Adding a new HVAC vent
Hi all, I am constructing a new bathroom in my home within the existing square footage. It is fairly small (5x9). I would like to put an HVAC outlet vent into the room. There is an existing duct that rooms to one of the bedrooms very closeby in the attic. I was hoping to simply Tee off of this line and go into the new bathroom. I don't think there will be heating or cooling capacity issues since I am not adding square footage. Are there any issues I should be aware of? I am in California and my city uses the state code with no modifications.
It your new bathroom is adjacent and opening to the bedroom just undercut the door and add an exhaust fan (exhausting to the outside) to the bathroom. Operate the fan off the light switch.
If you want to add a duct into the bathroom just make sure the fan exhaust more CFM then the supply air from the new grill, say 45 CFM in and 60-75 CFM exhaust. Check the code for the exhaust requirement.
I'm not sure if CA Title 24 will allow you to just tee it off without bringing the duct system up to spec under a ACCA Manual-D design or at a minimum, proving/testing the flow to the new & modified section. You're likely to be required to make provsion for return as well as supply, which may include a dedicated return register. You may be required to test (and remediate, should it be outside the limits) the entire duct system for leakage. Most HVAC contractors will have some familiarity with the regs on this.