Attaching a timer to my water heater

[lappir]

My current location has metered electric and using my water heater I have kept it on the LP Gas mode for a couple of reasons. I don't require a lot of hot water and it's almost faster to heat a pan of water on the induction hot plate than it is to wait for the water heater to heat the 10 gallons for a quick pan of dishes or a wash up, so that's what I usually do. I will turn on the water heater for the dishwasher and the shower and always plan to turn it back off when finished, but yesterday after work walking by the water heater side of the trailer I heard the water heater heating and I had not been home all day. Such a waste keeping water hot when you don't need it. Light bulb moment. How about putting one of those bathroom timers you see in most hotel/motels for the "infrared" heating bulb. 

 

Has anyone done this?  I'm sure setting it for an hour in the morning would be more than enough for me to run the dishwasher and take a shower. Getting ready to look at the wiring under the switch might post a photo later of what I find. 

 

Rod

[Kirk W]

If I were to do that I would put it in the 12v supply as that would be the same as turning it off with the controls. If you’re 120v side is not controlled by the circuit board you may want another 120v one where the wall switch is. 
 

I have never done it but see no problem with doing so. 

[palmeris]

Just make sure the timer switch you select can handle the current of the heater circuit it will be interrupting 

[Kirk W]

54 minutes ago, palmeris said:

Just make sure the timer switch you select can handle the current of the heater circuit it will be interrupting 

A valid point. The current load shouldn't be a big problem if the 120V heater is an OEM one, it will have a heating element between 1000 & 1400 watts, That means current load of 9-12a for the 120V side. 

[ms60ocb]

If the the timer contacts is installed in parallel to the control panel ON-OFF that would be low voltage for the control board.

Are you using a mechanical timer or if looking at programable timer make sure the contacts are isolated from the supplied power.

Clay

[Kirk W]

25 minutes ago, ms60ocb said:

If the the timer contacts is installed in parallel to the control panel ON-OFF that would be low voltage for the control board.

The timer would not turn it off if wired in parallel. That would allow either one to turn it on but require both to turn it off. The timer should be in series and one that has an always on position. 

Edited September 12, 2021 by Kirk W

[Star Dreamer]

If you want to control the propane side of the hot water heater, you will have to put the timer on the 12 volt side. Actually on our hot water heater both are controlled by a 12 volt switch. As an alternative, you could do what I recently did which was adding LED indicator lights to our switch panel so that I can see which one is on easier. We accidentally left our electric switch on while we were running off the inverter and about 4am the inverter kicked out on its low voltage setting. Heard it alarm and noticed the switch still on. Still had enough voltage to fire the generator and recharge to batteries. 

[lappir]

Thanks to all for the replies. There are two separate switches for the heater. One turns on and off the gas portion and it has a nice red light that indicates when the gas is running or it's trying to light and the tank is empty. The other one is in a really bad place and is no longer working, and part of the reason I am currently using gas. I replaced that switch once and it worked for while but now I think the electric side of the thermostat that turns on the heat when the water temperature falls to a certain level has burnt out. The heater still works well on the gas side. 

Depending on which park I am able to get into at my next location will determine if I wish to fix the electric side yet or not. One park charges a little more and has no meters for electric the other one only charges if the meter goes above $50. I'm hoping to get into that park, but there seems to be a waiting list even for the winter months. 

My current park charges monthly for electric and my highest bill has been a little over $40 with temperatures in the 90's for most of the month. I have not tested my electric when I'm heating instead of cooling yet. The charge last month when the temps were more to my liking was a little over $20. 

 

Rod

[Wrknrvr]

  What model water heater do you have.   some Dometic heaters have 12 vdc control relay on the back side of the unit. That relay controls the 110 vac. Or you could install one of those relays to do the job.

 

   Vern

[sandsys]

In my van my water heater was electric and it had its own circuit breaker. I would turn it on to heat water then turn it off after just enough time has passed to heat water to shower temperature without adding cold water. It would then stay warm enough to do dishes later. Mine was only a 2.5 gallon heater so that took ten minutes. I don't know how long it would take for a 10 gallon heater.

Linda

[Kirk W]

3 hours ago, lappir said:

The other one is in a really bad place and is no longer working, and part of the reason I am currently using gas. I replaced that switch once and it worked for while but now I think the electric side of the thermostat that turns on the heat when the water temperature falls to a certain level has burnt out.

The question is, if the switch is 120V or not. If it was supplied as part of the water heater then is should look like one of these.

   

With the Atwood, both switches are 12V and I believe that is probably true for the Suburban, but I have not seen one like it nor can I find a schematic for their water heaters to be sure. From what you say in your post it would sound like you have a wall switch such as in a stick house?  If so I'm quite sure that it will be 120V as that has been quite common in RVs.

