hydronic water system problems part 2

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by dwivey, Nov 21, 2004.

  1. dwivey

    dwivey New Member

    Oct 23, 2004
    We recently remodeled a small main floor addition. The plumber split the main floor heating zone into 2 zones. The original zone was plumbed with 3/4" copper piping. He split off of the old zone with 1/2 inch copper piping to some black plastic tubing. This services the new area. The existing area was re-run with the same 1/2 inch tubing into the existing baseboard units. He installed zone valves in each zone. Two thermostats control the the zone valves, circulator and gas furnace for each zone.
    Problem: When the thermostats call for heat, and no other zones are on, and the furnace starts to fire, it makes some serious noise, hammering, banging, pipes rattling, for example, but only while it's firing. I'm wondering if by going to the 1/2 inch tubing the volume of water through the furnace has been reduced and that the furnace is being stressed and this is what is making the noise.

    Opinions, comments, suggestions, remedies are all welcome...PLEASE!!
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    You'll get that sort of thing if there is air in the system. Basically, the boiler heats up, makes steam (not good), senses the overheated situation, and then shuts down for awhile Things stay hot enough for it to bang and pop for awhile after it shuts down. Could be other things, but if you have the instructions for your boiler, check the purge valve and see if you can get any air out.

    One of the pros may have some other ideas.
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  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    By reducing the pipe size he either raised the velocity of the water through the system, or he reduced the heating capacity of the system. Neither one is a good situation. The banging could ibe nsufficient flow through the boiler or hammer due to the higher velocity. We cannot tell you the exact problem without seeing and checking the entire system.
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