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Steam Trap Temperature Readings

I’m back with a follow-up to my questions about radiator steam

traps.  I got myself a Ryobi IR001 InfraRed Thermometer to check on my radiator steam traps, got some interesting results and would like some help on what it all means.  In 4 or 5 radiators the temperature on the side away from the radiator

was higher than the piping nearer the radiator (in one case by almost 30

degrees).  On others there was no real difference and some radiators had the readings to be expected (i.e. the reading was significantly lower on the outlet side of the trap).

I have two radiators on the 3rd floor that are basically stone cold unless the boiler is running for a long period of time in which case in one radiator the inlet pipe and a small part of the radiator gets warm.  The other one stays stone cold.  The one that heats up a little is above (and I assume runs off the same pipe) a radiator where there is only a 2 degree temperature difference with the steam trap.  The one that remains cold is above a radiator where the readings are extremely high and backwards to what one would expect. 

I also have a radiator with severe water hammer that hasbackwards readings.  It is above a radiator that also has backwards readings.  Lastly, I have another 2 radiators that run off the same line in which one is on the first floor and the other on the second.  The first floor radiator has backwards readings and the second floor radiator has a hissing sound at the valve and doesn’t heat very much at all.

Most of these traps are ancient (Dunham Bush 1A’s) and many have layers of paint on them.  I’m tempted to just replace the whole bunch of them or at least keep some on hand so I’ll have them if I need them.

I know that this is a lot and appreciate any thoughts you have since I’ve got a technician coming over tomorrow and would like to speed the process along.  I may ask him to loosen the traps so I can put in the replacement cartridges myself and maybe save some money.




  • Trap Temperature Readings

    Hi Steve-  If you have "The Lost Art..." I'd suggest you read Chapter 10 (Page 140) just to refresh your knowledge on steam traps as this will be of help. Before I approach a steam task I always re read the appropriate section in "The Lost Art..". (It always amazes me even though I have read a section "umpteen" times, there always seems to be a another morsel of knowledge to be had) 

     Keep in mind where in a properly working 2 pipe system where the Heat (Steam) should be.(Hint- Not in the return! :) ) If you have heat (higher temp) on the downstream side of the trap that means another trap has failed and is letting steam into the dry return The hotter the temperature, the closer the failed trap (radiator)   Traps are supposed to close when they fail but Dan says they are more likely to fail open so you may find them both ways.

    If the temperature is lower on the outlet side, this may mean the trap is okay (working).

    The one where the temperature is extremely higher on the reverse may mean this trap has failed in the closed position and also means the the steam is coming from a failed trap of a radiator close by.  When trying to figure out your temperature figures also keep in mind the steam flows from an area of higher pressure to an area of lower pressure and so if the pressure is the same at the entrance  and the exit of the radiator, steam doesn't move.

    The big thing you have to do is be prepared to correct all the bad traps in the same boiler shutdown period as steam in the return, from a remaining bad trap(s) , will "waste" your new replaced trap elements.

    I'm interested on what you thought of the Ryobi  IR unit?   I tried one out at Home Depot, The only thing I noticed is you want to get fairly close when measuring as the farther you get away, the more spread out the area is that you are getting a reading from. The IR thermometer I have used before (borrowed from work) had a "tighter" measure measurement area.  The thing I found is that the more you use the IR, the better "feel" you get for predicting the results

    - Rod
  • Steve_D
    Radiator Steam Traps

    Rod,  Thanks for the information.  It will definitely help going forward with this.   I've read Dan's two other books on steam but don't yet have The Lost Art.  I may need to pick it up.  Regarding the thermometer.  I'm still getting used to it but it seems to do a pretty good job.  I do find it helps to get it within a foot of what I'm measuring.  I bought the less expensive one ($30) since it seemed it would do what I needed and I saved $35.  Thanks again for the help.

  • Jamie Hall
    Jamie Hall Member Posts: 23,446
    Sounds to me

    as though you have found a few returns to which are connected one or more bad (open) traps each.  Traps aren't that expensive -- thing to do is to identify a return which has these backwards or odd readings and which is isolated from other returns which are working, and replace all the traps on it.

    I've always used the "that's warm" versus "eoouch!!!" technique to identify a leaking trap, but I have to admit I wouldn't mind having an IR thermometer!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Isolation

    Hi Steve - Jamie mentioned the word "isolated" and I remembered I forgot to mention that it maybe a thought to consider shutting  down the whole system (each radiator) and test the traps (radiators) one at a time. I've never done it this way as I was usually only looking for one bad trap though it might be a better way to do it. Anyone have a comment on testing the traps this way?  It might give you further input on your trap situation.  With the "feel" method I don't think you'd do it this way but with the IR thermometer it should be quick and easy. Just a thought.

    - Rod
  • IR Photos of Steam Traps

    Steve- Here's a link to some IR pictures of steam traps which are on Gerry Gill's Website which i thought might be of interest to you. These guys are really "state of the art"!   


    - Rod
  • Steve_D
    Thanks Rod and Jamie

    Thanks for the ideas.  I'll see if I can get this done before the technician comes today and save myself some money.  The saga continues and hopefully we'll get this system running well before the end of the heating season and without spending my retirement fund to get it finished.  We have found out that the previous owner wasn't much at doing routine maintenance.   Just a heads up for everyone.  We had a home inspection done by a very respected guy and he didn't pick up on any of these issues even though he tested the system.

This discussion has been closed.