IMHO it is advantageous to have the fan and light operate independently. It is often desireable to have the fan run for a while afterwards (especially after eating beans) and that way you avoid having to leave the light on also. They have great electronic fan timer switches with preset time buttons (5-10-20-30 or 10-20-30-60 minutes) that are ideal for toilet fans (otherwise known in the trades as fart fans). In order to have separate switches you will need to run an additional switch wire, however, if you are going to add a wall to enclose the toilet, it's pretty simple to run the wiring at that time. Most fan light combos have the ability to operate separately. It's also pretty easy to drop in a recessed can light and have a fan only unit.

If you're not trying to be 'defiant' of our reasoning, you're certainly trying to convert us to your way of thinking, and I don't think it's going to happen. Clearly you are not open to this idea, but others may at least consider it. So far the inspectors have not said anything. I consulted with two of them, the city engineer, my contractor, and fan suppliers before doing it. Firstly, I'm not going to contradict a building code, especially when there's no discernible logic (ok you disagree but fail to impart what actual advantage your system offers) or advantage to it. I'm not going to run to the library immediately to check the code, but I do get there reasonably often and will check. Again, the inspectors who are familiar with the code are okay with my installation. It could be that a fan is not required simply because I have ventilation into the room via the AC ducting and/or a window, so whether I have a fan in the room is my call. You mentioned your area does have mould issues....(as do all areas I guess) - your system is particularly unwise due to that. You are creating an unnecessary hazard. There seems to be no mold issues in the southwestern deserts or the Rocky Mountains. Our weather is heavily influenced by the Gulf of Mexico so we have humidity in the summer. I don't think it is going to be a problem but is certainly is an issue. Definitely not a hazard. You may even have created a fire hazard You're being alarmist. Explain to me how my house catches fire because the bathroom doesn't vent to the outside. There are a couple advantages to my system. First the fan draws only dry air into it. This keeps the wet dust from collecting on the fan blades and reducing the fan efficiency to near zero in a few months. Second, the fan is mounted 24 inches above the floor in the bedroom. If I need to clean it, which I doubt I will anytime soon, its right there at knee level instead of overhead on the ladder. Third, the air at 24 inches is blown up to the ceiling in the adjacent bathroom 9 inches down from the 9-foot ceiling. As you pointed out, warm air rises. My system blows relatively cool and dry air in a the ceiling height to thoroughly mix the warm/moist air with cool/dry air to get a more uniform air temp and moisture throughout the room. Fourth, air sucked into a fan is only sucked extremely locally. Without a few classes in aero I can't really get into how that works, but you'll notice the exhaust of a jet engine, or even an electric fan for that matter, can be felt much farther away from the blades than the intake air induction can be felt. You have to hold your hand directly to the back of a fan to feel any air intake at all. My system, even with a diffuser at the opening into the bathroom, blows the air into the room hard enough that I can feel it against the far wall, thus ensuring thorough air stirring and mixing. Fifthly (?), in the winter humidity is not a problem here. In the summer it can be if your AC is not properly designed. Mine seems to be but this room has not endured an entire summer. Actually spring is slightly worse for humidity because the humidity is up but the temps are not warm enough to trigger the thermostat. In the summer the AC runs day and night as the outside temps sometimes don't come down into the 80s for several days at a time. It's rather like 'vacuuming' or should I say reverse vacuuming, a room by blowing it all out with compressed air. There may be something about that system you like, but you're just taking the dust from one room (read humidity and bathroom smells) and spreading it throughout the rest of the house. And your vacuum system sucks dust in from outdoors and blows it all over the house. Which is better - the dust you already have indoors or the new dust your vacuum system is sucking in? I knew which fan you were talking about, but I was way off on my house fan power specs. Apologies. I'm not sure what model of blower I was looking at but mine is 3/4 horsepower - more like under 500 watts versus the 750 watts used by my directed fans. If