6 ms·

It is extremely common, even default in the US in my experience, to not have vent fans not actually... vent. As a renter, I don't really get a choice in the mat

by i80and 4y ago

It is extremely common, even default in the US in my experience, to not have vent fans not actually... vent. As a renter, I don't really get a choice in the matter. Opening a window significantly is also pretty unfeasible most of the year.

rascul 4y ago
I see many of them that simply vent into the attic. This requires a properly vented attic, and has the downside of introducing moisture into the attic, which can lead to damage. That said, mobile homes pretty much always vent outside in my experience.
- stefan_ 4y ago
  A lot of them do not vent at all. They just draw it up through a coarse filter and out the top again.
  - rascul 4y ago
    Yes, I see those too. I work on houses for a living though and those are not too common, at least around here. I typically might see those in the older houses, or in half assed renovations.
Spivak 4y ago
In new construction people are installing those microwave vents that literally do nothing except blow the air out the top of the microwave. It’s not totally worthless but it’s next to worthless.
- mastax 4y ago
  Then the cabinets above the microwave get coated with a sticky layer of polymerized(?) oil - even quicker than they normally would. It's gross.
- 2ICofafireteam 4y ago
  New construction person in B.C. here. We use them all the time and if they're not vented properly, we don't get occupancy. The HVAC designer or Engineer on the job wouldn't have it any other way.
- ChoGGi 4y ago
  Microwaves can vent if you hook up its vent to a duct, cheap construction doesn't do that if they can get away with it.
  - Spivak 4y ago
    Yes and no, while I suppose you could technically attach a vent to the top half of the microwave and route it outside the upper vents are absolutely not designed for that and you would have the most awkward ugly installation that blocks your upper cabinet doors. So yes the reason for these units is 100% penny pinching and cheap construction but better construction alone won’t fix the problems with these microwaves.
    - ChoGGi 4y ago
      "you would have the most awkward ugly installation that blocks your upper cabinet doors" No, you route it through the cabinet and if you don't want it to look ugly then you build a chase around it. I usually don't since the chase takes up more room, and no one really cares as it's in the cabinet. And yes they are designed for venting outside, that's what these are for: https://www.homedepot.com/p/Master-Flow-3-1-4-in-x-10-in-x-7-in-Hood-Transition-Fan-Boot-FB3-25X10X7/100126594 https://www.homedepot.com/p/Master-Flow-3-1-4-in-x-10-in-x-7...
      - Spivak 4y ago
        We’re talking about two different kinds of microwaves. There are the ones you describe where the vent is inside the upper cabinet, those are designed to be vented outside. Then there’s the microwaves where the vent is in front of the cabinet doors, runs along the whole length of the microwave and blows up at the outside of the upper cabinet doors. There is nowhere you could even route it because anything on top of the microwave to capture it would physically block the doors from opening.
cplusplusfellow 4y ago
Do you also have a gas stove? I’ve lived in lots of places that have unvented blowers but none of them had gas. Would be against code in almost every city in America.
- tssva 4y ago
  The last 2 houses I have lived in both had gas stoves and unvented blowers. Both recently built.
- i80and 4y ago
  Yep, gas stove unfortunately. I can't speak to code, but most people I talk to share this experience -- I assume there's grandfathering at play.
  - lupire 4y ago
    It's just illegal and no one complained or enforced.
    - 2ICofafireteam 4y ago
      Where I am, it's called non-conforming and, unless there's a complaint, it doesn't become a problem until you pull a building permit AND a Building Official notices.
    - tssva 4y ago
      I just looked it up and section M1503.1 of the 2018 International Mechanical Code has an exception for range hoods which allows most to be used ductless. Some states, CA for example, don't allow this but the majority of states just follow the IMC code.
- asveikau 4y ago
  How much maintenance do those fans require to keep working well? I feel like the common thing is to basically not touch them, and they get pretty gross and don't seem to do much. Edit: I got downvoted for this? I feel like I've seen a lifetime of these fans being decades old and in poor shape. I think you folks are vastly overestimating how many people clean those or replace the filter.
maccard 4y ago
Those fans can be installed in two ways, venting or recirculating. In a recirculation mode you need to keep the filters clean, and they do an _ok_ job at keeping smells out of the kitchen, but if they don't vent outdoors then you need to open a window unfortunately

by i80and 4y ago

rascul 4y ago

I see many of them that simply vent into the attic. This requires a properly vented attic, and has the downside of introducing moisture into the attic, which can lead to damage. That said, mobile homes pretty much always vent outside in my experience.

