Wet Steam

PhilKulkarni · January 2

As suggested by @ethicalpaul, I have started this thread to steer the discussion from boiler pipe sizes and carryover to water quality induced wet steam.

Several standards are used to measure wet steam, among them IAPS Industrial Formulation that measures the dryness fraction of steam as a %. The ISO 5167 standard is used to correct steam flow rates by plugging in wetness correction ratios from a pressure table. Then there are inline instruments used to monitor steam dryness, a common one is a mass flow meter for that sets off an alarm when the liquid water content of steam drops below 80%.

I have attached a pic of the water level in the sight glass shortly after my main vents close. It falls another 1/2” towards the end of the heating cycle-typically 20-25mins. I have also shown my pressure reading and my 3” takeoff for my 63-03. I have one pipe steam with two headers.

Sorry but I am presently jet lagged; I will be glad to address any questions I might have missed.

How do I know I have wet steam? When steam reaches the end of my mains, my Bigmouth lets out two puffs of steam,3-5 secs each, before it closes shut. No water droplets fall out, but if I hold a sheet of paper close to this vent, I see several drops of water that are in the form of a mist. At the remotest rads. my #5 Moms will spit out water just before they shut off and a small amount after they shut off, meaning they open intermittently and will spit some water but for the most part remain closed. On my largest rad I have a #C Mom that seldom shuts off because the stat is satisfied before heating entirely, but the vent, not the rad, makes a gurgling sound.

I have a small rad in a bath that makes a gurgling sound which unfortunately has a 1/2” riser. It’s feed valve has a screw, not a knob, but is wide open. It is pitched but has a lot of water condensing in it. I am attributing this to wet steam.

Finally, I should comment about water quality. I drain the boiler to remove the crud because my vents get frequently clogged by rust particles and stop working. I get most of them to work by washing with vinegar but lose 1-2 each season. This is my 4th heating season with this boiler and I have skimmed it 6 times; 2x with washing soda. I had to skim it myself as my installer simply drained it once and added Surgex to it. When I drain the boiler for rust, I don’t see any oil on the rusty water in the pan or in the sight glass. @ethicalpauls video shows that when you have carryover the water level in the sightglass drops. In my case the drop is substantial despite the oversized takeoff.

By method of deduction/ elimination, if the water is leaving the boiler in such copious amounts, with no leaks,

where is it going? Wet steam?

ethicalpaul · January 2

is your water level at the designated mark when your boiler is at rest?

If so, you are experiencing carryover.

“Wet steam” isn’t a thing you can control in a residential boiler because all the steam created is by definition wet steam.

Your main vent behavior is just normal behavior. A small amount of condensed steam will escape just before it closes.

It is pitched but has a lot of water condensing in it. I am attributing this to wet steam.

all radiators condense a lot of water. If you hear gurgling it is due to something like a mid-pitched pipe or a partially closed or bad valve.

mattmia2 · January 3

or a takeoff that is too small or someone trying to use baseboard on 1 pipe steam.

unless your house is 212f+ eventually the steam is going to turn in to water somewhere

if your system is parallel flow, do the returns get hot before the runnounts and mains really start heating?

Eastman · January 3

To reiterate @ethicalpaul 's question slightly modified: does the water level eventually go back to where it was before the cycle? Or are you missing more and more water every cycle due to a leak?

PhilKulkarni · January 5

After draining the boiler to remove rust each month, I have to add 4-5 quarts of water. With each cycle I do lose some water but it only becomes evident after2-3 days of operation. I am estimating that I am drawing down 1+ quarts of rusty water and the rest is water loss from opening and closing of the main and rad vents. I have checked for leaks at the usual places but have yet to find one. During the installation of the boiler three years ago I had the installer check for leaks along the two mains and the wet returns.

I try to keep the boiler level 1” below the factory mark to minimize the carryover. This season, I have one Ventrite that is closed shut and I am using a #4 Mom in its place. I prefer the Ventrites because they have no problem closing with wet steam while the MOMs spit water even at 0.5 PSI when installed on small rads. They are ok on big rads since they seldom have to close.

@mattmia2, I have a combination of counterflow and parallel flow mains. I may not have entirely understood your question, but my wet returns are insulated and stay hot between cycles.

@ethicalpaul, you are right on point with the small rad that makes a gurgling sound. It has the steam inlet about a 1/4 distance from one end with a 4” horizontal runout towards the middle of the boiler. I had it pitched like all other rads, yesterday, however, I made it level to see if the water would drain back faster. I want to observe for a couple of days to see if it does. What is the right way to pitch it?

jesmed1 · January 5

I am not a steam expert, but the question of how much water a steam system should lose has been discussed before. You might find this thread helpful. Although the original question was about 2-pipe systems, some people gave answers about water loss in their 1-pipe systems.

https://forum.heatinghelp.com/discussion/160671/percent-of-water-lost-in-steam-boiler

ethicalpaul · January 5

Don't bother trying to pitch radiators, it doesn't matter. Just have them close to level. If interested, see my experiment where I pitched radiators the wrong way.

