What is this thing on my furnace, and what does it do?

[daveswoodhauler]

Ok, here are a few pics.

I have been working more and more in my basement lately, and just not sure if I have never noticed this.

(Its an oil furnace with forced hot water)

I am guessing it is some sort of pressure valve, but I am not sure if there is supposed to be a small amount of water coming from it?

Basically, there was a little brownish stuff on the top of the valve, so I just wiped some of it off with a rag, and it seems like a little chunk of gook came out, and a steady flow of water. (The stuff around the top was sort of brownish/tan and flakey....guessing sediment as we have well water)

Should this little valve on top be open a little? A little water leaking out normal?
It seems like it should be open a small amount, but if I close (screw) it all the way down, I still get some water coming out. (I left it open a smidge)

Anything to worry about, or normal?

(The water isn't gushing out, just like a drip/drip, but when the top fills up with water it leaks down the side into the furnace)

 

[colebrookman]

Looks like the vent to bleed air from the system automatically. No problem unless it really starts leaking amounts of water. Sometimes it gets gummed up from minerals and needs cleaning.
Ed

 

[MikeP]

Its an air bleed valve. Ideally that style automatically bleeds the air, there is a float inside, when air from the system rises into the valve, the float settles a little releasing the air. Water replaces the air and the float rises back up. Since its leaking, probably a good idea to replace it. You can put another auto one on, or you could just put a manual bleeder, like on heat registers, just have to remember to bleed it on occasion.

 

[daveswoodhauler]

Thanks guys...so I took off the liitle valve on top (not the entire unit...just the bleed valve) and cleaned it out. Put it back down all the way, and it was still leaking a small amount of water....so I put a little teflon tape and it sees to just drip a small amount now.
I have a furnce cleaning coming up in Feburary, should I just have it replaced then? or replace sooner?
I am guessing that the seal of the float is probably corroded, so there is a small amount of water coming out?

 

[colebrookman]

It's a toss up. I'd keep an eye on it and maybe move up the cleaning. I'd also follow MikeP's advice and replace it with a simple manual bleeder if possible. Be safe.
Ed

 

[jharkin]

If you do decide to replace it those vents are not expensive and its simple to replace (thread off/thread on with power off to make sure any auto water feed doesn't trip). Get one at any local plumbing supplyor an online dealer like pex or state supply.

All you need to check is the thread size. Cant tell exactly from your pic but it looks like its maybe a 1/4 NPT ?
http://www.pexsupply.com/Taco-426-2-1-4-Hy-Vent-4552000-p


BTW, cant resist but to point out that is a boiler, not a furnace (flame suit on)

Good luck,
Jeremy

 

[ROBERT F]

auto air ti water seperator, just replaced one on my boiler at start up in oct. 7 bucks from the propane dealer. 3 minute repair. if its the valve leaking, just screw the cap down all the way till it seals, an you just created a manual bleeder untill you can replace it.

 

[Gooserider]

Agreed with all the above - Essentially think of it as working like the float valve in a carb, except it lets air out, rather than allowing gas in... It should not be leaking water, but the things get old...

Since this is a boiler topic, moving it to the boiler room...

Gooserider

 

[ohbie1]

If you take the little cap off, you will find a Schrader type valve like the one in a tire valve. If you take a small diameter Phillips screwdriver or bolt, you can push the middle of the valve down (just a quick poke or three). Small squirts of water will come out, and sometimes this clears out whatever is unseating the valve and making it leak. Of course if it has deteriorated this will not work.

 

[daveswoodhauler]

Thanks folks. I cranked it down all the way now so it does not leak.
How often should I bleed the valve to let the air out? daily/weekly? (Just had the furnace tech out a few weeks ago, so I am going to have it replaced with my cleaning scheduled in a month or so.
I have been going down on a day for a quick turn and I hear about a half second of air come out, then a little water.
THanks.

 

[jharkin]

Thanks folks. I cranked it down all the way now so it does not leak.
How often should I bleed the valve to let the air out? daily/weekly? (Just had the furnace tech out a few weeks ago, so I am going to have it replaced with my cleaning scheduled in a month or so.
I have been going down on a day for a quick turn and I hear about a half second of air come out, then a little water.
THanks.

A heating tech would know better, but once all the air is out of it once, you shouldn't ever need to bleed it I think? Unless there is a leak somewhere...

 

[Tony H]

I would bleed it every few days until I no longer hear any air escape then once every week or two until you get it replaced.

 

[Fred61]

It appears that you have no way of isolating the air eliminator so you will have to draw down the water in order to change it. When the tech changes it, be sure to have him install a small ball valve between the boiler and the eliminator. from the photo, it appears that you have a 1/4 to 1/8 inch coupling. These components are typically 1/8 inch. These things fail more often than many components on your system so a valve to isolate it is IMHO a good investment. You will have air to release after you install a new part and refill the boiler more or less, depending on how much water you need to draw down to remove and replace the component.