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.

Radiators "pinging" and interesting old pressure gauge

AMservices
AMservices Member Posts: 610
edited January 2017 in THE MAIN WALL
I answered a call from a woman saying her radiators have what sounds like water hammer. There's probably more than 20 original radiators left in the house, but the problem only exist with 4 of them. She said it only happens when the radiator is heating up and knows enough that it being a forced hot water system, it couldn't possibly be water hammer but more along the lines of the thermal expansion of the steel pipe. She was thinking it was the pipe rubbing against the wood floor, but also said it was a metal to metal pinging.

She had her boiler replaced around 5 years ago and had the company that did the installation return to have a look. They said it was her radiators (cast iron, free standing, tube style) and she needed to have them replaced. Then they said they wouldn't replace them because.... well, I guess they didn't want to be responsible if it proved to be a can of worms.

I said I would have a look and see if I can pinpoint where the noise was coming from and if it was the radiator making the sound, I would inspect the radiators to see if I noticed any signs of leaking where it could be expanding on the chase nipples.

When I got there I went over to the radiator and had her turn the heat on, within seconds I heard the pinging she was describing. Sounds just like water hammer.
The first few pings seem to come from the union 90 and moved into the radiator with the heat. Then after a minute, it sounded like it was under the floor, possibly rubbing on an old hanger. But there would be no way of knowing for sure unless we ripped apart her finished basement. I inspected for leaks on the inner portions of the radiators. Discovered that they used to be a lovely shade of brown, but overall it looked like a solid radiator

So then we moved on to another one of the problem child's that lives on the second floor. This one pings so loud it wakes her out of a dead sleep she tells me.
I walk over to the radiator, put my hands on it as knelt down to have a look and before my knee hits the floor "PING"! The heat wasn't even on.

She brought me over to the last 2 and this time as I was walking towards them, "ping". A very faint ping came from the cold cast. We both heard it. I said "it's not looking good for these rads".

I asked to see the boiler and started asking the normal questions, how's it working, Any balance problems, noises from the boiler room. She said "no, everything worked great" and she saved a lot of money on her gas bill. She Said in the beginning it took awhile to get the temperatures set right and she wishes there were 4 or 5 less thermostats.

Nothing looked out of place, I'm familiar with the company that did the installation and know their not hacks. she was really happy with the boiler and how the house was heated, "it's just the pinging!"
As I was looking around, my flashlight noticed a old gauge tucked in the corner and I noticed the dumbell in the piping right under it. I said "wow" that's nice. Then asked if the contractor said anything about it and give you a reason for leaving it? She said know it never came up.
Can someone fill me in on its purpose? Is that an appendix that should be removed?

So now I have to tell her what I think the noise is and I hated to say this but it's all I could come up with. "I think you need some new radiators" considering how we can hear the sound when the radiator is hot or cold, it's only happening in 4 out of 20 radiators, I've never seen this problem and I've never heard of this problem with cast rad's, but that's all I got. The good news is, I can help and asked if she was interested, I'd be happy to quote new rads. Wasn't what she wanted to hear.
I also told her I would ask around, see if there's anything I'm missing or if anyone has had this problem. And about the dumbell.

Thanks for heating helping










Comments

  • Canucker
    Canucker Member Posts: 722
    I have a similar pinging that happens with a few of my cast iron rads, usually after a DHW call is satisfied and the zones start calling again. The feet of the rads stick ever so slightly to the floor when it heats up and as the feet slide to accommodate the expansion, the rad pings like it just got tapped with a small hammer. ISTR @Jamie Hall mentioning that you could cut pieces of milk jug to put under the feet so they slide a little easier. I haven't gotten that far as my system runs at a fairly low temperature most of the year so it isn't pinging all the time.
    The dumbbell looks like a Honeywell Heat Generator. If it is, it's probably full of mercury.
    You can have it good, fast or cheap. Pick two
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Some people with this problem, have incorporated outdoor reset in the system to reduce the wide temperature swings in the water going to the radiators.
    Is she using temperature setbacks at all? Suddenly allowing the system to catch up to temperature would give the piping a heat boost with subsequent expansion of the pipes, and rubbing against the wood floor.--NBC
  • Abracadabra
    Abracadabra Member Posts: 1,948
    Do the radiators have threaded rods/push nipples holding them together? I've run across a situation like this where the rods were loose and floor movement and heat would cause the radiator to shift and ping. Even after tightening down the rods, the pinging continued. Ended up replacing the rad and silence returned.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,455
    1/16" metal shim and a crowbar won't cost much.
    It's worth a try.

    How many zones?,
    Pumps or zone valves?
    Dhw off boiler?
    Tankless or indirect?
  • AMservices
    AMservices Member Posts: 610
    There are eight zones all using pumps.
    The radiator looks tight and I didn't notice rods holding the sections together.
    She did say that the contractor had to come back several times to adjust the heating curve, but it's working good now.
    I like the idea trying to slide some plastic underneath the feet of the radiators. I agree it's worth a shot.
    I was thinking the dumbbell was a heat generator in that it could have been filled with Mercury. I have an opened up my classic hydronics book yet but it's on my list of things to do.
    I'll reach out to the customer tomorrow or Monday with these suggestions.

  • Jamie Hall
    Jamie Hall Member Posts: 23,170
    One of the reasons the milk carton trick works -- at least sometimes! -- is that the plastic has enough give to allow all four feet to bear... unless the floor is really wonky, in which case a nice shim helps too.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • lchmb
    lchmb Member Posts: 2,997
    have to put that in the back of my mind in case I ever run into it...what an incredible place to learn...
  • AMservices
    AMservices Member Posts: 610
    I had a felling I was looking at an old heat generator. I knew it had mercury in it. The thing that threw me off was how it could still be in a loop with circulators?
    I opened my classic hydronics book to refresh my memory. Basically it was a way to pressurize a gravity hot water system. You couldn't have a pressurized gravity system with out one because those systems where open to the atmosphere through the expansion tank in the attic. With the water under pressure, you could run temperatures over 212°F and not worry about making steam. The hotter the water the faster it moves.
    The generator had the mercury pot at the bottom that mixed with the water on the return piping, the top chamber was connected to the expansion tank in the attic. The mercury was the seal between the pressurized boiler and the open atmosphere. If the damper controls for the fire box didn't close fast enough and the pressure got to high, the water would push through the mercury, up into the top half of the generator, where the mercury could separate and the pressure could leave through the expansion tank.
    The thing that threw me off was it looked like it was piped in line, on the return piping, not like it was going to an open tank. And that gauge was vibrating like water was whipping by it.
    So now the question is, what do I do about it?
    First I hope I'm wrong and some one didn't pipe that in line on the return.
    If they did maybe the pinging is mercury expanding, being tossed around the radiators.
    Who do I call to get rid of mercury like that?
  • AMservices
    AMservices Member Posts: 610
    I'll send the owner and message with the knowledge you all shared.
    To be continued.