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Category: Plumbing
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Experience:  Licensed plumbing contractor state of Il, & Chicago
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Water heater wont refill after flushing it

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Water heater won't refill after flushing it
This is what I did:

Shut off the braker for the heater.
Hooked up the hose to the drain valve,
and shut off the cold water supply, opened the drain valve and drained the tank empty.
Then I open the cold supply and flushed maybe for 2 minutes.
Turned on the hot water on a faucet and closed the drain valve, to try to fill up the tank.
But the water is not filling up in the tank. The tank is completely empty. I know it because I hooked up the hose to the drain again and now no water is coming out unless I open the supply valve. There is water coming out of the faucet when the supply is open, but when its shot down nothing comes out.
What is wrong with my water heater?? Please come with ideas, anything will help.
anytime you fill a hot water tank you should turn on the hot to a sink, this will let the air out and let the tank fill, if you don't open the hot on at least one sink then you might have it lock up with air and not fill. Anytime you turn the water off to make a repair or service the plumbing system it mixes up minerals and sediment in the water, these then get stuck in the pipe and cause a pressure loss or no flow of water at all, this might be your problem the in on the hot water tank might be clogged with iron and other minerals. Make sure the valve is on and working, if no water is going threw the valve then thats where the clog is, if you are getting water past the valve but to the tank then the cold feed for the heater is clogged and will need to be cleaned out, remove the pipe from the cold feed and look inside the pipe with a light , there is something blocking the flow. If its a old gate valve with a round handle that you turn on and off then these can go bad and the stem of the valve breaks off and then just spins and spins and never opens or closes again.
you must turn on the supply valve or you wont have water flow, the supply valve should be left on when you are done working or servicing the heater. If the supply valve is closed then no water can enter the heater.
Customer: replied 7 years ago.
What is strange to me is that when the supply valve is open, it drains water from both the preasure relieve valve and the drain valve. If i close the drain the tank is still not getting filled, and I can tell on the watermeter that there is no water moving.<br />If I close the supply valve, and try to drain, barely any water comes out from either of the two, and the tank does not start to fill either.<br />When tried I filled up the tank, hot water on faucet was turned on and lots of air came out of it until water started to come out. <br />To respond to your answer, the supply valve is on, but still no water in the tank
you might need a new pressure relief valve, if its not staying closed then it has gone bad and needs to be re-place. If the supply valve on the cold water that feeds the tank is on and you still have no water flow then the valve is closed or the pipe going into the tank is clogged. the drain must be closed and the pressure relief valve handle must be closed if the drain or relief valve is open then the water will just come out the drain and not fill the tank.
Customer: replied 7 years ago.
Thanks for helping me.
The drain and the TPR is closed, and still no water fills the tank with the shut off valve is open. There is nothing wrong with the cold water shut off valve on tank for sure, since I get the same result with closing the main valve.

When I try to drain with the TPR or the drain valve with the supply open and water is accually draining, doesnt that indicate the pipe going into the tank is not clogged?
How would it drain water with the supple open, if the pipe going into the tank would be clogged?

Customer: replied 7 years ago.
Hi again.
Since im sitting her and are waiting for your response, Im just wondering if I should expect an answer from you sometime very soon, or if you would need more time and are planning to answer me tomorrow?

The main feed for the tank must be on and open for water to pass threw, the drain must be closed or the water will drain out, if the main water is on to the tank and when you open up the drain the water flows then the tank is getting water to the tank, and the problem might be on the hot going out of the tank. try opening the feed valve then close the drain then as the tank is filling up with water, open the pressure relief valve and let the air come out there, once the tank is filled up water will then flow out the pressure relief valve and you will know that the tank is filled, the water flows out the relief valve after it fills.
Customer: replied 7 years ago.
So are you saying that the TPR wont drain water unless the tank is full?

yes that is right.


Customer: replied 7 years ago.
Thanks for your patience.<br />Right now, the main supply valve is open and the cold water inlet valve to the heater is open. The TPR and the drain valve are closed. I suspect that the tank is empty, because it seems very light and if I close the water supply and open the drain valve only a couple of ounces comes out. <br />Still the tank can be full?<br />You say that there is no way water will come out of the TPR unless its full, but when the supply valve is closed, and I drained the TPR only about 20 ounces came out.
no if its light then its not full, with the drain closed and the feeds on go and open the pressure relief valve and see if air comes out , it might be blocked with air called air lock. IF the tank feed valves are open and the drain is closed but no water fills the tank then the cold feed inlet is clogged.
open the drain and turn the cold water feed to the tank on , if water comes out the drain then the tank is getting water and the clog is in the hot out put. IF when you do that and no water comes out the drain the cold water feed is clogged and the tank is not getting water.
Customer: replied 7 years ago.
With the supply on, then opening the TPR, only water is coming out.
So you say that means the cold feed inlet is clogged, then how can water come out of the faucets in the house when the faucet is turned on hot?
no i didn't say that at all , if the supply is on and you open the pressure relief valve and water is coming out then the tank is full of water . then if you turn on the hot water at a sink and water comes out then it is fine and working fine and your getting water flow. I said if no water comes out the drain with the supply on then it is clogged, but you say you have water flow at the sinks so that means your getting water flow and its fine. IF the water is cold coming out then you might have to relight the pilot light so the burner will light back up and heat the water.
Customer: replied 7 years ago.
Okay. Thanks allot.
I just have an other question then:
If the tank is full, why isnt it draining more than 15 ounces from the drain valve when the supply is closed?
go open up a faucet it needs air in the system to drain because its locked out tight. if you want it to drain then open up a hot on a sink or open the pressure relief valve to let air in and loose its pressure . In the case that still doesn't work then the drain it self is clogged with sediment from the tank .
Customer: replied 7 years ago.
Again, thanks for your patience. <br />Can the drain valve be clogged when it is draining water with the supply on, and not draining water when the supply is off?<br /><br />I tried this now:<br /><br />I turned on the hot water faucet, closed the water supply on opened the drain valve, maybe 15 ouneces came out of the faucet and 15 ounces from the drain valve.<br />Maybe less than 15 also. Then I opened the inlet valve and water runs from the drain valve.<br /><br />So you think, with all the information you got from me, that the tank is full and I can turn on the electricity again?<br />The reason Im afraid of turning on the electricity is that Im afraid for the elements to burn without water.
Customer: replied 7 years ago.
are you there still?
The reason why only a small amount of water comes out the drain when you shut off the supply is because the pipe is under pressure and now its shut off and called air lock, you have to let air in to the system if you want it to drain. when you turn on the cold water supply valve open up the hot on every sink in the house, then as the tank is filling it will take some time to get water full in the tank and in the pipes going to each sink. Once water comes out of every sink on the hot then the system is full charged with water . now close all sinks and go to the pressure relief valve and pull up real quick and if water comes out then the tank is full of water and it is safe to turn the electric back on and wait for the tank to get hot.
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