Low Hot Water Pressure

rv-time · 05-05-2008, 04:14 PM

MH: 2003 Winnebaga 32ft Brave

The LONG story and symptoms...

Took the MH out of storage and purged the water system of all antifreeze. Quarter filled the water tank with fresh H2O (and a dash of Clorox) drove around the block and dumped the water tank. I quarter filled the tank again and switched the water heater bypass to normal and fill the whole system with fresh water.

Thinking we were ready, we hit the road for a short weekend at a campground an hour away. Hooked up the campground water supply (city supply). Testing the faucets all seemed to have equal pressure. The next morning when showering, we had little to no hot water pressure at the showerhead. Trying all fixtures, all the hot water faucets in the MH. Had low hot water pressure. It would start out with some pressure and slowly become a dribble. The water was hot, but no pressure. We did have full pressure on cold-water side. Tried every thing I, and a group of fellow RV'r, could think of that morning.

The most interesting... we turned the bypass valve away from the hot water heater, and had full pressure on both H and C sides. Turn the valve back to normal (heater), loss of hot side pressure to a hot dribble again.

Then, turned the valve to bypassed the water heater, opened and drained the heater tank (plenty of hot water came out, open the pressure valve to speed emptying of the tank) left plug out and turned the bypass valve back to the water heater and only got a trickle of water coming out of the heater drain plug.

You cannot see behind the water heater, so using a digital camera and reaching behind the heater we took several photos. There appears to be two hoses (1 top & 1 bottom) into the tank. We I couldn't tell if there were any valves on the backside of the heater in the photos.

My next check will be is the bypass valve functioning?

Any comments or similar experiences?

If I have to remove the water heater, is there some manual on plumbing and installation? I'm willing to try it myself, but I'll need instructions for an all thumbs novice.

Thanks,
Jim

rv-time · 05-05-2008, 04:14 PM

MH: 2003 Winnebaga 32ft Brave

The LONG story and symptoms...

Took the MH out of storage and purged the water system of all antifreeze. Quarter filled the water tank with fresh H2O (and a dash of Clorox) drove around the block and dumped the water tank. I quarter filled the tank again and switched the water heater bypass to normal and fill the whole system with fresh water.

Thinking we were ready, we hit the road for a short weekend at a campground an hour away. Hooked up the campground water supply (city supply). Testing the faucets all seemed to have equal pressure. The next morning when showering, we had little to no hot water pressure at the showerhead. Trying all fixtures, all the hot water faucets in the MH. Had low hot water pressure. It would start out with some pressure and slowly become a dribble. The water was hot, but no pressure. We did have full pressure on cold-water side. Tried every thing I, and a group of fellow RV'r, could think of that morning.

The most interesting... we turned the bypass valve away from the hot water heater, and had full pressure on both H and C sides. Turn the valve back to normal (heater), loss of hot side pressure to a hot dribble again.

Then, turned the valve to bypassed the water heater, opened and drained the heater tank (plenty of hot water came out, open the pressure valve to speed emptying of the tank) left plug out and turned the bypass valve back to the water heater and only got a trickle of water coming out of the heater drain plug.

You cannot see behind the water heater, so using a digital camera and reaching behind the heater we took several photos. There appears to be two hoses (1 top & 1 bottom) into the tank. We I couldn't tell if there were any valves on the backside of the heater in the photos.

My next check will be is the bypass valve functioning?

Any comments or similar experiences?

If I have to remove the water heater, is there some manual on plumbing and installation? I'm willing to try it myself, but I'll need instructions for an all thumbs novice.

Thanks,
Jim

Lt46 · 05-05-2008, 04:44 PM

Hi Jim,
I just went through this same thing. I actually had to pull the wh out to fix my problem. First thing I did was flush the tank multiple times, each producing some scum, but nothing to write home about. Played with the bypass in each direction and it was obvious that on normal setting, flow was diminished. Learned about backflow preventer valves on both, inlet and outlet pipes from the wh. Couldn't reach them in the nano space provided by Winne, so pulled the heater. Shutoff propane, disconnected 110v, disconnected battery...wanted zero chance of any juice from any source. Disconnected propane line, removed all screws (alot of them) from the exterior flange, and dug and scratched and dug some more at the sealant used by Winne when they put this thing together. That was a real PITA but got it done. Set up a work bench, same height as the wh and pulled it out enough to do a reach around. Bench held the weight of the wh while I disconnected the water lines and finally, removed the backflow preventers. Cheap little suckers, brass exterior with plastic components inside. Found an "O" ring dislodged from it seat and buggered up beyond repair. It actually kept the backflow device from opening much at all. Bought all brass replacements and installed. Put it all water lines back together, flow some water to ensure I was leak free. Used butyl tape around the exterior flange and pushed it back into its space. Screwed everything back in, reattached propane line, used soapy water to check for gas leak and fired her up. Took a few times for the air to expell from the lines but off she went. Flow is much improved, but still not as good as the cold side. I attribute that to the the multiple bends and turns the hot water has to make before hitting the faucet. But showers are definetely much better, much,much better!!!
Took all of 4 hours with parts at the ready.
Don't know if this will cure your problem, but maybe????
Good luck.

Peter

wnbago · 05-05-2008, 05:01 PM

Hi Jim,

Had a similar problem on my 2000 35U (lost all hot water). Problem was with the brass check valve on hot water supply, located on back of hot water heater. Simple part to remove and check .
Hope this helps

Jackm · 05-06-2008, 12:20 AM

The check valves on RV water heaters are an endless source of problems. As a result, many technicians simply remove them since they play a minor role. Sounds like your problem may be related to the check valve that's at the top of your heater (at the rear). Best of luck.
Jack

rv-time · 05-06-2008, 04:36 AM

Between here and another similar RV MB, it sounds like I definitely have a check valve problem (on the inlet side).

Looking at all those screws that holds the unit in, the black goop surrounding the unit-copper pipes-wiring, and the tight quarters... is a little intimidating. Looks like I need to deticate a weekend to this project.

Thanks to one and all for the input... and further comments and suggestions is always appreciated.

wnbago · 05-06-2008, 05:18 AM

You shoud not have to remove the hot water heater to replace or remove check valves. Tight quarters but rather simple task.

Good luck

rv-time · 05-06-2008, 07:53 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by wnbago:
You shoud not have to remove the hot water heater to replace or remove check valves. Tight quarters but rather simple task.

Good luck </div></BLOCKQUOTE>

Have you ever heard the saying...
"Like putting 10 lbs of _ _ _ _ in a 5 lb bag." ?

That might be me squeezing between the water pump, all the tubing and the hand winch used to manually open or close the slider.

But who knows, if Houdini could do it, perhaps I can too.