Add Timer to Circulating Pump for Instant Hot Water at Camper Bath Faucet

    The purpose

    Circulating pump addition works nice.. the below, adding a timer, mostly for my own use/documentation as I go. Just shear laziness, instead of holding the momentary to get hot water, which counting early in the morning sometimes a challenge, the timer would allow just touching switch and wait till pump turns off. Whether or not useful to anyone doubtful but you've been warned...

      The "Proof of concept" (or round 3 of circulating pump install)

    After successfully completing install of the hot water circulating pump that had been on the round-to-it for several years I pondered a timer, either heat measuring or timed. Just a matter of convenience so pump run time is controlled by it instead of holding switch.

    Looking around most options were either to elaborate for what I wanted, required more space than I had, were plumbed into water lines or simply way too expensive. I'm not sure how but I stumbled upon these small electronic multi-functional timers. Other wise likely I wouldn't have done anything and continued manually using momentary switch.

    timer at

    But if these timers actually work would be way simple to wire in. I honestly felt like it was snake oil, but watching the videos was what convinced me to try one. If nothing else to verify, "that cant work". For the price and to satisfy my curiosity I felt worth the gamble just to see. It would be perfect.

    And it is. Though I cant address longevity they have lifetime warranty. Having installed and used the timer its just an amazing little thing and perfect for our use. I'm just using its most basic ability, turn on component for X amount of time and then shut off. What you can program this timer do is unreal. I usually don't offer recommendations much, direct links less but I'm impressed. If you have the need, these timers worth looking at. The options and adjustability and what they could be used for worth watching the videos, downloading the manual just to check out. One is the optional trigger feature. Not only does it cycle our pump, but I could set up where another action causes timer to start, say put a micro switch in bath medicine cabinet, open the door and hot water circulates in anticipation you might want hot water. Just one use. I likely will be getting another timer to control a relay that will power USB charging ports were adding.

    Unfortunately my install may detract from the simplicity of the timer but without it I'd still be "holding the button".

      Round 3

    Adding timer switch.

    Ordered Monday, it arrived few days later. Unfortunately was a brake light flasher. I believe their primary business. oh boy-maybe I should have heeded my apprehension. Emailed seller and received response within an hour-- on a Saturday! Correct one is in the mail. Wow! That to me says a lot. Get so used to dealing with corporate mentality forget what its like to deal with people and small companies who really do consider customer No 1. So refreshing. Still, as I have another few days for timer to arrive decided to rewire getting ready.

    Timer is a small electronic box no bigger than a postage stamp. I don't know & wouldn't offer a clue how this it works. I'm basically adding new timer inline between momentary switch and pump. I could change switch to an on/off, turn on and timer runs programmed time and then shuts off. The issue, if it is one, is turning power to timer off and back on to rerun.

    Though mostly too lazy to replace existing switch, by using momentary switch and adding a relay, the timer becomes self latching. Or more simply, briefly push the momentary switch which sends power to timer, it turns on and sends power to pump AND triggers relay. The relay once turned on connects power from un switched source (before momentary switch) and feeds the timer. Creating a loop. When timer shuts off power, relay also shuts off. No power used when timer stops.

    And the plan, installing so that circulating pump, timer, and momentary switch is still fed by power being sent to main water pump.

    I added constant power lead (small red wire from water pump switch) that by passes momentary switch and relay to make timer setup easier. When not used and I assume once timer setup and happy with how long pump runs, this wire will feed a needed light inside cabinet. It is switched by the water pump switch, I have some different plunger switches that I'll add inline so the only time light will be on is if door is open and water switch turned on (light not burning up precious volts when washing dishes etc).

