I know very little about water heaters and plumbing. Done some minimal work, but never water heater hookup.
I need to replace my 20 year old AO Smith 50 gal gas water heater in a house I've owned for nine years. Water heater is in the basement, all pipes are copper. The hot water outlet pipe at the top of the water goes up a few feet and branches to several pipes supplying water to various areas of the house.
But there is something curious about the way the drain on the water heater is setup.
A plumber giving me a bid noted that the drain outlet on the water heater has a valve, which opens to a two way junction. One side of the junction goes immediately to a standard outdoor hose faucet (seems normal so far). The other side of the junction is a pipe that leads back above the water heater, through the basement wall, and eventually rejoins one branch of the hot water outlet pipe (probably 10-12 feet away), specifically the one going to the kitchen sink.
The plumber, who seems very experienced, was perplexed by this configuration, said he'd never seen it and didn't know why it would be this way, and told me he'd have to undo this when installing the replacement.
There is a 2nd water heater in another part of the basement that isn't quite as old (also gas, 40 gal), and that I eventually would like to decommission. This 2nd water heater appears to have been installed about seven years after the first, but appears to have the same drain configuration, same two-way junction with one side leading to a pipe that travels some distance away and rejoins another hot water outlet pipe.
Somebody obviously went to a lot of work to setup the drains on both water heaters this way.
I'm wondering what function this configuration would serve, whether it is important, and should I ask that it be retained. Thanks!