Log In | Register
Skip to main content
Topic: Fresh water return - while waiting for hot water return cold water to fresh tank (Read 325 times) previous topic - next topic
0 Members and 3 Guests are viewing this topic.
Fresh water return - while waiting for hot water return cold water to fresh tank
Hi,
I searched the forum using different words but came up with nothing.

I also looked at amazon and other sites and didn't come up with any standard parts.

I would like to add a fresh water return - for boondocking. 
You know the trick, turn on the hot water heater but then after you turn on the water save the cold water (often into a bucket) until the hot water gets to you, and reuse that cold water at a later time.
I have read all over the internet of people who put in a fresh water return, where instead of putting that cold water into a bucket you put it into a cold water return that goes back into the fresh water tank.  But no pictures or parts listed.

I would love something that was covered (e.g. to keep dust, debris, bugs, etc. out), you lift the lid, spray the cold water in (from shower hose or sink hose), then close back up once you get hot water to you.

Larry, Andy told me you put one of these in.  Did you use standard parts or ??

Thanks for any info on this.

Jane
Jane & Scott
Currently have a 1989 TK  LD we did a lot of upgrades on.
Bigfoot 25RQ Twin on order with early summer 2024 ETA

Our smartphone autocorrects into very poor English.
 We disclaim the illusion of ignorance this creates as we have enough ignorance we rightly claim.
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #1 –
Never done anything like this, but what should work would involve a tee spliced into the inlet hose of the water pump, and switch valve in the hot water line very close to the shower. Turned one way, hot water flows into the shower. Turned the other way, it would flow into a plumbing run you add which runs over to the Tee you spliced into water pump inlet. Switch the valve, and the pump should run, flushing the hot water line of cold water. Switch the valve back, pump should stop, and you can get into the shower and use as normal.

Pump should function this way because the return line is open to the water tank, and cannot develop back pressure to stop the flow. So, I see no reason why this should not work, but I have not tried it.

Note: this will not work!

Steve
2004 FL
2013 Honda Fit
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #2 –

Rethinking, using a 'tee' fitting and an inline valve to the return line would do the job. E.g. :

1/2" x 1/2" x 3/8" Reducing PEX Tee, PEX Crimp Style Brass Fitting - PexUniverse

and one of these:

SharkBite 23382LF PEX Straight Shut Off Valve, 3/8-Inch by 3/8-Inch - Pipe...

with a run of PEX, crimp rings, crimp tool, to a return port plumbed into the water tank.

Steve

Note: This has been edited!

As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
2004 FL
2013 Honda Fit
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #3 –
Steve, what I was really looking for was a contraption on the wall you put the shower hose / sink hose into that just fed back to the fresh water tank.

I have seen return systems for sale similar to what you describe but it leaves the user   guessing the water temperature and if it is hot enough yet - eg running it without being able to stick a finger in to feel it.

I know others have put these in and I was pretty sure they just put the shower/sink hose in (or sprayed it in) and ran the water till hot. 

I don’t want an open pipe sitting up on the wall though I guess I could fashion something to cover the top (several choices come to mind), I just expected to have some commercial item available since there are a lot of people who have one of these - either came with their rig or put in after purchase.
Jane & Scott
Currently have a 1989 TK  LD we did a lot of upgrades on.
Bigfoot 25RQ Twin on order with early summer 2024 ETA

Our smartphone autocorrects into very poor English.
 We disclaim the illusion of ignorance this creates as we have enough ignorance we rightly claim.
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #4 –
With Steve's method, you could have a small digital temperature readout to tell you the water temperature at the 'tee' running back to the tank. RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
 
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #5 –
We use Andy's (and others) thermometer trick in our hot water tank.  The results are very rough.  It seems to depend on things like ambient temperature and maybe things like how the stars are aligned in the sky  :D .
Also, after the thermometer reaches the setting, the water continues to get hot - increasing a fair amount in the next 5 or so minutes.
The flaws of having the thermometer outside the tank not in the water.
But better than guessing the time it takes and using a timer, when the time it takes to make hot water changes over the days as ambient temperature etc. changes.

