Rheem Heat Pump Water Heater with Circulating Pump

PleaseGIVEmeWATER

We recently switched from a gas water heater to the Rheem Hybrid Heat Pump Water heater. Our master shower is the furthest away from the water heater, so we have a circulating pump that we put on Alexa in order to turn it on and off only when we are showering. It worked great! Now with the heat pump water heater, we have not been able to get the circulating pump to work in the same way. Does anyone have a circulating pump attached to their Rheem HPWH and it works? Our installers can't seem to get it to work. They have talked to the Rheem technical support but they don't seem to be very helpful. We appreciate your input and advice.

Larry Weingarten

Hi, I'm just guessing in the dark here, but it seems you have some sort of interconnection between your HP and Alexa. If so, why? Can't the pump be controlled independently? Demand controlled pumping like they have here: https://gothotwater.com/ is one way to control the pump.

Yours, Larry

JakeCK

Are you the same individual by the username "@Pelion" who messaged me about the rheem hpwh and recirculation pump? I replied to that message, but if it is you I'm curious as to why you have two separate accounts on here? 🧐

DCContrarian

1. Can you talk more about what this sentence means: "we have a circulating pump that we put on Alexa in order to turn it on and off only when we are showering."? Like how exactly it's configured?
2. It generally isn't recommended to use circulating pumps with HPWH's. The reason is that HPWH's are designed to stratify the water temperature much more than conventional WH's, so that cold water is always being heated. Normally circulators return to the bottom of the tank or to the cold water supply, this tends to stir the water in the tank and de-stratify it.

The recommended configuration is to have a small — say 5 gallon — resistance water heater in series on the outlet of the HPWH. The circulator returns into that tank so the HPWH is unaffected.

ethicalpaul

Our installers can't seem to get it to work.

What does this mean? What about it is not working?

JakeCK

It almost sounds like they have some kind of setup that they manually turn on with alexa before they plan to take a shower so they have hot water by the time they get to bathroom. Idk how long of a run it is but it seems like an awful lot of work to avoid a few seconds of cold water, however if they are using it on demand it shouldn't hurt the hpwh all that much. It'll just see it as a load on the tank like any other.

PleaseGIVEmeWATER

@DCContrarian It takes 2.5-3 minutes to get hot water to our master shower. When we had a gas system with a circulating pump that was on a smart plug, we could say "Alexa turn on pump for 10 minutes" and the water arrived within seconds. It avoided having the pump running non-stop or having a timer that may or may not align with different daily schedules. It worked great! We are trying to replicate this with a HPWH but we're not sure if it is feasible. Right now we are waiting 2.5-3 minutes to get hot water in the mornings.

PleaseGIVEmeWATER

@JakeCK No. That is my husband.

PleaseGIVEmeWATER

@ethicalpaul We are trying to get the circulating pump to work with the HPWH and it does not get the hot water to the furthest outlet any faster.

ethicalpaul

I assume you mean "it does not get the HOT water to the further outlet any faster"

Is the pump actually pumping when it is supposed to be?

WMno57

Maybe the pump went out in the trash with the old water heater.

PleaseGIVEmeWATER

@ethicalpaul correct the "hot" water. I edited my comment. Thanks.

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1803135#Comment_1803135

Yeah, as described it doesn't seem to have anything to do with the HPWH.

Is the pump still there? Is it still plugged into the Alexa-controlled outlet? Does the outlet still work? That's all easily checked. It's not really plumbing so I can see why the plumber might not be interested.

Jon_blaney

Shower heads and sinks have low flow fixtures, bathtubs do not. At shower time, turn on the tub hot water. Quick hot water availability saves electricity and small water loss. It will be hot before you are undressed.

PleaseGIVEmeWATER

I am leaving one final comment in case anyone is ever looking for help to get a circulating pump to work with Rheem HPWH. This is our experience and may not be the same for others, but just in case it will help, here is our solution:

AP23694_HPWH_Recirc_v1 2.pdf

This is the diagram from Rheem. I left the file name the same in case they change it at some point in time. This was current as of June 2024.

We were finally able to get the recirculating pump to work with our system. When turned on, the circ pump needs to push water back into the tank. This is the opposite of what is generally done on a standard gas water heater that pushes the hot water out to your faucets. Additionally, we have to turn on the circ pump prior to turning on the hot water faucet, then turn off the circ pump before turning on the hot water. How long you need to run the circ pump will depend on how far away you are trying to get hot water to an outlet. For us, we run the circ pump for 4 minutes. Turn it off, then it only takes 10-20 seconds to get hot water in our shower. Our circ pump is voice-activated via Alexa on a smart plug, but you might have a different setup. It took us a very long time to finally get to this point, but now that it finally works, we are happy to have this energy-efficient system. A big plus is that since the HPWH is in the garage, the garage basically has AC in the summer!