Two pipe steam question

Joe V_2

It didn't seem like a big deal at first but it seems to be a recurring problem:  The radiator condensate return loops (two of them) come to a point near the boiler and it appears that in the mornngs, so much condensate returns at once that it flows out of the small (@2"dia) Gorton vent above the boiler and above the return line to the boiler.  Nominal steam pressure is 3-6oz/sq in. 

It only does this when recovering from night time setback which is 67 going to 71.

Is there something I can do to eliminate this problem?

Unknown

Slow Return of Condensate

Hi- Has your wet return been cleaned  out lately?

- Rod

Steamhead

Something

is blocking the condensate. Is there a check valve in the return line after it drops from the vent? 

Joe V_2

Rod

Wet return is new piping.  Actually, boiler is new install.

Joe V_2

Steamhead,

No check valve removed or replaced; is is a straight drop (approx 7ft).  As far as I can tell from TLAOSH and this forum, I have a Trane Vapor system.

Brian_74

Hidden check valves

Hi Joe, I have the same problem. I had thought mine was due to have an oversized boiler, so I've been following your thread with interest. I don't know how much you know about steam systems, but I didn't know that I had check valves until other Wallies pointed them out to me. In the photo below, you can see two check valves. There's a fairly obvious one on the far left, and a not so obvious one between the two wet returns. Anyway, I thought this might help.

Joe V_2

Hi Brian

my boiler is definately 25% oversized because I plan on adding 3 radiators this summer which will make it an even load.  I am certain it is not a check valve or blockage because it only happens during first firing of the day. 

It is the only time I have seen it trip on pressure.

Steamhead

Are the original Trane vents

still on the system? If so, they are vacuum vents which can hold water up in the system. Replace them with standard vents and that should solve the problem.



Measure the length and diameter of each steam main and we can tell you what you need.

nicholas bonham-carter

spitting vents

sre these main vents mounted up on a nipple above the return at least 6 in, and away from the "tee" of the return?--nbc

JStar

...

What size are the returns? How do they join up before going back to the boiler?

Joe V_2

I believe the mains

Start out as 2" for about 10' then reduce to 1-1/2" then 1-1/4" dry return. Two loops about 60' longeach. The original vent was bell shaped like an argon gas bottle cap. The new one is a small gorton. About 1-1/2" dia. The main vents are both gorton #2. The vent in question does sit six inabove the drop. The returns are 1" pipe that tap into 1-1/4" to boiler. Each return is 30'.

Joe V_2

Yes. Pls reAd description above

Working off of iphone late at night sorry for typos

Steamhead

Maybe not a total blockage

but a partial one could cause your problem. During the day there would not be enoiugh condensate to back up from only a partial blockage.



Time to look at those returns where they drop below the waterline.



Also- when that vent spits, are the dry return lines steam-hot? They should never get that hot. If they do, you have one or more bad traps.

Joe V_2

The pipe that drops below the waterline is 1-1/4 ...

and brand new (two months old)  which is why I am resisting the blockage theory. 

 I have to back peddle a little here.  Last night when I went down to look at the boiler, I found the return line wet.  So the problem isn't limited to morning start.

I'm wondering if my vent is too small causing the condensate to be too slow when in the vertical to boiler.

The dry returns are hot.  I would say radiator hot because I hold it longer than I can the hold header.  The condensate returns are cold.

The radiator traps are brand new as well.  There is no hammering.

How do you guys feel about a larger vent?

Joe V_2

photo of one of the original vents

can't remember if it is the one in question or main.

Charlie from wmass

Do they join and drop

or drop and join? before goin back to the boiler? Also did the returns get sized to the load and what does the Hartford loop look like?

Joe V_2

Hi Charlie,

Photos tomorrow. H loop is textbook. On the return loop, the second loop taps in about 3ft back before dropping. The original return to boiler was 1-1/4" and i did not change it.

Guys, I greatly appreciate your thoughts on this. Thank you.

Joe V_2

THIS is the actual original retu

vent. It has been replaced with a gorton # 1

nicholas bonham-carter

blocked return?

did i understand that the returns join up before they drop; or are they dropping down separately to the wet return? my view is that the returns should not be connected above the floor.

that main vent is quite old, and may have earned its retirement. i believe its capacity to be best replaced by a gorton #2, in order to keep the same generous venting.--nbc

Joe V_2

Good thoughts

on having both loops drop but that's original piping and I didn't see a reason to change that portion of it.  Maybe I'll reconider if larger vent fails to correct it.

Here's photos of h-loop and header.

Forgive the sloppy insulation.  It is temporary.  Ran over budget removing asbestos on mains/ returns and replacing with 1" fiberglass.

Joe V_2

Darn

Larger vent did not resolve spitting vent issue.  Will flush returns this week end.  I suppose  something may have dislodged upstream during initial days of operation and hung up in a tee or elbow.  The system has not been used for 15 yrs. and hasn't been maintained prior to when we bought the house.

Joe V_2

The solution

The Problem of spitting condensate vents is finally resolved.  The answer was in TLAOSH all along.  When the programable thermostat wakes up from a temperature setback of more than one degree, the boiler fires, creates steam which pushes out the air through the vents until the steam closes the radiator traps.  With the traps closed, radiators hot and the t-stat not satisfied, the boiler continues to fire and build up pressure.  Because I have a pressuretrol and not a vapor stat, pressure builds up to 1.5-2psi before cutting the burner off.  Until then, the pressure pushes the water in the boiler down into the return line and out the vent.  Thanks for your assist folks.