What is water heaterin construction?

It depends on the demand profile, and the estimator's job is to price what the schedule shows. Tankless banks suit steady or peaky demand without dedicating floor space to storage, while tank and storage systems handle large simultaneous draws like gang showers. Swapping one for the other is an engineering decision, not a bid-day substitution, because venting, gas pipe size, and electrical loads all change with the swap.

Plumbing codes generally require a pan with an indirect drain wherever a leaking heater would damage the building, which in practice covers most heaters above slab or in finished areas. The pan drains to a floor sink or other approved receptor through an indirect connection. The pan itself is cheap; the drain routing is the cost, especially when the nearest receptor is rooms away. Condensing units add a separate condensate drain with a neutralizer for the acidic discharge.

The plumber sets the heater and runs the water, vent, and drain connections. Gas piping is usually the plumber or a mechanical sub depending on local practice, and the electrician provides the circuit, disconnect, and controls power even on gas units. Flue routing can pull in sheet metal for shaft work. Buyout tip: make sure exactly one sub carries the flue and one carries final connections, because heater closets are a classic scope gap.