one of my little fans wears out, I have backup. If my furnace fan wears out, it's a service call and a $12,000 AC system (mine is ready to be updated). Your bizarre method and logic may make the condensation evaporate more rapidly (or so you may think) because you are encouraging it to evaporate I guess into a larger area, however, that capacity would diminish over time, since the overall humidity will increase to the point of what is it - equilibrium? Where the air will hold no more moisture, and condensation begins to reform. This is where the structural damage sets in, mould forms and it becomes an unhealthy environment. From a heat transfer point of view, you need to watch your terms better to make that make sense but I think I know what you were trying to say. Still, the last sentence is the important one. The humidity increase from a shower is unlikely to saturate the 18,000 cubic feet of air in the house. However, this is exactly what I'll be looking for in the summer. These bathrooms are at the far end of the house. The concern is getting that air moved out of the confines of the bedrooms and out to the AC air intake in the living/dining rooms. I don't think it will be a problem in the summer with the AC on all the time, but we'll see. I'm more afraid of freezing my butt off in the shower with all that dry air coming in on me. I may have mentioned that I do not get any condensation in my bathroom now and I do not get any even when the fan is off. The reason for that is not clear. I'm working on the theory of massive tile heat sink where the moisture is actually condensing on the cooler tile but there is so much tile that I'm not noticing it. But there is never any fog in the bathroom and no condensation on the mirrors. Ceiling fans may have their drawbacks and I don't love cleaning them either, but I think I'd prefer them to a bunch of fans sitting around on the floors Clearly I'm not going to change your mind on that either but I have convinced several friends to use floor fans, especially in the winter, to mix the hot air at the ceiling with the cold air on the floor. Suddenly my short friends can get warm and my tall friends don't have cold feet. If the thermostat is at 5 feet off the floor and you're 5 feet tall, you live in a world where all the heat is above your head no matter what you set your thermostat to. But if you're six feet tall or taller, your face is always hot and your feet are always cold. With the little fan on the floor pointed at the ceiling behind the sofa, the air mixes in the entire room and everyone is comfortable. Everyone I demonstrate this effect to is amazed. A ceiling fan can be reversed and pointed at the ceiling, but you get into the problem again of the air intake being at 8 feet off the ground blowing air up to the 9-foot level. You really have to have the fan honking to blow that air to the walls and down. Then people seem to complain about the wind in the room. My little fans simply punch a localized hole in the thermal layers and mix them up. I keep ignoring the indelicate subject of bathroom odor, because that does not seem to be a problem in my household. It must be all the lard in the tamales down here ;-) Actually my wife pumps the veggies and fruit into us - I'm not a dietitian. Sorry I'm getting so wordy. Maybe this will stop now that we realize we're not going to change each other's minds.

I'm curious only.. where do you live? I was suprised to hear you have mold in the attic from the amount of moisture from a bathroom. If you're in Houston or other humid area I can understand the moisture never leaving. I would ask about the 'as is' sale of your house. that is, if it was not 'as is' then you have recourse especially if the mold is due to the duct not being connected. Where do you live? I say I'm surpised to hear of the dramatic effect of the fan from a bathroom into the attic I say this as in my experience it's usually little moisture from a bathroom fan and the attic being warmer or vented can get rid of the moisture pretty fast. Good luck. I'd figure your home purchase is going to be backed up via the real estate agent who sold the property. Anyone know where he goes first to complain? I'll have a look back in a week or two. Andre

Yes the plan is vent through the roof. My question is since I'm getting a new roof, should I create two openings in the roof and each connected to its own pvc pipe back to the 2 exhaust fans? Or should I use something like fantech where the fan is sitting in the attic and I'll need one opening in the roof? Supposedly it makes it quieter since fan is in the attic but I know the panasonic units are also fairly quiet. I'm looking for something that will last a long time https://www.amazon.com/Fantech-Premium-Bathroom-Exhaust-Vent/dp/B01COPXHVW?th=1