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Avoiding Scale in Heating Systems

HeatingHelp Administrator Posts: 653
edited September 2018 in THE MAIN WALL
Avoiding Scale in Heating Systems

Most hydronic heating systems are closed to the atmosphere, so if you're getting a lot of scale, suspect that too much water is entering the system. Close the automatic feed valve and watch the gauge. If you're losing pressure, the system probably has a leak. Go find it and fix it.

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  • ADEY_NorthAmerica
    More to this, scale is formed as a result of oxidation inside untreated hydronic heating systems and we completely agree with Dan - chemicals need to be used correctly in order to be effective. Often, contractors maybe get frustrated and therefore over-apply the treatment because they are not aware, or do not realize that there are other steps involved in capturing iron oxide (sludge).

    Water treatment chemicals can be very effective, but not on their own. Yes, a cleaner lifts magnetite and scale, and a protector forms a protective layer on the pipework to prevent future build-up, but without flushing and filtering; the scale and magnetite lifted by the cleaner will just circulate around the system, causing more problems such as clogged waterways, heat exchangers and pumps, which often cause boilers to break down.

    The ideal process would be to use a cleaner to lift the sludge, use a flushing device to cleanse the system, install a magnetic filter to capture any on-going scale and sludge, use a protector to ensure iron pipework is protected, and test annually for residential systems / every 6 months for commercial systems to ensure that the system is maintained.

    Of course, filtration and water treatment is vital for retro-fit systems, but it is also just as important for new systems. Just because a system is new, doesn't mean that sludge and scale isn't going to build up - it is vital that you protect any system from the beginning to ensure total system health.
  • Jamie Hall
    Jamie Hall Member Posts: 23,635
    Only comment I might add, Dan, is that to effectively fight scale or sludge or whatever is that you have to figure out what it is you are dealing with. Appropriate treatment for a calcium carbonate scale, for instance, will be different from that for iron oxide sludge or iron tuberculation on the pipes.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Jackmartin
    Jackmartin Member Posts: 196
    edited September 2018
    When I was the HVAC supervisor at Winnipeg Schhol Div.1 we had a water treatment company treating the water for the 140 steam boilers we had. In two years before I arrived they retubed 60 boilers. We only have one outfit in Winnipeg that retubes boilers and even he was telling the school div. this should not be happening. I brought Dearborn in and they did a comprehensive review of all the water treatment and told us the old chemical company was making the water PH 3 ,I guess the tubes were not lasting. Dearborn came in and in two years later we did not retube one boiler. The thing that had the school div. conned was their own prejudice. The guy from the old company had a chemistry degree ,so of course ,he knew more than the non chemists. I do not know what a university he graduated from but ,he had to have graduated at the bottom of the class.
    All the best Jack
  • hot_rod
    hot_rod Member Posts: 22,468
    Scale and sludge is a non issue if it isn't inserted into the boiler and piping, usually in the initial and ongoing fill water.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream