HVAC questions

Three questions: 1) installing a bathroom exhaust fan in my basement and *think* I remember hearing that the outside exhaust vent needs to be 4" horizontally from the nearest window. Unfortunately I only have 7 feet of space between my windows, and 7 feet between one of those windows and my kitchen sliding glass door. Am I remembering this requirement right, and if so, is there anything I can do - such as install a diverter to force the exhaust air downward? Does the kitchen sliding glass door count as a "window"? I can't really go any other direction since this is a townhouse with neighbors on either side and the fourth wall of the basement is the garage. Any chance an inspector would let me get away with 3.5 feet on each side? 2) for extending duct runs to heat the basement is the flexible metal ducting material as good as the ridgid tin? I'll have a few runs that have multiple 90 degree bends, so the flexible would just be way easier for those (which will only be about 10 feet in length). 3) Do I need to be worried about return air lines AND combustion air calculations? I had done the combustion air calcs and had planned to just connect the mechanical room to the rest of the finished basement with two grates exceeding the requirement, but now I'm thinking if I add 3 heat supply lines at 6" each, I'll need to add a return air grate/duct to the return air line of about 10" diameter. Do I really need to do the return air for this (I ask because the permit was issued without any note regarding return air)..
Thanks so much.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@gmail.com wrote:

4 feet for flue piping, I'm not sure about a "bathroom exhaust vent."
--
Zyp



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.