I have switched to using a ductless heat pump for heating and am planning on removing my gas boiler but leaving the hot water baseboard radiators and 65-year-old galvanized pipes (in the crawlspace).
I am wondering if it makes any sense to leave water in the pipes before capping them off. There is no risk of freezing since the crawlspace walls are insulated.
It seems like it would be difficult to purge all the water out (using compressed air?). I'm afraid that any remaining water might rust and cause a leak if the pipes are used again someday. My understanding is that the existing water has already used up all its oxygen and won't cause any more corrosion.