The device that I see being sold is showermi$er. 
However, you would need one at each location you wanted to return your cold water - shower (and bathroom sink if they are separate) and kitchen sink.  Depending on your hot water tee locations, maybe you could have one that does double duty (knowing just the last 5' or so is cold water, not the entire length from the hot water heater to the fixture.
Jane & Scott
Currently have a 1989 TK  LD we did a lot of upgrades on.
Bigfoot 25RQ Twin on order with early summer 2024 ETA

Our smartphone autocorrects into very poor English.
 We disclaim the illusion of ignorance this creates as we have enough ignorance we rightly claim.
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #6 –
Quote from: JandS2  - 
We use Andy's (and others) thermometer trick in our hot water tank.  The results are very rough.  It seems to depend on things like ambient temperature and maybe things like how the stars are aligned in the sky  :D .

The device that I see being sold is showermi$er. 


We have used a thermometer, with the temperature sensor glued to the water heater tank, for years and it works OK, once you figure out at what temperature to shut the heater off at.

As to the recirculation system, Steve is on the right path and it should work fine.
The device you listed still needs a return line back to the water pump inlet, so what you are getting is a fancy looking 3-way tee valve.  The kit doesn't come with the new PEX line or any fittings.
*Due to various lengths and installation points, the return line and tank or pump connections, are not included."

For many years, our LD has a tee valve, in the shower, used for diverting the cold water to an outlet that allows it to be recaptured in a jug or teapot.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #7 –
Quote from: Larry W  - 


We have used a thermometer, with the temperature sensor glued to the water heater tank, for years and it works OK, once you figure out at what temperature to shut the heater off at.

As to the recirculation system, Steve is on the right path and it should work fine.
The device you listed still needs a return line back to the water pump inlet, so what you are getting is a fancy looking 3-way tee valve.  The kit doesn't come with the new PEX line or any fittings.
*Due to various lengths and installation points, the return line and tank or pump connections, are not included."

For many years, our LD has a tee valve, in the shower, used for diverting the cold water to an outlet that allows it to be recaptured in a jug or teapot.

Larry
Is there a photo of the tee in your albums? Yes, I'm too lazy to scroll through all of them to try to find one.  :)

Chris
Formerly: 2002 30' IB
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #8 –
To help save water I installed an adjustable thermostat for the hot water heater.  I got the idea from a post years ago from this group.  In my stick house I have the thermostat for the hot water heater set so hot water temperature is 105F in the shower.  In my new to me 2003 T/K it was 132F after a full heater cycle in the shower.  Hot enough to burn the skin off a chicken.  It had the original non-adjustable thermostat installed.  I changed it out with an adjustable thermostat and adjusted the temperature to the lowest setting.  After a full cycle hot water temperature at the shower is now 110F.   Still to hot for me but helps for those times when I forget to turn off the heater before the full heater cycle.

JohnF
2003 T/K and 1987 MP w/roof sleeper(for sale this Spring)
2003 TK
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #9 –
Quote from: JohnF  - 
To help save water I installed an adjustable thermostat for the hot water heater.  I got the idea from a post years ago from this group.  In my stick house I have the thermostat for the hot water heater set so hot water temperature is 105F in the shower.  In my new to me 2003 T/K it was 132F after a full heater cycle in the shower. 

An adjustable thermostat saves propane and reduces or eliminates having to mix hot with cold water, for a comfortable shower.
Ours water heater stays in the 105-110 degree range. Installing one takes about ten minutes and should be good for the life of the water heater..
Amazon.com: Atwood 93105 Adjustable Electronic Thermostat: Automotive

Larry
As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #10 –
Quote from: Chris Horst  - 
Is there a photo of the tee in your albums? Yes, I'm too lazy to scroll through all of them to try to find one.  :)
Chris


No, I didn't think it was all that special, it is plumbed into the shower hose.
I will try to post a pic. For adding a return line, something different would be more appropriate.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #11 –
Larry - that device I listed has a hot water indicator on it (cold, getting hot, is hot - no actual temps) - I think that is why it costs the big bucks :).  Yup still needs  plumbing added and the installation says make a hole in your shower (though apparently their device covers up the hole).

Jane

Sent from Yahoo Mail for iPhone
Jane & Scott
Currently have a 1989 TK  LD we did a lot of upgrades on.
Bigfoot 25RQ Twin on order with early summer 2024 ETA

Our smartphone autocorrects into very poor English.
 We disclaim the illusion of ignorance this creates as we have enough ignorance we rightly claim.
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #12 –
Quote from: JandS2  - 
Larry - that device I listed has a hot water indicator on it (cold, getting hot, is hot - no actual temps) - I think that is why it costs the big bucks :).  Yup still needs  plumbing added and the installation says make a hole in your shower (though apparently their device covers up the hole).
Jane

After you have used a hot water bypass a few times, you will know about how long it takes to flush the cold water, a temperature indicator is nice luxury but not necessary to accomplish the task.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #13 –
Just a note that I decided my original plan would cause the water pump to lose prime unless the return line were to run directly to a new port installed into the water tank. This might work for some floorplans. I edited my previous posts.

