Live steam from the condensate return

fixitguys

Howdy, I am the new maintenance guy at a 58 year old school building in Pennsylvania and am slowly educating myself about steam heating and controls, fascinating! Today the fire company showed up due to a heat sensor in the boiler room. The Admin onsite said the room was "full of steam" so they shut the boilers down. When I arrived and fired them up there was nothing unusual going on other than the excessive steam coming back through the condensate return which has been getting worse the past two months, of course it has been very cold during this time as well. If I understand how the system works, the only reason I should get live steam in the condensate return would be due to steam traps failing open? Is that a true statement?

I have replaced a few cages in classrooms that had water hammer or coils that would not stay hot and solved those issues, but there are a hell of a lot of traps in this building. There was a trap survey done in 2007 indicating a boatload of failing traps but it appears nothing was done about it or if there was, there are no records.

What else should I look for ?

Thanks troops,
Mike

Paul48

You can get a lot of useful info with a cheap IR gun. A pipe temperature before and after a trap that is the same= a failed trap. Gotta start somewhere. What are you running for pressure on the boiler?

fixitguys

They typically run at 5 pounds. Thanks for answering!

Paul48

No matter what it costs to get the traps fixed, you will save money in the long run by being able to get that pressure down under a pound. You're not using the steam for process, just heating right?

fixitguys

Exactly. Heating only. So do you agree there should be no other reason, than failed traps, for steam in the condensate return?
Thanks Paul

Paul48

Yes......You need a steam pro in there. You might as well be standing in the boiler room burning $20 bills. Where in PA are you?

EBEBRATT-Ed

Traps, Traps, and more traps. You need to impress on the school system how much fuel your wasting. Not only dumping BTUs to the atmosphere your also

adding a ton of fresh make-up water (and oxygen) to the system that you have to bring from 40 deg. up to steam temperature at least 212 deg. The oxygen will start to rot out the piping --boiler feed piping is the first to go followed by the boiler and the condensate piping. If this keeps going you can loose a boiler, if your lucky only the feed water piping between the boiler feed tank and the boiler will be shot.

Paul48

At 5psi it's a lot higher than 212 deg, and that's the wasted fuel

fixitguys

Paul: Phila suburbs. Ed: Thank you, I have been tracking city water use and of course that is up and the chem use is up as well. Traps it shall be! Thanks guys

Paul48

Get that pressure down as far as possible too.

fixitguys

Thanks a lot gentlemen!

sreja

As has been said earlier: It's all about traps if you are getting steam in the return line.

But here's a tip from my own experience with a large building -- it's not just the radiator traps that are obviously visible. There may be larger end-of-main traps that are in non-obvious places that you need to worry about.

In our 12 unit building, even the plumbing pros missed a couple of large end-of-main traps that were slightly hidden and out of site. only when those were fixed did we eliminate steam in the return line.

JUGHNE

I had the same thing in a school with steam in the boiler room. The maintenance man's solution was putting box fans to blow it out of the room.
Steam was coming out of the cond pump vent and also an air vent. There was an end of steam main in a pipe tunnel that had been walled over. Cut the wall open found the trap passing steam with leaking return pipe also . All original parts.
All the traps were original to 1955 and the only saving grace was orifices had been installed in the supply valves. All the traps were changed and new downsized orifices installed.
Pressure lowered from 5 PSI to as low as control could go, about 2.5 PSI. Why was 5 PSI used for 40 years??....because that is what someone told the maintenance man it should be and who would argue with someone from a boiler company that is 200 miles away? Eliminated some leaks with this step alone.
If low pressure is maintained it may be possible to install orifices in the hand valve unions for less than 20% of the cost of new traps. This is not for all forms of radiation.
I have also done this on a small residential system that has no traps at all and the owner is reporting good results.
Search this site for "Henry Gifford-Energy Savings in a Two pipe steam system". I went with his guide lines. But first you need to find the lowest steam pressure that the system will perform at. You drill the orifices depending upon EDR and pressure applied. You can always increase the orifice size but I'm thinking one trip around the building would be enough work.
My school project (1660 EDR with 2 X oversized 1,000,000 BTUH boiler) is I am sure is pretty small potatoes compared to what you have.
This is only for the radiation and your end of main traps still need fixing (probably).

fixitguys

Looks like I'm in for a trip to the crawlspace. "End of Main" traps, I assume, are the F&T traps at the very end of the main steam runs? And these failing can cause steam in the return? I seriously doubt these have been touched in 58 years. Had the blueprints out today and there are 8 of those. There are also a number of F&T traps somewhat midway on the longer main runs.

JUGHNE

If your building is 2 or more floors tall, then the steam main risers would probably have F & T traps at their base. I found one hiding in a records closet that was always locked. Or hanging heaters, say in a shop, would have a trap on that riser somewhere.

nicholas bonham-carter

If your water use goes down to zero, you can forgo all the chemicals, whose concentration must be building up over time.
You could buy a number of trap repair kits for the barrels of chemicals.
High pressure equals a more acidic mix, with condensate grooving as a result.
Sometimes, "better living through chemistry", is only for the chemical sales department!--NBC

Pumpguy

Keep in mind that the lower the steam supply pressure, the lower will be the mass of steam that leaks past bad traps. This alone will mean less steam in the return lines.

Now, if you had vacuum pumps on your return lines, you could lower the steam supply pressure even more. The lowered pressure (i.e. vacuum) in the return lines will make up for the lowered steam supply pressure by increasing the overall pressure differential through the system and across the traps.

JUGHNE

Have anyone heard anymore from this poster? It seemed like an interesting project with easy hanging fruit that would have made a lot of difference for this school.