I'm sorry to make my first post a request for help, but I hope someone can take pity on a slightly overwhelmed first-time homeowner.
I have an Amtrol Extrol 2 gallon expansion tank for my gas furnace. It is connected to (or in series with, if it were an electrical diagram) both a valve that turns water to the tank on and off, and something called a quick-fill knob.
My question is about that knob. After bleeding the radiators (a necessity it seems after having someone replace the flame sensor), I opened the valve and turned the quick-fill knob to 'open' to increase the water pressure back to 12psi or so. But now I'm not sure if that quick-fill knob, which doesn't start water flowing into the tank on its own, should be turned to open or closed after reaching normal pressure. I can't remember if I actually turned it to 'open', or it was like that already. I ask because the water pressure got very high last night after the flame sensor was replaced, to the point where the pressure relief valve was needed (30+ psi).
So, should that knob be turned to open or closed? Is this even relevant in light of the pressure increase?