Quote:
Originally Posted by Epicbite
yes that is exactly how my water heater looks and it was the top right that blew. and that is the black switch i am referring to. I am purely running the electric part of the water heater, not gas. I checked that valve and it does seem pretty rough. ordered a new one. It doesnt seem like its healthy for the unit to let it continously release pressure though. Is it supposed to be turned off after every use?
still cant share my photos. I looks like the JPEG size is too large.
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The easier question, on your vintage heater, the little black rocker switch is a power on/off switch for the electric element on our vintage heater. But, pending where the heater is installed, if can be extremely difficult and a royal pain to get to that little switch to turn on and off the water heater.
On your vintage water heater, some folks added a 120 vac switch in the romex cable line feeding the heater out in the open to turn it on and off. Others, use the circuit breaker in the power convert box to turn it on and off, again on electric only. The next generation water heater after yours, has a on/off switch by or in the tank panel for the electric operation.
On gas mode, there is a flip switch most times on the tank panel for the gas mode. When running on gas, you can hear the roar of the heater and then when the roar stops, you know it made it up to temp. On electric mode, you really have no idea when it is at temp other them time and knowing how long "your" exact heater takes to get all the water in the heater hot.
Now to your piping blowing off, from what you told us, after 1 to 2 hours the top hose blew off, I'm assuming you mean the red hose?
That means the heater over that time period was heating, but since it was on electric, you or we, do not know if the call for heat ever was satisfied as you cannot hear anything. On gas mode, the gas burner would shut down when it reached what it thought was at temp.
You might have a bad T stat (one that does not open when at setpoint)
and it is letting the electric portion run non stop. That would be something to test/check for. BUT, there is another issue, the hose blew off. The pex piping is rated at 150 psi, the hose should not have blow off, the safety relief valve outside should start to open when the pressure or temp gets hot enough.
Another unknown is, did your safety relief valve get stuck closed with heavy calcium and corrosion and not allowing the system to weep/ blow off outside? This can happen if the relief valve was weeping a long time from heavy calcium build up. And if the owner never did annual maintenance on the relief valve which is to open and close it at least once a year so it does not get stuck.
The relief valve is a combo unit, temp and pressure. The white stem is the temp probe in the center of the valve inlet. Here is one out of the heater to show you.
And then, there is the "air pocket" in the top of the water heater that acts like an "expansion cushion" so when the water heats, it can expand into that air pocket and not build pressure so high. In your case, the air cushion may have dissolved even if the system is heating correctly. When the air cushion if lost, the relief valve can weep off excess pressure. Then it can create a lot of mineral build up on the relive valve seat, and create either be a dripping leak that will not stop, or affect the valve stem to not open if left go long enough. The pressure can build beyond 150psi when doing normal heating if there is no air pocket in the heater. The relief valve is made to open at 210F or when the pressure is close to 150psi.
With all that explained, you are left with, why did the hose blow off?
Was the pex fitting not tight enough or cracked?
Was the safety relief valve weeping?
Was the air pocket dissolved and let the pressure get too high?
Was the safety relief valve stuck closed?
Did the water heater go over 140F water temp due to high mineral build up in the tank?
Was the T stat on the electric element control stuck on?
Or is there a combo of them?
You sort of need to test/eliminate each of them and you might find another issue.
You have bought into a older water heater that may have some issues. Since this is all new to you, you really may not know what normal is supposed to be. But, since you had a hose blow off, that is a problem and can create a really mess quick.
As to do you leave the water heater on all the time like at home, or do you turn it off when you are done with hot water? This is a separate topic, but in any case, the pipe should not blow off even if you leave the heater on all the time. That needs to get corrected and then the rest of the heater checked so you know all is good.
As far as to what is good practice on leaving the heater on or off, I'll give you my take on this. We turn ours off when we are done with it. And turn it in 30 to 45 minutes or more when we need to use it. Now to why do we do this?
The RV water heater setup is not like a house system, there is no expansion tank system other then the infamous air pocket in the top of the heater. Over pressure building during normal water heating can makes the relief weep and start degrading it and the water weeping ends up on the controls below it. You cannot hear this water weeping issue, but it can be going on 24/7 if the heater is left on all the time if and when the air pocket is dissolved. And, leaving the heater on 24/7 bakes on more hard water minerals all day long being hot all day long. We only use hot water for approx. 2 to 3 hours a day. The other 21 hours the heater is cooking it self into mineral build up. If you want the heater to work right the longest before problems start, we turn it off and back on when needed. And we deal with making sure there is an air pocket in the tank when we setup camp. I also do annual maintenance on the heater to help stay ahead of the issues.
See if any of the above fits what your camper. We can go into more detail on how to test things if this seems to fit your situation.
Hope this helps
John