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Copper boiler?

Dave_22
Dave_22 Member Posts: 232
in THE MAIN WALL
I was looking at a chart today on the thermal conductance of different metals. It looked like aluminum was about 3X greater than steel and copper was double than aluminum. How come no modulating copper boilers then? Isn't something that makes the Ultra so good is the aluminum heat exchanger? Maybe a dumb question-just wondering....

Comments

  • hr
    hr Member Posts: 6,106
    There are

    modulating burner copper boilers out there, Laars, Raypak, RBI.

    What you don't see are copper condensing boilers due to the ph level of the condensate.

    The coppers boilers used for low temperture radiant, that died early, were the ones that ran extended periods below condensing temperatures and rotted the fins and tubes away as a result of the "waters of combustion"..

    hot rod

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  • Dave_22
    Dave_22 Member Posts: 232
    Ahhhhh...

    OK- thank you!!!!
  • Sweet_2
    Sweet_2 Member Posts: 143
    Copper tube boilers

    such as the Raypak are pretty cool 86% eff. Two stage heating Raypak claims boiler wont condensate down to 105*. Put outdoor reset on it and it becomes pretty darn eff. There great for older tubing that doesnt have oxygen barrier.
  • Dave Stroman
    Dave Stroman Member Posts: 766


    4 year old copper boiler. Wasted.

    Dave in Denver

    There was an error rendering this rich post.

  • Sweet_2
    Sweet_2 Member Posts: 143
    Looks like

    someone should have paid attention.
  • hr
    hr Member Posts: 6,106
    Sweet

    I don't agree, at all, with running them at 105° without a condensing problem!

    As you see in Daves pic the problem starts in the flue unbeknownst to the owner or installer. The condensing is going on in there when they run cold, or real short cycles do to the low mass and efficient HX. Micro zoning also worsens this problem.

    Corroding flue component by products (which you are looking at in Daves pic) and draft divertors then plug the HX and goes down hill quickly from there.


    I've seen it happen exactly as Dave shows, dozens of times.

    Raypak does come with a built in bypass that helps with the HX return temperatures.

    hot rod

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  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Looks like

    no bypass on a high mass system... Am I close?

    ME
  • Sweet_2
    Sweet_2 Member Posts: 143
    Yea hr I dont run them that low either

    THe Manuf. literature boasts of 105* without condensation. So when a manuf. says this what would be the lowest temp you would run it at?
  • Sweet_2
    Sweet_2 Member Posts: 143
    With all that said hr

    My original post was not recommending running these boilers or any non condensing boiler below say 130 return temps, I understand. However the Manu. does state this info. That being said it is my h.o. that at 86% eff. and outdoor reset its not a bad idea at about a third the cost of a condensing boiler. Thats all I was saying. Thanks
  • Dave Stroman
    Dave Stroman Member Posts: 766


    You are correct, plus it was not pumped right, it was vented into an unlined brick chimney, and the little #15 expansion tank was shot and the relief valve was popping and filling up a 5 gallon bucket twice a day for the last year or 2.

    I have stopped using copper for standard residential use. Believe me, I have installed plenty of them. I used to think they were the greatest thing. No more. Even when everything is installed the way it should be, they short cycle like mad and rot out flues. They work fine on things like snow melt systems or domestic water heaters where you can full fire them until the load is satisfied and they turm off. I now use cast iron, the heavier the better, or a modulating condensing one like the Trinity. The new Buderus may change my mind.

    Dave in Denver

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  • Sweet_2
    Sweet_2 Member Posts: 143
    I gotta ask

    whats the optimum life expectency of a condensing boiler 10 20 30 yrs????? I mean what do the stats say about SS HX? With proper annual inspections(which should be stated) copper boilers should provide reliable, economical , heating. Even the premiere condensing boilers need ANNUAL service. Its the old C.I.s that can sustain years of neglect, and not melt down. Especially where climates are mild condensing boilers are a hard sell. Not everyone lives @ -10* -20* design temps.
  • hr
    hr Member Posts: 6,106
    The problem with copper boilers in the radiant industry

    they were misapplied and mis-installed!

    But, in the back of my head I still hear the reps voice telling me they were perfect for low temperature radiant applications. No problem running them at 110° continously, they told us. WRONG :)

    It's the multi, micro zoning that did them in. Even with a yearly breakdown and cleaning the "match" was wrong.

    Keep in mind the condensors we see are a very close copy of the low mas copper boiler, EXCEPT, they are designed to handle the condensate and modulate to the load better. Look inside the common long lasting MZ it's a fin tube HX!

    Time will tell if this low mass coil type or alumunum block condensing concept works better than the plain copper, non condensing, low mass.

    hot rod

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