Wet steam

tsayles50

When we moved in I had this problem where very wet steam was coming out of the air vent when the heat was cranking. It resolved after putting a new air vent on. We were away for several days so the heat was lower and it’s cold now so I turned the heat up. This is happening again. When the heat is on consistently this doesn’t happen only when it’s cranked. Also, this is the only radiator where this is happening. We have a one pipe system.

why is this happening and what can I do?

ethicalpaul

All steam gets very wet when it condenses, and that vent shouldn't let any (or very very little) steam out anyway (the vent is supposed to close when steam hits it). Any steam escaping from it is going to condense at or near the exit right where I see that drip in your photo.

That alone is not an indication of the presence of "wet steam" in your system.

I'm not a fan of that vent type, but it might work OK. Have you tried any other vents there like a Gorton or a Maid O Mist or Hoffman? (stay away from big box store vents, they suck)

tsayles50

I haven’t tried any other vent. I got this one because my father in law used them, he’s had steam heat for 20+ years. I replaced some other vents with this kind and haven’t had issues. It’s only a problem when the heat really cranks. Other times they work fine. 

ethicalpaul

What does "really cranks" mean to you? Do you know the high pressure limit of this boiler's pressure control? Residential steam boilers typically have just two modes that are visible to this vent: "Making steam" and "not making steam". There is no "really cranking" mode although pressure can build higher depending on the pressure limit control.

The reason I ask is that it may be that the pressure is too high for that vent to withstand, so it starts to leak steam which you see as drops of condensation. The pressure ideally should be like 1/4 psi or less

tsayles50

Really crank here means - temperature in the house was 65. Long story short we turned it up to 71. During this time when the radiators were going is when steam was coming out of the air vent. 

I know it isn’t the pressure because we keep the pressure at the lowest possible level. 

Maybe there is an issue with the radiator because this is the second air vent where I’ve had this issue.

random12345

One more issue to ask a pro about if/when he comes by. Could be your radiator is tilted down towards the vent end so water has accumulated inside. It should be level or preferably very slightly angled towards the valve. You can use a couple quarters and an air wedge for this purpose if you're careful https://homedepot.com/p/Original-Patented-Winbag-Air-Wedge-and-Leveling-Tool-Lifts-up-to-300-lbs-WB20-SR5-4-40/303979798. Using a level, the bubble should just barely touch the line. We already know your near boiler piping is wrong and main venting inadequate and there's copper steam piping, and as @ethicalpaul suggested pressure may be too high. What's your pressuretrol set to? Why wet steam lowers efficiency: https://www2.tlv.com/steam-info/steam-theory/steam-basics/wet-steam-dry-steam. Varivalve has a high venting capacity, which is not necessarily what you want. Be sure to read this if you haven't already: https://heatinghelp.com/assets/documents/Balancing-Steam-Systems-Using-a-Vent-Capacity-Chart-1.pdf

random12345

Forgot to ask, did you calculate the EDR already? If your boiler is oversized, that could be a contributing factor too.

Dan_NJ

I had something similar in an old bathroom.  In my case the tapping for the vent seemed to be angled down a bit, enough it caused condensate to collect in the vent and similar behavior.  More angle than i was willing to try to fix by propping the radiator up.  My fix was a 1/8" street 90 into the tapping and then mounted a 1/8 straight vent on top of it. I think I added an extension too to raise the vent up an inch or so.  Did the trick with minimal fiddling.

Mad Dog_2

I use Gortons or Hoffman Vents.  Period. Most reliable and well made in my experience.  Mad Dog 🐕 

ethicalpaul

Really crank here means - temperature in the house was 65. Long story short we turned it up to 71. During this time when the radiators were going is when steam was coming out of the air vent.

OK thanks. A better descriptive phrase for that might be "a long call for heat".

So if it's only happening on long calls for heat, then it's when all the air has exited the radiator and steam is hitting your vent. You said above "steam was coming out of the air vent" which means the vent is just plain not doing its job (of closing when steam gets to it). It doesn't get much clearer than that as far as troubleshooting this.

Replace the vent with a better one is my advice. There's nothing wrong with the radiator.

Waher

What's the pressurtrol setting on your boiler? Heat Timer VariValve vents are known to not fully close and if your boiler is running a too high of a pressure to begin with they will vent steam.

Mad Dog_2

I love The Heatimer company and Varivalves, but they  can be very finicky as you said AND if your steam IS too Wet, they will gush condensate like a Delta Faucet.  Mad Dog 🐕 

clammy

I be never meet a varivent that at some point did not behave properly ,I avoid them and have never brought or installed one Groton ,Hoffman that’s about it
Peace and good luck clammy

Mad Dog_2

Me too.  Gorton or Hoffman.   Mad Dog 🐕