         

If you have a volt/ohm meter it is pretty easy to check to see if there is voltage to the switch and whether or not that switch is good. With an Atwood water heater that uses the double switch assembly, the same thermostat is used to control temperature for either heat source. The only schematic that I can find for a Suburban combination looks so much like that of Atwood that I'm not so sure it is from Suburban, but if accurate it also shares a thermostat. If you have the wall switch type situation, then there is a separate thermostat for each heat source no matter which brand yours is as both manufacturers at one time used completely separate control systems with an RV builder supplied switch for the 120V element. The advantage to that was they it was possible to use both gas and electric at the same time, which I'm not sure about with the latest combination units. 

[lappir]

Mine is a Suburban and has what I believe is a 12 volt line to it for both the gas and electric switches. Will check voltage before making any changes. Didn't have time today with other more important jobs to do. 

Thanks for your reply and suggestions. 

Rod

 

[Kirk W]

Keep us posted. If you get the chance, post a picture of the problem switch. 

[noteven]

Those water heater switch panels are designed to confuse rookie rv'rs'z right?

... um ... what does "I" and "O" mean on a switch again? 

 

Edited September 13, 2021 by noteven

[ms60ocb]

On 9/12/2021 at 8:39 AM, Kirk W said:

The timer would not turn it off if wired in parallel. That would allow either one to turn it on but require both to turn it off. The timer should be in series and one that has an always on position. 

Not to disagree but I assumed the timer having open contacts at rest and closed contact(s) when the timer is counting down the time interval. Wiring in parallel gives you the either switch will engage the heater, where as using series contacts would give heat only when the timer is running. and power switch is on.

#1 advantage of Series contacts is your water will only be heated on your command of the timer.

My #1 advantage of Parallel contacts is if the outside temperature is below freezing you may need to have the water heated all night (and especially if you have wind hitting that side the RV)

Clay

[bobsallyh]

noteven, I don't care if you are a rookie or a veteran RVer, don't get me started on the "I" and "O" deal on switches. Like the old AT&T commercial "I could just reach out and touch someone".

[Kirk W]

Quote

 Wiring in parallel gives you the either switch will engage the heater, where as using series contacts would give heat only when the timer is running. and power switch is on.

And if the switch is closed timer does nothing. Actually what I would do is to replace the switch with a timer that has an always on position as most timers do. 

Edited September 13, 2021 by Kirk W

[hemsteadc]

You have a dishwasher in your RV?

[Kirk W]

Here is an example of what I think that I would use if it will fit into the space available. It allows you to preprogram the times on and off, or to override it to be on or off. 

In my opinion I really believe that this would be much better than my previous reply and eliminate any issue of series or parallel switches. 

Edited September 13, 2021 by Kirk W

[JimK]

When it comes to shower water, I follow Sandsys's protocol.  I set an egg timer for the length of time needed to heat water for a shower.  I heat the water so I can take a shower without adding cold or needing to adjust the temperature.  For dishes, I heat a kettle of water.  

[noteven]

Ray on the Love Your RV channel did a video about installing a thermometer between the tank and insulation with remote read out.

[lappir]

Finally here is the photo I took of the switch for the gas portion of the heater. Haven't dug out the multi meter yet to check the voltage, but am feeling it's 12 volt. Other activities have prevented me from shopping for a simple timer. It will be the simple mechanical one I hope. 

Rod

[Kirk W]

3 hours ago, lappir said:

Haven't dug out the multi meter yet to check the voltage, but am feeling it's 12 volt.

I would bet a huge amount that it is 12V since the propane side of both Atwood and Suburban water heaters use only 12V power and even if you had one of the combo switches that i posted pictures of, those are also 12V, direct current from your RVs battery & converter supplied circuitry. That looks like the exact switch setup that we have in our travel trailer for our Suburban water heater. Ours doesn't have any 120V heating capability, which makes me wonder if the 120V heater that you have might not be an aftermarket one that was added by a previous owner?

3 hours ago, lappir said:

It will be the simple mechanical one I hope. 

I would get one of those which also has the always on position on the timer and then just mount it next to the existing switch. I'd leave the wires on the light so that it would still operate, just as it does now and then connect the two leads from the present switch to the two connections of the timer. Turn off all 12V power first to prevent any arcs and sparks!

[podwerkz]

Years ago (back in 2000!) in my old Itasca Class A, I installed a wind-up timer switch in series with the on-off WH switch on the 12v propane side. I drilled a hole and mounted the switch and the plate it came with in an easy to access area, close to the ON-OFF switch panel.

I used a 30 min rotary switch because that's all it took to heat water enough to take a quick shower (one person) in the winter. Summer time, I'd wind it to the 15 minute mark. Still plenty hot enough. If you are boondocking, as I was, it's a good way to save propane.

You just leave the rocker switch ON and control the WH with the wind-up switch.

And you never ever have to worry about it again. 

If yours has the 120v element, you could control that side with a separate wind-up switch, as long as the current rating is adequate. 

 

 

 

 

 

 

 

 

Edited September 16, 2021 by podwerkz