SteveMcqueen
New Member
Hi all,
I had to pull my water heater to do some drywall repairs and have decided to install a new one while I'm at it. My home has a dedicated hot water return line and with the old plumbing (the HW return joined the cold water supply just downstream of the shut-off valve, no check valve or expansion tank in the old plumbing) I often felt like hot/warm water was backing up in to the cold side, aka I could never get real cold water when I wanted it. When installing the new heater I plan on adding an expansion tank, new Grunfos recirc. pump (UP 10-16 temp.) and a check valve just downstream of the cold water inlet shut-off valve. The new grundfos pump also has a built-in check valve and will be routed back in to the tank at the drain valve (using a tee obviously)
Does this sound reasonable to you experts?
Here's a link to an article that describes what I was experiencing, and proposes the solution.
https://www.pmmag.com/articles/98049-installing-check-valves-in-a-recirculation-system
And the relevant bits...
"If the recirculation system connects to the cold water supply to the water heater, the water can reverse course and go into the cold water supply. If a faucet or fixture is opened to only flow the cold water, the hot recirculating water will flow into the cold water. Hence, hot water will come out of the cold water faucet. This phenomenon doesn’t last long. As soon as the pressures equalize, the cold water again begins to flow out of the faucet.
But who wants hot water out of a faucet before they get the cold water?
In that same situation, if the recirculation pump is off and someone opens the hot water faucet near the intersection, cold water will come out and probably continue to come out of the faucet. That is because the pressure differentials allow the cold water to flow to the fixture rather than the hot water. In this example, hot water may not come out of the faucet until the recirculation pump turns back on.
What was just described is an installation where two check valves are necessary: one on the cold water supply to the water heater before the connection of the recirculating piping, and the other on the recirculating piping after the last connection of a hot water fixture. Without two check valves, the system will not work properly."
Also, is the shut-off valve that's downstream of the expansion tank absolutely necessary? What is the purpose/benefit of this valve?
I had to pull my water heater to do some drywall repairs and have decided to install a new one while I'm at it. My home has a dedicated hot water return line and with the old plumbing (the HW return joined the cold water supply just downstream of the shut-off valve, no check valve or expansion tank in the old plumbing) I often felt like hot/warm water was backing up in to the cold side, aka I could never get real cold water when I wanted it. When installing the new heater I plan on adding an expansion tank, new Grunfos recirc. pump (UP 10-16 temp.) and a check valve just downstream of the cold water inlet shut-off valve. The new grundfos pump also has a built-in check valve and will be routed back in to the tank at the drain valve (using a tee obviously)
Does this sound reasonable to you experts?
Here's a link to an article that describes what I was experiencing, and proposes the solution.
https://www.pmmag.com/articles/98049-installing-check-valves-in-a-recirculation-system
And the relevant bits...
"If the recirculation system connects to the cold water supply to the water heater, the water can reverse course and go into the cold water supply. If a faucet or fixture is opened to only flow the cold water, the hot recirculating water will flow into the cold water. Hence, hot water will come out of the cold water faucet. This phenomenon doesn’t last long. As soon as the pressures equalize, the cold water again begins to flow out of the faucet.
But who wants hot water out of a faucet before they get the cold water?
In that same situation, if the recirculation pump is off and someone opens the hot water faucet near the intersection, cold water will come out and probably continue to come out of the faucet. That is because the pressure differentials allow the cold water to flow to the fixture rather than the hot water. In this example, hot water may not come out of the faucet until the recirculation pump turns back on.
What was just described is an installation where two check valves are necessary: one on the cold water supply to the water heater before the connection of the recirculating piping, and the other on the recirculating piping after the last connection of a hot water fixture. Without two check valves, the system will not work properly."
Also, is the shut-off valve that's downstream of the expansion tank absolutely necessary? What is the purpose/benefit of this valve?
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