[Nevinator]

I recently moved to The Villages and my home has a Rheem tankless hot water heater. When running one bathroom faucet and the shower at the same time (with the little O-ring in the shower head removed) it takes 1 minute and 16 seconds to get hot water to the shower. Due to the length of time that it takes to get hot water to the master bath I installed a Watts premier water recirculation pump.

I previously installed the same pump on the water heater at my previous residence with no issues whatsoever. The only difference being that my previous residence had a standard type water heater as opposed to the tankless water heater used in my new home

After installing the pump and setting the timer, the hot water heater would not turn on and displayed a “P1“ error code, which indicates that there was not enough water flow being generated from the pump to the hot water heater in order to get it to turn on.

I’m reasonably certain that some other people have installed water recirculation pumps on tankless hot water heaters and was wondering if anyone else has experienced the same error code after doing so? What did you do to correct the situation?


UPDATED 5/1/24 @ 9:57 a.m.
I contacted Mike Scott Plumbing in Wildwood and inquired about having them install a water recirculation pump for a tankless water heater. They informed me that they only provide this service for the standard hot water tank installations - not tankless hot water heaters.

I next contacted RHEEM and described this issue I was experiencing. The support person I spoke with provided me with some documentation on a TACO recirculation unit, however, the installation process was quite a bit more detailed than the solution I initially installed. I inquired about other possible solutions from other manufacturers but the only one they could discuss with any certainty was TACO system.

I guess my updated question to the forum is this: Has anyone on this Forum who has a RHEEM tankless water heater installed a water recirculation pump? If so, what brand/model did you use?

Thank you.

UPDATE 5/2/24

After a lot of research I found a solution that works. Another call to Tech Support at RHEEM and I explained the complications involved in installing a dedicated return line and my preference to use a bridge valve. The person I spoke with told me that the specs on the RHEEM tankless heater model that I have requires a minimum of a 5 GPM flow rate and a 25 Head. She explained that as long as I had a way of turning the pump off when the water was heated, that any pump with those specs should work.

I found a pump on Amazon made by BACO Engineering (unfortunately made in China) that has a 20 head and up to 13 GPM flow rate. Since the terrain here is fairly flat and I have a one-story home my hope was that the 20 head would provide an adequate lift to maintain pressure throughout the system to the bridge valve. The pump is equipped with a flow meter that automatically turns off the pump once the water passing through the bridge valve reaches 95 degrees and causes the bridge valve to close.

There were a few minor issues experienced while installing the pump since the pump is chinese and the thread on the male end of the pump inlet didn't seal well on the NPT fitting, but that was resolved with a lot of teflon pipe tape.

The pump tested well and is now equipped with an Alexa plug that has a routine set to turn the pump on/off at designated times. The total cost of installation (Pump + Bridge Valve + CPVC and flex hose fittings was about $190. Some may argue that the juice isn't worth the squeeze, but for me it's more of an issue of saving water. After running the recirculation pump I get reasonably hot water within 10 seconds.

Thanks to those of you who offered advice.