New trap not working

richarddowling

I have a 2 pipe steam system. Twice I have replaced trap with new Barnes Jones 2168 cage unit on one large radiator with Hoffman Specialty #8 trap. Steam flows through new trap to condensate line each time. I replaced trap cage unit. Should I be using bellows type cage unit Hercules 2168H?

Fred

@Sailah , a member on this site is also from Barnes and Jones. He can tell you exactly what you need for that Hoffman #8 trap. Sailah, sorry but I seem to be referring a lot of people to you recently.

neilc

R U sure you're working on the correct trap?
how do you know?
is it possible another trap is failed and you're just feeling/seeing the heat on this one?
pics from below ?

Sailah

I'm sorry you are frustrated. The 2168 is indeed the correct cage unit. Having 2 fail essentially instantly is not really possible. I suspect you may have other issues. Did you verify the seating surface is clean? Our cage unit is designed to seat down to this surface with a gasket and be held in place by spring pressure from the cover. If you have a clean seating surface and a little spring pressure should work perfectly. Please confirm these two things.

And you have a regular 8 not an 8C correct? Send pic of cover of in doubt.

Last is how are you verifying steam is passing the trap? As mentioned it could be a false reading from another trap feeding the same line. Are you checking inlet and outlet temps?

We make Hercules cage units and I don't think that's what you need. I'm more than happy to test or swap cage units but I suspect it's something else.

You are welcome to call me tomorrow and we'll get you fixed up.

Jamie Hall

In addition to @Sailah 's comments -- which is a bit presumptuous on my part -- I would mention that it can be remarkably difficult to determine whether steam is actually getting through a trap, or whether it is just really hot condensate. The only really reliable way I know of is to actually measure the temperature of the outlet pipe below the trap and compare it to the presumably similar material and painted inlet pipe.

Sailah

@Jamie Hall we find that your way is typically the fastest way to check radiator traps but as mentioned you can get false readings from other traps dumping into the condensate pipe and back feeding a good trap. When you don't have the luxury as we do to check to atmosphere ( which BTW is how we check every single trap that leaves our building) the most reliable way to check is with an ultrasonic tester. A trap blowing by is easily discernible with its tell tale whistling. But not everyone has a ultrasonic tester handy.

Much can be done with a simple IR thermometer aimed at the pipe threads , I find they give the most accurate reading as they are the thinnest part of the piping and don't give bad readings like shiny surfaces. You are looking for a 10-15 degree delta between inlet/outlet for low pressure.

When checking a large building with 100s of traps, the temp gun or FLIR is done first. When questions arise, the ultrasonic comes out to properly diagnose the real leaker.

richarddowling

Thanks Sailah, Jamie. Trap is HS 8 not 8C. Seat is clean and plenty of spring pressure since I just installed cage. I'm thinking maybe just hot condensate but return pipe down below radiator in basement is hot to touch. I'll try to purchase IR gun to check temp differential. This is only trap on radiator. Others in line seem to be working correctly as they are shutting off steam when radiator gets hot and returns are not hot to touch.

Sailah

@richarddowling Your returns should be "hot", the trap is designed to drip the condensate once the temp subcools 10-15 degrees. So 215 minus 15 is still 200 degrees. I can't envision a return directly downstream of a working trap that would be warm, not hot.

I think from what you describe the Hoffman 8 is now working correctly and maybe the others you have are not?

I'm always more than happy to test traps for you. I'll even cover the shipping and turn around same day.

I'm even more interested in the inlet and outlet temps now on your other traps

Jamie Hall

@Sailah and @richarddowling -- from my experience it can be a bit of belt and braces type of problem -- but I am working with a vapour system. I have found that if a radiator is properly throttled, most of the time the return (and, for that matter, the trap!) is not all that warm. It's when a radiator is more open and running fully hot across that the return pipe can get up to 200 quite easily (and stay that way for some distance downstream, I might add). But there should be that temperature difference, even then. Problem is, of course, that at least for me that 200 degree return with a working trap is still at the "yeouch" level -- which is why you need a good IR thermometer.

But the cool return bit really only applies to a vapour system with the inlets throttled (orifices or valves) and not working at full capacity...

richarddowling

Thanks again guys for your info. As I understand from Dan's book, once the steam flows through the radiator and closes the trap, steam stops flowing and moves to the next radiator in the loop. I have radiators where I can hear steam flowing, and then hear it stop flowing once trap closes and the condensate return below the trap is barely warm(?) Am I correct in describing this is how cage trap works?

Jamie Hall

Um... well, that's how the trap works, sort of -- it will stay open to let air or water out, but if steam hits it it should close.

However... ideally, the steam in the main gets to most of the radiators at least more or less at once, or it will if the main (and dry return) venting is adequate. So it's not sequential, radiator by radiator. Or it shouldn't be.

richarddowling

Jamie,
When boiler is running, should I always hear air hissing from vent on each main line. Do these vents go bad? I have replaced them once in past 4 years.

Jamie Hall

Not always. You may or may not hear air while the steam main is being filled with steam (some vents are much more audible than others) but once the steam gets to the vent, it should stop. Do vents go bad? Sure. But not, usually, unless they have either been abused (over pressure, water hammer, that sort of thing) or they are really old. Of the two vents on the system I care for, one is about 10 years old; the other getting on for 90 -- and they both work fine.

richarddowling

Thanks Jamie once again. Really appreciate your info!