Customer had carbon monoxide alarm go off. Fire department came out and turned gas off to the home thinking it was the tankless water heater Tankless water heater was installed years ago. Exhaust for tankless does not have adequate clearance from openings including crawlspace vents and windows. Due to model of tankless and age, recommendation is for replacement with a Navien tankless water heater that uses separate pipes for exhaust and air intake instead of concentric like the current tankless water heater While in crawlspace, discovered that the vent for the furnace exhaust is completely rusted out and detached. Exhaust from the furnace is discharging directly into the crawlspace. Customer needs hvac out to address this serious issue. Also noticed condensate pump for AC is not working as well. Left estimate but can be addressed when venting for furnace is addressed Left estimate tankless replacement as well as installing a water conditioner for the cold water supply to the tank