water heater holding substantial pressure after opening faucets, pump off..

[centerline]

before posting, I have checked the water heater manual, but it only talks about how to properly use and care for the water heater, but nothing the theory of operation, or troubleshooting water flow issues...

Suburban water heater...... when preparing to change the winterizing and WH bypass valves in the trailer, I needed to drain the water heater.... so i shut the pump off, then opened both faucets to releave the line pressure, both in the kitchen and the shower, AND the outdoor shower with the sprayer removed to drain as much water from the lines as possible.... then went to remove the drain/anode plug.... and found there was still a lot of pressure in the hot water tank... way too much to be normal.

the hot water seems to work as normal, but slightly weaker at the faucet than the cold water.... and the shower is nearly useless.
I thought it was a pump issue, so i upgraded the pump to a 4gpm/55psi unit, with very little change......

I know there is supposed to be an air bubble in the tank to allow for expansion and contraction of the water during heating, which does compress in volume when the pump is active, but I thought it should depressurize once the faucets are opened while the pump was off

my question is, what could cause this pressure?... is there a pressure check valve in the tank that could be faulty... or some other issue elsewhere?

before tearing into it, I am looking for ideas, or maybe someone else has seen this issue before, that could give me some educated instruction as to what to do to fix it..... thanks

 

[danemayer]

Did you open the temperature/pressure relief valve on the water heater? If you don't, when the anode/drain is unscrewed, the pressure can send the rod flying.

There's a check valve on the hot water output of the water heater. That would prevent backflow of water and possibly air into the tank. So even though drainage might occur through the cold water input, the check valve might hold enough vacuum to keep the water heater from draining through the cold inlet.

Actual pressure and flow of hot and cold at the faucets should be about the same. But getting a comfortable temperature mix is different and will be affected by the temperature of incoming cold water.

If you have a significant difference in pressure and flow at several fixtures, I'd start with the hot water outlet from the water heater. If there's a restriction in the check valve, or mineral buildup, my guess is that would be the most likely place. And, a flow restriction there might also play into the inability to drain the tank.

 

[centerline]

Did you open the temperature/pressure relief valve on the water heater? If you don't, when the anode/drain is unscrewed, the pressure can send the rod flying.

There's a check valve on the hot water output of the water heater. That would prevent backflow of water and possibly air into the tank. So even though drainage might occur through the cold water input, the check valve might hold enough vacuum to keep the water heater from draining through the cold inlet.

Actual pressure and flow of hot and cold at the faucets should be about the same. But getting a comfortable temperature mix is different and will be affected by the temperature of incoming cold water.

If you have a significant difference in pressure and flow at several fixtures, I'd start with the hot water outlet from the water heater. If there's a restriction in the check valve, or mineral buildup, my guess is that would be the most likely place. And, a flow restriction there might also play into the inability to drain the tank.

no.. I didnt open the over pressure valve before pulling the anode. on every other trailer ive owned there was never this much residual pressure after shutting the pump off and opening the faucets... and yes, it did blow the anode out, but I caught it before it got all the way out, which allowed the water to soak me good. not hot luckily..

and im not sure about the scale build up in the tank, but after my soaking there was none to be seen that may have came out of the tank... I will take a look inside the tank.... do you happen to know if the check valve on the tank outlet is removable?

 

[JohnDar]

The outlet check valve is removable, but may be made of plastic. They have been known to break apart when being removed, so you may need to dig the threaded end out. Replace it with a brass one. It’s always a good idea to open the relief valve when emptying snd filling the heater tank.


Sent from my iPhone using Tapatalk

 

[danemayer]

. do you happen to know if the check valve on the tank outlet is removable?

As JohnDar mentioned, it is removable. On a 2011 model, it's very likely plastic and also very likely it won't come out in one piece.