RV plumbing

[codgerbill]

I was recently at a rally and the neighbor coach mentioned a way to not have to dump the cold water into the gray tank while waiting for the hot water to make it to the rear sink faucet or shower. He told me that he had a switch mounted in the bathroom near the sink and turned it on prior to turning on the hot water faucet. After a very short period he would then turn on the hot water faucet and there was no more waiting for the hot water. I had a drawing that I made for my motorhome (Winnebago product) and I added the above mentioned system to show the additional pump and fittings to make the system work as was shown to me. I don't know if it applies to other RV's in general.

 

[John Hilley]

Very nice diagram and it should be universal for all RVs.

 

[Gary RV_Wizard]

It's certainly possible to add such a bypass pump to most any RV (assuming you can get access to the necessary water lines without tearing apart a wall or floor), but it also seems like a lot of solution for a very small problem. Depends on how often and how long you need to go between gray tank dumps, I guess.

You need to tap into the hot line as close as possible to the faucets and then deliver the water back to the heater inlet line fairly close to the tank. That maximizes the value and minimizes energy loss.

 

[John Canfield]

Great idea Bill!  Love the CAD diagram also.  I've thought about doing that for the coach and the stick house - I hate like heck to put cold water in the gray tank when we're boondocking.

Is your diagram accurate for your Winnebago model?  If so, that looks like a good candidate for the Forum Library (if you can do a little write-up)  - Winnie section.  If the diagram is generic, then it is a good candidate for another section of the library.

 

[codgerbill]

Thanks John.

The drawing is actually for the Winnebago Adventurer I had. It would be difficult to adapt for the Suncruiser as the bathroom sink is on opposite side as the water pump on the Suncruiser. The fellow who showed me his system also had an Adventurer and his bathroom sink was on the same side of the coach. It was a straight shot to run the pex tubing for his instillation. The difficulty for me would be to get the pex somehow on the other side of the coach.  But....we don't really boondock so water conservation is not that big of a deal.

Regarding the drawing for the Library just let me know what you want and I will be most happy to make the necessary additions/changes. I do feel that the drawing is pretty much generic and I am sure that others comments will tell the tale..... ;D

 

[artdecamper]

What a great idea! Would work the same on my Itasca Sunrise 32V, but would be hard to get the water line back to the water tank, but definately worth the look.

 

[codgerbill]

Here is a drawing (generic...I think) of an RV plumbing system...sans the recirculating thingy. 8)

 

[codgerbill]

Ummmm....another tweak to the drawing......

 

[John Hilley]

I have a 2003 Adventurer 38g with the bathroom on the opposite side of the motor home. It wold be hard to get to the water heater input, but not so hard to return it to the fresh water tank.

 

[Pierat]

Another way is the recirculating hot water line pump used in some houses, so the water in the hot line is always hot. Not very efficient though.

 

[Lou Schneider]

If you're returning the water to the fresh water tank, you don't need a second pump.  Just a valve on the hot water line with it's output going to the tank since the tank isn't pressurized.

I wouldn't use the line running to the inlet side of the fresh water pump for this - too easy to let hot water get directly into the cold water pump and lines.  But a separate line going into the fresh water tank should work.

 

[hdmox]

To stimulate thinking, my dad had a hot water ?loop? in his split level house that kept the hot water gently circulating by convection?hot rising to the top of the loop and cold falling back to the hot water heater on the lower level?no pump.  You always had instant hot water, but as Pierat said, you do lose energy from the constantly hot piping, depending on its location and insulation.  I don?t know if there is enough rise from the water heater in the basement of the RV to the faucet in the bathroom to make this work, though.

Codger, your diagrams are awesome!  They certainly match my Suncruiser layout.  And I really like Lou?s observation that a return to the unpressurized fresh water tank would obviate the need for a second pump.  Having personally dumped many Burger King cupfuls of ?cold? hot water into a gallon bottle for transfer to the fresh water fill, I?m going to look a lot more closely at these great ideas!  8)

 

[codgerbill]

Dean,

Thank you for the compliment. I am not sure if I had made my original post clear. The second pump for the system is turned on only when you are going to turn on the hot water tap (faucet(s) or shower). After a short period of the auxiliary pump circulating the cold water back to the hot water tank the auxiliary pump is turned off. One could install a switch near the galley sink and one near the bathroom sink. The auxiliary pump is only turned on for a short time to get hot water to the hot water taps.

 

[codgerbill]

Boy do I feel like a dummy. I posted the drawing that has no axillary pump on it. Please forgive my codger faculties. Herein is the one I wanted to post. :

 

[John Hilley]

I have a 12 VDC solenoid water valve that I plan on installing to send the hot from the last hot water point in bath area to the fresh water tank. I will hook up a momentary switch to open it and empty the cold water in the hot water line to the fresh water tank.

 

[hdmox]

John,

Cheering you on, I await pictures, instructions, and source and price of said valve.  Does the valve fail safe to closed or is there a manual override in case of failure?

 

[codgerbill]

The gentleman that showed me his system,  did not have a check valve in his system. His reasoning was that once the bypass system had run for enough time to get the hot water to the desired tap he shut it (the axillary pump)off. He said that once the hot water reached the desired tap he considered that the hot water system was now "charged". He also said he used it when boondocking with no problems.