vent filling with water?

ChrisJ

Early on when I first fired up the system with the new boiler I kept running out of steam.  I had radiators that refused to get hot some times.



Now after insulating my header and 80% of my mains as well as adjusting vents on certian radiators to keep rooms for overheating like my bedroom which I like cold,  another problem has showed up.



I have a radiator which is first on the line and also on my short main which loves to take steam first which keeps getting water in its vent and then it stops working for obvious reasons.



The radiator is 11 sections and 28sqft of EDR.  I have had the Hoffman 1A on it wide open at #6.  Originally it was pitched wrong so I corrected that but yet again over time the vent filled with water.

This is the only rad I have had this problem with.  is this to be expected from a rad so close to the boiler venting at this speed?  Most of my other radiators are also set to #6 and seem to work flawlessly, at least so far.

BobC

Try turning it down

A radiator that is the first on the line can get steam quicker than those down the line but usually the vent rate is throttled back to let all the radiators have steam available at the same time. Then you can adjust vent rates up or down so everything heats at about the same rate. What pressure is the boiler running at and what kind of main air vent are you using? Pressure should be kept below 2PSI and preferably below 1PSI.



Was that new boiler sized so it would match the EDR (all the connected radiators)? Boilers should match the load they are driving. Was the boiler skimmed after it was installed? Is the water bouncing up and down in the sight glass, and if so how much?



The 1A will vent at about 0.15cfm at 1 oz of pressure, try turning that down to 1 or 2 and see if that helps. That will slow the venting down but you really want to vent the mains fast and the radiators slowly.



Bob

ChrisJ

EDR

I sized the boiler to the EDR of the system.



Main vents are 3 Gorton 1s on a 29' main and one Gorton 1 on a 11' main. I have the system set to cutout at around 1psi and back in at around 0.5psi I have yet to see more then 0.5PSI in the system even when bringing the house up 5 degrees. I am using the typical 3psi WIKA gauge.



I am still in the process of insulating pipes, however I have most of the mains insulated finally.



I have skimmed twice, water line currently moves around 1/4" when boiling.

BobC

All sounds good

All of that sounds just like it should. 1/4" is normal in the sight glass, if it's less I always wonder if the pigtail is ok.



Are all the other radiators set for the same venting? Try turning the vent rate on that problem radiator down and see if it stops misbehaving AND if it still heats up ok.



Bob

ChrisJ

Yep

Most of the radiators are set on #6 except for 3 large ones which either are in my bedroom or effect the thermostat.



Though I can say for sure none of them get steam as fast as the problem one. The reason I had the problem one cranked all the way up was just to keep that area biased towards the warmer side. I have the valve on #4 right now which I carefully set. I'll report back with what happens over time.

malex

Could it be

sludge in the radiator preventing the condensate to drain fully and making the vent fill? We all have that one radiator that for some reason won't cooperate. Mine is in the master bedroom and starts acting up at 6am every morning.



11 sections is heavy so Im wondering if there is an easier way to completely drain it than turning it on its head. Just bought a 8 section from a poor woman who lost her boiler to Irene and is now converting to electric (my gain). I was turning it every which way to get it into the car but it wasn't until I got how and stood it on the inlet that about a quart of rust water came out. And now I have a red garage floor.

ChrisJ

clog

Don't know, I suppose anything is possible.



11 sections is a light weight in this house. I have four like this. 53sqft. Ah, the bold look of Kohler.

ChrisJ

This radiator must hate me.

I'm still having the same problem.



This radiator and another radiator are giving me problems with the Hoffman 1A getting water in them.  I'm suspcious that both of them ran fine for days and then suddenly ruduced output and finally none.

I have tried several vents, all new from the box and have seen the same results.

Now both of these radiators may have one thing in common.  One of them is in my downstairs bathroom and I have not insulted the pipe going to it which passes through a cold crawl space.

