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Plugged Takagi

Don't see many of these used as a radiant source. But got a call today from a homeowner asking if I would mind being the 3rd guy in on a problem. 1st guy installed pressure switch, 2nd guy installed a new fan. 10 year old Takagi Jr. Nobody bothered to open the thing up and actually look at burner and heat exchanger. Pretty ugly. Burner was fairly easy to clean up. Heat exchanger is a whole different can of worms.
Copper Fin type heat exchanger. Completely plugged from byproducts of combustion, as well as severe condensation.
Exchanger is encases in a bluish/green rock hard quagmire.
Today I removed heat exchanger, figuring I would hit it with some chemical cleaner and a good water flushing.
Started with CLR, then a citris cleaner, then Rydlime, then a commercial descaler.
Every time I flush with water, I get a blue/green discolored slurry out of the unit.
But after 3 hours of cleaning, soaking and flushing, I've really gotten nowhere.
Sitting here tonight debating......
Do I dare try an acid based cleaner of some sort? Or did I go to a muriatic acid, or stronger? Sulpheric?
Looking for some advice.
Thanks Gary


  • Jamie Hall
    Jamie Hall Member Posts: 22,952
    Ick. Your best bet is going to be muriatic (hydrochloric) acid. And lots and lots of patience. And acknowledge a very real risk of significant damage to the heat exchanger. The blue green colour is basic copper carbonate (maybe with a little sulfate for good measure) -- and the copper comes from the fins.

    And it may not solve the problem.

    Be careful. Strong acids aren't good for you. Glass containers... good ventilation.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • kcopp
    kcopp Member Posts: 4,396
    Why put time and effort into a unit that should not be in there. There are plenty of good wall boilers that could go in...
  • Larry_52
    Larry_52 Member Posts: 182
    edited December 2016
    The way you wrote it I am confused if you are talking inside exchanger or outside.
    Pretty sure you mean outside of exchanger. I would mechanically clean with some media blast or CO2 dry ice. You can buy a cheap sand blaster and crushed dry ice.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,250
    Hello, Might be worth looking at the cost of a new heat exchanger if you can get one. The problem with fixing the current one is nobody can accurately guess the remaining life in it. You get to be on the hook. I really like to keep heaters going, but there is a limit... :o

    Yours, Larry