No problem with furnace working 100%
Replace pop up ass gasket . Seal. And leak check.
empty existing water heater. Install 20"pan with drain. To line to pan earthquake straps to code . Sediment gas dip code Bonding clamps code. Gas flu system for water heater. New shut off valve and supply lines. Reconfigure water supply with house shut off valve for hot cold [water heater and washer dryer] Set and secure kitchen sink and replace drain system w/trap Repace both angle stops galve Install shower Cartridge and trim[note::if shower valve is damaged will need to be replaced at 2598$ with new plumbing Install shower head. 2 man job water to be shut off 2 hours minimum dryer vent
Install new Navian 98% afu tankless water heater with built in Recirculation pump. Dispose of old water heater install new tankless as per code To include; new gas flex, new water supply lines, new tankless flush kit, new power surge protector, run new flu and intake start up and test run equipped for propane
Only access is roof we do not do roof vents