I've got an Espar Hydronic 4 that is leaking coolant
at the expansion/overflow tank. The fitting at the bottom of the tank appears to be the culprit (I believe it's just come loose, it's pretty clear that's where the leak is) and I can't find any other evidence of leaking at any point in the system.
I've had a couple people tell me that rather than replacing the existing tank with the same (or sealing the fitting if that's an option) that I should install a "proper" expansion tank.
I don't see much info on this particular tank being used as an expansion tank except as an overflow for a "proper" expansion tank.
What do you think? Is it reasonable to replace this tank with similar, try to seal the fitting, or do I need a metal tank with a pressure safe cap?
[Edit: The pictures aren't oriented correctly but the plastic tank is the tank in question and it's the plastic fitting at the bottom that's leaking at the tank, not the connection to the hose.]