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BUDERUS GB142 Boiler brackish hot water from tap.

trouts2 Member Posts: 9
Questions about a BUDERUS GB142 Boiler that produces
brackish tap water. (I don't know which size the boiler is
i.e. 30/40/50 & etc) I think they are all the same outside
of capacity. ?

I’m asking for my neighbor so don’t know much about this
boiler or boilers in general.
The system seems to be a continuious water heater. It is a
wall mounted boiler.
There is a large tank beside it for the hot water. I’m not sure
if the tank holds warm preheated water the boiler draws from
to fully heat to final temperature. It may be the boiler heats
the water and puts the heated water into the tank. I guess it
would under pressue to circulate around the house.
Regardless, the water was getting more and more discolored.
The neighbor had “it” flushed. I think they were referring to
the big tank versus the boiler on the wall. She said all the water
was let out so possibly the big tank. After that the water was
clear for a few days but now brackish again but less than
I think the tank internally may be rusted and the issue.
But since it was flushed I would think that the water would
run clear for a long time before the water became brackish
again. Maybe the rust is coming back much faster than I
figured. ??
It may be that there are chemicals in the boiler part that
are causing the problem but I doubt that. It could be
some chemicals are causing the rust to develop very
quickly. ??
Is this just a straight forward rusty tank problem?


  • Jamie Hall
    Jamie Hall Member Posts: 22,050
    There should be a complete separation between the boiler and the tank; from your description it sounds as though the big tank is an indirect, which is heated by the boiler water circulating through a coil inside -- but sealed from the domestic water.

    First thing to do is look at the pressure gauge on the boiler. It should read somewhere between 15 and 20 pounds when cold -- nothing more than that. If that is true, then there is no way boiler water can get into the tank, which is at the higher domestic water pressure.

    Now having verified that, the problem may be the tank is rusting out. However, given the speed with which the problem recurs, I'd be very concerned about the domestic water supply -- particularly if the water really is brackish (which is salt in the water). Is this a private well? Is there a water softener? A filter?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • trouts2
    trouts2 Member Posts: 9
    Jamie Hall,

    The water supply is Quabbin Reservoir in Massachusetts and
    the quality very good & clear. My house is next door and there
    are no issues. The neighbors cold water supply is fine, no issues. The
    brackish water is only in the hot water shower and faucets.

    The brackish water is red tinted and could be from rust. The
    water looks about what my water looks like when I flush
    my boiler. Lots of rust in mine. Mine is a steam system
    and that water for the radiators only.

    When I was there I did not see a pressure gauge or filter.

    I was at the house two weeks ago as they had water in their
    basement. The water was from a pipe at the bottom of the
    boiler. While there the boiler purged a lot of water from that
    pipe in a fast flow to the floor. As a guess it may have been
    3-4 gallons. The pipe seemed to be a pressure relief outlet.
    There was an error code on the boiler. The owner reset the
    unit and has not mentioned another purge since.

    I’m guessing. I think the big tank is the hot water tank for
    the hot water in bathrooms and kitchen. There are radiators
    so maybe that part of the boiler is a continuous circulating flow
    separate from the tank. So the two hot water parts would be
    It would be reasonable for the rust to be from the radiator
    part of the boiler. But since the faucets have brackish water
    may be there is a connection/leak between the faucet part
    of the system and the radiator part. I would assume the
    faucet part and radiator parts are separate systems.

    There may be a coil in the tank that gets heated from
    the boiler. That coil may also supply the radiators. It
    might be the coil is leaking into the hot water tank so
    radiator water getting into the tank faucet supply.

    Minimally there seems there was over pressure
    releases but “cured” with the owner resetting the
    system. ?
  • trouts2
    trouts2 Member Posts: 9
    Is it correct that the boiler works like this?
    The boiler has two parts. One part heats
    the water for the radiators. That part likely
    has an automatic water fill to keep it’s level
    Some of the water for the radiators is used
    to heat a coil in the domestic hot water tank.
    The water in the coil does not go into the
    tank. It goes in the coil pipe in the tank
    to heat the domestic hot water but all
    flows back to the radiator side. So the
    two systems water, domestic and radiator
    are separate. The boiler heats the radiator
    water and the coil water inside the domestic
    tank that I think you call the independent
    part. If that is the case then there is likely
    a leak from the coil into the domestic tank.
  • Jamie Hall
    Jamie Hall Member Posts: 22,050
    Your basic explanation is reasonably correct there. I don't think the water is brackish -- technically, "brackish" refers to water which is less salty than sea water, but still sufficiently salty to taste. Quabbin water isn't.

    Which is not to say that the water isn't a mess!

    But let's consider the boiler and the water tank. The water in the boiler -- which is certainly not fit to drink, by the way -- should be at a pressure less than 20 psi. Please go over and check that pressure gauge on the boiler; it sounds as though there may be some real problems there. The pressure in the domestic water should be at no less than 30 psi, and more likely around 50 to 60. Now there is no way if the pressures are correct for water to move from the boiler side to the domestic side if the pressures are correct. Can't happen.

    Though it can go the other way, from the domestic side to the boiler side.

    So... we have at least one, and maybe two problems (the second being whatever caused the flooding in the basement). There should be valves on the pipes between hot water tank and the boiler -- one on the inlet and one on the outlet. If your neighbour can be without hot water for a while, close both those valves. Now do two things -- run at least the volume of water out of the hot water tank that it contains -- 30 to 50 gallons, likely -- and let it sit for a while. Then check the boiler pressure, and if it is over 20 psi drain just enough water from the boiler to bring it to 20 psi and let it sit for a while.

    The boiler pressure shouldn't change at all. The water from the hot water should be clear and stay that way.

    Report back, if you would.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • trouts2
    trouts2 Member Posts: 9
    I called Bosch in NH that is also Buderus. He confirmed the coil in the DHW tank part. The coil water and radiator water seems to
    mix but since the coil is a closed loop to the boiler there should be
    no coil water getting into the DHW tank. It seems it does though
    so a possible leak there.
    The neighbor had a plumber there that just flushed the tank. I
    think he may not have been familiar with the system so did not
    do any check. The neighbor said he only flushed the tank and
    did not do anything else so I think no pressure checks.
    I’ll send your pressure check to my neighbor. He knows zero
    about this stuff so won’t do the check. But he will have the info
    and hopefully get a Buderus qualified guy in there. I’ll talk
    with the wife this afternoon. She is actually more tech savvy
    than the husband.
    The need to resolve the water and pressure release issues. I
    won’t be around if they have someone fix it but will speak
    with them and update the post.
    Thank you for the information and help.

  • Big Ed_4
    Big Ed_4 Member Posts: 2,518
    The GB uses a indirect to make hot water unless a direct fired water heater is used . If there is a issue with the heat exchanger , as a leak the higher house water pressure (65#) would feed into the lower boiler pressure system (17#) and pop the 30# relief valve .... The problem is either the water coming in or the indirect tank . What type water system and what make indirect ?
    I have enough experience to know , that I dont know it all