Backflow into the storage - Question?

[eriesigtau]

Guys/Gals,

I just got my gasser fired up and have a small problem with backflow. My storage is in parallel. When th house calls for heat and the boiler temp is above 125, the house gets heat directly from the boiler. If that temp falls below 125, then the tank will heat the house. The tank charges when there is no call for heat from the house. Heres what is happening... When the house is calling for heat and the boiler temp is above 125, the heat is circulating through the house but it is also flowing back through the tank return pipe from the manafold and still charging the tank even though the tank circulator is not on. If I turn of the tank return valve it works fine so I don't think its an airlock problem. Does anyone know how to prevent this???

 

[wood thing]

Do you have a flow control valve on the storage supply or return ? You can also use a flow check circ.

 

[eriesigtau]

the circ that feeds the storage has a flow check built into it. The water is flowing from the boiler to the manafold like its supposed to but some of the return water is going to the boiler through the return and some is flowing through the tank return, then through the tank, and back to the boiler. Every check valve in the system is built into the grudfos 15-58 circs and are all on the supply side.

 

[eriesigtau]

Wouldnt a check valve on either return pipe prevent the proper flow when the tank is heating the house?