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  1. #1
    Join Date
    Jan 2008
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    Default Clanking Hot Water Radiators

    I have a 1924 home that was converted from a gravity fed hot water boiler to a Trinity TI 150 (forced hot water). The system works great except when it starts to heat up several of my radiators make a loud bang/clank noise. It's like someone hit the radiator with a hammer.

    I checked the affected radiators and they all appear to be level, plus I bled the all the air out.

    Our basement (where all the pipes run) is basically unheated and is about 52 degrees. Does that have anything to do with this noise?

    Any help on what is causing this issue or how to fix it is appreciated. Thanks.

    P.S. This is definitely a HOT WATER system, NOT steam.

  2. #2
    Join Date
    Aug 2007
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    Default Re: Clanking Hot Water Radiators

    I'm not an expert but I do know that the system you originally had was a gradual warming of the components ....pipes and rads , etc. ..... whereas the forced hot water system heats the components more rapidly ... so these components will expand more rapid than before.

    Just a guess.

  3. #3
    Join Date
    Aug 2007
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    443

    Default Re: Clanking Hot Water Radiators

    Canuk makes a good point.

    How long has the system been operating as a conversion; is the noise recent or has it been doing this for some time??

    I believe the Ti 150 is a variable condensing unit??

    How many floors to the house, and are the offending rads on the top or bottom floors; are there other rads that are working ok??

    When they put in the new boiler, did they leave the wide diameter 3" steel supply/return pipes near the boiler???

    Radiator banging is usually associated with steam systems because of flow restrictions; it can be caused in HW systems by:

    1) The contractor left the large piping in the cellar from the old system in place.
    2) they left the orifice plates (flow restrictors) from the old system inside the radiator stubs, causing flow problems.
    3) the boiler water temp is set too high (190-200 degrees, instead of 140-170), and this is causing expansion noises when it hits the cold water (or any sludge buildup) in the rads during heatup (canuk's point).
    4) You have thermostatic radiator valves (TRV's) connected to the rads and the needle valves inside are banging (common occurance on some model TRV's).
    5) The through-piping (risers) to and from the radiators are rubbing against the floor board holes to make noise as the heated pipes expand.
    6) The water pressure on the boiler gauge is too low (should be 12-18 psi, depending on how many floors you have); the low psi is causing water pressure fluctuations and water hammer.
    7) There is sludge buildup in the bottom of the rads that is causing a flow restriction (common in old gravity systems; rads may need to be flushed out).
    8) The contractor put in the wrong size circulator (pump) at the boiler that's producing too much or too little flow thru the system.
    9) Sometimes in houses with hard water, mineral deposits build up in the boiler housing and produce noise when the boiler fires; this noise is easily transmitted to the radiators via the piping, so it seems to come from the rads.

    Please post back to advise what the psi gauge & water temp readings are & whether you have TRV valves on the rads, and also if you have hard water.

    Also advise if the supply piping from the gravity system has been removed and a 1" supply/return piping system is now in place.

    If the rads were working ok when the new boiler was put in, they probably removed the orifice plates from the rads.

    I can see no reason to expect that the basement temp is the cause of the problem.

    There is a good article on gravity system conversions by heating expert Dan Holohan at the site below; scroll down & click onto "gravity hot water heating" at the site.

    Since there are so many possible causes, have you had the installer, or a heating tech over to try & find the cause???

    http://www.heatinghelp.com/heating_qa.cfm
    Last edited by JacktheShack; 01-16-2008 at 09:32 AM.

  4. #4
    Join Date
    Jan 2008
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    2

    Default Re: Clanking Hot Water Radiators

    Jack, thanks for all of the tips. I've put my responses in BLUE

    How long has the system been operating as a conversion; is the noise recent or has it been doing this for some time??

    The system was converted in 2006, the radiators have been making this noise since the conversion, but it seems like it's getting worse.

    I believe the Ti 150 is a variable condensing unit??

    Yes, I belive it is. All of the specs are available here: http://www.nythermal.com/Media/Docs/...ual_4_5_06.pdf

    How many floors to the house, and are the offending rads on the top or bottom floors; are there other rads that are working ok??

