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Author:
Guitar8 (AL)
First, I'll try my best to describe my setup.
Navien NPE 240A gas tank-less water heater. Circulating hot water throughout my house using the internal circulation pump. I have a ¾ inch insulated hot line that runs to all my fixtures and back to the water heater. The temperature is set to 125 degrees.
In the shower in my master bath I have 3 Delta 1700 pressure balanced valves. These valves have a big handle to control the flow and a smaller handle to control the temperature. One valve controls a pair of jet sprayers, one controls a wand sprayer and the third controls the main shower head. All valves have the internal limit stop set to allow full hot water adjustment. This bathroom is about 40 feet from the heater. While all of the valves are right next to each other, the jets are the closest to the heater followed by the wand sprayer followed by the main shower head. The issue we are having is in this shower.
This setup has worked well for about 2 years. All three valves could be run at the same time and we had plenty of hot water. My wife and I mainly use the main shower head. We keep the temperature setting on the valves at roughly halfway. About a week ago, I turned on the main shower and the water was cool. I had to turn the temperature all the way to the hot side to get a warm shower. If I turned the temp all the way cold and then all the way hot, the water was very hot (roughly 125 degrees and too hot to use). However, as I moved the temp slightly back towards the cold side, the water almost immediately got significantly colder again. After which I had to move the temp back to all the way hot to get the temperature warm enough to take a shower.
So, to recap:
1. Temp in the middle, cool water.
2. Slowly move it to 100% hot produces warm water.
3. Move the temp to 100% cold and then quickly move it to 100% hot, 125 degree water.
4. Slowly move it back towards the cold side, cool water.
5. Move it slowly to 100% hot again produces warm water.
The above description is what I will refer to as the valve “not working”. “Working” is where the valve works as expected and the temperature control makes the water go from 100% cold to 100% hot without issue. I explain that because here is where it gets interesting.
As mentioned, I have 3 valves. Jets (A), wand ( and shower head (C). If only one valve is on it doesn’t work. If two valves are on, the earliest one in line works but the next one in line doesn’t. So, if valves B and C are on, B works and C doesn’t. If valves A and B are on, A works and B doesn’t. If valves A, B and C are on, A works and B and C don’t. If valves A and C are on, A works and C doesn’t.
Now, there is a sink in this bathroom that has separate hot and cold handles. When I turn on the hot only, the water is 125 degrees so I know I’m getting hot water to the bathroom. With the hot turned on in the sink the heater is putting out 127 degree water at .4 GPM. So, I know the heater can provide hot water to this bathroom. When the shower is running at 100% hot (working or not) the heater is putting out 127 degree water at 1.8 – 2.0 GPM.
Also, there is a shower on the other side of the house that has the same valve in it. It’s real close to the hot water heater and it appears to work just fine.
Things I have tried:
1. Replacing cartridges on valves B and C with brand new Delta cartridges. When I did this I turned on the water without a cartridge in the valves for a few minutes to flush out the lines.
2. De-scaling the hot water heater and cleaned both the inlet and recirculating filters (both were clean).
3. Completely disabling the recirculation on the hot water heater to try and eliminate the circulation pump from the equation.
4. Tested for a cross connection by turning off the supply to the hot water heater and then turning on a hot water valve in the house. Water came out for about 3 seconds, enough to relieve the pressure, and then stopped.
None of the above has made any difference at all.
A few other things to note:
1. While I was in the shower with valve C on 100% hot (warm water) my wife flushed a toilet and I got scalded. This is with the new cartridge in the valve. Makes me think I have a pressure issue of some sort.
2. I turned on a number of other hot water faucets in the house trying to see if it’s a flow issue with the heater. All other faucets had hot water while the shower valve still had the issue.
3. A shower closer to the heater with the same Delta 1700 valve seems to work fine.
For the past week I’ve been working with a guy from a plumbing supply place here in town who is very knowledgeable and we are both stumped. I don’t have confidence in the plumber that installed it as he doesn’t know anything about tank-less water heaters. I don’t think it’s a heater issue though. I don't know how to find and/or fix a blockage in line if one exists.
Any ideas would be appreciated. Thanks in advance!
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Author:
srloren (CA)
Sell the house.... no, just kidding. Your situation is complicated and what you describe cannot be understood without a drawing showing each valve and also include the proximity of the water heater to the bathrooms. Also show where the return line comes from the furthest fixture back to the heater. If you can provide the sizing of the copper tubing, that definitely helps. Often scalding while in the shower when someone flushes is linked to improper sizing of your lines in the home.
Personally I do not like this type of water heater. My son had one that took over 2 minutes to get water from the heater to the furthest fixture which was a lavatory in the Master Bath upstairs. A real water waster. The heater was installed on the Garage wall next to a common wall with the house. They may have made improvements on these heaters since this one was installed approximately 3 years ago in So Cal.
Consider this. In California we must be Frugal with water use. LEAKS ARE EXPENSIVE!
Regardless of the size of the leak, it represents waste!
In worn faucet washers, toilet flappers, leaky sprinkler valves, ect.
Diameter of Leak Galllons Wasted Per Month
1/32 inch 4,800
1/16 inch 10,200
1/8 inch 76,900
1/4 inch 307,700
3/8 inch 692,400
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Author:
Guitar8 (AL)
Here is a simple drawing.
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Author:
packy (MA)
i would do it a little differently. tee between B and C with the return to the water heater being smaller size such as 3/8 soft copper or 3/8 pex. also should show insulation. otherwise, the drawing does show the concept..
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Author:
Guitar8 (AL)
Thanks for the comments.
A couple of things to note. First off, this is the way my house is plumbed. It has worked flawlessly for over two years. I can turn the hot water on with the faucet that is the furthest away from the heater and count to four and have piping hot water. I have no leaks.
Yesterday I took out the cartridges of valves B and C and let the water run over five minutes to try and flush anything out of the lines. The issue remains.
Keep the suggestions on how to fix my issue coming! Thanks!
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Author:
srloren (CA)
You may have addressed this but in my limited experience with these wall hung water heaters, they require that you flush the minerals out of them on a regular basis depending on the conditions of your water. I attended a class on installing these water heaters and they require special venting not required by tank type water heaters also pipe sizing is critical to proper operation. These type of water heaters are high maintenance and you cannot neglect it. Just asking if you have eliminated this as a cause of your problem?
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Author:
Guitar8 (AL)
Yes, I did flush the heater two days ago and did all maintenance. This heater and the fixtures have worked perfectly for two years. My issue didn't start until 6 days ago.
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Author:
Paul48 (CT)
Is this off a well, or city water?
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Author:
Paul48 (CT)
Is it pressure regulated in your home?
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Author:
Palm329 (VA)
Move cartridge a to c, b to a, and c to b.
Observe if system operates the same as it does now. Noticed you replaced b and c but not a, any reason for that?
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Author:
srloren (CA)
It is recommended to install a pressure regulator on your home if the pressure is 80 psi or more. In fact most Auto Washer and Dishwasher manufacturers will not honor a warranty if they learn the water pressure exceeds 80 PSI. I like 60 PSI for my home as it cuts down on wear and tear of the copper tubing.
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Author:
Guitar8 (AL)
I had a local plumber come out to my house. I turns out that a check valve in the kitchen touch faucet has failed. Evidently the two times I did my cross connection check this valve must have been in the off position. When moved to the off position all shower valves worked perfectly.
Thanks for everyone's input!
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