Using Heat Pump Water Heaters with Recirculation Systems

There is a lot of talk these days about heat pump water heaters being the most environmentally friendly and efficient water heaters available. However, owners have reported issues when using heat pump water heaters in conjunction with a dedicated recirculation loop.

The issue is that running a recirculation pump causes radiant heat loss from the water as it recirculates through the loop. Heat pump water heaters, when run in energy saver mode, require a large difference in temperature between the water coming into them and their current tank temperature in order to turn their heat pump and/or resistive heaters on in order to maintain the tank at the set temperature. So when a recirculation pump runs all the time, the loop is slowly radiating away heat which slowly cools the tank off until the water heater hits a low threshold value before turning the heat pump and/or resistive heaters back on in order to heat the system back up. This can result in you ending up with luke warm water.

You can read about this in the Rheem technical bulletin. Rheem recommends only using the unit in High Demand mode or Electric only mode and says that Energy Saver mode won’t work well with a recirculation loop.

Fortunately, the Smart Recirculation Control 32 solves this problem for owners’ of heat pump water heaters as our control only turns the pump on when hot water is demanded and off when the loop is up to temperature minimizing radiant losses and preventing the heat pump water heater from cooling off thus restoring peak efficiency of your water heater investment while still providing you with the convenience of hot water at your fixtures.

Even if you don’t have a dedicated recirculation loop you can take advantage of on demand hot water with our Smart Thermostatic Control 32 Complete System. This system uses thermostatic cross over valves installed underneath the sink(s) at the furthest location(s) from the water heater and allows cold water in the hot water line to be recirculated using the cold water supply as the return line.


See what customers say about using the Smart Recirculation Control 32 with Rheem and heat pump water heaters:

“Branko H. (verified owner)  

I have a Rheem hybrid water heater. The nuance of such a water heater is that they do not recommend a circulation pump when using the Energy Saver mode. The programming and electronics don’t like recirculation pumps. However, the Smart Recirc Control 32 helps dramatically by only recirculating water when needed. It also does not run all the time and therefore the inlet to the hybrid water heater stays at a reasonable temperature to not confuse the electronics and programming. I have found that I’m saving energy costs by implementing this smart control with my hybrid water heater. In some ways I have cheated the programming and I still have recirculation of water and hence on-demand hot water. I would recommend on long recirculation runs that the temperature probe prior to the pump is placed as far upstream as possible. This ensures that hot water does not come close to the inlet of the hybrid hot water heater. Great product!! ”  see original verified review on product page

“Art U. (verified owner)  

Here’s my situation – new heat pump water heater, fairly large house with hot water recirculation plumbing. You really shouldn’t use a heat pump water heater with recirculation – the heat pump will just end up running constantly. So, I purchased this controller. It was very easy to install – I was already redoing the plumbing for the new water heater, so adding the flow sensor was easy. Wiring was easy, connecting the unit to my phone app was easy, and set was easy. And it’s working exactly as it should! I still get quick hot water throughout the house when needed, and the water heater isn’t running when hot water isn’t needed. I’m very happy with this Leridian Dynamics controller!” see original verified review on product page

*Customer reviews verified by CusRev.com