spiting air vent

hi

the air vents on the last radiator at the end of the house is spiting water, i changed the vent but didn't help, so how do i proceed? what would be the next thing to check?

Rod

Vent Water Problems

Hi- What is the make and model of the vent? 

You might also want to make sure that the radiator valve on the steam pipe is fully open. Radiator steam valves should be either fully open or fully closed. Being half open the water leaving and the steam entering the radiator collide, which can cause excess water to get backed up in the radiator.

You might also check the slope of the radiator. A 1 pipe radiator should be slightly sloped towards the steam pipe end of the radiator as this "encourages" the water to flow out of the radiator and back to the boiler. Place small shims under the radiator feet farthest from the steam inlet.

- Rod

nicholas bonham-carter

Venting problems

I would check your main (not rad) vents, and make sure they have a low resistance to the air flowing out of the pipes and boiler, at the start of the firing cycle. A 0-3 psi gauge will show you how adequate the main vents are. Classic Hoffman 40's work well with generous main venting. If your boiler is properly sized for the radiator load, the air can be removed at a pressure of several ounces. The alternative is to pay your fuel supplier to squeeeeeeze the air out of constipated little vents at higher pressures.

If the pressure is too high, and the radiator vents are doing all the work, then the higher air velocities can pick up water and blow it out. Are your radiator vents noisy? If so that is the sound of money being extracted from your wallet!

This makes the heating very uneven as the radiators closest to the boiler heat up first, while those at the end of the line warm up slowly, or not at all.--NBC

hi

re:

the air vent is a Gorton #C

the inlet valve is all the way open and the radiator is sloped properly and its STILL spiting!

BobC

It's a matter of balance

For best performance venting the radiators slowly and the mains fast usually works best. Is the piping in the cellar insulated and is it all sloped back top the boiler? If there is a long length of main and runout feeding that last radiator there will be a lot of condensate so slope and insulation might be the key. Don't trust your eyes, put a level on it.



You said the problem radiator is a Gorton C, what kinds of vents are on the other radiators and what kind of main vent do you have?



Bob

STEAM DOCTOR

Spitting

Good morning. In my experiance air vents never spit water due to defects in the air vent. The air vent is not designed to hold back water. It is designed to let out air and hold in steam. In my experience, spitting air vents are almost always caused by too much water in the steam system. The last radiator in the house often ends up as the unfortunate victim because the steam carries the water down the main pipes until the water has nowhere else to go. The water then gets carried up to the radiator and out the poor air vent(who then gets blamed for something that isn't his fault).

The real question is, why is there too much water in your system? There are a lot of possibilities. If this is a fairly new problem I would say that dirty boiler water is the likely culprit. A sag in the main pipe or a clogged wet return pipe or a clogged main vent might also be the culprits. Its also possible that the the pressure is too high or that the near boiler piping was installed incorrectly.

What is the history? When did the problem start? Where there any changes made(moved radiators,new boiler etc)?

hi

RE:

the vents on the radiators are mostly gorton c or d

the main vent is american standard "FAVORITE NO. 528" (looks really old!)

BobC

Large vents

Gorton C's and D's are large vents and they are much larger than most radiators need, the D vent could act as a main vent on a small steam main. I have no idea what the capacity of your old main vent is. If you can tell us the length and size of your steam mains we can tell you what size main vent you should have. Once you have the right main vent you can then use smaller radiator vents so everything heats evenly.



As bn said spitting is a sign of improper system setup, high pressure - dirty boiler water -bad near boiler piping - bad pipe slope - etc.



Bob

hi

RE:

the main is 2 inch and its about 50 feet long,



there is a second main thats small (about 15 ft. long) that doesn't have a vent at all is that a problem? (i don't recall having major issues with those radiators but I'm new to this house and I'm finishing the basement, so if it needs to be corrected i would want to take care of it now, not find out later!!)

BobC

The answer is

The 50 ft main has about 1.1 cu ft of air in it and would need a Gorton #2 vent, the 15 ft main has about 0.33 cu ft of air in it, a Gorton #1 would be fine for that -how many radiators feed off the 15 ft main?



Bob

hi

RE:

there are 2 radiators on the first floor and the 2 on the second floor running from this main, they are 38" column radiators 2 have 5 sections and 2 have 6.

how would i put an air vent without repiping the whole main??

BobC

Couple of ways

You could have someone drill and tap a 1/2" hole in the side of the pipe or a fitting at the end of the main and add an elbow and a nipple to mount the vent on. Air vents should be as far above the main as practical. make sure that main has some slope back to the boiler unless it has a drip at it's end.



Another way would be to mount a Gorton D vent at the input pipe or valve of a radiator on that run and then use a very small vent on the radiator itself (Gorton #4).



Is this the main with the spitting radiator?



Bob

hi

THANKS!

this is not the main i was talking about, however this part of the home was not occupied last season (and i bought the house before this past winter), so i don't know if it was ok or not.

Thanks a lot for all your help.

BobC

happy to help

I'm just passing along what I've learned over the years. One you get the kinks out of that system you should have even, comfortable and economical heat. Steam can be quite economical and you don't have to worry about frozen heating pipes during power outages that last a week or less.



I live in a 90 year old 1,100 sq ft 2 story house a block from the ocean just south of Boston, I have insulation in the attic and good windows. Last year I burned 539 therms of gas (equiv to 385 gallons of oil) and it was not a mild winter.



Bob

hi

near boiler piping

i just took a look at my boiler piping and it doesn't match the manufacturers directions.

the boiler is a Burnham independence model no. IN7 that calls for two 2" risers from the boiler and then 3" header,

i have only one 2" riser (the second is plugged) and the header and main are all 2", is that a problem?

hi

near boiler piping

here are some photos

STEAM DOCTOR

YES

The near boiler problem is definitely a contributing factor. Undersized near boiler piping will result in excess water being carried into the system. Some of that water may end up squirting out of the air vents.

STEAM DOCTOR

Steam speed

The near boiler piping SHOULD be designed to slow down the rate at which the steam exits the boiler. The faster the steam exits the boiler the more water it will carry out. Back in the old days, boilers were designed so that the steam would exit at a rate of approx 15 feet per second. With your current setup the steam is exiting at 57 feet per second at 0 psi. The bigger the pipes are, the slower the steam will exit.

BobC

That's a problem

That near boiler piping is not correct, having it fixed would probably make everything happier but it could be expensive to have someone do that for you, how old is the boiler? If it's in good shape you could get some quotes on piping it correctly and adding a skim port if you don't have one.



The name plate indicates that boiler will supply 545 sq ft of radiation, do you have anything like that much radiation attached? I remember you saying some of your radiators were 38" high, it turns out almost all of mine are the same. If those are 3 column radiators then a 38" high section is 5 sq feet so a 6 section radiator has 30 sq ft.



If it is too big for the job there is not a lot you can do to correct that but I lived with a grossly oversized boiler (596 sq ft vs 200 sq ft of radiation) for 16 years and by correcting a lot of the other system problems it became a reasonably efficient steam system.



Bob