turbelence at return lines preventing circulation?
so, i recently added a third heating zone to the third floor of my house.
have been having circulating issues.
today i installed a drain valve at the return end, just before the shutoff valve. then fired up the boiler, manually opened the zone valve, had the shutoff turned off, and opened the drain to purge all the air. it sputtered air, then water. after the boiler got up to speed, scalding hot water would spew out of this drain. then, i turn off the drain, and open up the shutoff valve, and within about 10 seconds the pipe turns luke warm, then cold. i had the 2nd floor zone also running.
here's my suspician:
originally, with just the two zones, they met at the return pipe with a "wye" fitting (shaped like a Y).
when i installed the new zone, i chopped out this wye, along with two leaking valves i thought were shutoffs, bu t were actually balancing valves.
i wound up using the WYE on the supply end to encourage water to flow into the third zone (it works well).
so now, zones 1 and 3 T into the main return pipe, and zone 2 is a straight shot.
it seems like this configuration is causing turbulence at the Ts and preventing smooth (or any) circulating, particularly of zones 1 and 3.
i've had several pro heating techs and plumbers assure me that this T configuration is standard and not at all an issue.
however, common sense tells me the WYE was there for a reason, and the way the valve can bleed out hot, but then when i open the shutoff it gets cold, seems to indicate this.
here's a crude sketch of how my returns are.
the question is: do i need to get two more WYEs? i can't seem to find them anywhere. none of the supply stores stock them, not on ebay, etc...
what am i missing?
thanks a lot.
each zone has a shutoff valve and a drain valve right next to each other right before the T.