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WCohn
WCohn, Journeyman Plumber
Category: Plumbing
Satisfied Customers: 508
Experience:  Journeyman Plumber/Estimator
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Just flushed my tankless water heater and now I'm having

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just flushed my tankless water heater and now I'm having some issues of the heater not turning on when I flow hot water

Hello my name is ***** ***** I look forward to helping you

Is it flowing through the unit? Are you getting an error code? What make and model is the unit?

Customer: replied 1 month ago.
I flushed my tankless water heater this weekend and now I'm having some issues with the water heater not turning on when I flow hot water
Customer: replied 1 month ago.
I hear the water flowing. Where would I find a code? I'm not at home to check it. It is a Rheem

Do you have a pressure relief valve plumber to the outside?

Customer: replied 1 month ago.
I flowed that to make sure I have water flowing at it is good
Customer: replied 1 month ago.
it is good
Ok then the water heater isn't the issue. It's going to be something else. Are all the valves open to and from the unit?
Customer: replied 1 month ago.
Customer: replied 1 month ago.
some times they work great but other times it will not activate the water heater
Customer: replied 1 month ago.
Prior to the de-scaling of the water heat it was working fine at all faucets

Try this for me. Turn on full hot at a bath tub. And then go back to the unit and tell me if it fires

Customer: replied 1 month ago.

I have the feeling you have cold mixing with the hot or you have a flow restriction so I am trying to determine if it's a low flow issue or not

Customer: replied 1 month ago.
Could I have some of the scaling caught up in the pipe of the hot water side at the bottom of the water heater? I did not check that area.
Customer: replied 1 month ago.
I just used the flushing ports...
Customer: replied 1 month ago.
But why would it work at all the faucets and showers sometime and then not work sometimes

Well if the pressure relief valve produces hot water then it's a lower flow issue. You may have scale caught in the flow sensor. Try flushing it again and see if it dissolves. What happened when you ran the tub?

Customer: replied 1 month ago.
the tub and shower are working great, it's the kitchen and the farthest bathroom that I have seen have issues so far.
Customer: replied 1 month ago.
Flush the tankless water heater again with vinegar?

So it's a low flow issue. Try this before flushing again. Turn off the valves under the kitchen sink and then see if it still happens at the shower.

Customer: replied 1 month ago.
I haven't had a issue at the shower yet

So the only issue is the kitchen sink?

Customer: replied 1 month ago.
The kitchen sink (which is the closet to the water heater) and the back bathroom (which is the farthest from the water heater, but I've never had a issue before the flush at either location)

Turn off the cold to the sink and then run hot water several times to test it.

Customer: replied 1 month ago.
Sorry I'm at work dispatching fire engines other wise I'd call you

I understand the phone call issue. Thank you for what you do.

Customer: replied 1 month ago.
Much appreciated
Customer: replied 1 month ago.
I've even cleaned the screens at each sink that I have seen have issues
Customer: replied 1 month ago.
it's just weird that some times it works now and other times it doesn't since the flush

I'm 90% certain it's got nothing to do with the water heater and more to do with cold water mixing. Is this in your house?

Customer: replied 1 month ago.
It's got to be something simple I'm missing
Customer: replied 1 month ago.
this is at my residence

Do you have a hose Bibb that has hot water hooked up to it?

Customer: replied 1 month ago.
the flush site

Please explain that setup.

Customer: replied 1 month ago.
just your standard flush site right below the tankless water heater
cold inlet and a hot outlet
Customer: replied 1 month ago.
cold inlet flush is just after the normal cold water inlet
and the hot water flush site is just before the normal hot water outlet

But not a hose Bibb that has both hot and cold hooked up to it?

I'll load a pic. Tell me if it's what you have.

Customer: replied 1 month ago.
both flush sites are male hose bibs
Customer: replied 1 month ago.
ok

Zoom in to see

Those are Naviens I'm installing now.

Customer: replied 1 month ago.
like the one I just sent you

At the far bath is it effecting the shower or the sink?

Customer: replied 1 month ago.
sink only
Customer: replied 1 month ago.
tub and shower in that bathroom are fine
Customer: replied 1 month ago.
I've cleaned the screen at the sink faucet

Turn off the cold valves under both the kitchen sink and that bathroom sink and try again. I'll bet it'll work just fine

Customer: replied 1 month ago.
well I can't try it till tonight... :(
Customer: replied 1 month ago.
if it does work then what is the issue?

If it does work then we know you have cold entering the outside at one of those faucets. Most likely the kitchen. Then open the cold to the lav faucet with the kitchen still off and see if it changes. There's is a check valve in most kitchen sinks and it may be stuck with debris from the flushing.

Customer: replied 1 month ago.
I may need to take apart the kitchen sink to clean it or look for some kind of filter?
Customer: replied 1 month ago.
Hopefully it works, if not how do I get a hold of you again?

Yes. Send me a pic of it when you get home.

Right here. I'll leave the question open

Customer: replied 1 month ago.
just go into my email when I get home tonight and respond back and you should get my response?

Yes sir.

Customer: replied 1 month ago.
thanks alot Mr. Cohn...much appreciated

Any luck?

WCohn and other Plumbing Specialists are ready to help you

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