Steam Trap

fjcruiser105

Can someone please help me to understand how a steam trap works. I am under the assumption that my steam trap is broken, due to lack of heat in one of my radiators. I removed the top of the steam trap (Marsh 1A) and after inspecting the inside noticed that the diaphragm was about 1/2" from the top, so I figured it broke in the closed position. I ordered a new one from Aquatrol and they sent me the replacement, but it was stamped with a 1N on top and it doesn't look like the one I removed. Did they send me the wrong one? Either way how does it function since there are no moving parts.

Unknown

Thermostatic Steam Trap

Hi- Here's a link to an article of Dan's that explains how thermostatic steam traps work.

http://www.heatinghelp.com/article/231/PHC-News-articles/1531/Steam-Traps-Trap-Steam

 I've also attached a drawing that might be helpful. I haven't use Aquatrol but one of the following should be of help.

- Rod



Source for complete traps & parts:

State Supply

http://www.statesupply.com/steamTraps.jsp



Rebuild parts for Steam Traps (Thermostatic,  F&T)

Barnes & Jones

http://www.barnesandjones.com/



Tunstall

http://www.tunstall-inc.com/tunstallsteam.html

jpf321

your original trap

may have been fine .. they are normally open when not in presence of steam temps .. try boiling it in a pot of water and see if it "closes" (expands) .. as dan has said, the radiator WITH the heat has the bad trap .. the rad WITHOUT heat may be just fine.



jpf

fjcruiser105

boiled trap

Okay, so now I understand how they function, and yes my old steam trap did expand when boiled. So what I can't figure now is why the radiator wont get hot. Steam does get to the radiator when I loosen the union on the radiator valve or when I take the top of the steam trap off. But now that I realize the steam trap was working all along, whats preventing the radiator from getting hot when everything is connected tightly. Its the first radiator to branch off the the feed and its on the second floor. Could the return line be clogged/blocked ?

jpf321

because ...

the reason why this rad doesn't get hot when another has a failed trap .. a failed trap causes steam to pass .. and so the steam passes from a failed trap and enters a return and then the steam hits the good trap and it closes (from the outside so to speak) .. once the trap is closed from the outside, there is no way for the air to be expelled from the rad and it stays cold .. got it? see if there is another rad sharing the same return line that is hot.. that's probably where you have a your trap problem.



basically you have to check all the traps on the hot rads if a shared return isn't obvious .. but you know how now :-) .. although I'm not sure if boiling is the best diagnostic tool ... perhaps it is .. i don't have traps myself

Unknown

Steam Trap

While it's possible the return line might be blocked, it's more likely that one other radiators has a trap that is bad and is allowing steam to get into the return and this equalizes the pressure differential so that steam does not move through the non functional radiator.

If you know what order your radiator are located on the mainline. Try shutting them off one at a time in sequence. Allow a bit of time to pass before going on to the next one.  If the non functional radiator starts to work just after you have shut down one of the radiators that is the one with the bad trap. Note : This method only works when you have only one bad trap. The other approach is to shut them all  down but the non functional and see if the non functional now works, Then open them up one at a time until the non functional devbelops problems. Shut that radiator back off as it has a bad trap and move on and see what other ones are bad,

- Rod

fjcruiser105

Steam Traps

I remember how hard it was to get the first trap apart so I think I'm going to try shutting down the radiator valves instead. Do I check for the bad steam traps during one cycle of heating or do I try shutting off one radiator each heating cycle until I find the culprit, aassuming I only have 1 defective trap.

jpf321

once you...

once you shut down the bad rad .. and the steam in the return condenses and the trap which was closed from the outside cools .. then your cold rad should start heating up .. so this can be during a single cycle provided the cycle it pretty long and you wait a few mins between attempts in order to allow cold rad trap to cool

fjcruiser105

What if?

Always thinking of the worst. What if my shut off valves dont work being the house is 70 years old. Will I have to test each steam trap in boiling water, or is there another way?  I will try this in the next few hours, and hope the valves hold. Thanks again for everyone's help.....

Unknown

Trap Testing

There are several ways you can test your traps. You can do it by feel. In the basement start at the radiator closest to the vent (the last radiator) and feel its return line. Be careful they are hot!  Work your way up the line towards the first radiator felling the return lines on the way . The ones with bad traps will be noticeably hotter.

Another method which is more accurate and far less hassle is to use an IR thermometer.

You can get a Ryobi Tek4 4V Professional Infrared Thermometer at Home Depot for about $65.  Here's a site with more info: http://www.ryobitools.com/tek4/#/professional-infrared-thermometer

You point the red lazer dot at the pipe leading out of the trap and it gives you the temperature reading. Take the reading from fairly close (12 inches or less) as this is more accurate. Play with it a bit. Once you have done a few radiators you get a pretty good idea of what temperatures to expect.  On a properly working trap you should get temperature differential between the readings taken from both side of the trap. The IR thermosmeter is good for other things too. You can easily tell where steam is in your system and also tell where your insulation is bad or where cold air is coming into the house.

- Rod

fjcruiser105

Now What?

Checked all the radiator valves and they all worked, so I just shut them all down to see if the faulty radiator would get heat. Waited till the other mains's radiators started to get steam and checked the faulty one, and it didn't get hot. So I removed the top of that steam trap and heard the steam starting to rise through the feed, shut down that valve. I started to open the other radiator valves one at a time, moving from one to the next only when the radiator was fully hot, each time checking the trap that I had opened to see if any steam/air  was coming from my return. But after opening all the valves and getting heat to all the other radiators I still wasn't getting any air coming out of the open steam trap. Next heating cycle, I once again left the steam trap open using it as a air vent, steam started to rise through the radiator, condesate started to form in the bucket of the trap, a couple of air bubbles from the return and after a bit, radiator is hot but the trap is starting to fill will water until it reached the top of the inlet opening, so to not get hit with spitting water I put the top of the trap on again and am now scratching my head. What's next?

Steamhead

Check the return line from that trap

to see if it has a pitch problem. This would trap water, keeping air from leaving the rad.