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Topic: hot water mixing

Posted By: hornfrog on 01/03/09 06:30pm

I have had 3 motorhomes, but I now have my first with a 3 way diverter valve. Here is my tank heats up, I have the diverter valve in correct position (45 degrees) and my shower faucets are all tight in the off position, but I get about 15 seconds of hot water when I turn on the hot water tap. The pump comes on and in a few seconds the water turns cold...Can a 3 way diverter valve malfunction when set properly?

2002 Fleetwood Storm
Burleson, TX

Posted By: BillArf on 01/03/09 06:41pm

Check your utility closet. Be sure the hot and cold water faucets there are turned off. You can get mixing there. The sprayer nozzle keeps the water from running when you have those faucets turned on. Mixing occurs there resulting in no hot water at all other locations in your RV.

Posted By: hornfrog on 01/03/09 06:59pm

Thanks for the quick reply...the outside shower faucets are off. I have been messing with this for a month, replaced thermostat, back flushed hot water line into tank, drained and refilled tank to make sure air pocket was restored, tried diverter valve in several positions, etc
I have 2002 Fleetwood Storm with Atwood 6 gal tank that I bought used (9 k miles. I may be down to replacing the diverter valve, but it looks tough to remove and replace without special expansion tool at pex joints.

Posted By: wa8yxm on 01/03/09 06:59pm

45 degrees is the proper angle for the diverter? Normally it's zero or 90

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Posted By: hornfrog on 01/03/09 07:05pm

I had read that 45 degrees was to help prevent scalding at the hot shower faucet....0 (vertical)shuts off tank filling..will try a full 90 degrees to see what happens ( I'm pretty sure I did, but maybe not)...thx

Posted By: BillArf on 01/03/09 07:13pm

On my 2002 Fleetwood Southwind the water heater bypass handle is down to the left (zero degrees) when I do not want to bypass the water heater.(Normal operation)

If I do want to bypass the water heater, the handle is turned so the end of the handle is straight up. (90 degrees)

So, normal operation is handle set at 0 degrees. Your 2002 Storm should be as mine.

Re-worded to make clearer.

* This post was edited 01/03/09 07:23pm by BillArf *

Posted By: hornfrog on 01/03/09 08:10pm

thanks...I am trying that as we speak (the tank is heating up)
If it is really that simple, my wife is going to kill me after a holiday trip with no hot water and having to use the camp showers!

Posted By: hornfrog on 01/03/09 09:00pm

ok...filled tank, tank heated up...I turned handle horizontal so tank would refill as needed...turned on hot water to outside shower. Got hot then warm then after about 1.5 gallons (into bucket to measure) turned cold.

Burner did not come back on even though cold water was filling tank...I drained water had pressure and lots of still pretty hot water...

Just baffling...

Guess I should call Atwood on Monday.

Thanks for the help...I am now sure horizontal is correct for the valve handle..

Posted By: Kirk on 01/07/09 08:39am

Were is this "3 way diverter valve? I have never heard of such a valve in any RV that I have ever seen? It sounds to me as though you are looking at a valve who's purpose is to fill the fresh water tank from a city connection. If so, the only time it should be in the tank fill position is to put water in the tank. When using city water there should be a different position for that and only a two position valve. But, if that is what you have it does not do anything for hot water in or out of the water heater.

It would be my guess that your water heater is fine but you probably have the bypass valve for winterizing in the wrong position. If the water heater did not work properly, there would be no hot water at all. You seem to get some, then it mixes with cold and that is usually the bypass.

Both points made by Bill are very valid. The problem would not have to be on the outside shower if it is a shower head turned off with the faucets open. The one inside would do that same thing for any other place you use hot water so check the shower in the bathroom as well.

Tell us where this valve is and what it looks like as we are all guessing since the name of the valve is not one most RVs use.

Good travelin! ........Kirk
Professional Volunteer
Fulltimer for 11 years,

Posted By: beemerphile1 on 01/07/09 11:16am

A lever handle valve has the handle perpendicular to the water line when closed.
The handle will be parallel (in line with) the water line when open.

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Posted By: wa8yxm on 01/07/09 02:08pm

Most folks call a switch with 3 screws a "3 way switch" and a diverter valve with 3 pipes a "3 way valve"

The first is SPDT and unless it's center off really is only 2 way (some are center off)

The second... Same thing The only difference is "Single PIPE double throw" (One incoming pipe thrown to two outgoing pipes)

Again it may be center off

Unless there is another valve somewhere it should not be doning that.

