Hot water in toilets and urinals - commercial bldg.

Sounds like a huge screw-up to me. Maybe the lowest bidder got the job.

b) No

a) My conjecture would be there's a recirculating valve for the hot water that has failed allowing crossover.

In a large building there's always the outside chance that a supply line got crossed somewhere but the indication here that's not the issue is the correlation w/ the spray arm not all the time.

--

Never underestimate stupidity!

You either haver a bad check valve in the recirc line, or you need to add one.

HTH Lefty.

I don't know where check valves would normally be in a system like this, but what's happening is that when this valve is left on, it creates a path between the hot side and the cold side without allowing the water to exit when the sprayer is not in use. Also, the recirculating pump must be supplying greater pressure to the hot side than the cold. You could install check valves at that sink...or remove the sprayer so people don't leave it on...

To be clear, you would need the check valve on the cold side at the sink, although it wouldn't hurt to put them on both sides.

My father had a similar problem in a residence, with a temperature control mixing valve. He ended up buying two check valves, and install them. End of problem.

Many stores, their sprayer has a squeeze valve, and it's possible to leave hot and cold turned on at the mixing faucet. The syptomatic thing is to have the restaurant put check valves under their sink.

Do you mean remove the squeeze valve from the sprayer?

Sorry, what I meant was that one option would be to remove the whole sprayer mechanism (including the valve) which might mean replacing the faucet. If the sprayer gets used a lot, that might not be a good option. Or maybe they could get a sprayer without a lever on it. That way they are forced to turn off the faucet...

If they like the sprayer, adding check valves under the sink would probably be a better option, which should take someone with a little plumbing experience 5 minutes if you can find check valves with the same thread size as the faucet lines (and if there are cutoff valves at the sink).

Limp Arbor wrote in news:fe6c1cac-9dc2-4c81-9aba- snipped-for-privacy@d4g2000vbm.googlegroups.com:

First thing I wondered was how do you know this?!

Larry in dead-on about this...if you put a valve (sprayer) after a mixing valve it allows a back-feed when there is a demand on the cold...water passes through the mixer from hot to cold. HTMS

bob_v

. . Like the case quite a few years back where the oxygen lines in a hospital got crossed with another gas supply. Apparently the 'acceptance' tests did not include 'actually breathing' from the oxygen equipment! It all seems rather basic, after the fact! For example. Does the electricity work? Plug something in and see if it works; eh? If the electrical item dies or doesn't work .................... !

I finally went to the kitchen and took a look. What is happening is the H&C faucets are being left on and because of the circulator pumps keeping the hot side pressurized whenever someone goes to a water fountain or flushes a toilet the hot is crossing through the faucet into the cold water.

Weird that a check valve is not required in this situation or the inspector missed it.

Thanks.

Good detective work. Thanks for sharing with the rest of us, always good to learn.

How was the hot water discovered????

It was deep too...

I had a similar (and intermittent) problem in my house, but the warm water was supplied to *all* cold fixtures, basically "reversing" what came out of all of my faucets, showers, toilets, etc. Warm from cold taps, cold from warm.

We finally tracked it down to the "Y" hose on the spigot outside the garage. I have both a hot water and cold water spigot by the garage. The cold supply is before the pressure reducer, thus at street pressure. The hot supply, which obviously comes from the WH, is after the pressure reducer.

If we leave the spigots open, with a hose attached and the spray nozzle closed, the higher pressure cold will force it's way into the hot water line, back to the WH and force HW up through the cold water pipes.

This puzzled us for many years, since it only happened on rare occasions. One day I noticed it happening as my son was washing his car and a few simple tests confirmed the cause.

This is a very good examply of why vacuum breakers on hose bibbs (a form of check valve) aren't just nuisance code, but are a good idea -- here you were just feeding your potable water through a bit of Y hose; maybe a health issue, maybe not, but imagine the same hose sitting in the kids' wading pool (after they've used it for whatever kids do), or the muddy pool of much near the garden. All it takes is a low pressure event (within your house or from a neighbor or fire hydrant etc), and that dirty water is sucked into your house plumbing, into your next glass of "fresh" water.

I couldn't stand the vacuum breakers our builder installed because they sprayed water at you every time you turned off the faucet, but after replacing the whole hose bibb because they were crap and leaking elsewhere, I found that the new ones work great without spraying.

Josh

Oh come on...wading pool water is all that bad...