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Macerator Install Query

Discussion in 'Plumbing and Central Heating' started by dark_knightuk, 15 Apr 2021.

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  1. dark_knightuk

    dark_knightuk

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    Hey Everyone,

    So I have been reading these forums for a while as I am renovating a house.

    We are putting in an ensuite, and because the waste pipe is at the back of the house and the ensuite is at the front of the house, we have decided to get a macerator.

    I've done a bunch of reading but I do have some questions, for people who have them and/or installed them

    I have 2 options on how to run the waste pipe:

    Run it 1 meter straight, then verticle (straight up) 3 meters and then straight into the large waste pipe in the loft that is used by the bathroom up there. No joists or anything, the actual hot and cold feed is being fed off from the loft as it was the easiest run.

    Run it 1 meter straight, drop down, run through joists in the bedroom and through the hallway joists, into the room at the back where the hallway toilet soil stack goes and join in there under the floor?

    I mean they say **** doesn't flow uphill, so as much as the first option would be the easiest my concern is blockages as it's going to be pumping straight up, but all the macerators say they can do 5m verticle no problem?

    All joints will be 45 degrees as well, to reduce the chance of blockages.

    The next question is only the pressurised waste pipe from the macerator needs to be solvent weld, the sink and shower coming into them do not need to be solvent weld as its just normal gravity and no pressure?

    Also the connection to the soil stack that can just be a compress boss fitting as that's where the pressure dissipates into the big soil stack?

    Cheers!
     
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  3. just pumps

    just pumps

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    Option 1 in solvent weld however chose the muncher with care as not all claim to reach 5m. Download and read installation instructions before buying the pump to ensure you can install it to the MI`s.
    Pushfit from basin and shower will be fine.
     
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  4. Hugh Jaleak

    Hugh Jaleak

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    What size discharge pipework were you planning to use? Notching joists to take 32/40mm pipework will seriously weaken the structural strength of the timber and is not recommended, so unless you can run between joists, the latter option in your post is probably not feasible.
     
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  5. bernardgreen

    bernardgreen

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    If your discharge pipe goes upwards then if ( when ) you need to dismantle the jammed macerator to remove wet wipes there could be a problem.

    You may need to empty the liquid out of the discharge pipe before dismantling the macerator/pump assembly.
     
  6. just pumps

    just pumps

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    Precisely why I didn't consider it but didn't want to write an essay.
     
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  7. just pumps

    just pumps

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    You are forgetting the non-return valve :)
     
  8. Hugh Jaleak

    Hugh Jaleak

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    Wasn't sure if the OP was aware, wasn't so long ago we were advising a Poster to get a Structural survey on their floor after a Bathroom 'Fitter' had hacked half the joists out to accommodate the pipework!
     
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  9. bernardgreen

    bernardgreen

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    I have not forgotten the non-return valve, I just do not trust them when they are passing macerated poo.
     
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  11. just pumps

    just pumps

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    Yep seen far too many butchered joists. The other problem when going under the floor is that you cant expect the pump to cope if the pipe pops up above the floor at the end.
     
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  12. just pumps

    just pumps

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    In that case the pump would run in fits and starts.
     
  13. bernardgreen

    bernardgreen

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    The timing of the fits would depend on the ratio of volumes of poo in the pipe and the sump.
     
  14. just pumps

    just pumps

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    Well thats stating the obvious. :) I am really thinking that you have never worked on this type of macerator.
     
  15. bernardgreen

    bernardgreen

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    We had a whole house macerator pump for the house we built. But that was a positive displacement pump as it lifted from the sump to the macerator.

    I did once strip and un-block a "behind the pan" macerator. Needed buckets to collect the dribble coming back to the unit.
     
  16. just pumps

    just pumps

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    I rest my case M`lud. :)
     
  17. dark_knightuk

    dark_knightuk

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    all valid points, the joists are massive cos it's a Victorian house. If I am going straight up I can go with a bigger size.
    Under the floor, there is a void so I can skip a good bunch of joists, but it would be down, straight, up, straight and then through a couple of joists in the hallway and then one joist in the other room into the toilet waste stack that leads outside.

    The general consensus is to go upwards, which is fair.

    A lot of the macerators have discharge pipes that come out of the top anyway, so it would be a bit pointless going up 0.5 meters and then turning it.

    As it stands the macerator is mainly going to be for the basin and the shower with the toilet for occasional use.

    I was reading the install guide for the Stuart Turner wc3 and it said that the shower should not have a trap?

    It also seems the shower pipe coming into the macerator needs an NRV as well which makes sense.
     
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