Automatic air bleed, but how?

Stillkickin

How does my Maid-O-Mist automatic Auto Vent system work? It has a valve core like a car tire. How is any air going to be expelled past that? Wondered for years. Thanks

mattmia2

there is a float attached to that needle and seat. if the can gets enough air in it the float falls enough to open the needle.

mattmia2

caleffi and a few others have literature with cutaways

hot_rod

commonly called a float vent

It is into to ho on a high point in the system, or screw into an air purger

Larry Weingarten

Hi, Vents like this one are designed so they can be disassembled and cleaned if needed. 😉

https://www.supplyhouse.com/Amtrol-701-30-1-4-MPS-Float-Air-Vent?utm_adgroupid=1239150722961757&utm_targetid=pla-4581046494508461&utm_product_id=701-30&utm_matchtype=e&utm_adtype=&utm_adgroup=Hydronic%20System%20Components_X_X_X&utm_searchquery=repairable%20float%20vent&utm_category=Heating

Yours, Larry

hot_rod

Most brands have a screw top to allow cleaning or replace the cap and valve.

EdTheHeaterMan

The part of the vent that looks like a Schreader valve is not actually a Schreader valve.  They are not spring loaded to self close like you would find on a tire or a refrigeration system gauge port.  The valve actually closes by means of a float mechanism that replaces the spring’s function of the Schreader valve.   When the float is high the valve is closed.  When the float drops, the valve is opened and will allow air in the can to be released.  Once the air is released, the float will rise and close the valve.  

The part in the center of the valve, that you might want to depress will manually force the valve open against the pressure of the float mechanism (just like you would let air out of a tire), but doing that will often cause the float mechanism to fail since the water ends up higher that the design of the valve normally allows.  Do not check the valve by pushing the center of the valve down until you get water out of the vent. Do that too many times and you will have a defective vent in short order.    

HydronicMike

Put a mini ball valve on it to make cleaning and change outs easy. I’ve only used Caleffi ones for the last 5 years. Better built/made and able to clean repair. The one you have pictured, to me, is a throw away item.