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    • #274741

      I have a clunking in my residential boiler when the thing is heating. I have tried the recommended actions from an earlier posting. The vendor of the boiler says to run a cleaner through it. Will CLR or similar product work for this? What product do you recommend. If this doesn’t work the vendor recommend changing out the casting. It is under warranty but will require a tremendous amount of labor.

    • #290346

      Unfortunately, I don’t know what was recommended earlier. If the recommendation was to speed up the flow of water through the boiler to prevent steam forming in a pocket of the boiler casting and that was done, but the noise is still there, then replacing the casting is the way to go.

    • #290347

      Try and identify the problem before proceeding with work. Is the clunking noise similar to water boiling in a kettle? If yes then the problem is sedimentation of the heat exchanger. System debris settles at the bottom of the heat echanger (and other low areas in the installation). With the burners on, water actually boils between the metal casing and the sediment. The noise is tiny bubbles collapsing when they come to top of water within the heat exchanger.

      If the problem is sediment related or limescale, the answer is to chemically clean the system. In Britain, two types of chemicals are available. One is quite agressive and the other not so. While the agressive chemical will ‘polish’ the internals, it will also reveal weak areas in the installation that will at present be plugged up with the sediment. I have found that heat exchanger also cracks sometimes which is sealed by the sediment so no water leaks out. Cleaning leads to water leaking from such locations.

      Badly fouled systems lead to repeated pump failure. Open the pump and check the state of the impeller for sedimet coating

      Good luck.

    • #290348

      DP, do all of your boiler manufacturers in GB use metal to metal seals? Many US manufacturers use EPDM or other synthetic seals that may be damaged by chemicals, thus the manufacturer may void warrantee for using chemicals, while the vendor does not have the direct responsibility.

    • #290349

      A large proportion of European boilers have fibre seal made of material called Fasit. Some boilers also use ‘O’ ring seals.

      Majority of boilers sold in GB contain a booklet called the Benchmark logbook. The installers is required to enter data like burner pressure, temperature gradient, system cleanser used the type of inhibitor added to system water. This logbook can be a deciding factor for warranty claims. Annual services are also recorded here.

    • #290350

      Great idea. If you have to write in it, it might be read. Not a practice in the USA.

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