Posted By: javaseuf on 01/07/09 03:32pm

A winterization system that uses a single valve uses a "3-way" valve at the cold water side of the water heater. In one position, it diverts the in-coming cold water into the water heater and shuts-off the by-pass tube that goes between the hot and cold side of the water heater fittings.
In the other position, it shuts-off the cold water supply to the water heater and diverts it up the by-pass tube to the hot-water side of the water heater. There is a check-valve on the hot-water discharge side of the water heater that keeps this cold water from entering the water heater.
It sounds like your 3-way valve is in the incorrect position or the whole winterization system was installed improperly which should have been caught when the dealership did the PDI.

Also, it is very possible that the plastic socket (that slides over the valve stem) on the valve handle is cracked and when it is turned, it isn't actually turning the insides of the valve itself.

* This post was edited 01/07/09 05:23pm by javaseuf *

Posted By: hornfrog on 01/11/09 04:45pm

Thanks everyone...A pic of my valve can be found at...
I think this is sometimes called a 3 cold line in...two to tank and one to hot line (at 45 it splits the water to both tank and hot,no scalding at shower). Even when horizontal (i.e., only filling tank), I still get cold water mixing. Very confusing...
I have ordered a new valve in case it has a problem...just real tough to get off...will have to cut some pex pipe and find a way to get it all back together...My RV was purchased not sure about the factory system check.

Posted By: canttellu on 01/12/09 11:15pm

The valve you are messing with is the water heater bypass valve, only used to winterize the heater without filling it with antifreeze. In use, it should be wide open to the water heater, any other position will probably destroy the heater element if electric, or the tank if gas, or both if both.

Posted By: hornfrog on 02/07/09 03:18pm in new 3 way valve and installed it. It is in correct position to fill hot water tank (I can hear it filling)...I made sure inside and outside shower valves are turned off tightly.

I still get hot water at first then cold water (about 20-30 seconds later).
Beginning to suspect the outside shower is still letting cold water thru.

Thanks for the help and all the discussion...just can't stop the cold water mixing.....

Posted By: wa8yxm on 02/07/09 06:39pm

Connections to the faucet are standard 1/2 inch IPT

You can disconnect the lines from the outside faucet and re-connect them to a short 1/2 inch nipple with a 1/2 inch cap on it Or possibly even a plug depending on the design of the fitting (Not sure have not looked at 1/2 inch plugs lately)

Make sure there are no sharp nicks or such on the PEX end of the iron pipe

(OR use brass)

That way you know it's not passing water

Alternative.. Feel the outside faucet lines Run some hot water out the outside shower, Let the line warm up and see how fast it gets cold when the inside shower is running.

Posted By: hornfrog on 02/07/09 07:14pm

Thanks...I will try that.
Got to figure this out before our next trip.

Posted By: javaseuf on 02/07/09 09:49pm

With the single 3-waqy divertor valve, there needs to be a check-valve at the outlet (top) fitting of the water heater. This is there to keep water flowing back into the water heater when winterizing.
It is very possible that this valve is stuck shut so you are getting water through the 3-way valve in the bypass position and none through the water heater when the valve is in the correct position.
The easy way to see if your water heater is full of hot water would be to open the pressure relief valve and see if hot water comes out of there. IF it does, then there is still something that is by-passing the water heater and/or mixing the hot and cold side.

Posted By: hornfrog on 02/09/09 12:43pm

thanks...yes, the tank always has plenty of hot water and pressure left even after cold mixing at taps...I open P-valve and even drain plug just to make sure.
There must be a mixing point somewhere that I just haven't isolated yet...but I keep looking (shower taps, under sinks, along the lines, etc).

Unless...there could be some siphoning of cold water over to my hot water outlet inside the tank...(beginning to grab at straws)

Posted By: Deen on 02/09/09 06:31pm

wa8yxm wrote:

45 degrees is the proper angle for the diverter? Normally it's zero or 90
Yep, that's the way it's been on every one of our RV's that had the bypass.

Posted By: RedG on 02/09/09 08:11pm

Might this help?

