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After system modification radiator fills with water


I have recently put a pretty significant addition on to our house. Originally we had a steam system that was used to heat the entire house, but with the new addition our GC has added a hot air system for the new rooms. This led to a bunch of radiators being removed from the system. Also in order to put a door in for our new basement the contractor had to move the drain line.

All of this has led to a bunch of issues with the system

1) The steam pipes bang when the system first comes on in the morning.

2) One of the radiators fills with water coming out the vent when the shutoff turns on.

The contractor has shut off the troublesome radiator and removed and sealed the vent to stop the water from coming out. They possible have removed a main vent when they modified the system. It also looks like the piping they put into the system is copper not steel.

They are proposing to put a new return in to fix this problem and what I am trying to determine is if this will truly fix the problem or should I try to bring in a recommended steam person to fix the system.

I have tried turning down the pressure on the pressuretrol, but the water still came out he vent and the banging still occurred. So any additional insight would be helpful.


  • JStar
    JStar Member Posts: 2,752

    Any pictures of the boiler and piping? Sounds like it's not optimal.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,578
    edited February 2014
    Radiators removed

    There is a very precise relationship between the firing rate of the boiler, and the total radiation capacity of the radiators (EDR). When this relationship is altered by the removal of some of the radiators, the boiler is now too big, and can cause the system to have some of the problems you now have, as well as short-cycling.

    Possible remedies include:

    1. Reinstalling the radiators.

    2. Installing a steam coil in the new ductwork, and using that to heat the new addition.

    3. Down firing the boiler to match the new, lesser EDR.

    4. Installing a new smaller boiler to match the new EDR.

    As JStar suggested, post some pictures of the piping around the boiler, and of any lines which have been altered fro the original.--NBC
  • ecetta
    ecetta Member Posts: 2

    Here are the pictures of the boiler piping and the part of the new work that I can get access to and is not buried behind the wall.
  • Pumpguy
    Pumpguy Member Posts: 663
    Could you elaborate

    on what piping changes were made when the door was put in?  If these were changes in elevation and slope to steam mains or returns, this could cause real problems.
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
  • JStar
    JStar Member Posts: 2,752

    One of out Top 5 rules of steam heating is "If it's new, it's wrong". One of our other rules is "If you want to find the problem, look for the copper".

    Looks like a knucklehead plumber had his hands on this system, installing that copper. 95% of the time, that's where the problem will be.
    RDSTEAM Member Posts: 134
    The GC

    Is your problem. Those guys aren't plumbers, AC guys, or heating guys, nevermind being a steam expert. He should've brought in a guy that knows steam not some mom and pops plumber that he knows.how many rads did he take off the system. Just hope thats your only problem, cause thats already a big problem. Like NBC said, you can install a steam coil inside your air handler, or on the flip side run additional ducts off the new hot air furnace. One way or another your going to need a major revamp.