Hot Water/Plumbing Mystery - Can you solve it?

[mello mike]

This fresh water system problem was a strange one. I just solved it this past week, but wanted to see if anyone else ever heard of this problem. Here's the background:

Fresh water system in the bathroom was converted to PEX last summer. PEX installation included a hot water heater bypass for winterizing. The Atwood 6-gallon water heater was brand new. My Sovereign had never been fully used until the recent Four Corners Unit New Years Rally.

During the Rally I noticed that I had hot water in both the hot and cold water lines. Water was hot when turning a hot water faucet handle, warm water when turning a cold one. All water lines were correctly plumbed. No lines were incorrectly crossed.

Any ideas what the problem was?

[Chuck]

bad faucet valve, allowing hot to bleed into the cold line.

[thecatsandi]

Originally Posted by mello mike

This fresh water system problem was a strange one. I just solved it this past week, but wanted to see if anyone else ever heard of this problem. Here's the background:


Any ideas what the problem was?

Did you close the Water Heater bypass/crossover?

[DaveFL]

Originally Posted by thecatsandi

Did you close the Water Heater bypass/crossover?

Beat me to the answer I was going to give.

[HowieE]

Originally Posted by mello mike

I just solved it this past week, but wanted to see if anyone else ever heard of this problem.

If you solved it what was the solution?

If you did not solve try this.

The toilet may be the only cold water faucet in the trailer, as most sinks have a modulating faucet. Draw a toilet full of water and check if it is anything other than cold. If it is warm there is either a bad connection or a connection, most likely at a tee, that is acting as a "moniflow" valve. That type of fitting uses the flow through it to aspirate water from another source, in this case the hot water heater. This is done by a form of venture in production fittings. In your case that venture may be a piece of debris in one of the the fitting close to the heater.

[mello mike]

Yes, I did solve the problem. I wanted to test the knowledge of others here before I give the answer.

[tallytwo1994]

Ok, it's been a 4 hours test already. What's the answer?

Carol

[HowieE]

Originally Posted by tallytwo1994

Ok, it's been a 4 hours test already. What's the answer?

Carol

Not so fast there may be a prize and the polls have just closed on the west coast.

[azflycaster]

To get hot water into the cold water line (if everything is connected correctly) it would have to be flowing backwards through the water heater. For that to happen you would need cold mixing with hot somewhere in the system. My trailer has separate hot and cold valve at the sinks and shower, but some have a single valve that controls both. I am going to guess that the valve in the shower was letting cold water push the hot water back to the water heater and then push the hot water into the cold water lines.

The same thing could happen if you had a shower cut off valve on the shower head and left the faucets to the shower both on.

Do I win something.

[richinny]

i'm with richard. a neighbor reversed a shower valve and other folks in the building were getting hot water in the toilets. it would make for cleaner toilets

[overlander63]

Originally Posted by richinny

it would make for cleaner toilets

Yeah, there's nothing like the smell of boiling turds in the morning... Ask how I know...

[thecatsandi]

Originally Posted by richinny

i'm with richard. a neighbor reversed a shower valve and other folks in the building were getting hot water in the toilets. it would make for cleaner toilets

Nothing like a warm toilet in the morning help you ease into awake instead of shocked awake.

[mello mike]

Well, Michelle and Dave were the closest to guessing the problem. The water heater bypass valve was closed but it was defective. When closed the valve still allowed water by pass through. I replaced the valve and my fresh water system works great now.

Fixing this valve also greatly improved the performance of my water pump though I'm not sure exactly why.

Who would've thunk it! Has anybody ever had a defective flair-it valve? This problem stumped me and some professionals for several weeks.