2005 Newmar Dutch Star 4024 DP 370 Cummins
Towing my 2012 Malibu w/Blue Ox towbar & Patriot brake system

Posted By: hornfrog on 02/10/09 08:43pm

Thanks for the interesting link RedG. That's not my problem, we just use the cold-hot water taps at the showers and don't even fuss with the shower head on-off control...but it was sure interesting to see the great lengths that guy went to preventing back flow issues at his shower.

Mine is with everything open...I get warm (not hot) then it flows cold when pump comes on...abd stays cold.

Posted By: wingtraveler on 02/11/09 05:55am

I have a 08 Fleetwood Discovery. Fleetwood installed on the back of the water tank 1 way check valve, I had the same problem the valve was sticking once in a while and it needed to be replaced.

08 Discovery 40x
08 Hyundai Sonata GL toad
08 Honda Goldwing

Posted By: hornfrog on 02/12/09 06:17pm

hmmm...I can't find a check valve around my HWT anywhere....on my 2002 Southwind.
But I could see where that could be a problem if there was one and it was sticking...thx

Posted By: hornfrog on 02/14/09 02:36pm

Ok...I have isolated the problem. With the new diverter valve installed and in the proper open position to fill the would not fill. I took the cold line leading into the HWT loose...could not blow air into tank thru it!!! I think it should be clear and open.

My conclusion?...It must be clogged.

Can't remove the pex pipe because it makes a 90 degree turn inside the tank.
Does anyone know what might be at the end of the cold water pex tube leading into the tank (ie a back flow preventer?) or how it might get clogged?

Posted By: wa8yxm on 02/14/09 05:30pm

Interesting.. Looking at the tank, Where is the cold line .. At the top. bottom, right or left of the tank? More later

Posted By: hornfrog on 02/14/09 10:18pm

The cold water into the tank is about at the same height as the hot water out line on the side of the tank...both appear to be near the top.

The cold line into the tank is on the right as you look at both lines. Both come out of tank and go down and connect to the diverter valve...Wish I could attach a picture.

Posted By: hornfrog on 02/22/09 06:02pm

Ok...the latest on my hot water tank. As I mentioned before...the cold water line into the tank seems to be stopped up...I can't blow air thru it to the tank...Today I took a long plastic tube and inserted it into the cold line in. It went in about 18 inches and stopped. Any ideas what might be at the end of the cold water line inside the is preventing it from filling...

trying to save time and money...but may have to just remove the HWT...


Posted By: hornfrog on 03/19/09 09:50pm

After 2.5 months my HWT saga is over....I took it to a local RV Service Dept at Camping World...the problem?....the cold line in and hot water out lines were crossed at the HWT (behind the protective cover). We reasoned this must have been done at the factory by mistake and never worked properly.

He connected them correctly...The diverter valve worked prefect to fill the tank and no mixing at the tap!.......ahhhh, hot water at last.

Posted By: jjwms on 03/19/09 10:05pm

It sounds like the hot water tank bypass valve is in the wrong position to allow water to flow into the hot water tank so it can be heated. In other words it is set in the winterized postition. Check th owner manual to find out how the bypass should be set for regular use.

Fulltime RVer May 1997-June 2007
2013 Winnebago Vista Model 27N

Posted By: javaseuf on 03/20/09 10:35am

jjwms wrote:

It sounds like the hot water tank bypass valve is in the wrong position to allow water to flow into the hot water tank so it can be heated. In other words it is set in the winterized postition. Check th owner manual to find out how the bypass should be set for regular use.

Hey, keep up, man!! [emoticon] LOL!!!
Your suggestion was mentioned months ago (read the previous replies) and the post above yours states that the OP has fixed the problem. [emoticon]

Posted By: beemerphile1 on 03/20/09 01:50pm

hornfrog wrote:

After 2.5 months my HWT saga is over...the cold line in and hot water out lines were crossed...

Glad to hear you got it solved, it was a puzzler.

Posted By: hornfrog on 03/20/09 07:54pm

Bingo Bimmerfile1..!!..The diverter valve was checked out and worked fine (i.e., correct position).
This was all about a "Monday morning" factory screwup ...someone crossed the water pipes into to HWT. The service guy traced the lines.. swapped them in just minutes...cold water water out. I sure learned a whole lot about HWTs over the last 2 1/2 months..

Posted By: ShapeShifter on 03/20/09 08:05pm

Congratulations on figuring it out! You must be quite relieved now.

I've been following this since the first day, and it was a real stumper. Thanks for the update with the final resolution, it's nice to know the full story.

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