We have dual water heaters (parallel) in the basement with a separate hot water return line and a recirculation pump. When the pump is on, there is instant hot water and everything works fine. When the pump is off, there is an acceptable delay of 30-60 seconds on most faucets in the morning. The kitchen faucet and two other faucets, however, can take upwards of 7 minutes to get hot water. This can happen both in the morning and also later in the day.

We looked for a malfunctioning check valve or cross-connection, but my plumber states everything is working fine. He said to just keep the pump on as the kitchen and other slow faucets may just be at the end of the return loop.

He may be right, but I don't understand why almost all the other faucets would get hot water in under a minute, and the others (one upstairs, one in kitchen and one in the basement) all take such an exceptionally long period of time to get hot. I don't have a problem with having the pump on (there is a timer), but I just want to make sure that the pump isn't covering up some other problem.

Anything else we can check?