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Water Heater Advice Please


Five Wood

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I can only get a trickle of hot water out of my heater and would appreciate some advice. Let me give you some history.

 

It's a 6 year old Suburban 10 gal heater and I change the anode rod once a year or so and flush it out. Here's the problem. . . the last month or so the output has gotten slower and slower and I figured it was a calcium build up. The cold water pressure is fine.

 

So today I drained it and flushed it. The anode rod was six months old and in good shape. I did get a good amount of calcium flakes out of it though. I put 5 gals of white vinegar in it and let it sit for a couple of hours thinking that may help with any calcium build up. Well, now it's even slower. I can get only a trickle out of it.

 

If I open the bypass between the hot and cold water on the back of it to run cold water through the hot water lines I have good pressure. So the problem seems to be at the heater. After I drain it, it will fill up at a normal rate. So there seems to be no blockage on the way in. My theory now is that there has to be a blockage where the hot water comes out.

 

Does anyone know if there is a check valve at the exit point for the hot water? My next step would seem to be to disconnect the outlet pipe and run a brush back in that way. But I can't do it if there is a check valve. I know many of you are thinking my "next step" should be to call someone who knows what the heck they're doing and pay him or her to fix it. And it may just come to that.

 

Any thoughts?

 

Jim

 

 

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Check valve in the hot water outlet line is going bad. Time to replace it. Usually just stops completely.

 

Barb

Barb,

Is the check valve inside the unit or in the line? I know what they look like in fuel systems but I see nothing that would make me think it's a check valve.

 

Jim

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I agree with Barb that based upon the tests that you have run the 90% probability is that the check valve is the problem. In most modern RV water heater systems there is one check valve and it is on the hot water out connection.

 

hotwaterbypass.jpg

The check valve usually looks like a nipple and could be in both lines but usually is not. The cold side probably has a simple nipple only. On the hot water out they put in a check valve that prevents back-flow of hot water into the cold water lines and by placing it there it als eliminates one valve for the water heater bypass kit. The check valve may be either plastic or brass.

 

11lrrraVjHL.jpg11EAKiRLcYL._AA160_.jpg

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Well, it turned out that there was no check valve in the hot line. What turned out to be the problem was the hot water shut-off valve. The stem was broken on the inside and this left the valve partially closed. Over time junk clogged the limited pathway through the valve. The valve still appeared to turn off and on properly though.

 

Shouldn't a water heater have a check valve on the both the inlet and outlet of the unit? I now have a check valve on the outlet side but it would seem there should be one on the inlet also to prevent the unit from draining in case of a line break.

 

Jim

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Shouldn't a water heater have a check valve on the both the inlet and outlet of the unit? I now have a check valve on the outlet side but it would seem there should be one on the inlet also to prevent the unit from draining in case of a line break.

While it doesn't hurt anything to have them on both sides and I have seen that, it isn't at all needed. If there is a check valve in one side only that does prevent back-flow no matter which side it is on because for water to leave there must be water entering as long as the system is closed. If you open the relief valve or the drain plug that changes things. When the industry first started to install check valves on water heaters they were usually put into the cold water entry on the theory that it would prevent the water heater's tank from emptying accidentally. Later someone figured out that if you put that check valve in the hot water out side it would still prevent water from draining out but it also eliminated the need for a manual valve in the hot side for a bypass kit. The first of those kits had a valve in both entry and exit as well as the crossover line. Then with the check valve in the hot that valve was eliminated and currently many use only one valve, a three way valve at the point where cold can go either into the tank or through the bypass.

 

Most RVs today I believe have only one check valve and on the hot side of the tank.

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While it doesn't hurt anything to have them on both sides and I have seen that, it isn't at all needed. If there is a check valve in one side only that does prevent back-flow no matter which side it is on because for water to leave there must be water entering as long as the system is closed. If you open the relief valve or the drain plug that changes things. When the industry first started to install check valves on water heaters they were usually put into the cold water entry on the theory that it would prevent the water heater's tank from emptying accidentally. Later someone figured out that if you put that check valve in the hot water out side it would still prevent water from draining out but it also eliminated the need for a manual valve in the hot side for a bypass kit. The first of those kits had a valve in both entry and exit as well as the crossover line. Then with the check valve in the hot that valve was eliminated and currently many use only one valve, a three way valve at the point where cold can go either into the tank or through the bypass.

 

Most RVs today I believe have only one check valve and on the hot side of the tank.

 

Kirk

 

That makes sense, I get it. By the way, nice pictures that you posted. They helped.

 

Jim

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