Recycling shower

 

Simple DIY recycling shower for the boat

 

Relatively simple.

Requirements

• Use onboard pressurized water.
• Use onboard water heater as main source of heat.
• Allow to work in "clean shower" and "recycling" mode.
• Automated temperature control.
• Total cost below $350; 
• Nice to have
  
• Hair strainer/filter in return line.
• Capability to use electric heater for recycled water.
•  Service cycle to refresh system with clean water.
• Winterizing cycle to fill shower system with antifreeze

 

Revision 2 (Thermally regulated valve, pressurized mixing/ water-air separating  head)

Construction

 

Air/water separator

• Separator constructed from 1 ft long 4" PVC pipe. 
• From bottom reducer 4" to 1/2" mounted
• From top side reducer to 1" mounted
• Over the top T connector with 1"x1/2"x1" then reducer to 1/2".
• 1" to 1/2" reducer drilled out to let pipe go thru.
• Pipe inserted down to  about an inch stick down to  4" pipe volume.
• 1/2" Thread adapter installed on the top.
• 1/2" Thread adapter installed on T and tank bottom
• Two water sensors  mounted in 1/4 tank height and 1/2. (Level1 and Level 2  on picture)

Design is in development

Revision 1 (just  electric valves, no pressurized mix tank)

 Construction

 

Two pumps ($130)

1. Pump 1 - shower pressure pump membrane  type.
• centrifugal pressure pump may be installed but will require tank mounted above it and air discharge line - tiny tubing from pump outlet back to the tank.
2. Pump 2 - return/discharge pump mainly membrane type
• Centrifugal pump may be used if small sump box added at shower pan discharge.
• If  you use centrifugal pump must be able to make a pressure to use simple solenoid valves, otherwise, motorized ball valves requires. 

Small water tank (left on the picture) ($20)

•      must be about 8 liters size to serve water to shower for  at least 30 seconds to let water time to recycle.

Tank level sensor to maintain water flow. ($15)

• 0->Level A - Bottom 3 liters - "mixing bowl" minimum volume to mix water, control temperature, and make right temperature .
• Level A->Level B - 3 liters  - Zone to maintain level when recycling in use
• Level B -> Level C - 2 liters - Recycle "safe overfill zone"

Electrically controlled valves. Qty 7 ($5 x 7 = $35)

Pipes, fittings, clamps and other matherials ($20)

Ip67 foot switch (Cheap windlass switch) $15)

Microcontroller board and control ($95).

 How it works.

1. Shower prep step.

• User set temperature and press button to prepare shower.
• Open V7 and wait until return to tank water gets above set or fixed time what will be first.
• Controller closes V7 and start manipulate V5 and V6 to fill tank with warm water.
• V5 and V6 close at Level A 
• Controller reports "ready" or "ready cold" if temperature is not hot enough.

2A. Option "option clean shower"

• Pump1 and  Pump2 run.
• V1controlled by foot switch. (shoot off in 10-15 seconds or instantly if switch deactivated)
  
• V2 closed
• V3 open. 
• V4 closed
  
• V5 and V6 modulate fresh water to keep water above Level A.
• Valve V7 Closed
  

2B. Option "recycle shower"

• Pump1 and Pump2 run.
• V1controlled by foot switch. (Switch works in On/Off mode)
  
• Valve V2
  
• V2 closed if Tank level Below Level C
• V2 closed if Tank level Above Level C (discharge from tank if overfilled)
  
• Valves V3 and V4
  
• V3 open, V4 close  if tank below Level B (run recycle water to feed tank)
  
• V4 open, V3 close  if tank above Level B (run recycle water overboard)
•  
  
• Valve V5 and V6 
• ValveV6 opens if need get water temperature up.
  
• Add water if level drops below Level A. (temperature control works)
  
• Valve V7 Closed 

3. Finishing (activates "Off" button or by 15-20 minutes timeout )

• Pump1 and Pump2 run.
• V1controlled by foot pedal.
• V2 Activates after timeout if pedal not activated for couple minutes. 
• V3 Open
• V4 closed
• V5 and V6 closed
• V7 closed

4. Off  

•     All pumps and valves Off

5 Hot water purge (by demand button activated)

• Open V7 and wait until return to tank water gets above set or fixed time what will be first.
  

 

Service  FUNCTIONS 

 6. Tank Service  (wash the system or winterizing with main water source antifreeze.)

• User have to put shower head close to pan discharge.
• Some cleaning solution may be purred in discharge spigot.
• User activates clean cycle.
• Open V7 and wait until return to tank water gets above set or fixed time what will be first.
  
• V5 open for couple seconds. and close.
  
• V6 opens until level C reached and close. 
• [as an option it may continue little more to purge air vent with water]
  
• Pump 1 start run
• Wait 5 seconds
  
• Pump 2 starts, V4 and V1 open.
• System runs 5-10 minutes (running water in cycle)
• V4 close, V3 open (start discharging return water over board)
  
• Wait 10 seconds
• V2 Open, V1 close (start discharging shower water)
• Runs all until tank gets below Level A and add time to pump all water from the tank (1 min) after

  6.  Local "Winterizing"

• User have to put shower head close to pan discharge.
• Function activated by user
• Pump 2 starts.
• V4 open
  
• Drain gallon of  antifreeze (or cheap vodka ;-) to shower pan.
• Run some time enough to suck a gallon + 30 seconds to let user be not in rush. (a minute?)
• Start Pump 1 , Open V1
• Wait for minute.
• Open V3 and close V4
• Wait time enough to drain half a gallon (10-15sec)
  
• Close V1, Open V2
  
• Wait time enough to pump all out (1-2 minutes)
• Stop pumps close all valves.
  

Improvements may be done but not essential:

Small sump box in between pan and Pump2.

Strainer and filter, UV lamp in recycle line before Pump 2.

Insulate tank  to keep water warm.

Insulate return pipe. 

Add aux heater into the tank.

Add

Control board

I will designed board with small controller on it, not a hard. 

(Specialized board cost about $70 + control switches 10$ +  Ip68 box $10 + 2 temperature sensors $5)

Inputs:

• Resistive level sensor float type sensor will be the best option because it does not react on splashed water and measure real liquid level. (but reliability may be an issue in long run)
• other option 3 optical capacities sensors more reliable, but may false react on  splashed water.
• User control buttons 
• "Off"
  
• "Prepare"
  
• "Fresh shower"
• "Recycle Shower"
• "Service"
•  "Foot switch" input. 
• "Temp. up"
• "Temp. down"
• Two Temperature sensors  

Outputs:

• Indicator (3 x 7 segment LED indicators )
• 2 x 3 color LED to show work mode
• 7 solenoid control activation outputs
• 2 pump control outputs
• Aux. Heater element output control