Cannot get air out of hot water lines, any ideas?

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neil30076

neil30076

Well-known member
Joined
Jan 16, 2012
Posts
56
Location
Cary, NC
Subject says it all. 2000 miles into our xcountry trip, everything was fine, then for no obvious reason, hot line will not prime, but cold line is fine. Tried opening all  faucets with pump off then turning it on per the manual, but no change. Hot water pumps out in short spurts, not a continuous flow.
Anyone have any suggestions on what to try next?
Regards
Neil ( temporarily in Newport News, VA)



Edit by John:  Changed message icon to Topic Solved
 
Try draining your hot water tank.  Make sure you let it cool first.  Make sure that you turn on the pressure relief valve too.  Close valve, then let it fill up again.  Had the same problem with our rig too.
 
Thanks all,
I assumed it was because my hot water tank was not full, so my question is how to ensure it is. I'm going to try the suggestion by ruthandken CDN, as that was to be my next step anyway; then the check valve.
 
2000 miles into our xcountry trip, everything was fine, then for no obvious reason, hot line will not prime, but cold line is fine
Click to expand...
Something obviously changed. After I do a first fill I have to bleed but not after using Ok unless I run out of water. Did someone accidentally turn on the electric bypass valve inside? Ours is next to the electric hot water heater switch.
Also, check to see if someone left the (inside or outside) shower faucet on with the head push button shut off. It won't leak but you won't get any hot water anywhere else if so.
 
You shouldn't have to "prime" the water heater.. If the pump is primed and is pushing cold water around, then it should cycle on when you open the hot water valve, and likewise on shore water. It should at least be pushing air out if it's really drained. You've had a check valve or winter bypass flipped somewhere in your 2000 mile journey..  If you think the tank is really empty I wouldn't be heating it up until fixed.
 
Turn your water pump switch on, open hot water faucet in your unit, and let run until a full stream of water runs out.....My water heater is 10 gallons, and while filling, the air is released through the hot water faucet and it spits water until the HW tank is full and then a full stream comes out.
 
My guess is that a check valve in the winterizing bypass set-up is clogged, probably due to hard water. The heater generates a lot of mineral salts when hard water passes through the tank, and bypasses that use check valves are notorious for getting jammed up when that happens. Try draining and flushing the tank, but odds are you will have to replace the check valve(s) in the bypass plumbing. Note": If your bypass has three manual valve handles, it probably doesn't have a check valve. Single handle bypass plumbing has two, one where cold water enters the tank and another where hot water exits. It is usually the exit one that gets gummed up. You can remove it for now - it is only needed when the system is in bypass mode.
 
neil30076 said:
Thanks all,
I assumed it was because my hot water tank was not full, so my question is how to ensure it is. I'm going to try the suggestion by ruthandken CDN, as that was to be my next step anyway; then the check valve.
Click to expand...

Easiest way to fill hot water heater is to opens hot water faucets, connect to shore water, open pressure relief valve on water heater, turn on shore water, close pressure relief valve on water heater when water starts to come out and run until all the air is out of the faucets. You indicated that cold water was ok at faucets, that means your pump is working fine.
 
Hot water does spurt out when the faucet is on hot only, not a continuous flow. if i let cold mix in i get warm at reasonable pressure, as soon as i go to full hot only, it just splutters out bursts of very hot water.  One other clue - the shower single handle faucet is jammed in the exact mid position, only moves up and down not to left or right.  so it is stuck on a warm mix. I'll look into all the above suggestions and report back.
Thanks all.
 
One other clue - the shower single handle faucet is jammed in the exact mid position, only moves up and down not to left or right.  so it is stuck on a warm mix.
Click to expand...
Can you get any flow, cold or hot, out of the shower head? Not sure what brand you have but some have that "constant temp control" valve on the hot side that might be acting up. I would definitely dig into that handle to see why it is froze in the center position.
 
I had a problem that seems similar on my hot water tank.It is a Suburban but I bet you have a check valve on the outflow side of your tank. Mine actually fell apart so some times it worked ok and other times it didn't work at all.  Went to Lowes and bought a flapper type to replace and works fine now.
 
Duh, seems my hot water bypass has been in bypass position since i bought the rig a  few months ago! SCVJeff got it, thanks!!
Turned it to the normal position and hot water now flows. Also dismantled and cleaned out the shower faucet valve and it works as well, wife is now happy :)
 
Congrats to Jeff for coming up with the correct answer!  Glad you got the problem solved Neil!

This would be an excellent time to flush out the water heater.  Buy or make a wand thingy like this one.
 
After some more testing, not fixed yet.  Winnebago service suggests replacing the hot water exit valve at the top rear of the tank, but how do you get to it?
 
Laying on your back under your unit while looking up at your water heater compartment from below, you will see a trap door screwed to the back of the water heater metal enclosure.....unscrew it, and get with it.  ;)  Oh the fun of maintenance and repairs!  ;)
 
Mark, That's what i needed to know - now i'll go and take a look ( next weekend that is), thanks.
 
Fixed, and what a pain. No access hatch, so unscrewed all lines and pump from  the 1 inch thick wood panel wall on the side of the heater, removed the panel  and crawled in as far as i could. Found not one but two check valves, one on cold in, one on hot out. Pulled the drain plug and removed both, and found the top ( hot) had fallen apart, and the cold one jammed partially shut. Both were brass and had been replaced before. With a hose to 1/2 adapter back flushed from the hot, cold and drain. Replaced with new backflow prevention valves , hooked it all back up, filled with water, and now have full pressure again and hot water!
 
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