Radiator Steam Traps - Two-directional?

Unknown

No!<BR>The condensate <i>pools</i> slightly to cool the bellows so it contracts to empty the excess.<BR>Live steam entering <i>backwards</i> would smash into this condensate & hammer like crazy.<BR><BR>Dave

Rob Pickard

Will radiator steam traps block steam from return line?

My six-story condominium building has a two-pipe steam system. I know that some of the steam traps (thermostatic) on the radiators have failed because some of the radiators will get hot from the steam trap side first. This is noticeable when the valve on that radiator is shut off.

This indicates to me that steam has gotten into the return lines, and whichever steam traps are letting the steam into the returns have failed.

However, have the steam traps that have allowed steam back into the radiator also failed? I'm not clear on whether traps are supposed to block steam from either direction.

Jack_44

Stupid @#$%^&amp; traps

Danger, novice opinion follows:

Traps are dumb - they sense steam & close, condensate cools 'em off & they open. They can fail open or closed. So, yes, if steam were already on the return side, they could close (or not, if they had failed).

Our host's books would help you understand the component. It can be hard chasing down the failed traps. I really like his suggestion to plumb in a trap testing station.

A question to ask your super (or whoever maintains the boiler) is whether regular trap maintenance is practiced. Traps can fail quickly (if abused, say, by other failed traps) or last a human lifetime. A lifetime is how long they'll last, but that will be in trap-years (kind of like dog-years...). Seriously, I believe traps are expected to last a handful of years, not decades. It's relatively cheap maintenance, but best done when it's warm outside.

Rob Pickard

So then traps should work in either direction?

It sounds like then that any trap that allows the steam back into the radiator probably has failed - has anyone else noticed this happening in other places?

I would like to try to get the homeowners' board (I'm on it) to test and replace steam traps. However, I would need to figure out a good way to do that, since the company that maintains the boiler doesn't understand that fixing steam traps is necessary.

Since it's unlikely that any sophisticated methods for monitoring traps will be affordable, is the most effective method to try and determine the temperature drop across the trap? I've run into problems with inaccurate temperature readings due to the pipes before and after being made of different materials.

Rob Pickard

Ok - so let's say there is no water hammer, and all that happens is that the steam trap side of the radiator becomes warm. Does this give me any sort of indication of the health of my steam trap?

Jack_44

I defer to Dave,

since I'm only a novice homeowner & he is a pro. His description of what happens & why it destroys trap inserts is graphic.

That said, the testing station that Dan promotes would NOT be expensive or sophisticated. For negligible material & installation cost, inserts could be tested & proven to be good or not. Why this is not standard practice I don't know.

Does your building committee understand:

1.) how wasteful failed traps are?

2.) that the whole trap need not be replaced but only the insert?

3.) how quickly inserts could be swapped?

A caution - repairing a failed trap without addressing the hammer issues would only wreck the new insert.

Listen to Dave - not me - but I'd certainly get the committee to stump up for Dan's books.

Edit - A little knowledge (what I've got) may be dangerous... but there is a scale to ignorance, and NO knowledge is bound to be more dangerous. Dan's books would at least help your owners weed out the un-pros.

Unknown

??? You mean

the rad itself dosen`t get hot, but the trap is warm to the touch?
Then I would say the trap bellows is kaput and you have live steam wandering around in the return lines from elsewhere.
Time for a steam Pro.

Dave

Rob Pickard

radiator will get hot

Dave - The radiator itself will get hot from the steam coming out of the return line, just as it will from steam coming through the input line. I know that it's the steam from the return line because I've noticed this occurring when the radiator valve is shut off, and I know that the valve works properly.

Given that the trap is actually allowing steam back into the radiator, your opinion is that the trap is ruined? In addition, the presence of steam in the returns indicates other failed traps elsewhere.

Rob Pickard

testing method

John - I have "We Got Steam Heat", but I'm not sure I know exactly which testing method you're referring to.

Let me know which book you mean.
Thanks,
Rob

Unknown

Of course,

if you have the rad turned-off, and it still gets hot, there is only 1 place it is coming from, the return lines.
What lets it get in there?, traps from somewhere else on the ladder of the system.
I repeat,, time for a steam Pro!

Dave

Unknown

All you need

is a branch line in the boiler room, the size of the largest trap to test, with a ball valve. Bush it down for the others.
Remove the trap(or bellows), insert-it into the line & open the valve.
If you don`t know when you take it apart, you`ll certainly know when live steam is admitted to it whether it`s failed or not.
PS-Tell them(building owners) to at least invest in Dan`s book LAOSH.

Dave

ttekushan_3

return pressure

Gosh. It takes a lot of pressure in the returns to force steam into a closed radiator backwards. This indicates to me several possibilities.

1) the other traps are bad forcing steam into this one. Don't replace it without judging where that steam in the returns is coming from. The new one will be bad within minutes!

2) someone has put an automatic air vent on the side of the radiator. Any steam present in the returns will easily make its way into the radiator. A steam trap and air vents really don't go together.

3) someone at some time has turned the boiler pressure waaaayyyyy too high to "solve" the heat distribution problems caused by a few bad traps so that the failure of all traps occurred. Must have awful fuel bills.

4) Maybe this is one of those ancient two-pipe with air vent systems (if there's an air vent on the radiators) that does have two pipes, but the outlet is supposed to have another smaller hand valve so that the radiator can be completely closed off. Steam in the returns is normal with these systems and its imperative that boiler pressure remains as low as possible to heat the system. There should be no steam traps, but its a common mistake for someone to randomly think, "Hey, where's the traps? Its got two pipes!"
Well, those traps quickly become toast and cause far more problems than they solve.

Don't replace anything until you get a copy of Dan Holohan's The Lost Art of Steam Heating. Honestly, you'd be hard pressed to find a single volume that describes just about anything you'll encounter in low pressure heating systems. Consider yourself lucky that one volume of ANYTHING is available to get you through a subject.

Besides, one or two ill-advised trap replacements will be more expensive than the book! As Dan mentions somewhere in the book, you are usually looking at a symptom of the problem, not its cause which could be as far away as the boiler room. He also says, If you're not sure of what you are doing, put your hands in your pockets and STEP AWAY FROM THE RADIATOR. In years of being a steam troubleshooter, I can attest to the truth of that statement. The good news is that its quite often that the origin of the problem is head slappingly simple and caused by unknowledgeable service personnel.

Jack_44

Again, listen to Dave

The testing station idea is in The Lost Art & your building committee should have taht volume on hand. Read it & enjoy. Filter out the knuckleheads.

Imagine - you could become the resident steam guru (at least, the resident steam amateur). On second thought, maybe you don't want to become that - the 2 AM calls of "no heat" might be more fame than your fifteen minutes allow for. Anyway, it's a great book, even a Great Book (for the rest of the English majors).

If the buildings' traps are all the same, you can plumb one in at the testing station & just test inserts. The trap bodies don't fail, unless someone with too much enthusiasm gets hold of some wrenches. I suppose you could to put a lock on the valve to keep inquisitive residents from opening live steam lines.

Unknown

John

Thank You John,, I appreciate your confidence in me!
If things are that bad, he needs a Pro though.

Dave

Jack_44

Couldn't agree with you more,

call a pro!

And thanks, Dave & Terry, for your time. What would we homeowners do without your generosity? What a great site!