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RobWNY's avatar
RobWNY
Explorer
Aug 02, 2018

Dometic 320 has weak flush using Water Pump

I replaced my Dometic 300 all plastic toilet with the Dometic 320 without the spray wand. The old toilet flushed fine using the 12v pump. There was plenty of pressure but the seat made so much popping noise when you sat on it that it woke everyone up and the seat couldn't be replaced without a lot of modification so I bought a new toilet. After reading numerous great reviews about the Dometic 320 toilet, that's what I bought. When flushing using a city water hookup it does a fine job of cleaning the toilet bowl but when using the water pump, the flush is weak and requires further cleaning. All faucets work as they always have so the pump isn't bad. Would a new high volume water pump be the solution or is it just how the Dometic 320 is going to handle flushing with any 12v pump?
  • Njmurvin's avatar
    Njmurvin
    Explorer
    Aug 03, 2018
    When I bought mine, it arrived in the box filled to the brim with styrofoam popcorn. Even the bowl was full of the stuff. I had to dig it out of every nook and cranny. If yours was similarly packed, it's possible a small chunk made it into the waterway. Not sure that would explain the difference between city water and tank/pump operation. I have used mine both ways. I don't recall a huge difference in performance. I hope you figure it out. It's a great toilet.
  • RobWNY's avatar
    RobWNY
    Explorer
    Aug 03, 2018
    I found the pump. Without taking everything apart, I was able to see that it's a Shurflo 4008 and pumps 3G per minute. Which model within the 4008 family of pumps, I wasn't able to see on the sticker. I'm betting that it's the bottom of the line/cheapest one as it's the original in the camper. I was able to see the strainer and it doesn't have any debris that would block water flow.
  • RobWNY's avatar
    RobWNY
    Explorer
    Aug 03, 2018
    I'll have to take another look for where the pump is to get the make/model info. It's not mounted in the obvious locations so likely behind the panel in the pass through. the weak water flow is in the front of the bowl. The water flows better in the back of the bowl. The shower has plenty of water pressure as do all other faucets other than the outside shower. They notoriously have poor pressure anyway. Like I said, on a city water hookup without regulation, everything works fine. I don't know the amount of pressure though. Likely not a blockage in the water line. I'll report back when I have more info to provide.
  • Isaac-1's avatar
    Isaac-1
    Explorer
    Aug 03, 2018
    I too have installed a Dometic 320 a few months ago, you might try adding an accumulator tank to give you some instantly available water volume.
  • MFL's avatar
    MFL
    Nomad II
    Aug 03, 2018
    Forgot to mention, I think the only difference between 320, and 310, is a better seat on the 20.

    Jerry
  • MFL's avatar
    MFL
    Nomad II
    Aug 03, 2018
    My 310 works perfectly with my water pump. Any more pressure would send water over the rim. Rob, do you have good pressure at shower, and other faucets with the pump? If good you may have an obstruction, or kink in toilet water line.

    For me, city water usually has to be regulated, or it will throw water over bowel edge.

    Jerry
  • rhagfo's avatar
    rhagfo
    Explorer III
    Aug 02, 2018
    Super_Dave wrote:
    Are you prefilling the bowl?


    The bowl is porcelain even if you don’t prefill it rinses clean easily. We had low water pressure at our last host site, and never had an issue.

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