questions on expansion tank

[hardyst]

I'm having trouble heating the 2nd floor when the temp drops down below 25 degrees. I'm thinking there is air in the 2nd floor zone. When the zone starts, I hear gurgling and the radiators just don't get hot, only warm. I've never had baseboard so I don't know what's normal. I just have a couple of questions.

I have 4 year old Burnham system. It has three zones, 1st floor, 2nd, and SuperStore hot water tank. I have and Extrol #30 expansion tank with a Taco Hy-Vent on connected in the pipe above the tank. Should the screw cap valve on top the the Hy-Vent be open a little or screwed closed? If open will I ever hear air released? How do I know it's working and the expansion tank is functional? How do I check to see if the expansion tank needs to be replaced? Can a failed expansion tank affect the heat output in a zone?

Pressure in the furnace itself seems to be okay, between 10 and 12 psi. The other 2 zones work fine. 2nd floor is new baseboard closed loop. 1st floor is older cast iron baseboard with valves on each radiator for bleeding.

I'm trying to figure it out myself since I don't know anyone in the business.

Thanks

[Ed Imeduc]

For two floors the boiler should have like 15 to 18 psi to get the water up there . With the pump off bleed the top bleeder till you get water.
A bad expansion tank will have the psi go wild and pop off the PRV.


ED ;)

[hardyst]

Hi Ed,

Thanks for the reply. I apologize for my ignorance, but I need some clarification. I'm guessing when you say "turn off the pump", you mean the circulator pump, but I'm not sure what valve you need me to bleed. The one on the Hy-Vent? It is already open? If you could please clarify, it will be appreciated.

Thank you sir,