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  • torbetron
    Posts: 4
    I haven't seen too much discussion about vents and fans in tiny houses.  Nor do I usually see vent pipes and fan ducts in photos of tiny homes.

    Do people who have made tiny houses have vent pipes as part of the plumbing?  Do they run these vent pipes through the exterior wall up through the roof, or out the side wall?

    As well, do people use "whole-house fans", especially if their house is well-insulated and -sealed?  Do they use fans for the shower and stove, and again where do they direct it, through the roof or out the wall?

    I'm planning on building a well-sealed home, and need to worry about indoor air quality.
    Thanks for your insights on this!
  • jamisonjamison
    Posts: 100
    Good question, I have never really thought about that. Would the vent be needed if the drain pipe is very short i.e. out the bottom? I have a vent/fan to go in my bathroom but I may not even install that. If there is trouble draining I might just open up the window a bit in the bathroom or kitchen.
  • JerryJerry
    Posts: 56

    Most I've seen (mainly on YouTube) have the vents on the side walls.  The roof is already near the maximum height on most tiny houses, so vent pipes sticking out of the roof would need to be easily removed during transportation.  A bathroom vent fan is IMHO a necessity to remove excess humidity and prevent mold/mildew.  Windows in the end gable walls usually provide plenty of space ventilation, but I have seen at least two tiny houses with ventilation fans in the loft areas.

  • torbetron
    Posts: 4
    Thanks, guys, I appreciate your responses.

    I'll definitely have a bathroom vent fan, as well as a hood above stove with fan to the outside.  I suppose these fans can just be mounted into the exterior wall, and there wouldn't be any ducts required?

    While those two fans would be intermittent, I'm thinking of having a constant small fan drawing air away from a home-made bucket compost toilet (fan mounted in a trap door that allows the bucket to be emptied from the outside).  And, maybe a whole-house fan mounted high on some wall.  According to a book I read on green building design, for good indoor quality one needs to replace 2/3 air in house per hour.

    Regarding plumbing vent lines, I just read a book about plumbing (Black & Decker), and it seems like a vent pipe is a necessary part of the drain pipe system.  There's no fan, rather it serves to prevent a vacuum when draining, allowing water to drain quickly.  It seems like if that vent pipe were not there, then there'd be a lot of gurgling when water tries to drain down the sink (or shower).  Do you agree that this vent pipe is necessary even in a tiny house?

    One thing I don't understand about these plumbing vent pipes is that on conventional homes this vent pipe goes up through the attic and then through the roof, and is just a bare pipe sticking up.  Wouldn't debris and bugs get in that way?

    Thanks for your comments!
  • JerryJerry
    Posts: 56

    You are right about needing a plumbing vent pipe when hooked up to a sewage system including RV blackwater tanks, though depending upon your shower/sink drains and holding tank (or lack thereof), you may not need one.  It's only a few dollars worth of PVC, so I would not leave it out of a good drain design.  The vent pipe ends on roofs are topped with a variety of covers that prevent most debris and bugs from entering them, and at least some are designed with cleanout plugs near any connections.


    You could use a wind powered fan such as this one designed for RVs, and connect the drains and composting toilet vent pipes to a single outlet pipe topped with it:

  • JammerJammer
    Posts: 3
    Both of my RVs have one vent pipe for each holding tank.  With a more or less flat roof they just terminate around 2" above the roofline using a flange made for the purpose. 

    The various "wind powered" vents sold by Camco and others, such as Jerry's example, are, in the RV world, a cheap patch for leaking vent systems -- which are common given the workmanship of most RVs.

    The ones I have are like these:

    And then on my other camper they are similar but don't have a cover.
  • LagomorphLagomorph
    Posts: 20
    You're right, this is an under-discussed topic.

    For our composting toilet I'm considering a small exhaust fan on a refrigerator switch. It would automatically turn on when you lift the lid.

    We will have an on-demand LP water heater in the house, which has very specific ventilation requirements. It will be in a small closet, but with large vents at the top and bottom to allow it to pull air from the rest of the house. It has forced air exhaust. Somewhere, likely in the same closet, will be a self-damping intake vent.

    We will also have a range hood that vents outside and a bathroom exhaust fan. My sweetheart is a fan addict, so we will also have a ceiling fan over the living room area (8'x8') and a window fan in the loft.

    We are also going to install a small hatch in the floor. It will serve as a pet door occasionally (house rabbits), but in the hot summer we will put a grate or vent over the hole. I figure the air under the house will be cooler in the summer, and if we have the the loft fan pumping air out, it will pull (relatively) cool air up through the floor. Chances are the bunnies will just lay on the grate, hogging all the cool air.

  • nichehaus
    Posts: 2
    From what I have read regarding plumbing vents in our build, the runs are very short and you probably could get away without venting the plumbing drain lines. HOWEVER, I'm still doing them but you can install "in-line" vents under the trailer in a "t" like fashion. This is what most builders do. All you need is the vacuum to insure the drains, drain. I'll post a link or photos once I get to that point.
  • Robert
    Posts: 6
    I'm contemplating building a simple heat exchanger to vent my tiny house. It's super tight and condensation is accumulating on the windows. Cold climate, and I'm trying to keep my heating needs to an absolute minimum.