    Anyway timer setup is accomplished by grounding leads #1&2 'then' turning on power, quickly disconnect ground from leads leaving power on. That puts you in time setup mode. Then ground #1 for desired time you want ( X seconds to hours) , I'm guessing 10 seconds. Once time set, briefly ground both #1&2 again- that puts in function setup mode. I believe timer has 17 different functions. Ill be using function number 2, turn on power for programmed time then shut off. So I will ground the white wire quickly twice. Once setup is complete turn Off main power, reconnect. Timer should in my case immediately turn on power for 10 seconds then shut off.

    If I want to change time repeat, disconnect power, ground both leads, turn on power then quickly disconnect ground leaving power on. Ground the white wire for time wanted. You don't have to repeat function selection so just exit setup by turning power off then back on. Timer should reflect change you made in time and still do same function.

    In case you were wondering above are really instructions for me. Same with wiring details-so down the road I have something to look at when trying to figure out what the heck I did.

    The rewire-

    First there is nothing in the bathroom to ground to. I had run a length of 22ga originally when remote water pump switch was added for led pilot lamp. When I set this new pump up i temporarily used but though pump draws less than an amp, not adequate. Plus I need to ground timer, relay and possible light fixture. I painfully ran a new 16ga lead from bath to ground lug at inverter. I made a ground buss to easily connect all this stuff and future use.

    Kinda fun. Out of the bathroom at least. Took water pump switch back out and to shop.

    The reality...

    Wired..Once timer arrives it will plug in. Because of limited room components will get mounted where they will fit. Hence the long wires.

    And tidied up. A is normal power that will plug into timer in E from momentary switch. Attached second yellow lead is from relay.

    B is alternate constant power from water pump switch (used for timer set up and then used later to power light).

    C is Pump lead that will plug into D, which is output from timer.

    So A feeds timer via yellow wire from momentary switch, timer sends power to pump via D/C, small red branch wire also energize relay sending power to timer via A so keeps timer powered after momentary released until timer reaches end of time cycle. Relay power is from water pump feed.

    Workarounds: If relay fails the momentary can be held to power pump, if continue holding, timer will still only power pump for set time. If timer fails, A can be directly plugged into C and pump can still be 'manually' timed.

    Most suspect to me is cheezy momentary switch. Where A is plugged into momentary could be unplugged and manually touched to other 12v source, timer would engage really and run pump. Or everything can be taken down by unplugging the momentary, or ground leads.

    Couple of days later

    Still waiting for timer to button this up decided to pursue couple of things. One is the configuration wires. Once this is all installed it will be painful to configure, locating and manually grounding the setup wires thru the cabinet door. The seller uses couple of momentary switches in his videos. But if I used a DPDT momentary I could use only 1 switch. Found one, USA made and at local RV shop. Same size, 1/2x3/4", as what's used on our stove vent Gen start, though cant imagine what a double momentary used for, prime. (IF other functions of timer utilized or trigger wire where green wire is also used singularly for setup this switch won't work-use 2 momentary)

    Then figured be easier if mounted so cut up an old switch plate using dremel.

    Shaped to fit space then cut a plug to fill remaining hole (couldn't have had a blank on hand). Installed a pilot lamp. It will be tied to timer power out to pump, ground using switch. Don't need a pilot light to know pump is on but I can and want to unplug the pump during setup and use pilot lamp to configure. Dremeled recess and painted to mark which is grounding both wires (to enter setup mode) and single for entering time or selecting function.

    Grounds added to center each pole. Soldered on small jumper to ground pilot. White wire from timer goes to both legs of bottom pole. Green only one side. So flip the switch to left grounds both wires, to right only the white. Should make set up simple and easily changed. All I have to do is unplug pump and plug timer to constant power. Ya I briefly thought about adding another switch..but really once setup, unless timer loses memory, shouldn't have to reset timer. But will be a snap if I want to adjust time.

    I was going to do some other day but went a head and setup light. Not really apart of this project but now that I have ground source and a power wire already available (And time) might as well since I'm here. Light is an old LED panel light, perfect inside cabinet. Made a small wood bracket to hang over door inside. Draws less than 0.1 amp. but when I get a switch I'll add to door so its only on if the doors open.

