Air admittance valves

[rtruluck (Russell Truluck)]

I just inspected a house that had 3 air admittance values on the same waste pipe along a 20’ length. There are in a basement ceiling right up against the floor insulation. Is this okay? Also, the 1 1/2" waste pipe reduces down to a 1" waste pipe as it exits the foundation.

Thanks for any help,
Russell Truluck

[mlarson (Michael Larson, WI Lic. # 1672-106)]

Can you day “do over”?

[jgilleland (Jack L. Gilleland)]

I’m pretty sure my daddy (50 yrs master plbr) said you can’t bottleneck a drain or a vent. And don’t they believe in vents.