Any experts in finding crossovers? Hot going to cold

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Pcmaker

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This might be a little tough to figure out, I'm hoping someone has an idea.

I'm a maintenance technician for a very large hotel/casino. There's around 1000 rooms. 10 floors. Almost all the shower fixtures are Kohler K-304 Rite Temp shower valves. The valves are about 10 years old now and we have hot water issues. Cold water is migrating to the hot side and it affects the entire stack. The water lines are fed from the ground floor all the way up, in between rooms that share the water lines. Then on the top floor is the hot water return that goes back to the middle of the two hotel towers.


Once we get hot water issues, it's hard for us to pin point exactly which shower valve in which room is the one causing problems. We just replace all the shower cartridges, all 20 of them on the stack that is having hot water issues, but now we're having issues with 4 stacks, that's 72 rooms. When the pandemic hit, they laid off half of the maintenance personnell. I'm the only one tasked with doing plumbing issues and this fell onto my lap.

Any pros here with any advice on how to narrow down which room is the culprit?


sDGcvEj.jpg
 
If you close all the service stops, the crossover will also stop.
Supply water can’t pass through the valve or the pressure balancer module.
 
Do the valves have separate diverters
Do you have janitors slop sinks with soap mixing stations connected to the slop sink faucets
do you have mixing valves stations for different zones/ riseres
Are there mixing valves under the lab(bathroom faucets)
 
Or maybe you could shoot an infrared thermometer at the hot and cold supply inlets.
While the stops are still open.

The valves that are passing would be different temp than the rest on the stack.
 
Geofd said:
Do the valves have separate diverters
Do you have janitors slop sinks with soap mixing stations connected to the slop sink faucets
do you have mixing valves stations for different zones/ riseres
Are there mixing valves under the lab(bathroom faucets)
Click to expand...

No mixing valves in the hotel tower aside from the shower cartridges. There are mop sinks that that have crossovers sometimes, but this isn't the case. The only affected rooms are at the end of the hotel tower, the 72 rooms. There's hundreds of rooms before them that have zero hot water issues before getting to the mop sinks. We also added angle stop check valves on every mop sink to prevent it from happening again. If there was a crossover from the mop sinks, it would affect the rooms closest to them.

We've had this issue many times before, and we resolve the issue by just replacing all the shower cartridges and more, importantly, pressure balancing units on every single room in the stack that's affected. But this time, there's 72 rooms affected.
 
Jeff Handy said:
Or maybe you could shoot an infrared thermometer at the hot and cold supply inlets.
While the stops are still open.

The valves that are passing would be different temp than the rest on the stack.
Click to expand...

Are you saying the room with the bad PBU will have a colder stop/hot water copper line than the rest of the stack if I take its temperature with an infrared thermometer?
 
Just a theory.

And the cold supply could be colder also, because water is flowing, not stagnant and getting warmed up by ambient temp.
 
I was thinking of pinching down the cold supply to the tower to help balance out the pressure with the hot supply.

*edit*


Maybe add pressure gauges to the cold and hot supplies at the end of the ground level. They're 3" copper lines.

Pinch down on the cold until the gauges show similar values. We have VFDs on 3 pumps that keep the hot water pressure constant.
 
Pcmaker said:
No mixing valves in the hotel tower aside from the shower cartridges. There are mop sinks that that have crossovers sometimes, but this isn't the case. The only affected rooms are at the end of the hotel tower, the 72 rooms. There's hundreds of rooms before them that have zero hot water issues before getting to the mop sinks. We also added angle stop check valves on every mop sink to prevent it from happening again. If there was a crossover from the mop sinks, it would affect the rooms closest to them.

We've had this issue many times before, and we resolve the issue by just replacing all the shower cartridges and more, importantly, pressure balancing units on every single room in the stack that's affected. But this time, there's 72 rooms affected.
Click to expand...
Are the handi capped units on the riser
If so they have hand held showers along with conventional shower heads there would be a separate diverter to go between the hand held shower and shower head and tub spout, if the occupants use that diverter to shut off the water rather than the valve itself
there will be a cross over
Had the exact same thing in a 22 story dorm only thing that was different were the handi cap units
 
Geofd said:
Are the handi capped units on the riser
If so they have hand held showers along with conventional shower heads there would be a separate diverter to go between the hand held shower and shower head and tub spout, if the occupants use that diverter to shut off the water rather than the valve itself
there will be a cross over
Had the exact same thing in a 22 story dorm only thing that was different were the handi cap units
Click to expand...
Must have check valves on the return going back to your hot water source feel the check valves the one thats hot is the one that's bad
 
Geofd said:
Are the handi capped units on the riser
If so they have hand held showers along with conventional shower heads there would be a separate diverter to go between the hand held shower and shower head and tub spout, if the occupants use that diverter to shut off the water rather than the valve itself
there will be a cross over
Had the exact same thing in a 22 story dorm only thing that was different were the handi cap units
Click to expand...

We have handicap rooms but are in the middle of the two towers, closest to the elevators. There's no handicap rooms at the end, which is where we're having crossover issues. Also, there's no diverters in those rooms, only handheld attached to the shower arm and have the same exact shower cartridges as the rest.
 
Geofd said:
Must have check valves on the return going back to your hot water source feel the check valves the one thats hot is the one that's bad
Click to expand...

We don't have check valves on any of the returns, that's something that shoulda been added day 1 of construction. The only check valves we have are the ones that screw onto the 3/8 port of the angle stop and those are only on the mop sinks.

I'd love to add check valves to every single returns on every stack, that would narrow down the crossover to each individual stack. That would drop down the number of suspected rooms from 72 to 18.
 
Pcmaker said:
We have handicap rooms but are in the middle of the two towers, closest to the elevators. There's no handicap rooms at the end, which is where we're having crossover issues. Also, there's no diverters in those rooms, only handheld attached to the shower arm and have the same exact shower cartridges as the rest.
Click to expand...
How do you switch from tub to shower
Is the diverter in the shower valve body
Or is it seperate
 
Geofd said:
How do you switch from tub to shower
Is the diverter in the shower valve body
Or is it seperate
Click to expand...

There's no tub in our handicap rooms, only shower.
Geofd said:
did you check the check valves at your hot water source??????
Click to expand...

Yeah, they're good. It's cold only at the end of the tower, the rest is hot and it's a very long way to the hot water source. The rest of the copper going to it is hot.
 
Were is your commercial kitchen the faucets with the spray hoses also
Pcmaker said:
There's no tub in our handicap rooms, only shower.


Yeah, they're good. It's cold only at the end of the tower, the rest is hot and it's a very long way to the hot water source. The rest of the copper going to it is hot.
Click to expand...
You mentioned check valves on your slop sinks, eco labs makes a connection thathreads on to the hose thread of the

faucet the hose from the soap device
Threads into one connection the faucet threads into another and there iß an aerator that is always on so the faucet can't be left on or cross over I think it's call a side kick
 
I hope our sinks don't have crossover issues, that would make things so much more complicated

All this time, every single crossover we've had in the hotel tower came from the shower pressure balancing units.
 
Pcmaker said:
I hope our sinks don't have crossover issues, that would make things so much more complicated

All this time, every single crossover we've had in the hotel tower came from the shower pressure balancing units.
Click to expand...
Is your commercial kitchen on the same
Riser......just thought of something else you must have a commercial laundry sometimes an electric solenoid valve can
Go bad,
Do you have soap injected washing machines, if so do you have testable backflow devices you would need rpz not double check devices
 
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