I have a multi branch recirculation pipe in my house. I recently converted from a tank water heater to a tankless water heater. We have noticed that the recirculation pipe has no valves separating the two branches. When we are in the master bathroom taking a shower and turn on The kitchen faucet, which are on two separate recirculation lines, The master bathroom shower gets cold. I also believe that the recirculation line may be tied to our cold water line, when all the hot water is shut off and lines blocked the water in the hot side of the faucet goes cold and has full pressure. My question is: would placing valves on either branch of our recirculating pipe help prevent flow from going to the two sides, thus Helping our shower not get cold when the other side of the house is being used?

HOW is the line connected to the heater?

It is attached to the cold water line coming into the water heater. There are check valves close to the water heater but the two branches of the recirculating lines connect together with no valves separating them.

Branch valves are not usually installed on a recirc line

Does the tankless have a built in recirc pump or is it external

It has a built in recirculating pump. I’m not specifically asking about a branch valve. I’m wondering about a check valve being placed at on each branch.

Only 1 check valve is required on the main run usually located near the pump,check valves fail it would be a nuisance to have them on every branch

her should be a check valve on every line to maintain flow to the heater and not circulate between the return lines. There should also be "modulating" valves so you can adjust the flows to control, and equalize, the temperatures in the lines.

balancing valves



==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

That is what I thought. Flow valve and check valve is what I thought. I am getting a second opinion as the first plumber said it likely won’t help our issue.

It de[ends on WHAT the issue is, even if that is NOT the issue or solution, they will be needed to keep the system working properly afterwards.

ditto

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

a few years ago i did a new house. i put a one inch x 8 outlets premade manifold buried up in the ceiling. it fed HW to 3 baths a kit and a WM. the 8th port i used as a return for the recirc pump located at the water heater. the check valve was integral with the pump. i had no issues at all.
if either of my friends from AZ/SC can describe what could go wrong i would like to know.

It appears you had ONE recirculating line, (and could have connected the circulator to the END of the manifold rather than one of the branches), NOT two or more, so the situations are VASTLY different.