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Contamination in water system

ascinc Member Posts: 1
Recently I had a service call for a radiant floor system using a gas fired water heater instead of a boiler. The system was approximately 18 years old. I found no water in the system and a locked up circulator pump. After replacing them the system ran less than a week and the new pump locked up. I found a white chalky substance in the water and in the piping. Could anyone possibly tell me what this could be? I told the customer he should replace the hot water heater with regular boiler and a new manifold since this contamination was throughout the system, flushing the radiant lines, of course before the installation of new equipment. The cost is outrageous according to the customer. Any suggestions?


  • Jamie Hall
    Jamie Hall Member Posts: 22,892
    Wouldn't care to guess on what the contamination is -- quite possibly something to do with the anode in the water heater -- but without chemical anaylsis I'd be guessing.

    However, IMHO you are entirely correct in what you propose to do to and for the system. If the customer feels the cost is outrageous, so be it; you can't help that. Let him go do something else and don't worry about him.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 21,820
    Its it a closed loop system, just the radiant on the tank, not combined radiant and DHW?

    White deposit is usually mineral scale, magnesium etc, or from an anode rod that is breaking down.

    If the system is tight and leak proof, not much new water should be entering, so mineral build up should not be much of an issue.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream