the 2 speed switch with a variable speed control wired to the motors high speed.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: