Water is hot, but no hot water pressure

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Olivetroad

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May 21, 2016
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I have a new to me 1998 Chieftain Winnebago on a Freightliner pusher chassis.

I have everything working, except there is no pressure on the hot water side.  Hot water heater is working and there is a trickle of hot water coming out of a faucet if I open it.

If I turn on the Water heater bypass switch under the fridge, then cold water comes out of hot water lines, so it seems to work.

Is there a winterizing bypass valve I am missing?  I shut the one under the shower and the one by the electric water pump. 

Any help?

Edit by staff - changed message icon to topic solved
 
Could be a valve, but more likely the check valve(s) on the water heater are stuck.  Sometimes opening and closing the bypass valves several times will free up a stuck/plugged valve.

If (after turning off the water heater and letting it cool down) you pull the drain plug, does cold water continue to flow into the heater as it drains?  If so, likely a check valve on the output side.  If no water into the heater, then somewhere on the input side there's a problem.
 
I pulled tank plug and I have good cold water flow and pressure feeding the water heater.

Any ideas on where to start looking on output side of water heater?
 
Are you sure the heater is indeed making hot water. Touch the relief valve carefully to see if it's really hot.

If it is hot, chances are the check valve has failed which is very typical. You'll need access the back of the heater to repair this. Look at the top pipe coming out of your heater. Disconnect the water line from what will probably be a brass fitting. This fitting is the check valve. Remove it. Look inside and you'll probably see some loose parts. You can use a screwdriver to drive the internals out so the hole is clear. Now if you'll never have the need to winterizing the RV, you can put it back in. Or you can put it back in temporarily until you pick up another one at Home Depot. They are just a 1/2" check valve and cost about $10.00. Some manufactures also put a check valve on the inlet pipe which is the bottom pipe. Most times it's the top check valve which is the culprit.

It looks like some Walmarts will also have them: http://www.walmart.com/ip/29764297?wmlspartner=wlpa&adid=22222222227021475514&wl0=&wl1=g&wl2=c&wl3=40838473952&wl4=&wl5=pla&wl6=78652082312&veh=sem

If you do replace it, make sure the arrow on the side of the check valve is facing away from the tank and if you replace the bottom check valve the arrow needs to be facing the tank.
 
Winnebago has used two check valves for years - one on the input and one on the output. I made a drawing of the system that you can see HERE
It is not unusual for one of them to fail. On my rig they looked like brass nipples and were screwed directly into the water heater input and output.
Some Winnebago owners have posted that they were not screwed into the heater but were close by in the water lines.
 
I found the water heater under the galley sink and the lines going in and out appear to have an extra fitting in them next to the brass fitting that threads into the tank.  I'm headed to the shop for tools.
 
WOO HOO!

Momma is going to get a hot shower after all!

Thanks for all the help - I took out the check valve and we are in business.  It was also a good way to be forced to learn the plumbing on this old gal.
 
Olivetroad said:
WOO HOO!

Momma is going to get a hot shower after all!

Thanks for all the help - I took out the check valve and we are in business.  It was also a good way to be forced to learn the plumbing on this old gal.
Click to expand...

Glad we were able to help you and especially Momma.  ;)
 
We certainly have a lot of hot water experts here!  Our Horizon was only a year or two old when one of my check valves started to 'buzz' every time there was hot water demand, I replaced it the easy way - with a credit card at factory service.  Pretty sure the other one was replaced also at that time or a year later.

For future reference, if there's no hot water (with no other plumbing anomalies), chances are great it's a failed check valve on the hot water heater or the outside shower wand has both cold water and hot water valves open (with the wand shut-off button closed.)

This is a great thread about troubleshooting a no hot water situation, I'm going to make a link to this thread in our Winnebago and Chassis Resources sticky thread.
 
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