To Pump, or Not to Pump?

Pressurize RV Water HeaterAn interesting debate came up while troubleshooting and fixing our RV slide out leak.

El Jefe suggested that whenever dry-camping, we should turn off our water pump at night and when we leave the rig unattended for a long time. I didn’t like the idea of doing this because the water heater needs to remain pressurized or the element could burn out.

Turning off the pump does make sense. It can avoid a big mess if a leak were to occur in our absence. René actually found a discussion online where one poor soul allowed his pump to run intermittently all night, only to awake to a seriously flooded compartment and empty freshwater tank.

However, our Arctic Fox manufacturer recommends pressurizing the water heater before turning it on. To me, this clearly means keeping the water heater pressurized whenever it is on.

For the few days we were investigating our leak, René insisted that we turn off the pump. I conceded. As far as we can tell, our water heater element was not damaged. But who knows how long it would take to actually burn up. And it’s not like it was dry – it was full of hot water. It wasn’t working very hard here in Florida either!

I suppose the best thing to do, would be to turn off both the pump and the water heater. But I like my warm shower in the morning. We finally agreed to follow the manufacturer’s recommendations. We leave the pump on and pay close attention to the water pump.

If you ever hear your pump engage regularly without any faucets on, turn it off and start looking for a leak!

But if you hear it once in a while, don’t panic. I’ve determined that it is normal for the pump to engage for a few seconds up to a few times a day. It must compensate for pressure lost by evaporation in the water heater, or air escaping the faucets.

6 Responses to “To Pump, or Not to Pump?”

  1. Well our little “RV” does not have a hot water heater but it does have a pump 🙂

    I do know a bit about hot water heaters and I agree with what el jefe and John have to say with one small modification to Johns comment.

    Pump off and heater on but keep your tank full. The higher the pressure in the tank the higher the boiling point of the water. Added bonus: a full tank provides no headspace for steam to build up.

    Jim, you also mentioned that you have both gas and electric heating elements, your electric element may or may not be at the bottom of the tank.


  2. pump off,heater on, chingow !!

  3. I was hoping this post might generate this type of discussion. Thanks for all the feedback.

    It got me thinking that leaving the pump on could actually cause more damage if there was a leak. Not just flooding, but if the the pump emptied the heater tank, the element would then also burn out!

    And yes, I suppose we could save a gram or two of propane by not heating the water overnight when boondocking. But the heater tank is small enough and so well insulated that it stays pretty warm anyway. So that debate could go either way.

    We have not yet actually put it to the test of letting it “cool down” overnight. But when we get to Colorado and need to get up at dawn to hay the horses, we will need two hot showers, and fast!

    FYI: The water heater in our Arctic Fox is either AC or propane, with DC voltage only required for ignition.

  4. The warning label is to ensure there is water IN your tank. As long as your element is covered, you will be fine. The electric element is fairly low in the tank. We have turned off the pump ever since we were newbeies… Just make sure there is some water in the Water heater tank. Sleep better, and turn off the pump when not in use. There is some argument that leaving the pump under pressure all the time will do damage to the pump itself.


  5. Mike and Cindi January 21, 2008 at 11:58 pm Reply

    How big is your water heater tank? Can’t be more than 6-10 gallons, if that.. How long does it take to heat up from an overnight of being off (both tank/heater and pump)?

    When you are on shore power I guess its just like at home when most tank water heater folks leave their hot water tank ‘idling’ 24 hours a day for the few times you might use hot water (shower/dish washing/etc..). When you are dry camping, are you are running your WH on propane or 12 volt DC only? Do you leave your water heater on all the time then or just turn it on prior to your needs?
    Just curious as to why it needs to be left on at all times or am I reading this wrong..?

    cold and rainy in Eureka


  6. what the sticker on the heater is advising you is to be certain that you have pushed all the air out of the heater tank so as not to have an air bubble that will cause heating problems. bleed the heater by letting the hot water run till you get no air out of the faucet. you will not harm the uniit if you turn off the pump overnight, you certainly avoid the chance of flooding the casa whilst you snooze !!

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