    Looks like a mess but its pretty simple albeit very crude. Once mounted should end up a bit more sanitary. When the timer arrives its just staking correct bullets or spades & plug it in. Easy to add after installing components in camper but I want to see it in the shop functioning. If it were not for the location (unseen) I could see miniaturizing considerably. Now that its done and laid out, even hardwiring components I used, could be the size of playing card. Other than the relay, I used an off-the shelf 30 amp automotive type, its huge, main bulk of this is just the wires and plugs. But a scratch build on a board this whole circuit could be about the size of a match box. I'm not, just saying you could. Other than timer and DPDT switch, all stuff I had on hand.

    Revised diagram

    ....still waiting for timer

    Hokey smoke its here-

    hokey smoke its tiny!

    Hooked it up and simply amazed. Played with it for quite a while. Just pretty neat. And I cant access some of the functions this little thing can perform due to setup DPDT switch i used. I set up to turn on for 10 seconds then off.

    Light is tied directly to main water pump power. When water pump turned on it turns on light and sends power to momentary. Hit momentary switch and it turns on timer which sends power out to circ. pump (for 10 seconds). Relay trigger (and pilot) is tied to power out so relay engages, keeping power on (for 10 seconds) without holding momentary. After 10 seconds timer shuts off, relay, pump and pilot turn off. Push the momentary cycle is repeated. Main advantage in using relay to make self latching. Using an on/off switch you would have to turn off the power to timer then turn back on to cycle timer.

    Anyway it works, fun stuff. I'm showing about 0.15 amps for this circuit, pilots- timer and relay. When circulating pump connected, rated at 1 amp, will be less than 1.5 amps for 10 seconds to have hot water at the tap! I have a 2 amp fuse. New timer is rated for 5 amp load so way under.

    Ready to put this prewired Octopus in the camper.

    Except...I had added the extra constant power wire from water pump switch to use when setting up timer and use to power light when not setting up timer. I realized once mounted in camper simply holding the momentary would be easier than swapping power source for timer. Which would involve unplugging timer from momentary switch and the light from constant water pump power wire, then connecting timer to the light wire. Then putting it all back after setup complete. Would be nice to not have to hold the momentary while setting up (really only takes a few seconds) but its all the wire swapping NOT. I briefly thought I could add a switch to select power source.

    However- even though plate holding setup switch is pretty much inaccessible unless desired, my plan is to disconnect the ground wire from setup switch when not using so timers setup isn't inadvertently screwed up. Also when setting up timer in camper if needed, planned was disconnecting power to the circulating pump so its not being cycled while setting up timer. Then it occurred to me a simple on/on or an on/off/on SPDT switch from ground buss. Run the grounds from pump and setup switch to it. Toggling to ground for the setup up switch would disconnect pump ground, toggling ground for pump to run would disable setup switch and pilot. NO wire swapping. Flick the switch for setup-flick the switch to run. So back to my salvage box....

    Found an old on/on DPDT flanged slide switch, wired it in after drilling plate and opening up hole. Slide the switch to ground setup switch, pump cant come on while setting up. Though relay does- hadn't thought about that- not an issue because all Ill be doing is adjusting time so its constant on. Adjusting function where relay might be switching on and off Id probably pull its ground but unless timer loses memory should never have to do that. For my use-this works and I think were done and put in camper.

    Finally back in the camper. Adding switches and shrink tubing staked fittings a LOT more fun than working in here... Got the relay hung and water pump switch remounted. Course I had to take back off- just not enough room to work past it to add ground buss, let alone see it. Camera sees a lot more than I can.

    And ground buss installed. Remounted water pump switch plate. Plugged everything in and attached the ground wires. Mounted the set up switch plate and timer. I ended up attaching another block of wood to support top of set switch plate.The timer is directly behind. I think adding the switch on grounds was a good call, plugging in the wires with one hand a bit of a pain. Ground buss easily accessible though.

