Backflow Valve on Hot water recirc

[Rick Bunzel]

On an inspection this afternoon my client was talking about a neighbor who was getting hot water back through the cold lines in their home. I was looking at the setup on this home and they have the backflow preventer on the return side of this system. Would they want the backflow preventer on the cold water feed to the hot water tank? If there was a restriction on the recirc loop wouldn't it be possible for the pump to push the return water into the supply loop? cold side is on the right and the circ pump is hiding behind the vent.

I didn't find any issues during the inspection but the house was vacant and the circulation off. Anyone know if this installation is correct?

[John Kogel]

I can only say that if you did not have that problem in this house, then the plumber maybe got it right. If we could see the entire loop it would be easier to analyze.
Who knows what some neighbor's plumber did?

What is your opinion on that switch installation? I would call out the flexible cord to the j-box as amateur wiring. Even with strain relief, that cord is wrong.

He could have put one half of the original receptacle on a switch loop and gone from there to the switch with flexible conduit clamped to the wall. Or he could have fished the cable in behind the drywall, not that hard to do.

[Scott Patterson]

I can't say I have ever seen a BFP at a water heater unless that is also the main supply line cutoff.

The BFP should be on the main water supply line normally right after the cutoff valve in my area. I can't really tell from the photo what is going on with the return line. I don't see an expansion tank or device?

[Mike Kleisch]

What is your opinion on that switch installation? I would call out the flexible cord to the j-box as amateur wiring. Even with strain relief, that cord is wrong.

I would call it out as wrong too, per NEC 400.8, can't use cords for fixed wiring, which I think this qualifies as. Unless, I'm looking at an illusion of some type, but it does look like the receptacle/switch is powered by the cord plugged into the other receptacle above the water heater.

I was also trying to figure out how close to the vent the cord gets...

[Ron Hasil]

What is pictured is a swing check valve and is required on a recirculation line to prevent the cold water from flow back to the fixtures on the hot side.

The issue with having hot water coming out he cold side is due to a failing single handle faucet cartridge. Most likely a Moen. It is best to change all the cartridges. Also look for any cross connections. I have seen places that no longer used the washing machine, so some rocket scientist hooked up a hose to the hot and cold hose bibs. So when someone bored turned on both hose bibs the hot was mixing with the cold