Spitting Maid-O-Mist air vent problem

bipbap

We have an air vent on one of the radiators on our one-pipe steam system which is spitting a lot, like a small puddle under the radiator.
It says it is a Maid-o-mist self-adjustable air vent.
Any suggestions?
We have a vaporstat set at MAIN 12oz and a DIFF of 7oz so figured it wasn't a pressure issue but we're new to this.
Thanks for any advice!

Kahooli

They can fail over time (or for any reason at any time). Buy a spare vent and swap it out.

I like the hoffman 1A and the heattimer varivent

nicholas bonham-carter

You should have a low pressure gauge, (Valworx, 0-3 psi), just to keep the vaporstat honest.
Observing the pressure as the air is escaping will show you how effective your main vents are. which may be your problem.--NBC

Fred

Hoffman 1A or Vent-Rite #1 are both very reliable adjustable vents. Many people have a problem with the Heattimer Varivent as they tend to spit water too. Whatever you do, don't buy the cheapo's from Home Depot or Lowes. They are a Chinese knock-off and a waste of time and money. Maid-o- Mist is a good vent also, if you want to replace it with another one.

STEAM DOCTOR

Might not be a vent problem. There may be excess water in the boiler or something might be trapping water in that radiator etc...

bipbap

Thanks for the ideas.
It is on a big radiator in a small room, ground floor almost closest to the boiler.
The vent hasn't been changed in the 10 years or so I've lived there.
I did have a reputable steam guy (from this site) add a number of vents to the basement mains so I can't imagine it's that.
I also have a low pressure gauge 0-3psi so will watch that next time.
I feel like I've addressed most of the other issues,
so can a spitting vent just be a sign the vent needs to be replaced?

MilanD

bipbap said:

I feel like I've addressed most of the other issues,
so can a spitting vent just be a sign the vent needs to be replaced?

Yes it can.

Also, it can hold condensate due to some debris being blown into it over a period of time, so unscrew it, shake it out, blow through it in up-right, then upside down direction and see if it closes when turned upside down. Then reinstall and see if it stops spitting. If not, get a new one.

Just be careful not to cross threads when threading it back into the radiator. Easy to do if not being careful.

bipbap

Ok, I'll give that a shot.
And if it needs to be replaced, any suggested type for that location and size radiator?
I've replaced others with various types of Gortons but not sure if that's the best option.

BobC

Check the radiator with a level to make sure the radiator is sloping back towards the input valve. What size orifice is on that vent?

Usually you vent radiators proportional to their EDR and the surface area of the radiator runouts, small radiators get small vents and large radiators get larger ones but remember don't go overboard. You want to vent the mains fast and the radiators slowly.

One of these will let you play with the orifice size and it's dirt cheap.

https://www.amazon.com/OMIST-0220-5L-Angle-Steam-Valve/dp/B003DV3AGE/ref=sr_1_1?ie=UTF8&qid=1510350956&sr=8-1&keywords=maid+o+mist

Bob