No heat on two radiators

Trivy

   I have one pipe heating system, the tees are in right place normal in the supply and venturi in the return, but two of my unit don't work no air when bleed just cold water.  They used to work before but I don't know what happen.

billtwocase

one pipe

I'm assuming you mean monoflo. Sounds like the valve is off at the radiator. That's probably why water is coming out of the coin vent and not air. Some are 1/4 turn valves, and the stop is either rusted off or it's bent. If that's the case, and you can't tell what position it is in, run the heat and slowly rotate until you feel the temperature change

Trivy

Heat

One of the unit is a 3' ft copper fin baseboard and does not have a shut of valve only a air vent, the other one is a cast iron radiator and it has a shut off valve.

billtwocase

is it

a cast baseboard or copper finned?  Either can have a valve within the endcap. Also follow the flow from the basement. Sometimes you find the vent on the supply side of the system. Tricky to get the air out. Best to not run the circ to bleed if that's the case. If it is a copper fin, lift the vented end up, if it moves, the air will rise out with the vent cracked open

Trivy

Heat

  I will tried to lift to see if this solve the problem, because the baseboard is in the bathroom and it get really cold in there.



Thanks for your help. 

Brian Chilton_2

Air!

Keep bleeding. Eventually hot water will come out.  If , after you bleed to get hot water,  make sure the supply is hot. If that is cold and the "return" is hot, the water is traveling backwards.....and you still have air in the supply. I have put in ball valves and a boiler drain to "block and bleed" some monoflow loops but usually only need to do this is they are on a 3rd floor.



Hope that helps.

TonyS

Add a ball valve

right after the monoflow t that feeds that radiator, shut it off and force the water through that baseboard and it will push the air back up into the main. Then open the ball valve and your back in business.