Radiators not working

[We B Good]

During the renovation of our house, we had two of the radiators that were removed from our second floor installed in the basement (temporary heat until the HVAC for the first floor gets done in the Spring). All of the second floor radiators have been disconnected. The first floor ones remain and work perfectly. The two in the basement were tapped off the main loop from locations that formerly served the second floor. We've bled them to no end. We've confirmed that they are not clogged. We've determined that the mono-flow valves on the source side of the radiators don't seem to be forcing water through the radiators. In fact, it appears that the water is trying to flow into the radiators through the return pipes. Consequently, the water doesn't seem to be flowing through the radiators at all, since there's pressure from two opposing directions. Any thoughts

Would a backflow preventer on the return pipes help this?

 

[Bahco]

there's pressure from two opposing directions.

Not heard that one before
Try turning off the rads that are working and see if the pump can force the flow through.
Check the pipes to see if they are heating up to the rads. It seems as if you have a blockage or valves not allowing water thru.

 

[We B Good]

Pipes are heating up, but only to about a foot or so from the main loop. With the bleed valve on the radiator closed, the return pipe heats up faster than the supply, telling me that the water is trying to flow into that pipe. Bleeding the radiator allowed the water to flow while the bleed valve was open, but once the valve was closed, the flow stopped. The guy working with it mentioned something about not being able to get heat to flow down from the main loop, only up. I don't buy it. In a closed system, under pressure, if the pump can force the water up to the radiators above, it sure ought to be able to force it downward. I'm still thinking that a check valve or similar on the return pipe, close to or at the tee into the main loop, might help.

 

[Bahco]

[
Try turning off the rads that are working and see if the pump can force the flow through.
Check the pipes to see if they are heating up to the rads. It seems as if you have a blockage or valves not allowing water thru.

 

[kevplumb]

are you sure they are connected correctly

 

[We B Good]

Positive