Here is the one pipe video, but I also did 2-pipe which you can find:

https://youtu.be/yFvba237kvQ

dabrakeman · January 5

@ethicalpaul I agree from your good experiment that the radiator doesn't have to pitch back to the inlet to avoid hammer, but, if it slightly pitches the other way would you have any concern over long term corrosion at the bottom of the radiator, much like a sag in a return pipe leads to through corrosion over time?

ethicalpaul · January 5

No because regardless of radiator pitch, radiators hold water at the bottom. The radiator castings have low spots at the bottom that are lower than the supply port, and additionally almost all supply ports have a reducing bushing on them resulting in more captured water.

Have you ever had a radiator not spill water out of it when you disconnect it?

dandub1960 · January 8

A couple signs (in my recent experience with new boiler) of surging and carryover besides the dropping level in the sight glass is a very rapid gain in boiler pressure (like an inch of water column every several seconds very early in the cycle, along with vibration in the header. At its worst I could literally see the header oscillating. That is gone now but I often double an old washcloth and but my hand on the reducing elbow of the equalizer to feel for vibration / impacts. What solved this for me has been a combination of skimming and dosing with Hercules boiler cleaner. My skim water is still pretty murky and carrying flecks of pipe dope. I see no oil stain. I think these Teflon dopes seem to cause rough boiling. Not sure why.

ChrisJ · January 8

https://forum.heatinghelp.com/discussion/comment/1880915#Comment_1880915

I agree,

Not only do the sections hold water, many of them are bushed down.

Going by memory here, so don't kill me if I'm wrong, but I think all of my radiators are 1.5" and most are bushed down to 1.25, and the smaller ones are all bushed down to 1". They're all built from the same sections so a 5 section has the same tappings as a 20 section.

Unless the radiator is almost on it's side, it's going to hold water.

Here's one of the many smaller ones that's bushed down to 1". I replaced the riser to it, but the valve is original to that radiator. That's how they've all been since the 1920s.

PhilKulkarni · January 9

Anyone know why my radiator which looks like a Sunrad has a port that has to be piped from the middle rather than from one side? After this post, I have leveled it and it continues to gurgle but heats ok. Not sure why it was bushed down to 1/2”. I found out that until 1976 my house was heated by a central boiler operated by the town and the stats were windows, and I am wondering if that has something to do with a small dia riser.

109A_5 · January 9

" Sunrad has a port that has to be piped from the middle "

Can you post a picture of it ?

BobC · January 10

<y Sunrad has a pipe that comes up in the middle but goes into a 90 - a valve and then into the end section of the sunrad. Maybe the 1/2" is because it was once used on hot water system?

Bob

pedmec · January 10

Does your sunrad has a return pipe? Its not trying to drain thru the 1/2" supply i hope. If you have a supply in the middle do you have returns at either end?

PhilKulkarni · January 10

Here are a couple of pics of the small rad-

@pedmec, I have a one pipe steam and only one port shown with a 1/2” copper connection. All others in the system are black iron 1” except the largest which is 1.25”.

mattmia2 · January 10

is that pipe somewhere where you can repipe it in 1" black? you can maybe make that work if everything is perfect but a lot of things are against you there. i'd set that sunrad dead level because it will hold the least condensate that way. try to give the actual runnout some pitch if you can

109A_5 · January 10

" Anyone know why my radiator which looks like a Sunrad has a port that has to be piped from the middle rather than from one side? "

I'd say they were designed that way to get the most radiator in a confined space (embedded into a wall).

Is the Red arrow below pointing to a cut off abandoned pipe ? Anyway if it works well enough and you can tolerate the gurgle, I'd leave it alone, if not bigger piping and a new valve is needed.

PhilKulkarni · January 10

Don’t know what that pipe is doing there but it is not carrying steam. I will check the rad’s level closely however. Would the copper fittings respond badly if I try to bend them downwards a bit while they are filled with steam? I am thinking about 1/8”, no more.

mattmia2 · January 11

if the pipe will move try to get downward pitch on it. you may have to lift the whole radiator evenly depending on how much pitch is currently on the pipe below the floor

109A_5 · January 11

" Don’t know what that pipe is doing there but it is not carrying steam. "

My point is, maybe it did carry steam at one time and it may be bigger than what is presently there.

I don't think bending the pipe will help much, and you could break something. Depending on how that valve is constructed there may be a bunch of water trapped between the valve and the radiator.

Wet Steam

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