Mainline Fullport Backwater Valve Question

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by mccallum, Feb 19, 2008.

  1. mccallum

    mccallum New Member

    Messages:
    7
    I planned a basement renovation on a 60yr old house and decided on replacing the existing cast iron lines with ABS, since I was already digging up the place.

    I decided on adding a new backwater valve that has been winning awards for its design. I purchased a 4" Mainline Fullport Backwater Valve and I was all set to install it this weekend. I broke up the concrete and I was surprised to find a 3" sewer main and not 4". The cleanout was 4", so I assumed the main would be 4" as well....wrong assumption.

    So this is my question...since Mainline only makes a 4" version of this type of normally open backwater valve, is it rediculous to use 4" to 3" reducers on either side of this 4" valve on the 3" main?? or will this cause problems?

    I really would like to use this valve....is it possible given the circumstances? I have doubts that code would allow this transition from 3" to 4" to 3".
  2. srdenny

    srdenny Plumbing Contractor

    Messages:
    361
    Location:
    SF Peninsula
    Use 2 4x3 bushings and call it good.
  3. mccallum

    mccallum New Member

    Messages:
    7
    Should I try to use a 4x3 Fernco Eccentric Coupling to prevent the sewage from hitting the hub in a regualar reducer?
  4. gear junkie

    gear junkie Plumber

    Messages:
    67
    Location:
    Virginia Beach, IPC country
    No idea what code you're working with but with IPC, you can definently not do a 4x3 reducer. You were right to assume the size of your line to be 4" since it is code that a cleanout has to be the same size as the line except for 6" or bigger.

    The encentric reducer would be your safest bet but I wouldn't feel right about the job. These type of fittings are extremely common in asia and europe.
  5. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    I'm pretty sure they make a 3" back water valve

    I do not recommend 4x3 reducers downstream
  6. BAPlumber

    BAPlumber Plumber

    Messages:
    227
    Location:
    Vashon, Washington
    I'm not familiar with this particular backwater valve, but. With a 3" line on the inlet and outlet and a 4" valve I think you would eventually have solids sitting on the bottom of the backwater. This would probably interfere with the flapper's operation. Since these valves need to be accessible you could clean it out every month.
  7. mccallum

    mccallum New Member

    Messages:
    7
    To place a backwater valve on the main line, it needs to be normally open. City likes to use my vent lines. Unfortunately, Mainline does not make a 3" version of this valve as 3" is not as common in homes. I could place 3" std. backwater valves on each branch, but in my opinion, placing cleanout hatches all over the place does not make for an asthetically pleasant basement.

    My existing cast system appears to have a 5.5% slope to it...quite significant. If I were to use a 4% slope with Eccentric Couplings, I am pretty sure that i shouldn't have any issues with restrictions occuring. If you think about it practically, typical cast iron sewers over time form a flat bottom inside with rust and sediment that can be anywhere from 1/2" to 3/4" thick. Just by adding 4" ABS to a 4" CI line, you would be faced with a similar restriction.

    Ideally, I would like to do this:

    - Solvent ~6" of 4" ABS to the outlet side (streetside) of the Backwater valve.
    - Install a 4" to 3" Fernco Eccentric coupling on to this 4" ABS stub.
    - Install a 3" to 4" Bushing on the inlet side of the valve
    - Leave the Main Sewer Line connected to the cast wye as it is.
    - Remove existing 4" Cast Cleanout at the hub and cap it off
    - Cleaning of all the scale buildup on the cast pipe that will come in contact with the Fernco fitting.
    - Use a thin cutting blade on an angle grinder and cut the 3" Cast line about 6" away from the hub (inlet side)
    - Connect the fernco coupling attached to the backwater valve on to the freshly cut 3" cast iron
    - Use 3" ABS all the way back to the main stack and branch into it along the way as required.
    - This would result in a 3" increase to 4" and then back down to 3" with a sigificant slope (>4%).

    Your comments are welcome.
  8. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    If I read this right from the site , They do make a 3" http://www.backwater-valves.com/

  9. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    I don't know why that valve would win any award but if I was handing out awards for an innovated, well thought out design that made maint. easy I would give one to this unit!
    http://www.cleancheck.com/
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,831
    Location:
    Cave Creek, Arizona
    valve

    Go ahead and use the 4x3 bushings, concentric or eccentric, but do not put too much trust in the valve's operation or security because it WILL fail when material builds up in its cavity, and you can rationalize all you want to about "buildup in a 4" line just leaving a 3" pipe", or anything else, but it WILL STILL FAIL.
  11. gear junkie

    gear junkie Plumber

    Messages:
    67
    Location:
    Virginia Beach, IPC country
    That is an excellent point and it totally blew right past me.
  12. got_nailed

    got_nailed DIY Senior Member

    Messages:
    277
    I’m thinking kind of on the lines of HJ. Everything I replaced would be 4â€. I would keep the 4†for at least 4’ (if possible) after the backflow valve then go down to 3â€. Make sure you put in a clean out after the valve. I would consider running the new 4†out side of the house a few feet incase you have to replace the rest of the line out o the street in a few years.

    I would go back down to see the building inspector about this before I go to far into it about the 3 to 4†reducer.
  13. mccallum

    mccallum New Member

    Messages:
    7
    I agree...these are not fail proof...no backwater valve is. They are not an 'install and forget' type of thing. I will still need to monitor it from time to time (every 3-4 months or when the city is expecting a major rain storm). Perhaps flush it out with a garden hose via the flush access box that covers it.

    Back in 1999, the city replaced the main up to the house, so I suppose down the road if I have problems, I could excavate the outside foundation down to the sewer line and replace the cast wye and the 3" to 4" ferco and tie it directly into the newer 4" sewer main. I shouldnt have to go back into the basement floor using this method...more work but plausible. Then I would have all plastic lines and I would have 3" mains in the house tied into the 4" city main via a std coupling.

    Does anyone have a good method for removing the lead/oakum from the cast hubs? Can a person use heat to liquify the lead? Any other tricks of the trade??
  14. got_nailed

    got_nailed DIY Senior Member

    Messages:
    277
    Rent a chain cutter if you can get behind the hub on the cast iron.

    If not last time I had to do it I ended up getting out my welding leathers, a brazing helmet, and my brazing torch. You will need plenty of ventilation with some fans pulling the air out. I hope I never have to that again.

    Why not finish off the job now and connect up to the new pipe. If it’s right out side the foundation it should not be too bad once the hole is dug. I’m thinking on this that your running the 4” out side the house now so you will need a hole on the other side of the foundation and to enlarge the hole in the foundation to get the 4” PVC through. I might have read it wrong. You would need to call and see if you transfer over to the new pipe.

    [​IMG]
    Last edited by a moderator: Sep 25, 2009
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