    The house has three floors including the basement. Finished square footage is 1500 (not counting the basement). The offending radiators are all on the first floor. There are 8 total radiators in the house, 5 on the first floor 3 on the second. Not all of the first floor radiators clang. There are three main offenders, and they happen to be the three largest radiators. Two of the offenders are approx 8 ft long by 2 ft high, the third is approx 2 ft long by 3 ft high.

    One important note, if I walk by offender #3 it will sometimes make a clanging noise. It's like my weight on the floor causes it to shift slightly and clang. I know for a fact it's not the risers on this radiator.


    When they put in the new boiler, did they leave the wide diameter 3" steel supply/return pipes near the boiler???

    No, all of the pipes in the basement were replaced with copper. The steel pipes had asbestos. There are 1 1/4" mains that feed 3/4" copper to the radiators. The cast iron riser pipes were re-used. The new 3/4" copper connects to them in the basement.

    1) The contractor left the large piping in the cellar from the old system in place. No, see above response

    2) they left the orifice plates (flow restrictors) from the old system inside the radiator stubs, causing flow problems.

    Not sure, how would I check this? Flow seems fine because I get heat to all radiators in the house.

    3) the boiler water temp is set too high (190-200 degrees, instead of 140-170), and this is causing expansion noises when it hits the cold water (or any sludge buildup) in the rads during heatup (canuk's point).

    Boiler water temp is set at 150 degrees

    4) You have thermostatic radiator valves (TRV's) connected to the rads and the needle valves inside are banging (common occurance on some model TRV's).

    I don't believe there are any TRV's in the system. Each radiator has a simple screw valve with a round knob on one of the pipes.

    5) The through-piping (risers) to and from the radiators are rubbing against the floor board holes to make noise as the heated pipes expand.

    I have checked this and I don't believe it's the case for any of the radiators. I know the main offending radiator doesn't have this issue, the holes through the floor are bigger than the pipes and the pipes aren't touching anything.

    6) The water pressure on the boiler gauge is too low (should be 12-18 psi, depending on how many floors you have); the low psi is causing water pressure fluctuations and water hammer.

    I was told by the installer to have it run at 15 PSI max when hot. The system psi varies quite a bit, when cold it dips under 10 psi, hot it's around 15 psi. I was told this is normal, but is it a problem?

    7) There is sludge buildup in the bottom of the rads that is causing a flow restriction (common in old gravity systems; rads may need to be flushed out).

    I believe the system was flushed when converted, but I'm not sure. Is this something I could do myself?

    8) The contractor put in the wrong size circulator (pump) at the boiler that's producing too much or too little flow thru the system.

    Not sure on this either, how would I check?

    9) Sometimes in houses with hard water, mineral deposits build up in the boiler housing and produce noise when the boiler fires; this noise is easily transmitted to the radiators via the piping, so it seems to come from the rads.

    I'm on city water (St. Paul, MN) and don't believe it's hard water. I'm definitely sure the noise is coming from the radiators and not the boiler, I've listened for it while in the basement to verify.

    Since there are so many possible causes, have you had the installer, or a heating tech over to try & find the cause???

    I've had them over several times. First they checked the risers, the second time they put cut up pieces of playing cards under the radiator feet. I wasn't there the second time (wife was home), so I'm not sure what that was supposed to accomplish. Maybe let the radiator feet move slightly when expanding? It seemed to help for a short while but then they started clanging again.

  5. #5
    Join Date
    Aug 2007
    Posts
    443

    Default Re: Clanking Hot Water Radiators

    Cyclone:

    This sounds like a restriction in the offending rads that is preventing HW flow; there's an outside chance it could be a defective on/off rad valve; otherwise, it's something inside the rad that's causing the restriction.

    The psi on the boiler gauge sounds ok; it is normal for psi to rise to 18 as the boiler heats up; water EXPANDS 5% as it is heated; the expansion tank absorbs this added volume.

    As I noted in my first post, it is HIGHLY UNUSUAL for a HW rad to make the loud, clanking noise you are describing unless there is a restriction present.

    Do you have a single pump on this system, and one thermostat, or do you have zones with a t-stat for each floor??

    Has anyone checked the on-off valves on the rads??