stefan_ 4y ago
A lot of them do not vent at all. They just draw it up through a coarse filter and out the top again.
- rascul 4y ago
  Yes, I see those too. I work on houses for a living though and those are not too common, at least around here. I typically might see those in the older houses, or in half assed renovations.

Spivak 4y ago

In new construction people are installing those microwave vents that literally do nothing except blow the air out the top of the microwave. It’s not totally worthless but it’s next to worthless.

mastax 4y ago
Then the cabinets above the microwave get coated with a sticky layer of polymerized(?) oil - even quicker than they normally would. It's gross.
2ICofafireteam 4y ago
New construction person in B.C. here. We use them all the time and if they're not vented properly, we don't get occupancy. The HVAC designer or Engineer on the job wouldn't have it any other way.
ChoGGi 4y ago
Microwaves can vent if you hook up its vent to a duct, cheap construction doesn't do that if they can get away with it.
- Spivak 4y ago
  Yes and no, while I suppose you could technically attach a vent to the top half of the microwave and route it outside the upper vents are absolutely not designed for that and you would have the most awkward ugly installation that blocks your upper cabinet doors. So yes the reason for these units is 100% penny pinching and cheap construction but better construction alone won’t fix the problems with these microwaves.
  - ChoGGi 4y ago
    "you would have the most awkward ugly installation that blocks your upper cabinet doors" No, you route it through the cabinet and if you don't want it to look ugly then you build a chase around it. I usually don't since the chase takes up more room, and no one really cares as it's in the cabinet. And yes they are designed for venting outside, that's what these are for: https://www.homedepot.com/p/Master-Flow-3-1-4-in-x-10-in-x-7-in-Hood-Transition-Fan-Boot-FB3-25X10X7/100126594 https://www.homedepot.com/p/Master-Flow-3-1-4-in-x-10-in-x-7...
    - Spivak 4y ago
      We’re talking about two different kinds of microwaves. There are the ones you describe where the vent is inside the upper cabinet, those are designed to be vented outside. Then there’s the microwaves where the vent is in front of the cabinet doors, runs along the whole length of the microwave and blows up at the outside of the upper cabinet doors. There is nowhere you could even route it because anything on top of the microwave to capture it would physically block the doors from opening.

cplusplusfellow 4y ago

Do you also have a gas stove? I’ve lived in lots of places that have unvented blowers but none of them had gas. Would be against code in almost every city in America.

tssva 4y ago
The last 2 houses I have lived in both had gas stoves and unvented blowers. Both recently built.
i80and 4y ago
Yep, gas stove unfortunately. I can't speak to code, but most people I talk to share this experience -- I assume there's grandfathering at play.
- lupire 4y ago
  It's just illegal and no one complained or enforced.
  - 2ICofafireteam 4y ago
    Where I am, it's called non-conforming and, unless there's a complaint, it doesn't become a problem until you pull a building permit AND a Building Official notices.
  - tssva 4y ago
    I just looked it up and section M1503.1 of the 2018 International Mechanical Code has an exception for range hoods which allows most to be used ductless. Some states, CA for example, don't allow this but the majority of states just follow the IMC code.
asveikau 4y ago
How much maintenance do those fans require to keep working well? I feel like the common thing is to basically not touch them, and they get pretty gross and don't seem to do much. Edit: I got downvoted for this? I feel like I've seen a lifetime of these fans being decades old and in poor shape. I think you folks are vastly overestimating how many people clean those or replace the filter.

maccard 4y ago

Those fans can be installed in two ways, venting or recirculating. In a recirculation mode you need to keep the filters clean, and they do an _ok_ job at keeping smells out of the kitchen, but if they don't vent outdoors then you need to open a window unfortunately