I have what looks like a sealed tank. There is a valve to shut off incoming water, and outgoing water, with a shrader type valve in between. The tank keeps becoming water logged after about 5 days. I drain the water, and open the shrader valve cap. I can hear the air escape, and I know it is empty. Do I need to add air through the valve even though the tank is sealed? Thanks

I recently bought a three story, 90 year old house. It is heated with hot water radiator heat. The first and second floors have always had heat. Because the third floor is never used the radiators were shut off. I am having work done to improve this area for resale value but because the house is so large it will remain unused while we are here. I added a little water to the system to pick up the PSI some and opened the radiators to see if they work as well to give my work men warmth. All but one gets hot but I know that it is full of air. When my men are through working I don't want to heat this unused space. At night our temperatures have been below 5 degrees. I know that turning off the radiators will stop the heat but do I need to be concerned with pipes freezing and bursting now that they are full of water?