    These can be tricky to check; even when turned all the way "off", they have a small hole that allows water to squirt thru to the rad; all the way clockwise is OFF; all the way counterclockwise is ON; see that the valve handle turns smoothly and easily; get down on your hands & knees with a strong light and mirror; there is usually a little metal stop that limits valve on/off movement; often this gets snapped off and the valve handle can be continuously turned in one direction (this will subsequently turn the internal valve on & off, closing & opening the water flow inside the piping).

    If the metal stop has been snapped off, try positioning the valve handle in different positions to see if there is any improvement in the noise problem.

    If it's not the on/off valve, the individual rads would have to be checked one at a time to make sure free HW flow exists; the only way to do this is to pull the rad by shutting down the system, squirting some penetrating oil on the nut connectors of the rad, shutting off the water inlet valve to the boiler, drain a gallon or two from the boiler drain valve, open the rad bleed valve to let air in, and use a large plumber's wrench to loosen the attaching nuts so the rad can be pulled away from the risers.

    It would be logical to start with the SMALLEST rad, since it would be easiest to handle.

    However, we're talking about shutting down the heat for a few hours in Minn. in January, and if you diy, there's always the chance something like a broken nut or cracked riser connector will prevent you from restoring heat promptly; if you can't get a service tech in right away the system could freeze.

    If you have given up on the service tech that has already worked on it, consider consulting the Yellow Pages under "Heating Equipment-parts", call several parts houses and ASK TO TALK TO THE PARTS DEPT. COUNTER MAN.

    They will be able to refer you several experienced HW ("wetheads") service techs that know HW radiators inside & out.

    Try to get an OLDER guy in his 60's or 70's; that has years of experience; they know a lot more about rads & HW systems than most younger techs.

    If it was warm weather, I don't think you would have any trouble doing this as a diy project.

    It's just that in January, you would have to pick a warm day, remove the rad, check to see that the orifice plates are out, check the on/off valve for proper open/close movement when you turn the handle, tip the rad to remove the iron oxide crud into a shallow pan, and use a hose to wash out any sludge that has accumulated at the bottom; if you blow in, & there's no free air flow, a sludge remover such as 8-way ($15/qt. at plumbing supply houses) would have to be fed thru the bleeder valve opening after the 2 bottom holes are blocked off to loosen the sludge for several hours, or perhaps overnight, then washed out.

    You would then have to fit a short length of rubber hose over one of the bottom holes in the rad and use your lungs to blow air in to assure there is a free flow of air thru the 2 bottom rad holes (making sure the bleed valve at the rad top is closed for this air test).

    Consult the site again below; if your piping system is a diverter type or two-pipe setup, anything but a LOOP arrangement, you can always block off the 2 riser attachments refill the system with water to 15 psi, and restart the system; this would allow you to let the sludge compound soak in overnite and heat could be restored without the rad being re-installed.

    The fact that there are shutoff valves on the rads indicates that you have a piping system that would allow this.

    Caution, if you try this yourself, this can make a mess on your floor or carpet; even small rads are very heavy; have a lot of old rags to surround the rad when you loosen the attaching nuts; the black, liquid iron-oxide crud that oozes out will permanently stain any nearby carpeting.

    If you have to clean out the 8' rads, it could be a big problem just moving these hulks, they weigh 300-400 lbs if not more, and these probably should be left to warmer weather when the heat is not needed overnight.

    You will learn all you need to know to work on the LARGE rads by working on the SMALL rad first.


    Other possible options:

    1) A 2nd hand rad can be picked up at junkyard, demolition yard, salvage yard; if it air tests ok and air blows thru it easily, & the price is right, it can be used as a quick replacement.

    2) A length of high output baseboard (a hundred times lighter than rads) can be easily installed in place of the rad; this can be a quick way to solve the noise problem; there are also floor convectors, high output convectors, etc. that can be used; see the beacon-morris site for ideas; click onto residential products; also check out the low cost baseboard at Home Depot/Lowe's or plumbing supply houses.

    http://<br /> http://www.heatinghel...heating_qa.cfm
    http://www.beacon-morris.com
    Last edited by JacktheShack; 01-17-2008 at 01:21 PM.

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