Do I need check valves when installing a Water Recirculator?

[jadog]

I'm planning to install a new AO Smith heat pump water heater (model HTPS-80) with a Grundfos circulation pump. I would like to know the proper way to install the circulation pump so that I can prevent cold water flowing down the hot water line and vice versa. It will only be used to run for a several minutes each hour, so I am not hugely concerned about the heat pump not keeping up with heating the water. The water lines will also be insulated.

Below is a basic diagram that I made to show what I laid out. There is a main shutoff valve where the water line comes into the house. Would it be a good idea to add a check valve on the cold water line prior to the expansion tank? And another check valve directly after the recirc pump on the return hot line?

The water heater also has an optional side inlet at the bottom of the tank. Is there a better way to connect this than what I came up with?

 

[MicEd69]

There are several ways one can plumb this. You definitely need a check valve in the hot water circulating line, but the one on the cold-water inlet to the water heater isn't required. And what you show is fine, but adding the circulating return to the optional inlet would be fine as well and may work better for access to the pump. Adding valves to the inlet and outlet of the pump should be done for easy maintenance/replacement in the future.

 

[jadog]

There are several ways one can plumb this. You definitely need a check valve in the hot water circulating line, but the one on the cold-water inlet to the water heater isn't required. And what you show is fine, but adding the circulating return to the optional inlet would be fine as well and may work better for access to the pump. Adding valves to the inlet and outlet of the pump should be done for easy maintenance/replacement in the future.

Thanks for the reply! So skipping the check valve on the cold water inlet before the water heater shouldn't allow much warm water from the recirc pump to flow to the cold water supply to my fixtures, right? Good call on adding valve to the outlet side of the pump as well.

 

[MicEd69]

So skipping the check valve on the cold water inlet before the water heater shouldn't allow much warm water from the recirc pump to flow to the cold water supply to my fixtures, right?

Right. The pump cannot pump hot water back into the cold-water line as it is simply circulating water in a closed system.

 

[jadog]

Perfect and thanks!

 

[GReynolds929]

Right. The pump cannot pump hot water back into the cold-water line as it is simply circulating water in a closed system.

Unless a cold faucet is opened while the pump is running...