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Old 03-19-2011, 10:30 AM   #1
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Hot Water from Cold Valve

When I turn on the cold water, I got HOT water for a bit then it goes to normal. This happens in the bathroom faucet as well as the shower. It happens most times, but not necessarily 100% of the time.

The hot valve only provides HOT water eliminating the possibility of a reversed connection.

2011 34' Classic

Any ideas?
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Old 03-19-2011, 10:36 AM   #2
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It's possible the cold water line comes close to a heat source. When you are not using water the heat source warms the water in the line. When you turn on the tap the warm water runs through first.
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Old 03-19-2011, 11:41 AM   #3
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Good point. To test, I should be able to turn off the water heater, run water until there's no more hot water, then leave it a while and test again. If I get hot water through the cold valve, you're theory is correct. If I only get cold through both valves, then the answer is one of two things...either the hot water heater is the "source" heating the cold lines or your theory is not the cause. Would you agree?

I like your idea, but based on the temperature of the hot water coming from the cold valve, I don't think that's the cause. The water is almost as hot as the water directly from the hot valve of the faucet. Make sense?

Off to test...I'll post the results!
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Old 03-19-2011, 12:00 PM   #4
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Our '83 Excella does the same thing when the shower water is turned off at the shower head. When turned off at the head, both faucets are on, and I believe that the hot water bleeds back into the cold due to the hot water being under higher pressure from the heat. When turned back on at the shower head, we get a short blast of hot, then it goes back to whatever temp adjustment was made before the water was turned off at the head.

I don't know why this would happen at the sink as the mixing of hot and cold won't happen until both valves are turned on.
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Old 03-19-2011, 12:33 PM   #5
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TX,

This may be nothing more than the SOLAR heating effect on your supply hose.

If you have a 50' hose sitting in the direct sun light the first 50 feet of water entering your trailer can be very warm, almost as hot as your heater produces.

Once the 50' of warm water has been pushed through your system the water will return to cold, or normal.

Sergei
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Old 03-19-2011, 04:36 PM   #6
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TX,

This may be nothing more than the SOLAR heating effect on your supply hose.

If you have a 50' hose sitting in the direct sun light the first 50 feet of water entering your trailer can be very warm, almost as hot as your heater produces.

Once the 50' of warm water has been pushed through your system the water will return to cold, or normal.

Sergei
Hi, this was my first thought also.
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Old 03-19-2011, 06:15 PM   #7
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I wonder what happens if you leave the bypass valve open...
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Old 03-19-2011, 07:13 PM   #8
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Mojo - great profile pic!

Group - I empty the hot water heater as described. I just now tested and sure enough, I get cold, then a long stream of very hot. While it was still feeding hot through the cold valve of the faucet, I turned off the cold valve and turned on the hot valve...no hot water (or even warm for that matter).

That eliminates the theory that it's pressure from the hot water heater or the heat from the hot water heater causing the issue.

As for the solar theory...definitely has merit! I cut my hose custom to the length I need 'cause I'm a full timer. It just looks cleaner than 50' rolled up. To test the solar theory, I'm gonna leave the hot water heater off tonight and test again in the morning. That should be a good validation of the solar theory despite the expected fool moon tonight. Ha!

Results in the morning!
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Old 03-20-2011, 04:02 AM   #9
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If this only happens in the bathroom it can't be your supply hose.
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Old 03-20-2011, 05:59 AM   #10
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Quote:
Originally Posted by Naper
If this only happens in the bathroom it can't be your supply hose.
Why's that?
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Old 03-20-2011, 06:35 AM   #11
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The hose supplies water to all the taps. Therefor the kitchen tap would have the same issue as the bathroom. I think your water line(s) are routed close to something hot like the fridge, water heater, furnace. When the water sits in the line it's heated.
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Old 03-20-2011, 07:48 AM   #12
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Quote:
Originally Posted by Naper
The hose supplies water to all the taps. Therefor the kitchen tap would have the same issue as the bathroom. I think your water line(s) are routed close to something hot like the fridge, water heater, furnace. When the water sits in the line it's heated.
Duh...Good point! Maybe I wasn't as awake as I thought this morning.
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Old 03-20-2011, 08:00 AM   #13
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Morning results...

