Undersized vent fan - good for anything?

[doitmyself]

Hmmmm. If you study attic/roof venting, it is more complex than one imagines. There's all sorts of warnings NOT to mix different vent systems, I.E., ridge vent system with gable or power vents. It can disrupt effective airflow. The ridge/soffit vent system works on the principle you have a sealed attic. Cooler air enters the soffit and exits the ridge, removing the heat accumulating between the rafters at the roof underside surface.

Air flow takes the path of least resistance. You stated you have a large access opening into the loft, which might negate the effectiveness of the ridge vent, air flow pattern, heat management, whatever. This might be the crux of your issue and the ridge vent/large loft opening simply is not an effective design. Air might be flowing directly up through your loft entrance (chimney effect) and directly out the ridge vent without pulling hot air out of the rest of your loft/attic.
https://ventilation-maximum.com/en/guide-to-attic-ventilation/#other

The challenge is what is the solution? In some greenhouses we use Horizontal Air Flow (Haf) fans to circulate the air bathtub fashion:

Maybe mixing the loft air would get better results? Mixing combined with different exhaust design vs. ridge???? Tough to know. There must be some design engineers that know the answer.

 

[JHZR2]

Hmmmm. If you study attic/roof venting, it is more complex than one imagines. There's all sorts of warnings NOT to mix different vent systems, I.E., ridge vent system with gable or power vents. It can disrupt effective airflow. The ridge/soffit vent system works on the principle you have a sealed attic. Cooler air enters the soffit and exits the ridge, removing the heat accumulating between the rafters at the roof underside surface.

Air flow takes the path of least resistance. You stated you have a large access opening into the loft, which might negate the effectiveness of the ridge vent, air flow pattern, heat management, whatever. This might be the crux of your issue and the ridge vent/large loft opening simply is not an effective design. Air might be flowing directly up through your loft entrance (chimney effect) and directly out the ridge vent without pulling hot air out of the rest of your loft/attic.
https://ventilation-maximum.com/en/guide-to-attic-ventilation/#other
View attachment 347526
The challenge is what is the solution? In some greenhouses we use Horizontal Air Flow (Haf) fans to circulate the air bathtub fashion:
View attachment 347527
Maybe mixing the loft air would get better results? Mixing combined with different exhaust design vs. ridge???? Tough to know. There must be some design engineers that know the answer.

Good thoughts.

First things first. Any ventilation I’d provide would be for my comfort when I’m in there. Not really any other time. The rest of the time (99.9% of the time for the building), the building would be unventilated/passive.

Second, in all of my garages, three buildings, a two car garage, 120 ft long garage, and the subject garage), none ever had any ventilation built In. They’re just leaky old buildings. When I re-roofed the garage in question, the shake roof was removed, and plywood decking was installed. They installed a ridge vent.

You’re right the new ridge vent (previously was solid) could have a chimney effect from the much cooler downstairs. But it remains super-comfortable downstairs so I’m not sure that’s happening. There are plenty of gaps in the upstairs for air to enter. The entry/hole in the floor is just a wide open space with the ability to see daylight in many spots resulting in many vent paths. Hard to tell that there’s any preferred path or breeze in there.

You can see the stairway hole in the floor in the foreground left. It’s probably 4x8’. Loft is 25x40. No soffit, just blocked closed at the rafter/top plate.

 

[4wd]

Good thoughts.

First things first. Any ventilation I’d provide would be for my comfort when I’m in there. Not really any other time. The rest of the time (99.9% of the time for the building), the building would be unventilated/passive.

Second, in all of my garages, three buildings, a two car garage, 120 ft long garage, and the subject garage), none ever had any ventilation built In. They’re just leaky old buildings. When I re-roofed the garage in question, the shake roof was removed, and plywood decking was installed. They installed a ridge vent.

You’re right the new ridge vent (previously was solid) could have a chimney effect from the much cooler downstairs. It’s just a wide open space with the ability to see daylight in many spots resulting in many vent paths. Hard to tell that there’s any preferred path or breeze in there.

You can see the stairway hole in the floor in the foreground left. It’s probably 4x8’. Loft is 25x40. No soffit, just blocked closed at the rafter/top plate.

View attachment 347613

Do you get much sun? This stuff works and made in many brands/sizes. I stapled it to the rafters. Have to use double foil so that one side of foil stays clean …


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