Flow Check Question !!

Fired up a bit early this year as per directive from the Office Of Homeland Tranquility.House is too warm.The thermostats are 6 -8 degrees over setpoint. What I found was the Taco flow check valves are not seating and allowing the boiler to boiler circulator to push heat upstairs to the first and second floor loops even though they are not calling. The workshop loop in the basement which is a low usage zone is performing as designed and no heat migrates there.I have cycled the pump without effect on the flow check.I have smacked them with a nylon faced hammer,no change.I have lifted and closed the manual movement stem.No change. The next step will involve water and pipe fitting tools. What have I missed?

What # circ on the boiler to boiler? 007? Flow checks usually hold well, but if the flow characteristics in that loop are powerful enough, you know the deal.....you risk a terrorist attack from within your home!!!
I assume you screwed the stems back in all the way on the checks.....try to put a long screwdriver up against the flow checks, then to your ear, and see if you can detect movement. Try with the circ on and circ off. (you have already I think)
This 'fringe' weather makes it tough on controlling the temps. Was this an issue in the past?

Obviously zone valves are positive closure, but still you should be able to control the 'ghost flow'.

Did anything else change? It is not common for flow checks to fail. Too big of a pump between the boilers will open the checks though.

why not circulate between the boilers only during heat calls?

Flow checks only take 1 foot of head to open.

All bets are off if there is head pressure against it from a boiler to boiler pump.

Water is a lazy bastard. It will always take the path of least resistance. If too much is going one way and it can overcome less resistance the other way, it will go both ways porportional to the resistance.

To answer the question about the pumps,there are 3 007's for the house and the boiler to boiler is a 007 also.If the pressure from the transfer pump needs extra pathways due to head pressure I can't get it in my head why it would not have lifted all three check valves.The basement loop remains closed and cool but the first and second floor are opened and hot.It is keeping the oil boiler hot and up to temperature.Furthermore,it has been installed about 4 years now and this is a first for the system.Can a 007 get more free from wear and create more r.p.m. and flow right before it croaks? Mike