Running a New Vent Line

I am installing a macerating pump and two gray water pumps for the new basement bathroom and wet bar. The pump manufacturer and local code dictate that these pumps be vented, however none of my existing gray water fixtures (i.e. kitchen sink, main level bath, second floor bath) are vented. The main level and upstairs toilets have a DWV pipe with a stack through the roof. I am going to run a separate vent line from the basement and tie into the dwv pipe from the toilets. My question is where do I tie the new vent line into the DWV line? Above the highest drain? How far? Can I tie it in on the first level? Thanks.

vents

Who installed those fixtures without vents? You can tie the vent into any "vent" pipe that does not have water draining down it from above. You tie it in at least 42" above the floor.

OK. So, I'll tie it in 42" above the second story floor. I'll probably tie-in a 2" main vent, then have the individual vents be 1.5" for the traps and pump boxes.

The original owner installed the sinks and tub/shower without vents when he built the house in 1976. I could probably tie-in the tub and upstairs shower when I install the new vent, but the sinks would be too hard, especially the kitchen. They seem to be working OK, no gurgling or empty traps.