See elec water heater pic: http://fast.info/wh in 2br highrise condo. What is tank A for? What is pump B for?

Question

(I am guessing that B is a pump)

Also any opinion on how difficult it would be to replace this heater with a tankless model?

Thanks!

Answer 1

The tank is an expansion tank. It has a rubber bladder with the water on one side and an adjustable air chamber on the other. It is just for expansion of the water while it is heated so pressure doesn't build up when the water is off.
The pump is a hot water recirculation pump. It comes off of the end of the hot water piping run and brings the hot water back to the inlet of the water heater. When running, it keeps hot water circulating so that when you turn a faucet on, the hot water comes out almost immediately instead of letting water run a long time to get hot water.
It shouldn't be hard to replace with a tankless model. Follow all instructions by the manufacturer. Piping should be the same.