The venting arrangement matters
A conventional atmospheric gas water heater and a power-vent model remove combustion gases differently. A power-vent unit uses a powered blower; a conventional atmospheric model relies on natural draft through its approved venting arrangement. They are not interchangeable just because the tanks hold a similar amount of water.
What needs to be assessed
An installer should review the existing vent route, other appliances sharing a vent, available combustion air, clearances and access. Electrical supply can also be part of a power-vent installation. Replacing a furnace or water heater may affect equipment left connected to an existing chimney. Do not alter a vent or reconnect a replacement tank yourself.
Compare the right price
Comfort Nest lists starting prices for CV40, CV50 and PV50 options on the hot-water page. The final scope depends on the installation conditions and the equipment selected. Ask what removal, connections and any venting changes include. Have the current model and photos ready, and describe whether you run out of hot water or are replacing a failing tank. If you smell gas or a CO alarm sounds, leave the building and contact emergency assistance from outside.