i take it you are talking bout expansion tank on a/c this is evaporation and is common on all vehicles if you are talking bout expansion tank on radiator, you have either got to much coolant in radiator,(check level when cold) or you have an air lock in the cooling system and need the system bled to remove air
No, an expansion tank is not required.
sound like cylinder head gasket has blown
to circulate water in fresh water tank to expansion talk.
There shouldn't be just water in the expansion tank. If the coolant (50% anti-freeze and water) appears to be boiling in the expansion tank, you may have a bad head gasket or cracked head.
I believe that the larger the hot water tank, the greater is the need for an expansion tank. Water expands as it is heated. This is why all hydronic heating systems require an expansion tank. A water heater would need expansion tank when a backflow preventer or check valve is installed in domestic cold water line directly after water meter. Some areas require backflow prevention, but not all. Have to check with local plumbing authority about that.
It would not perform properly and would possibly blow it's bladder before long.
To allow for the expansion of heated thot water
expansion tank
Depends on your code. If you have a PRV or, as you would say, pressure reducing valve on your water supply to your house, you need an expansion tank. If your pressure is above 80 psi, you need a PRV AND an expansion tank.
Yes, an expansion tank can be hooked up to a hot water line. This is commonly done in the case of hot water home heating systems.
Its a thermal expansion tank to absorb the pressure when the cold water heats in a hot water tank.
Many hot water heating systems with radiators need an expansion tank to operate efficiently. The fact you are in Concord NH is irrelevant.