Water heater runs but doesn't heat water

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Linearmotion

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Joined
Nov 13, 2018
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9
I bought a 2004 Terry Quantum and can't get the water to heat up.  I've already changed the thermostat and ECO.  Everything works except it won't stay on long enough to heat water.  Gas ignition and electric both work fine.  I can hear it run for about a minute then turns off.  I'm thinking this is pointing to the control board, but as it's about $100 I want to make absolutely sure before I buy it.  It will sometimes heat enough to just take the chill out of the water but then goes right back to cold.  What the heck is going on?!
 
There are two different major brands of water heaters and they work differently

Surburan (You can tell because if you open the outside compartment there is us an ID label) usually has two SEPERATE systems one for gas one for electric.

Atwood (likewise on ID) usually has a single system that handles both gas and electric.

IN both cases the flame sensor (Which is what usually shuts ''em of fast) is disabled on electric so Other than the control board.. Not sure.. Takes about a half hour to make hot. Make sure there is water in the tank.
 
I believe it's an Atwood.  The thermostat and ECO that I ordered worked and the thermal fuse is ok.  It's fires up on gas and I can hear it running on electric.  I even hear it cycle, but it only runs for a minute or two then I hear it click off.  When I open the showers hot side it runs but never gets hot.  What is telling to shut off so quickly?  The pressure relief valve gets hot but nothing else. 
 
Are your batteries low by chance. the controls still need 12 volt to operate. Test at the controls for proper voltage. Just a shot in the dark.
 
Linearmotion said:
The pressure relief valve gets hot but nothing else.
Click to expand...

Try opening the pressure relief valve and see just how hot that water really is. Be very careful. If it's real hot, check your outside shower if you have one. Make sure the water is turned off at the shower valves (hot and cold) and not at the spray wand.  Same with the inside shower. Make sure the water is shut off at the valves not the shower head.
If you find that one of those showers had the water turned off at the shower head what would happen is water would be able to transfer over from the cold side to the hot side and vise versa through the faucets cooling the hot water.

Please let usknow what you find especially with the temp/pressure valve.
 
Also, when I open the relief valve it only spits air, no water.  How do I check that the tank is full and the faucets aren't all puttin out cold water?
 
Leave that relief valve open until solid water is coming out.  Your HWH is filled with air.
 
If there is only a little water in teh tank then it may heat quickly and shut off.

Also if you have run showers and still have a tank full of air. Chekck your bypass valves. Likely in "Winter"mode.
 
Also how do I fill the tank?  Now I'm leaning more towards there being no water in the tank.  The bypass only let's out steam till the pressure is gone but still no water.
 
The battery voltage is good, but I'm also hooked to power and water.  If I turn on the pump now it continues to run.  Shouldn't it stop even when hooked to water?  I shouldn't even need the pump on, right?
 
First, turn off both the gas and electric switches to the hot water heater, it's sounding pretty certain there is very little water in it and the heater and/or electric element can be quickly damaged if running when the heater is empty.

Then, with shore water on, run cold water in a sink. Assuming you are getting water, go to the heater and make sure the bypass valves are not in the bypass position as PancakeBill suggests.

Then, open the over-pressure relief valve (what you call the bypass valve) and leave it open until water runs out. If after a couple minutes water doesn't run out, the tank is probably in winter bypass, so check that again. Once water runs out, close the relief valve and go to your sink and run straight hot water until all the air spits out.

Then turn on the water heater switches and try again. Hopefully your electric element has not burned out. Do not turn the water heater on until your are getting water out of the over-pressure relief valve and out of a sink tap.
 
Can you get to the backside of the water heater. If you can, you'll see a pipe connected to the bottom/back of the tank (cold water inlet) and another one at the top/back of the tank (hot water outlet).

Is there a short piece of pipe connecting the two? Do you see any valves on or near any of the pipes I just mentioned? If you do, how many are there and where exactly are they?

It would be great if you could take a picture of the backside of the tank and post it here.

If you're connected to shore power, you do not need your pump on. It may be that the shore power pressure is less than the pump pressure setting is and all you're doing is building pressure in the CG system.

As Scott said, DO NOT RUN THE PROPANE OR ELECTRIC ELEMENT UNTIL WE SOLVE THIS.
 
Linearmotion said:
The bypass only let's out steam till the pressure is gone but still no water.
Click to expand...

That is the pressure /temperature relief valve. If the water temperature gets too high or if the pressure in the tank get's too high, this valve will automatically open relieving the pressure. 

IT IS NOT a bypass valve.
 
I think I got it!  Thanks everyone!  Everyone kept mentioning the bypass valve but I could not find it.  Finally pulled out a drawer in the bathroom and there it was!  In bypass of course!  Turned those two valves and the tank started to fill.  It's heating now and I can already tell the water temp difference.  I'll let go an hour and check again.  I'll report back, but it seems that it was in bypass.  Thanks again everyone!
 
Linearmotion said:
I think I got it!  Thanks everyone!  Everyone kept mentioning the bypass valve but I could not find it.  Finally pulled out a drawer in the bathroom and there it was!  In bypass of course!  Turned those two valves and the tank started to fill.  It's heating now and I can already tell the water temp difference.  I'll let go an hour and check again.  I'll report back, but it seems that it was in bypass.  Thanks again everyone!
Click to expand...

You say there were 2 valves. Can you explain where they were at. Is there one in the pipe that connects the hot and cold lines?  If there is, that one remains closed during normal operation.  You should have turned one clockwise and the other counterclockwise.

Also, hopefully you didn't fry the 110 volt AC electric element. If you did, there only $11.00 or so at Home Depot, Lowe's or a hardware store. Just ask for a 1500 or 1400 watt 110 volt AC element.

Now, go take a hot shower.  ;D :D ;)
 
Thanks again folks!  That was it!  I was looking at a control board and it was just the bypass valves.  Perfect example of  newbie mistake!  I kept reading and hearing about the bypass valves but just couldn't find it and I wasn't told about it when I bought the trailer.  Finally pulled out a drawer in the bathroom and it was in there.  Turned the valves, the tank filled and heated up in about 30 minutes.  I knew it was somewhere, just couldn't find it!  Problem solved.  Thanks again!  I had to pull the drawer right next to the toilet and right above the water heater.  Pulled that drawer and I had full access to the top of the water heater.  Yes, one valve on the bypass line connecting the hot and cold side and I'm guessing the other valve was on the hot side to fill the tank.  The bypass was open and the other was closed.  I closed the bypass line and opened the other and could hear the tank filling instantly.  Such a simple fix, yet super annoying problem! Yes, couldn't take a shower in here and washing hands or rinsing my mouth with super cold water is not that fun!  All better now. ?
 
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