I need to vent a horizontal dwv branch. Can I use a san tee to connect the vent to the horz. branch? For some reason I thought that san tees should only be used vertically and that a horizontal setup would go against code. Though the hardware store only sells sanitary tees and wyes but no vent tee. Thanks!

Hello folks; This may seem like a assine question but I was wondering if someone could enlighten me. The watermeter that my municipality has installed is a ABBS Co. counter 5/8" meter . On the face of the meter are the numbers to be read in a direct readout and two dials. A needle counter and a triangle. This is installed in my basement garage. My question is that the triangle vacillates. It never advances but has a small vacillation to it. It moves slightly forward then returns to its previous spot. This goes on continuously. None of the other counters advance. I have turned off the water on the house side of the meter and it stops. That appears to me to eliminate municipal fluctuations. I then commenced to turn off / on sequenialy, from furthest to closest, all valves with no change. I then turned off the cold water to the water heater and it stopped. This is a Armitron large capacity heater. Has anyone else seen this before? Could there be a minute exchange leak in the heater or is it nothing to worry about? Could air be trapped somewhere in the line? The boiler does not fire anymore than usual for the hot water supply. This may be nothing but it does have me perplexed and I hope I haven't added too much to confuse any readers.