Tee-ing into dishwasher supply line?

[danm5620]

Hey folks, I own a couple restaurants, normally I hire a professional for real plumbing jobs, but this one seems simple ... I think ... so I hope to tackle it myself.

I want to install a cup rinser at the bar sink, and the easiest place to tap into the hot water line appears to be at the under-counter bar dishwasher supply. However, this is a bit more complex than just a water line running to the dishwasher. See the attached picture, it includes several valves and a gauge. I believe one of these is probably a backflow preventer, not sure what the rest are. Seems like I can just tee in where shown and run a line up to the cup rinser. Any problem with that? Do any of those valves serve some function that would negate the ability to simply tap in? Thanks

 

[havasu]

That area seems plausible provided it is mixed water. You sure don't want to scold hands trying to wash your cups.

 

[Geofd]

Havasu is onto something, if this is a commercial dishwasher it's gonna have a booster on it which will bring the temp up to 180° for cleaning and rinsing, this dishwasher would require a backflow device on the hot and cold, I'm guessing it's chemically injected you need to find a potable hot water line you can't tie in there

 

[breplum]

FYI, the first device on the upper right is a wye strainer, the next is a PRV, pressure reducing valve.. possibly the next thing is a water hammer arrestor, which is required on solenoid operated devices like a DW (both residential and commercial). Like havasu said, you likely need to have an adjustable tempering valve that mixes cold in, to adjust to non scalding water to your cup rinser.

 

[tailgunner]

Could also be a low temp dishwasher that uses chlorine to sanitize instead of 180 degree water.

 

[Twowaxhack]

I’d start by cleaning the area very well.

 

[danm5620]

Thanks all.

Yes Twowaxhack, it's disgusting back there. The job will start with a thorough cleaning.

This is a very hot dishwasher, but the dishwasher contains secondary heating to bring the water to high temp. I believe the line in the pic is just straight from the hot water heater.

I hear what you're saying about mixing in cold, but the problem is there's just no easy way to tap into cold water. The sink in question has soldered copper piping right to the faucet with very difficult access for tee-ing in. And the hot water at the sink isn't scalding. In fact, they currently rinse glasses using hot only no problem.

Breplumb, what does a wye strainer do? What does a hammer arrestor do? I understand the pressure reducer. Sounds like those valves etc. in the picture shouldn't be a problem for tee-ing off. Agreed?

 

[tailgunner]

The "strainer" has threaded access that can be undone to access a strainer screen, which can be removed to clean accumulated debris.

 

[Geofd]

In the picture were you have incoming water it's probably already gone through a backflow preventer, which means it's not suite for human consumption,even cup rinsing so you really have 2 issues finding a potable hot/and a potable cold water source
And one that's tempered the plumbing inspector, backflow device tester,and board
Health will pick up on that

 

[danm5620]

Thanks Geofd. I hadn't considered that there may be a possibility that this particular water supply isn't potable. But then again, it feeds the dishwasher so it must be good right? At least good enough for a cup rinser?

 

[Geofd]

If you follow it back before the dish machine I bet you will find a hot and cold backflow preventer that feed the machine, after the backflow is considered non potable because you inject chemicals to wash your dishes,it doesn't matter that your only rinsing. A cup rinser is fed by a potable water source

 

[danm5620]

Nope. That line in my picture that says "hot water to dishwasher" plugs directly into the dishwasher, and that's where I intend to tap in.

 

[Geofd]

I work for northeastern University in Boston we have a few commerical dish machines, some have hot / cold feeding it with testable backflow preventers near by others have state approved protection in the machine (air gaps) anyway if it's potable and the temp range is reasonable you will be ok I just can't tell from the picstures