Steve


2004 FL
2013 Honda Fit
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #14 –
Quote from: Steve  - 
Just a note that I decided my original plan would cause the water pump to lose prime unless the return line were to run directly to a new port installed into the water tank. This might work for some floorplans. I edited my previous posts.

Why do you think the pump will lose its prime? No air is being introduced into the system, hot water circulating pumps in houses do the same thing.
How do you plan on returning the water directly to the tank? There are no available inlets unless you tap into the water fill tube.
That could tun into a very complicated plumbing run.
I would hesitate drilling a hole in the tank and glueing a fitting in. Normally fittings are either spin welded or hot-air welded into the plastic tanks. 
Glues do not bond well to polypropylene.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #15 –
Quote from: Larry W  - 
Why do you think the pump will lose its prime? No air is being introduced into the system, hot water circulating pumps in houses do the same thing.

Larry, sent you an e-mail. Splicing a ~20' run from the new valve of 1/2" PEX into the pump inlet line, which is initially filled with air. Turn on the pump, and it will suck in that air and lose its prime. Without prime, it cant pump the water it needs to flow to fill that 20' run. Let's say you somehow pre-fill the run with water, before turning on the pump the first time. Then, it might work. But, as soon as you turn off the pump, the line may start draining. Alternative, put the valve at the pump inlet end of the run. Valve closed, turn on the pump. It will run, filling the line until air pressure stops the flow. Open the valve, and the first thing the pump encounters will be the trapped air, and will likely lose prime. Last alternative, put a new bung in the tank for the return line:
Self Sealing TF-1 ½ Barb Tank Fitting - Specialty Recreation Inc TF1 -...
This avoids the issue by avoiding losing pump prime. I don't think I want to risk it, so have nixed the project.

Steve
2004 FL
2013 Honda Fit
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #16 –
Quote from: Steve  - 
Larry, sent you an e-mail. Splicing a ~20' run from the new valve of 1/2" PEX into the pump inlet line, which is initially filled with air. Turn on the pump, and it will suck in that air and lose its prime. Without prime, it cant pump the water it needs to flow to fill that 20' run. Let's say you somehow pre-fill the run with water, before turning on the pump the first time. Then, it might work. But, as soon as you turn off the pump, the line may start draining. Alternative, put the valve at the pump inlet end of the run. Valve closed, turn on the pump. It will run, filling the line until air pressure stops the flow. Open the valve, and the first thing the pump encounters will be the trapped air, and will likely lose prime. Last alternative, put a new bung in the tank for the return line:
Self Sealing TF-1 ½ Barb Tank Fitting - Specialty Recreation Inc TF1 -...
This avoids the issue by avoiding losing pump prime. I don't think I want to risk it, so have nixed the project.

If the return line is a closed loop, feeding directly into the pump's supply line, the initial prime would take extra time to flush the air out but it should do it. The pumps are positive displacement and are quite capable of self priming after being run dry.
The Revolution 4008 pump data sheet shows it is capable of self priming a 6' lift, it has plenty of suction power.
https://stage.shurflo.com/images/files/RV_Product_Data_Sheets/Fresh_Water_Pumps/pds-4008-101-X65.pdf

I see no reason why an additional length of hose, added to the circuit, would eliminate this capability, it might take a few seconds longer to prime, the first time it is powered up. . Once the return line is flushed air, it should never be an issue again.
Our LD's water pump often loses its prime after a long drive, within 20 seconds of running time, the pump flushes the air and starts working normally. I bet the same thing would happen with a close loop recirculation line.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #17 –
Larry, if you want to try it first, I'll lend a hand!

Steve
2004 FL
2013 Honda Fit
Re: Fresh water return - while waiting for hot water return cold water to fresh tank
Reply #18 –
Quote from: Steve  - 
Larry, if you want to try it first, I'll lend a hand!
Steve

I'll think about it
I once figure we lose around a gallon of water, every four to five-days (as long as a full tank of water last), waiting for hot water at the shower. Not sure how much work I'm willing to do to save such a small amount of water.
I was hoping you would prove the concept.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze