Plumbing Mystery

[JD 4520]

I was planning on posting this earlier when I couldn't figure out how to trouble shoot my plumbing problem but I got lucky and tripped over the answer.


The past couple of days I would use the hose bib in the back of the garage and get warm to hot water. Inside the garage on the same wall is a utility sink. I would get warm to hot water out of the cold facet there also. This went on for a couple of days. My wife and I thought about this all day while working outside. We were at the front of the garage (opposite side) using the hose bib there to water plants when we discovered it was doing the same thing, warm water. Well, this hose bib is a dual hot and cold. The hose with a nozzle was on that hose bib. I discovered that the hot water had been left on part way and was back feeding into the cold water thus pushing hot water to the back of the garage hose bib and possibly elsewhere in the house.

This was bizarre and makes me wonder if this is designed this way or how would this just happen? Any thoughts?

 

[dave1949]

Thermo-siphoning?

If both cold and hot valves on the hose bib supply were open and connected with a wye of some sort, the cold line is going to absorb the heat from the hot line, even if the water is not moving?

 

[the old grind]

I had one of those check valves diverters that bled hot water to the stool to prevent the tank from sweating. The valve had stuck open and the reversible hot/cold connection meant a burst of hot from CW faucts, esp tub & lav. Seems the closer you were to the stuck valve (path) and/or the more hot that flowed to a branch, the more pronounced the effect. Didn't have a clue for years as to what caused it. Found the valve when I remodeled and plumbed it out. Problem(?) solved.

Is it the hotter water, and rapid expansion of gasses trapped in the tanks considerable volume, that causes a brief imbalance in pressure when paths cross and generates the 'spurt' at the 'spout'? Hmm... :confused3:

 

[DFB]

Yea I'm thinking if the the cold side of that mixing valve was open too, the hot did just probably backfeed across the mixer and over to the other hose bib as you were drawing water. Might be good to install a one way check valve on the cold side to that mixing valve just so it cant inadvertantly happen again.