hot water radiator flow question

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    • #273782
      MasterPlumbers
      Keymaster

      I just moved a small cast iron radiator on a hot water system about 8 feet. I am not sure if the flow valve is stuck in the closed position or if I connected it improperly. Last spring when I disconnected it I did not note how it was connected. I just connected the in flow to the left and the out flow pipe to the valve side. Does it matter. When the boiler and circulator run the inlet side seems to get very hot but the other side stays cool. Why? Iseems like I get some heat from the unit but it does not seem like there is free flowing water. I never remember the unit getting very hot, even in the prior location. That is why I think the valve is not opening. I can replace the valve but wonder about the flow direction. Is this important? Please help. Thanks

    • #288529

      The radiator is becoming hot on one side because hot water is flowing into it there. As the water passes through the radiator, the radiator gives the heat of the water to the air around it. The flow of water into the radiator is slow enough to not let the other end of the radiator become hot. This result may or may not be a desired result.

      The mystery here is the valve. If it is the kind of valve that automatically regulates the flow of water into the radiator, it is working properly if the room is the desired temperature. If the room is cold, there is not enough water entering the radiator and the valve must be opened more, or the pipe/pump combination arranged to let more water into the radiator.

      These are clues an experienced plumber would seek during a visit to your home.

      The direction of flow from right to left, or left to right, or whether the valve is properly installed would have to be described or seen to be known, as there is no information given to identify the radiator construction or the valve.

    • #288530

      HI WB, It really doesn’t matter all that much which side of the radiator the valve is on (supply or return) with a non electric thermostatically controlled valve. ON HOT water Systems.. Steam is another story

      Once the set point temperature is reached the valve closes and stops Or slows the flow for the desired temperature to be maintained and it doesnt matter if it is supply /return as the flow is stopped/ restricted.

      Now if only half your radiator is hot and the other side is cold you have an air bound conditions which means the air must be bleed out as you cannot have air and water in the same place.

      Most older H/W isolation valves cannot be a positive shut off as they are designed to have a constant circulation with a small orifice drilled in the valves cylinder or gate depending on the type you have.

      The reason is to protect the system by have the water circulating to prevent freeze ups by forgetting to turn it on again.

      In NYC it is not uncommon to find several variations of heating valves on the same system and most unfortunately do not say open or closed.

      Some of the older ones even have a the same kind of throttling as an old gas cock BUT on hydronics they call them balancing valves as when they are installed they normally gave a gauge near by so each zone can be balanced by the return temperature GREAT SYSTEM but very old as nothing can go wrong once adjusted.

      I think your best bet is to call a Licensed plumbing contractor and have them show you about the proper bleeding procedures. Good luck

      [Edited by SylvanLMP on 31 October 2000]

    • #288531

      HI WB, It really doesn’t matter all that much which side of the radiator the valve is on (supply or return) with a non electric thermostatically controlled valve. ON HOT water Systems.. Steam is another story

      Once the set point temperature is reached the valve closes and stops Or slows ( throttling condition) the flow for the desired temperature to be maintained and it doesnt matter if it is supply /return as the flow is stopped/ restricted.

      Now if only half your radiator is hot and the other side is cold you have an air bound conditions which means the air must be bleed out as you cannot have air and water in the same place.

      Most older H/W isolation valves cannot be a positive shut off as they are designed to have a constant circulation with a small orifice drilled in the valves cylinder or gate depending on the type you have.

      The reason is to protect the system by have the water circulating to prevent freeze ups by forgetting to turn it on again.

      In NYC it is not uncommon to find several variations of heating valves on the same system and most unfortunately do not say open or closed.

      Some of the older ones even have a the same kind of throttling as an old gas cock BUT on hydronics they call them balancing valves as when they are installed they normally gave a gauge near by so each zone can be balanced by the return temperature GREAT SYSTEM but very old as nothing can go wrong once adjusted.

      I think your best bet is to call a Licensed plumbing contractor and have them show you about the proper bleeding procedures. Good luck

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