Protect attic ventilator fan motor?

Status
Not open for further replies.
zbang said:
One of the best things I did for a house I used to have was install a full-length ridge vent when the singles were replaced; made a huge difference.
Click to expand...


yes thank you.

there was a ridge vent. I think it was installed about 10 years ago when it was re-roofed (two layers) it was on two sections a couple ridges. they weren't really long and there was a couple leaks that a roofer said their may be an issue with pitch not being enough so water may be getting in. He removed it and put in regular shingles. Was thinking about adding a ridge vent back again but not sure it's enough for the NFA thing (doubt it) and also when he pulled it up this past fall and it hadn't rained in a few days it was a bit moist underneath like it was wet from side driven rain.

Besides protecting the roof system the other reason it needs to be done is that a new air handler was installed in November. Pretty sure although they're made for attics that heat can't be good for it.

Thanks again
 
zbang said:
One of the best things I did for a house I used to have was install a full-length ridge vent when the singles were replaced; made a huge difference.
Click to expand...

Ridge vents are fantastic but sometimes a hip roof won’t have enough ridge length to provide adequate ventilation.
The closer the house footprint is to square, the shorter the ridge.
 
A ridge vent makes a roof fan worthless as the fan will only pull air across the top... In terms of a gable fan I am not sure how well it would do. However, a fan needs air on the intake otherwise the motor will work harder.... maybe I am wrong but that has been my experience.
 
Dennis Alwon said:
A ridge vent makes a roof fan worthless as the fan will only pull air across the top... In terms of a gable fan I am not sure how well it would do. However, a fan needs air on the intake otherwise the motor will work harder.... maybe I am wrong but that has been my experience.
Click to expand...

A couple points: if the ridge vent is long enough, and there is adequate soffit opening area, no motorized vent will be needed. You’re correct, the fan won’t move air as desired.

A fan starved for intake air will require less HP, not more. The problem with this scenario in an attic vent is that if the fan is starved for air, it means the attic isn’t being properly ventilated and the higher resulting ambient temperature will cook the motor even though it’s using less power. The motor also need the airflow to cool properly.
 
Don't like making roof pentation's for anything. When living in Minnesota, they were always a source of warm air melting snow. The melted snow would make ice damps. Then after a while the melted snow would fill the ice dam and run back into the house. Since then, every new house I have had, had ridge vents. I have also in the past installed gable end vents in the wall to increase venting in the attic.
 
ritelec said:
Firestat

mymaxxair.com

Adjustable Thermostat with Firestat for Power Attic and Exhaust Fans

This temperature controller features a fusible link which will shut off your electric attic or exhaust fan in unsafe operating conditions exceeding 183° F, and is also used for the daily operation of your fan as a typical thermostat with a bi-metallic switch. This thermostat mounts to a rafter...
mymaxxair.com mymaxxair.com

Click to expand...
The "firestat" pretty much just cuts the power to the fan if the temp is too high - so that the fan isn't feeding air to the fire that is likely already started.
 
These ventilation motors typical for this are thermally protected, but automatically resetting. Problem is usually the bearing seizes up, fan can't run and it sits there cycling on the thermal protector for potentially an indefinite period and never really cools off other than enough to cycle the overcurrent protection again. eventually the motor winding fails and opens the circuit - but if it would have more of a catastrophic failure and drop sparks or molten metal, fire risk goes up. Dust buildup on the motor also increases potential to ignite that.

I suppose a little extra protection is possible by placing something non combustible below the fan for sparks or molten metal to fall on. These motors are typically open design with air over rating so sparks or molten metal can easily fall out of them should they occur.
 
RCC1 said:
... roof [penetrations] ... were always a source of warm air melting snow. ...
Click to expand...
It's not because of a few roof penetrations exhausting warm air; it's because there wasn't enough attic insulation and/or ventilation to keep the roof cold. With enough insulation/ventilation, the roof stays cold all winter, the snow never melts (until spring) and ice dams never form.

Anatomy-Of-An-Ice-Dam.png
 
drcampbell said:
It's not because of a few roof penetrations exhausting warm air; it's because there wasn't enough attic insulation and/or ventilation to keep the roof cold. With enough insulation/ventilation, the roof stays cold all winter, the snow never melts (until spring) and ice dams never form.

View attachment 2556460
Click to expand...
That is how it works on basic roofs, but if you have valleys you still get ice dams in the valleys in some situations even with good insulation. Sun hits high areas of roof and melts snow/ice but lower areas are in shadows and it freezes and dams up there. Later in day when sun moves across the sky it may be able to melt this dam, or it may not. but water does back up and can get under shingles and make it's way into the structure
 
kwired said:
The "firestat" pretty much just cuts the power to the fan if the temp is too high - so that the fan isn't feeding air to the fire that is likely already started.
Click to expand...

There isn't any way for that to tell what the temperature of the motor is or whether it is even running. By the time that shuts off a fire is already started.

-Hal
 
hbiss said:
There isn't any way for that to tell what the temperature of the motor is or whether it is even running. By the time that shuts off a fire is already started.

-Hal
Click to expand...
Guess I could have worded that better as it was kind of what I was getting at, it isn't for motor protection it is for shutting the fan down after ambient temp is high enough that there likely is a fire involved. It is a thermal fuse that needs replaced when open (not resettable)
 
LarryFine said:
I think they're considered impedance-protected.
Click to expand...

update:

Talked to GAF tech support with a few questions about their fans. They are thermally protected. Set to open at 185 degrees.
They are manufactured to open one time and that's it.
BUT, he then mentioned, they sometimes reset themselves.......

ha ok!!
 
Status
Not open for further replies.
Top