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Fincab
Shower gets cold

Hi everyone,
I have a tankless water heater. It was installed in 2004. For the past year ( yes, I've been battling the problem that long), my shower will start out hot and then suddenly go ice cold. I called the manufacturer, Noritz, and they had me change the flow sensor, motherboard, ignitors, etc., but nothing worked. I paid a "certified" Noritz plumber $850, but he couldn't find the problem. I recently called Noritz, they told me that I must have a connection between the hot and cold side in one of my single-handled faucets. I replaced the cartridges on all of those faucets. But the problem persists.

I don't want to waste anymore money on a plumber who can't solve the problem. Does anyone have any ideas?

bill
Re: Shower gets cold

it sounds like you have a by-pass. so what this is a connection from the cold side to the hot side that allows cold water to jump( because it is at a higher pressure) from one side to the other. It could be a laundry machine , shower faucet , mixer . many other connections.

If you can go and shut off every valve or connection you have you can pinpoint which fixture this is.

Bill

Fincab
Re: Shower gets cold
bill shack wrote:

it sounds like you have a by-pass. so what this is a connection from the cold side to the hot side that allows cold water to jump( because it is at a higher pressure) from one side to the other. It could be a laundry machine , shower faucet , mixer . many other connections.

If you can go and shut off every valve or connection you have you can pinpoint which fixture this is.

Bill

Thx Bill,
I have already change all of the valves in all of the single-handle faucets and showers. I will try the clothes washing machine. You said it could also be a "mixer". What's that? Do dish washers have hot and cold? Could it be that?

bill
Re: Shower gets cold

A mixer is a hot shut off and a cold shut off that combine mixed water to supply some other fixture. this allows the cold to run directly into the hot. some people install a mixer to supply lukewarm water to a garden faucet . if you shut off the faucet but not the shut off valve you have made a by-pass.
Or if you have a shower head with shut off and open both hot and cold faucet but shut off the water with the shower head shut off
or if you have a laundry machine with a Y hot and cold connection hose .

These are just some of the possibilities, i have seen many more.

Bill

Fincab
Re: Shower gets cold
bill shack wrote:

A mixer is a hot shut off and a cold shut off that combine mixed water to supply some other fixture. this allows the cold to run directly into the hot. some people install a mixer to supply lukewarm water to a garden faucet . if you shut off the faucet but not the shut off valve you have made a by-pass.
Or if you have a shower head with shut off and open both hot and cold faucet but shut off the water with the shower head shut off
or if you have a laundry machine with a Y hot and cold connection hose .

These are just some of the possibilities, i have seen many more.

Bill

On your advice I checked the washing machine. I have two hoses going into the machine. There is no connection on the outside. Could it be a dish washer? If so, how could I check?

Again, I appreciate your help

bill
Re: Shower gets cold

as i said before
If you can go and shut off every valve or connection you have you can pinpoint which fixture this is. you must shut off every fixture singularly and try .

Fincab
Re: Shower gets cold

Unfortunately there is no separate shut off for the clothes washer, so I don't see a way to shut it off and keep the water going in the rest of the house. So I don't know how I would test it. Likewise, I don't know if there's a way to shut off just the dish washer. I do notice that when the dish washer cycle finishes, it always signals that it didn't get enough hot water. The question is: Is this a problem with the dish washer itself or is it a symptom of the same problem that I have in the el rest of the house?

bill
Re: Shower gets cold

You should have two shut off valves for the clothes washer. if not then it could be the problem. Install a hot and cold shut off for the clothes washer, and see what happens when you shut them off and take a shower.

Bill

Fincab
Re: Shower gets cold

Hi Bill
I installed the shut off valves and the shower still went cold. So now I'm at a loss. I've put new cartridges in all of the single-handled showers and faucets and turned off the washing machine hot and cold water supply. I don't know what else to do. The last plumber I called tried some things which didn't work and charged $850. Can you think of anything else I could try?

bill
Re: Shower gets cold

do you have shut off valves for every faucet? if yes the close all of them and see what happens. if not then install shut off valves and then shut them off. All houses that i do have shut off valves not every thing.

Fincab
Re: Shower gets cold

I spent a while on the phone with the maker of the water heater. What we found was that the flow of just hot water to the shower was about 1 gallon/min. Whenever even a small amount of cold water was added, the flow of hot water went below half a gallon/min. That's below the heater's threshold and that's why it shut off. I removed the low-flow devices from the shower heads and now the hot stays on, but it seems like a big waste of water. Also, the dishwasher continues to show that it isn't receiving enough hot water. Could there be something clogging the pipes? How could I tell? My house is about 20 years old and has all copper pipes.

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