Cross mixing?

thegirlplumber

WE installed a new hot water heater gas side vent in a condo. The heater is in the parking garage in a room with another heater from another condo. Each condo has its own water meter. Changed the heater because it was leaking all over. New heater installed condo is not getting hot water. We have turned every faucet off at each stop including all cold water and still no hot water. WE isolated an oxbox laundry hook up and when this is in the off position we get hot water in one bathroom but not the other bathroom. Kitchen sink will start out hot then spit or like a burp of hot water and then cold within seconds We get enough hot water to fill a bathtub so we know the hot water heater is working as the pipe coming out of heater is hot and remains hot as it delivers a tub full so we have ruled out dip tube. We have changed balancing spools in kohler faucets. Any ideas would be appreciated

JUGHNE

Pictures of piping around water heater might help.

Cross connection at washer or shower/hose might cause this.

H&C connected wrong at water heater?

ratio

Any old gate valves in service? Had a job once, called a week later to say no hot water. Traced it back to the old shutoff valve, the gate had wedged off & pulled free from the stem. There was another valve not too far upstream, so I pulled the top off the failed valve & pulled the gate out!

Zman

Is there a hot water recirc line in play?

Ironman

"A new hot water heater gas side vent"

Are you referring to an instantaneous water heater like a Rinnai? If so, and if there was a tank heater there previously, then that may be your problem.

Instantaneous water heaters have a tremendous pressure drop through their heat exchangers. This may be why you're getting very little or no flow.

If the above scenario is accurate, you could confirm it to be the problem by temporarily connecting the cold to the hot so it bypasses the heater. If the flow is restored, the you have your answer.