The one pictured above which is the repeat offender is the only one in the house to have its pipe pass through a wall.  I do not know if this pipe was insulated prior to the wall being sheetrocked around it but I'm willing to bet it wasnt.

If wet steam is indeed causing this I don't understand why.

Why would wet steam have any effect on the vents? Shouldn't it simply bleed into the radiators condensing back into water and draining out just as dry steam would?  Both radiators have plenty of pitch on them and both heat silently and fast until the vent gets water in it.

I'm planning on changing the one at the top of the stairs to a Gorton vent as well as insulting the pipe to the downstairs bathroom, but I want to understand whats going on and I really don't.



Any ideas?

crash2009

Hot water valves?

Can we see a closeup of the shut-off valve?  Maybe you could find a model number on the valve.  Is it possible, that, at one time, the radiators may have been used for a hot water system?  Maybe the valve is not big enough to drain the condensate and allow steam at the same time. 

ChrisJ

Impossible

Theres no way this system was ever hot water.



The radiator uses a 1" pipe from the basement to the second floor which goes down into an 1 1/4" runout to the steam main. A few of my radiators are piped this way and all fall into spec according to TLAOSH.



This doesn't mean the valve isn't wrong. I'll try to get a model number off of it. At the same time though, there is no way this radiator is filling with water. Like I said until the vent gets plugged with water the radiator heats great and is silent.



If it was filling with water even a little bit I'm sure it would let me and maybe even my neighbors know about it.

JStar

RE

Can we see pictures of where the radiator is piped off of the main?





And here's a thought outside of the box...



The radiator is on the edge of the stairs, right? Maybe the natural air currents in the stairwell are cooling the air-vent side of the radiator faster than the other side, causing the steam to condense unevenly. And since the air vent is thinner metal than the radiator, the condensate will form there first.

crash2009

Air vents wont drain

I wasn't suggesting that your system might have been hot water in the past.  I was suggesting that you check the valves to eliminate them as a possibility.   My biggest rad is 55, and it has a huge old pot-bellied valve on it.  I can imagine pounds of steam and gallons of condensate flowing through the valve at the same time in two different directions, without making a sound 

This thread from 2010 suggests you are not alone with this problem.  Suggestions to possible solutions range from adjusting the gas pressure to changing the vents, and everything in between.  http://www.heatinghelp.com/forum-thread/132200/Steam-Radiator-Air-Vents-Wont-Drain 

More than likely, your water is just dirty and causing wet steam.  It takes a long time to get it clean.  Have you figured out what to look for when you boil your boiler water on the kitchen stove? 

Secondly, velocity.  Both Kings wide open?  Mains vented fast?

Mark N

Vent

Have you tried this vent on a different rad. If the problem moves with the vent then the vent is the problem. Make sure the rad is tapped straight. If it isn't when you thread in the vent it might cause it to be pitched back toward the vent.

ChrisJ

vents and pictures

I have not tried the two vents on different radiators but at this point cannot see any reason it would change. 



Here are two pictures showing how the radiator is piped to the main.  These are old pictures which were taken while I was doing all of the work though this piping has been left unchanged.  It isn't piped the greatest, though it has some pitch on the runout its not much.

Sorry I can't get new pictures right now as I can't read our new 4GB SD card.  Didn't realize I needed a new reader when we bought it last week.

ChrisJ

water and valves

Hi Crash,



Both king valves are wide open and the boiler water seems relivly clean with little surging while running.

This radiator is on the main I am currently venting slow with a Hoffman 4A.  The problem was happenign before I switched from a Gorton 1 though.  I did this to keep this main from stealing all of the steam.

Dave in QCA

Vent is probably the problem

I was getting ready to comment, then saw the new post by Mark N and he is thinking along my train of thought.



