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Trouble with an old diverter-tee hot water system

clammy
clammy Member Posts: 3,111
Dan before you spend all that coin on abatement and cutting in circuit setters and such ,check your circulator pumps and look around your boiler room for maybe some old circ laying around as mentioned before check the circ impeall and gossett unless this system has never worked properly before then nothing has changed ,have they adding a addition to the building i have seen this before and it drove me crazy ,be a dective and look around in some cases it's just some thing stupid peace andgood luck clammy
R.A. Calmbacher L.L.C. HVAC
NJ Master HVAC Lic.
Mahwah, NJ
Specializing in steam and hydronic heating

Comments

  • Dan_44
    Dan_44 Member Posts: 2
    Trouble with an old diverter-tee hot water system

    I have a problem in one part of my building (zone). I have a hot water boiler. It is from 1949 it is a diverter-tee system When ever I try to raise the temp up to 180 degrees. Four (5ft) fin tube radiator below the main line will shut down I have two smaller ones (3ft) one in the beginning and at the end and they will stay working at 180. There are also four above the main in the upstairs and they don’t shut down at 180. I can bleed the four below the main all day and get no air I get hot water across them and they start to flow and in less the ½ hour they will be ice cold. The only way I can get them to work is to drop the temp back to 150-160 bleed the radiator then they will work good but 150-160 is not hot enough to heat the room it is 1700sqf and when it is in the teens or below zero it will not heat the room I have read the complete part about diverter-tee in heatinghelp.com and have had 5 heat guys in here and a engineer he said air the rest said flow. We are a YWCA and my maintenance budget is almost nonthing so any free advice I can get would be a great help and help me determine what to do…Thanks
  • Big Ed
    Big Ed Member Posts: 1,117
    Not Air

    Air will not trap in the lower part of the system.Your problem is flow.The system don't have enough force to over come the hotter water need to rise.The force is created from a pressure drop formed by water flowing across the two radiators riser tees.

    Either you need a circulator with a larger flow , install a second diverter tee on the supply side of the lower convectors. If they are not there already as they should.
    Or the riser tees are too close together...The futher they are spaced the more pressure drop is created...
  • clammy
    clammy Member Posts: 3,111
    in agreement

    I,m in agreement with big ed this sounds like it a flow promblem not air ,i would check your circ pumps ,like pull the circs impella(sorry bout spelling) off and check it out be may be wrapped or it's vanes damaged ,also look for open by pass piping ,stuck check or flow valves ,also how is the piping and water conditions if for any reason there's sludge or alot of rusat in the system i could see sediment building and effecting your mono flow system .i know you stated that the original system was old but has anyone added any additional raditorsor loops off the original system ,if so then there's your promblem ,it seems that when some one startes cutting in tees and adding to these system with out taking evevrything into account there's allways a price to be paid ,on another note has the cicrdulator been replace recently it could be that some one did install a large enough pump for the systems pressure drop or that the original pump was outdated and the newer model does not produce enough head or from what i have seen maybe the correct impealla was not installed alot of possibablity peace and good luck clammy PS Big Ed is correct
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • Dan_44
    Dan_44 Member Posts: 2
    I think it is a flow trouble to

    Thanks I think it is a flow trouble to we are assuming that the piping is right it has not been modified the only reason I no is that it is all got the original asbestos on it. That is why I can not check to make sure there are 2 mono flow tees on there. it is in a enclosed soffit and is covered in asbestos so in order to check the pipe fitting I would need a abatement crew come in and remove it before I could tell what is up there. I have a company that wants to do a (NEBB) certified performance survey. They want to put in a circuit setter and do a bunch of test it is not cheap. But nothing is any more.
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