The bathroom, shower, and kitchen faucets provided hot water through the cold valve. Close the cold valve and turn on the hot valve and immediately get cold water (remember I left the hot water heater filled with cold water and turned off). Close the hot and turn the cold back on and it's back to hot water for a while then it goes cold.

So, solar heat is eliminated. Hot water heater ambient heat is eliminated. Hot water heater pressure allowing hot water to leak into cold line is eliminated.

It's gotta be the line is being heated by something in the walls. But what? I'm in a 34' so both bath & kitchen faucets along with the shower are on the street side while refrigerator is on the curb side. Microwave/convection wasn't used during the tests.

I wonder if it's an issue with my UV filter that I've got outside the trailer right by the site supply faucet. If that's the case, I should be able to allow time for the heating to occur and then open the valve for the auxiliary hose connection the AS has as part of the fresh water inlet setup, right?

Results in a few more hours.
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Old 03-20-2011, 08:08 AM   #14
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hippiefish,

Your first paragraph above perfectly describes the effect of solar heating on your outdoor supply hose.
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Old 03-20-2011, 02:16 PM   #15
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Quote:
Originally Posted by SmokelessJoe
hippiefish,

Your first paragraph above perfectly describes the effect of solar heating on your outdoor supply hose.
I agree! With exception of the fact that I drained it after dark last night and tested before the sun this morning. The moon wasn't THAT bright last night. Ha!

The other part that doesn't support the solar theory is this afternoon I did the test with auxiliary hose connector built into the fresh water inlet of the AS and it was not hot or even a bit warm. If it was solar heat or heat from my UV filter, wouldn't it have come from the auxiliary faucet?
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Old 03-20-2011, 02:52 PM   #16
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I wonder what happens if you leave the bypass valve open...
I think Mojo is onto it; have you checked to be sure your hot water heater bypass valve is closed? (This is the valve you open when you are winterizing, and close when Spring finally arrives).

Pat
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Old 03-20-2011, 09:22 PM   #17
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Originally Posted by pmclemore

I think Mojo is onto it; have you checked to be sure your hot water heater bypass valve is closed? (This is the valve you open when you are winterizing, and close when Spring finally arrives).

Pat
Pat - I'm a full timer so I've never winterized. How else can I identify the bypass valve? Would it be inside the AS or outside accessed through the hot water heater access panel? Do you know off hand? If not, I can do the research.
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Old 03-21-2011, 10:43 AM   #18
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The valves for my water heater are reached from inside the bathroom cabinet; I usually remove the top drawer and pull out the second drawer; then I can reach in and turn them. The pipes are laid out in an H shape.

On mine, there are three valves above the water heater: one each for the cold-in and hot-out. There is a third, kind of between these, that is the bypass. To winterize, you close the cold-in and hot-out and open the bypass. In the spring, open the cold-in and hot-out and close the bypass.

I could see that if the bypass were left open, then hot could get into the cold side of your piping.

But if you have never winterized, then this shouldn't have been a new problem. Oh, well.

Good luck. Pat
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Old 03-23-2011, 02:51 PM   #19
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Sorry for the delayed response. Things have been crazy so I haven't had a chance to explore the bypass valve configuration yet. Hopefully I can get to it this weekend. I'll post the results for sure.
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Old 04-02-2011, 09:44 AM   #20
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I finally got a chance to explore the bypass valve. It looks like the bypass is not open. I've attached pics for second opinions.

From feeling around the lines, the cold in is actually warmer than the rest of the cold lines. Could it be backing up out of the hot water heater into the cold in until it reaches the main cold supply? The additional temp would create additional pressure from that direction and supply hot water until the temperature/pressure equalizes and then it pulls normal cold supply? Just thinking out loud.

Here's two pics
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