Long wait for hot water

[dwsir]

Please help me to solve this puzzle. I had a Rheem gas water heater with a recirculating system for quick hot water. I never ran recirculating, as just by leaving the shutoff valves in the recirculating loop open, I started getting hot water coming out of the shower heads upstairs in about 15 seconds. (Interestingly, when I closed the shutoff valves, it took longer to get the hot water to arrive.) After 10+ years, I had to replace the old Rheem with a new Rheem bought from Home Depot. The plumber did the replacement, but now running the same way as before, it took over two and a half minutes for the water to get warm. We just couldn't figure out why.
An observation: I ran the recirculating pump, the water did get hot after a minute and a half, which is too long. Also, after recirculating a while, the piping between the pump and the heater felt warm, but that on the other side of the pump remained cold – perhaps this is an indication of the problem?

 

[Sylvan]

The newer heaters have an aquastat lower set temperature lower then the older hears because of the Mc Donalds scalding case. Also you mave have to check the impeller of the recirculation pump as they can become ineffective with mineral deposits or the impeller could be warn out in some cases with the palstioc types

 

[Sponsor]

 

[Jadnashua]

It sounds like your old system was able to work by plain convection. It does not take much of a change to then cause that convection loop to stop working. If the plumber moved the checkvalve, it may not be closing properly, and when that happens, and you open a hot valve, it can suck water through both the top (hot) and the bottom (cold, eventually), you'd end up with warm verses hot.

 

[dwsir]

Thanks to Sylvan and jadnashua. Jadnashua, the plumber only cut the recirculating piping in one place and reconnected it again, so I don't think he touched the valve directly. I would check with him.

 

[Gary Swart]

I had a somewhat similar problem with my recir system. Still had hot water quickly, but not as quickly before. Changed pump innards and that fixed the problem. I run my system 24/7, had done so for about 8 years so not such a surprise to need a new pump.