Moving a vent pipe

I want to install a new exhaust fan in a bathroom remodel. The place where I want the fan is occupied with the vanity sink vent (1 1/2" ABS). Can I 90* it up and over the fan and then 90* it back down to the sink wall where it is going into the attic. Currently it is laying flat on the attic side of the ceiling joists with a 90* turn to the sink wall. I would be adding 3 90* turns to achieve this.

Thanks

Not an ideal situation if you're in a cold climate. You're giving condensation a place to freeze by bringing it up higher than the insulation. How big is the fan? why could you not offset around it?

Hi Matt30

I am in a cold climate in Ontario but not as cold as yours in Nova Scotia. The vent pipe would be under insulation. The rafter joists in my attic are only 2x4. Didn't know that until I started this bathroom remodel! The fan is about 11x11 and a good 8" deep. The fan is centered in the room. When you say offset it around the fan, that would keep it at the same level (which I understand would be better) but it would still require adding in 2 additional 90* bends. I guess my question ultimately is can I install those additional 2 turns in a vent pipe?

move the fan, typically a fan goes over the toilet area and the light goes center of the room

Like a drain the vent should be able to drain down into the sewer.
So the question is where does the where does the other end go? does it tie into another drain stack which will allows both ends to drain down into a stack.

Mr David, the vent is for a vanity. It runs up the vanity wall into the attic, it then runs away from the vanity across the attic joists and then makes a left where it ties in with the main vent stack. I'll say "main" but I think there are two such stacks. The toilet and shower also use this stack as a vent.

Frodo, the bathroom is only 7x7'. We don't have the luxury of separate toilet and showering areas. I figured the fan in the middle of the room would make the most sense.

The fan should favor the side of the shower then to better control condensation on your ceiling

put it over the toilet. takes care of the smell, and its close to the shower
after a month, you will not even notice it.

I read his post wrong....I thought he said the toilet and shower were not close. If they are both in a 7x7 room, I always put the fan central to the two, and light fixture centre of the room.

If you're dead set on having the fan there, having an offset in the piping will not harm anything as long as water has a place to go.

I've read in two separate posts here that water has to have a place to go. I am a bit confused as this is a vent pipe, not a drain pipe. Is the water you're referring to from condensation? I thought having it under the insulation would prevent condensation. Please clarify.

Thanks

Condensation and the possibility of small amounts of rain water that may enter the vent stack.

You will have warm methane gasses and air moving thru the vent pipes, in the attic there's always a chance of condensation. While under the insulation it won't freeze, but the temperature difference will cause condensation.

Even if you don't think it will condensate, it's also the code if that's incentive enough for you.

rain water also. them vents get a lot of water rained down them. more than you think

Thanks Matt30. I now see that water can form in the vent and it needs to have a place to drain. The vent will have two places to drain. You don't have to scare-me-straight with "code". That is why I am here asking the questions.

Back to my original question, if I may: is it okay to have two extra 90* turns in the vent in order to offset it around the fan? I'm assuming they are as they are needed to make the offset around the fan but it would be nice to get an answer to that.