Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Water Hammer + Gushing + Level in Probe-Type Cutoff

Dave_J Member Posts: 3
Very thankful that this board exists - thank you for reading! So we are new to this house as of last April, never owned (or worried about maintaining) a home before. The house has a boiler and single pipe steam system (which I learned after reading We Got Steam Heat!) The system is also controlled by a thermostat, which we set 6 degrees cooler at night. When we got the house, our realtor pointed out that the boiler is pretty new (3ish years). However, there have been some problems. Primarily, the water hammer is what has been annoying us. So far we have insulated the supply main that runs around the basement (was bare when we got the house), replaced the vent valves on the radiators that didn't seem to be releasing, and tipped the radiators back toward the supply valves where it seemed like they weren't already. Still getting water hammer. So we called a pro (from the same company as installed the boiler back before we had the house). Pro came out and pointed out that our main air valve in the basement was sealed shut, had been painted, never cleaned out. We put a new Hoffman 75 on it per his instructions, which seems like a good move based on what was in the book too.

We are still getting water hammer though, the vent valves throughout sure seem to whistle all the time, plus recently when the radiator at the very far end of our line was knocking, I tried opening the vent valve and water came gushing out - probably a couple gallons before I could shut the supply valve. Oh also, the level in the probe-type cutoff seems to vary a LOT - like it goes from all the way full to all the way empty. In the book I read that it should only go from about 2/3 to 1/3 is that right? Sitting next to it for a bit it seemed to be running short cycles, like the water in the probe would get pushed all the way out of the probe, a bit after it would turn off, then within a minute or two it would restart.

On the plus side, the house heats just fine, we are comfortable temp-wise and each radiator gets hot. Maybe operationally we just keep the temp the same all the time to prevent more condensation at night (though there is some water hammer in the day too). I will also say - there is a mysterious stub along the main in the basement, capped. I am wondering if this was once a second main air vent, but at any rate now its just a plug.

So, what do you think, does the diagnosis seem clear or should I call the pro back out and just let them poke around at it for a bit? Thanks again for considering and if any additional info would be helpful I'll be happy to provide.

PS - Also, maybe separately, after reading the book some things about the boiler piping that make me think maybe the setup the pro did is not so great are that it's copper piping and there doesn't seem to be a Hartford loop (to my uneducated eye at any rate), but maybe these are just things the old owner didn't care to pay for. On the plus side their customer service has been great, they've charged quite fair prices, and offered useful info (they recommended we insulate the pipes and replace the steam valves on the radiators early on.)


    JUGHNE Member Posts: 11,021
    edited January 2021
    Find the install manual for your boiler, look at your model number and find the mininum piping requirements for your model. It may want 2 risers and a header sized larger than the risers.
    The copper is leaking already.

    This is probably throwing water up into the main and causing water hammer.
    No there is no Hartford Loop, just a check valve that could be sludged up and keeping water from returning.

    At this time the best thing you could do is skim the oils off the top of the boiler which contribute to the water being thrown up.
    Show a picture of the other side of the boiler there may be a skim port or plug. It needs to be above the water line.

    He was a Pro at something, but not at following install instructions.....you may find the book in the basement without a fingerprint on it.

    You may do better for now to set the tstat at 68 on hold. Cold starts may contribute to your problem.
  • neilc
    neilc Member Posts: 2,667
    everything Jughne said, and,
    what are you seeing for pressure when the boiler is boiling, and the hammering is occurring?

    if you could get the gage out, and add a nipple, you could skim from there,
    or there's a way to skim thru the sightglass also, this could be discussed further
    known to beat dead horses
    EBEBRATT-Ed Member Posts: 15,317
    Un fortunately the installer didn't do the right job. We see this on a daily basis. Look in your boiler manual the piping diagram is in their. Another installer who can't or won't read.

    Good job on what you have done so far and learning about steam but your boiler needs to be repiped.

    If it was me I would search for the right contractor and have it done this summer. I am sure you can make it another 2 months

    Check "find a contractor on this site" And post wher you ar e located someone may have a recomendation
  • Jamie Hall
    Jamie Hall Member Posts: 22,916
    Yeah, unhappily that boiler piping is doing you no favours. It's not so much that it is copper, although as @JUGHNE noted, it's leaking already. More to the point is that it goes straight on up past the connection to the equalizer -- and any water being carried by the steam (and there will be quite a bit) is going to keep right on going, too, and get into the steam mains. That may be the cause of some of your hammering, as I also note only one very small drip at the far end of the main down to a wet return (I think...?) which may not be adequate.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Dave_J
    Dave_J Member Posts: 3
    Thank you all.

    Jughne - to your points: looks like the model is a Crown BS172. I found the system piping in the install manual (excerpt in images below) and it says a second header is optional, but as you thought it does say a size reduction is needed in the equalizer line where it comes off the header. Also seems like the equalizer line should not peel off before the horizontal header like I've got here. A few more photos of the other sides of the boiler are below - I don't think I see a skim port or plug.

    Neilc - is the gage that says "internal siphon" telling me the operating pressure? That was right around 1 psi while some knocking was going on upstairs. Your skimming method recommendation sounds like it might be a bit advanced for an amateur - what do you think - is that ok to attempt by a newbie such as myself?

    EBEBRATT-Ed - ok sounds like that's the thing to do to really get this fixed. I am in Shaker Heights, OH and searching here on the site it looks like G.W. Gill is nearby. Certainly open to recommendations if people in the area see this.

    Jamie Hall - 10-4 on the boiler piping. Like you say I am seeing in these install instructions "If the near boiler piping is not correct, wet steam will enter the system and the following problems may occur:• Short cycling on low water [check!]• Boiler or system Flooding [check - at the one radiator at any rate]• Hammering [check!]" As far as the wet return's vertical line down, it starts at ~1.5" OD black pipe and then changes to 1.2" OD copper after the tee for the main air vent. Is that size a no-no?

    Youngplumber - ok good to know, I will find someone else for sure to hopefully do the repiping come summertime!

  • neilc
    neilc Member Posts: 2,667
    well, hey, wudyano,
    that capped nipple left of the safety valve is your skim port,
    get Gill there to guide you and your decisions,
    that copper needs to be redone,
    if the water is bouncing alot when firing then a skim could help a little right now,
    or will be needed after repiping
    known to beat dead horses
  • Dave_J
    Dave_J Member Posts: 3
    Ah, I see. Ok sounds like a plan - thanks for the guidance.
  • ethicalpaul
    ethicalpaul Member Posts: 5,605
    I found the system piping in the install manual (excerpt in images below) and it says a second header is optional, but as you thought it does say a size reduction is needed in the equalizer line where it comes off the header. Also seems like the equalizer line should not peel off before the horizontal header like I've got here.

    The issue is not a "second header" (I don't actually know what that is). The issue is that the "first" header (only header) is badly incorrectly piped and as the earlier folks all said, it will bring you a lot of pain until it's fixed.

    Your manual is kind of hard to read because of the lines they used, so let me share a better drawing that might better show you what's wrong with yours. Look closely at the path of the steam as it comes into the pipes. The header MUST force the water and steam to turn corners. This gives the water drops a chance to continue horizontally then back down to the boiler, and the steam to turn the corner upward (without the water).

    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el