Hot water issue

[Craig Illman]

This is a mostly a seed to plant in the back of your mind when you get this unusual symptom with the hot water output at your galley sink or head sink.

Situation: Our first overnight cruise of the season and I'm getting significant alternating of warm and cold water at the galley faucet with only the hot water valve on. Changes to the boat from stock: PEX water line upgrade. Tempering (mixing) valve on the hot water tank output to mitigate the scalding risk of 165 degree engine heated potable water.  Changes over the winter: Accumulator tank on the cold water side to reduce pump cycling.

So, my primary theory was there was something interfering with the tempering valve operation, like scale keeping it from smoothly blending the hot/cold to maintain the desired 120 degrees output because I could feel the brass body of the valve being plenty warm compared to what was coming out of the faucet. I had also changed engine coolant over the winter and was a little suspect of an air bubble. Continuing troubleshooting, I also bypassed the accumulator tank on the off chance that it was affecting things with no resultant change in symptoms. Lastly, when I got back to the slip, I pinched off the short hose (not PEX) between the cold feed and the tempering valve with vice grips to keep cold from reaching the tempering valve, thus only hot water should be flowing. Again, no change in symptoms. Grrr!

My partner then jumps in and starts asking me about how things are plumbed and I'm trying to describe the flow paths to her. She then asks about the water lines going to the cockpit shower and how they connect. I told her that I have valves and tees to isolate and drain them in the winter so they don't freeze. Then was the "Ah Ha!" moment. I'd recently plugged the drain tees and opened the inline valves to the stern, but when draining in the fall, I'd left the cockpit valves on. The shower wand has a "trigger" to allow flow out the wand head, but it was off, so nothing was leaking at the cockpit under pressure to give the clue that the cold was bleeding back into the hot side. She turned off the valves in the cockpit and everything returned to normal.

Palm of hand to forehead, Duh!  I'll never forget that again. 

Craig

[KWKloeber]

Craig

"This is a mostly a seed to plant in the back of your mind"

Is that the lesson, or is it " when in doubt, check with the Admiral"? 😍

I usually try to make a list of things to remember if it involves, recommissioning, replacing, or whatever. So that I don't have to remember it (having CRS.). Then  promptly lose the list  🙄

k

[Craig Illman]

Ken - Well, Patti's logic sometimes lives in a parallel universe, but it certainly jogged my brain a bit and made me step back and re-focus. I rather pride myself on my problem solving skills, so it was a little embarrassing.

[KWKloeber]

Ken - Well, Patti's logic sometimes lives in a parallel universe, but it certainly jogged my brain a bit and made me step back and re-focus. I rather pride myself on my problem solving skills, so it was a little embarrassing.

Craig

I'd need all appendages and then some to count how many times I've been humbled by stepping back and/or forehead slapping (there should be an emoji on here for that.)

Many may years ago my ASA instructor tried to drill into our heads about his "stop, grab a beer, sit down, and it will become clear" approach to just about any problem.  It's worked too many times for me.  The times it hasn't for me, I've regretted, like pushing ahead and "fixing" the catalina-installed crooked (off plumb) keel when I removed and rebedded the joint.  ooops, wasn't my best decision.  I should have stopped and drank at least a case.

k