      UPdate 5/19 adding this pic cause I went to pull this plate and couldn't get it off. Adding a switch in kitchen to activate circ.pump...tieing to output of this momentary switch so needed access..

      Simply forgot I had added small block that's screwed to side behind switch mentioned above...doh
      Add second circulating switch

      Mounting the light

    Glued and screwed the mount block to hang light. Light is screwed to bottom edge. Mounted the light and plugged it in.

    Wow! Turned on the water pump switch to test circulating pump and timer function. Little LED light is nice!

    Pushed the red momentary, circulating pump ran for 10 seconds-shut off. Slid the ground switch over to setup. Hit the momentary, only the red pilot (& relay) comes on, no pump. Push and held 2 dot momentary set up switch, then pushed and held the red momentary releasing the setup switch, red pilot blinks letting me know timer is in set up mode. Released the red momentary turning off power to timer canceling out of set up. Slid the ground switch back over to pump-hit the red momentary circ pump comes on and runs for 10 seconds. Cool-happy camper...Tomorrow Ill light the water heater- check time on circulating pump. If its not enough may actually decrease the time, so for subsequent reheating when water isn't being used pump doesn't run unnecessarily. Initial cold start means reheating when water isn't being used pump doesn't run unnecessarily. Initial cold start means bumping momentary twice, hmm maybe not.

    I'm sure when she's washing her face in the morning the instant hot water will be appreciated, but got a feeling this little light as much so. It was impossible to see in there.

    Final wiring diagram

    Just to recap.
    My other convoluted wiring removed-basic self latching timer

  • Timer power and circulating pump is from water pump feed so can only be activated when water pressure present.
  • When momentary switch pushed it turns on timer,
  • Timer sends power to recirculating pump for its programmed time and also to relay terminal #86 turning on relay
  • Relay on, it connects 12v from 'before' the momentary switch thru terminal #87 to #30 which powers timer, keeping alive.
  • This 'loop' maintains power to timer, bypassing switch until timers program turns off, disconnecting relay, turning off               circulating pump.
  • So briefly push momentary switch, circulating pump runs for programmed time, shuts off. Hot water available.
  • Alternately could just hold momentary switch instead of relay until pumps shuts off. Of coarse at that point you could just use an on/off switch and not use a timer.

  1. Turn on pump switch A (main power)
  2. Slide switch D to right (removes ground from pump, grounds switch C, setup mode)
  3. Push & hold configuration switch C to : side. (double dot)
  4. Push & hold power switch B, release switch C (Red pilot will turn on for 3 seconds, now in setup.)
        NOTE continuously hold the red power switch B until configuration complete, last step #8.)
  5. Push switch C to . side. (single dot) X seconds and release. (Sets pump run time -ours is 10 seconds)
  6. Push & hold switch C to : side. (double dot) Red pilot will light for 3 seconds, back in setup next mode.
  7. Push switch C to . side (single dot) & release two times. (Timer function is now set to #2)
  8. Release power switch B, slide switch D to left (restores ground to pump, now in run mode)
  9. Push red button A to test, pump should come on for 10 seconds then shut off
 10. Turn off pump switch A (main power).
   To change only pump run time steps 1,2,3,4,5 holding for new time, then 8.

 Once setup, at any time when main water pump switch A is on,
  pressing the red button B will turn on recycling pump for 10 seconds

      Update 04/2019
    At this writing, about 3 1/2" years later, system is still working well. We discovered when the bathroom circulating pump is activated, kitchen faucet is also instant hot. Even though closer to water heater so not as much water wasted, when cold, would go to bathroom to turn on circulating pump. Decided to add a momentary switch in kitchen (Link) to activate circulating pump. Opened up this page to see where to tie in new switch. (piggy back off of momentary switch output or relay #30).

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