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Buderus Flow Setter Valves

pyme66 Member Posts: 4
In my hydronic system I installed two years ago, I have a zone with Buderus panel radiators. The zone has a two pipe reverse return configuration. Everything run fine the first winter, but this year I have three panels (out of 8 panels in the zone) that have flow setter valves (see attached image for velvet) that are frozen shut. The panels in question get no flow. I went through the usual troubleshooting routine checking air bleeding, isolation valves, etc. are narrowed it down to the flow setter valves. I have removed the Danfoss sensor heads and can see some oxidation around the stem of the valves.
Does anyone have experience with servicing these valves? I have information about how to remove them and clean them.
Thanks in advance.


  • clammy
    clammy Member Posts: 2,912
    Couple questions are you using the by pass valve or just isolation valve on the radiator ,is this a home run system ? Possibly you had a bad head have you tried switching them w another head that your sure is working . Do you have the flow setter set to n which is used w the bypass valve at the n setting your at full flow which means if using the by pass valve your running about 33 % through the rad and the rest is bypassing according to buderus lit o5her wise there’s usually some velocity issues and noise , You most likely have to replace the whole body most likely due to water chemistry and or water make up . Do a water test see what your tds are high tds and make up water can lead to sticky valves ,when the system was installed was it flushed and cleaned w a hydronic cleaner ,flushed and filled w a good quality water ( low in tds and chlorides ) I have installed a few buderus pangel rads systems using the by pass valve and home run piping and have had no issues .hope all this helps peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • Big Ed_4
    Big Ed_4 Member Posts: 2,243
    They can be replaced if need be , first hit them with a little penetration oil and free them up .
    I have enough experience to know , that I dont know it all