edr capacity of 1 in angle steam valve

Robertw

Ok so i have a spitting air vent on a steam radiator. Systems clean. 1 inch riser to it on the first floor and the radiator is 30 edr. Burnham heating helper book states 25 edr for a 1 inch riser so i know im over that. But if i remember right Dan mentioned in his lost art of steam heat book that there was an overlap on valve size. Referring a situation where the riser capacity of 1 inch is greater than a 1 inch angle steam valve can handle.

Any one have that capacity number handy? My lost art book isnt with me.

Thanks for any help

ethicalpaul

How much is it spitting?

I often wonder about these spitting situations…I think much of the time it is the vent's fault, where it is allowing steam to pass.

For your valve to be the problem, it would basically be the entire radiator filling with water and I think that would be more water than "spitting", but different people have different ideas of these terms, that's why I ask.

I'd be very shocked if your 1" valve couldn't handle 30 EDR. Everything in steam seems to be 2-4 times conservatively engineered. Which reminds me, is this something you see only when the radiator is fully hot?

Robertw

Starts spitting after roughly half the radiator is hot. Sems like the higher speed of the steam coming in wont allow for counter flow of condensate. I've dropped the air vent size to slow the venting but cant find a happy medium between not enough heat and leaking vent

Steamhead

Check the valve- sometimes the washer disc comes off the stem and blocks the hole, so condensate can't get back down the pipe. You'll need to disconnect the rad and look inside.

ethicalpaul

OK so the vent is not steam hot it sounds like. How much water is exiting the vent?

I can't picture how the incoming steam could be stopping the water from exiting unless you were experiencing the radiator actually filling up with water.

If the bottom third of the radiator were actually full of water from the steam preventing outflow, I would think there would be significant gurgling sounds, etc.

What model vent is spitting? Please don't say Vari-Valve 😅 If that's what you have, I'd say switch to a Gorton or Maid o Mist

Robertw

gordon valves. its banging a bit as well when she spits. spits enough water to be a nuisance until the valve closes completely. Then obviously no heat. The slower valves seem to help get more heat to the radiator but cant find a sweet spot. This is why i went to charts. Unfortunately Dans book isnt with me. I had this issue a few years ago on another job and had to change the 1 inch angle valve to an 1 1/4 valve and use a bushing to the 1 inch riser and it solved the problem. Using the charts in the lost art of steam heat i noticed that a 1 inch angle steam valves edr capacity was lower than the riser's capacity. That's where i think i am now.

I'll dig up the book when i get home i guess and figure it out.

EBEBRATT-Ed

Good luck trying to find valve capacity. I looked up a few valves including Hoffman and Watts and found no sizing information.

I think you had a good idea putting an 1 1/4" valve on with a bushing on the riser.

Robertw

That what fixed it. All good now.

NY2024

In case helpful, I took a photo of the relevant page in the Lost Art of Steam Heating regarding EDR capacity of one-pipe radiator supply valves.

Robertw

@NY2024 Thank you. I couldn't remember the exact number's ,just that it was a possible situation. I appreciate the follow up.

ethicalpaul

What would make a vent "spit" in this scenario? Are we saying the radiator will fill up to water all the way up to the vent?

If not, what is the mechanism by which liquid water is carried to the vent?

NY2024

Not sure what would make the vent "spit" in this scenario, but I'm dealing with a similar scenario. I have a 24 EDR radiator (2 column, 6 sections) on my third floor. This radiator is fed by a one inch riser connected to a one inch radiator supply valve. I have a maid-o-mist size 6 vent on the radiator. Generally, when the steam begins to move past the 4th section of the radiator and into the 5th section, the radiator begins to have water hammer inside the radiator. My assumption of what is causing this is that the one inch supply valve is too small to accommodate both the incoming steam and exiting condensate. This off-season, I am going to try to replace the one-inch supply valve with a one-and-a-quarter inch supply valve (or perhaps just remove the supply valve entirely and run one-inch pipe directly into the radiator).

Robertw

My understanding is that the incoming steam is moving too fast for the condensate to counterflow and drain. Kind of like putting a condensate drain line on the return side of an air handler with out the trap.

Hammering and banging was the symptoms and due to the radiator potentially having large amounts of water in it depending on run time. The air vent was th weakest link and would leak water.. or in my case spit it out like it was under pressure.

I tried slowing the air vent down which helped but then i didn't get enough heat.

ethicalpaul

OK so it could be the radiator is actually filling up with water on a long call for heat. That is the only scenario I can think of that would lead to "spitting"

@NY2024 you might try a slower vent like Robert did—maybe you will get enough heat and avoid the radiator filling up

NY2024

I have the same issue. I can't go below a size 6 vent on that radiator without it getting enough heat. Hoping that swapping the supply valve for a larger size will fix the issue. My guess is that it will, considering the radiator is pitched properly, the boiler water is pretty good, the system operates at very low pressure. I think this is the variable that will fix things.

Steamhead

@NY2024 , check the inside of the valve to see if the disc has come off the stem. This can block the water returning from the radiator, causing the issue you are having. Often you'll hear a rattling noise as well as banging and spitting if this happens.

NY2024

Thanks! Don't hear any rattling or have any spitting. Just the water hammer that happens when the steam starts going from the 4th section into the 5th section.