I'll add some additional thoughts as to why.   You have determined that the radiator itself is not becoming water logged, so the condensation and/or water from wet steam, if it were present, is all draining out of the radiator.  We all know that even dry steam condenses to form water, and that is exactly what normally happens inside of a steam air vent if the steam is up long enough to cause full heating of the radiator and closing of the air vent by presence of steam.  However, the steam that condenses inside the vent has to be able to drain out and the close tolerances inside the vent tend to cause capillary effect, which interferes with good drainage.  That is why most vents, including this model, have a tongue sticking out of it.  The purpose is to provide a channel that draws the water out of the vent in a separate pathway from the steam going in. 



There are some conditions that could interfere with the proper drainage of the vent.

The tongue could be bent, mangled, or cut off. (I have seen it). 

The boss area of the radiator, and/or the thickness of the casting could be such that the tongue is not in the clear inside the radiator. 

The threaded 1/8" hole in the radiator could be partially obstructed with rust and corrosion. 

Teflon tape could be partially obstructing the area that is supposed to open and clear. 

The threads in the radiator could be corroded or fouled to such a degree that the vent will not thread in far enough for the tongue to be hanging in the clear.

If I were you, I would inspect all of these possibilities.  I am confident that the issue rests with improper drainage out of the vent... for some reason that is unknown at this point.



Make sure you let us know how this turns out.

Good luck with it, Dave

Mark N

I had the same problem

Chris



I had the same problem a few years back. The 2 smallest rads in my house would do the same thing. They both had Maid o Mist vents. Replaced them with Gortons and haven't had the problem since.

Long Beach Ed

Slow it Down

I know I'll get beat up on this, but water spitting out of the vents is only caused by water failing to drain from the radiator.  This can be caused two ways -- insufficient pipe sizing or too much velocity.  



Since this radiator is very close to the boiler and you say the pip sizing is correct, I believe velocity is your problem. 



When you vent a main quickly the steam velocity is very high.  That's good until the steam hits a radiator full of water that's trying to drain.  The velocity of entering steam obstructs the drainage of condensate.  The result is a spitting vent.  



Reduce the venting rate of that main and your problem will go away.  Sometimes it's a tradeoff:  Instant venting mains with spitting

radiators or quiet radiators that take an extra couple of minutes to

heat.  









We see this all the time when people attempt to vent mains quickly.  

ChrisJ

main vent

Ed,



You want me to reduce it from a Hoffman 4A to something even slower?

Mark N

Main Piping

Chris



You have 2 mains, and that rad is on the short main. I have a friend whose system has a short main also. His is counterflow, is yours? If it is maybe that would account for the problem. Counterflow should be 1 pipe size larger.

ChrisJ

nope

Both mains are parallel flow.



I turned the Hoffman 1A way down to #1 which the cap on this one is made like garbage so its more like #2 on the other vents. Either way its venting much slower so I guess time will tell.

Dave in QCA

REATRACTED

my post on this thread, which I have now deleted was in answer to another thread entirely.

I stand by my previous posts.

Mark N

Run-Out

I gave the picture a better look I see that the run-out to this rad comes off the side of the main, not at a 45 or 90 degrees. I don't know could be part of the problem. Hopefully slowing the venting down will help.

crash2009

Red Marker?

Yea, I took a better look at the pictures too.  Looks like you found the problem.  Question is how are you going to fix it.  You got no room, unless you start hacking up the joist.  This pic I just sent back, with your red marker on it, Is this the take-off to the rad at the top of the stair? 



If it is, I think the steam is driving the condensate right up into the rad and the vent.  It is unable to drain before the next cycle. 

ChrisJ

yep

Thats the one.



My question is wouldn't this cause really bad water hammer if it were true?

crash2009

Your answer

 is on page 87.  Hope you didn't put the tools away yet.

ChrisJ

pitch

Crash if you look closely at this picture you will notice the runout does not come off completely horizontal. There is a little pitch to it.



I realize its not perfect, but there is no easy way to fix it.

crash2009

I don't know Chris

1.   Thats just how it looks to me.  Maybe someone can suggest another way to wiggle out of it.