Flexible bath waste?

[StephenStephen]

I have an acrylic bath that I really don't want to drill a hole in, so I'm thinking to attach a flexible waste, run that though and under the floorboard, back up the other side, and join into the T connection.
I'd welcome any thoughts, particularly:

-Can I use the flexible loop under the floorboard as the trap?
-Where's a good source of flexible pipe and connectors/adapters?
-What's the minimum diameter bath waste that won't cause problems?

Many thanks for your thoughts, Stephen

 

[oldbutnotdead]

It'll give you a slow draining bath at best and continuous blockage problems at worst. Don't do it
If there's no room under the bath for the waste with adequate fall then lift the bath by 50mm or 75mm or whatever you need to make it work

 

[ktuludays]

Recipe for disaster. Do it properly first time. Can you not adjust the waste pipe that goes outside. I assume it's above floor level currently.

 

[StephenStephen]

Unfortunately I can't get a waste pipe run to the soil pipe under the floor without going through a number of floor joists, and it's also too tight in the corner of the room to get a new boss into it.
(The soil pipe is boxed in internally, and runs about 15 metres under the floor in the rooms below to reach the drain).

The particular difficulty is the tightness of the space between the back of the bath and the T joint, but maybe I'll just have to resign myself to carving up the floorboards!

 

[Madrab]

A bath trap is serviceable, it's specifically designed to be removed and cleaned and provides a specific depth of water seal to ensure the flow is adequate but still seals the system from the sewer.

It is more important to fit proper fittings and follow standards to minimise any problems in the future. Sometime floorboards need to be moved or baths to be set higher to get everything to fit, that just means the design/setting out needs to suit the situation.

 

[StephenStephen]

Unfortunately my plan to raise the bath on a plinth was vetoed, and the wall mounted tap is now fixed, plumbed and tiled over, so I can only raise it by a couple of centimetres.
What I'm wondering now is whether it's better to put in a trap, connect that to the McAlpine flexible connector https://www.screwfix.com/p/mcalpine-flexcon2-flexible-connector-white-40-x-460mm/43713#BVQAWidgetID
and back up to the waste T joint, or have fewer connections by connecting the flexible pipe direct to the bath waste? (effectively using the flexible connector as the trap).
It's looking like a choice between a double trap or a long (approx 30cm) trap - which is the least problematic, do you think?

Unfortunately I don't seem to have a way to raise the bath sufficiently for the bottom of the skirt to be above the waste T joint.

 

[StephenStephen]

The other question I'm wondering about is:
-The fitting instructions direct to silicon around the bottom edge of the skirt - is this just to keep it in place? If so, could I instead rout out recesses for the feet in the ply sheet I'm going to sit it on?

 

[foxhole]

Maybe a pic would help , you haven’t explained why you can’t use conventional bath trap?

 

[oldbutnotdead]

Well whoever vetoed lifting the bath up has caused a triumph of design over function (it looks pretty but doesn't work).

Pics will help -there may be ways round.

 

[StephenStephen]

Photos here

 

[lostinthelight]

Any reason you can't sink the low part of the trap through the boards? I would have that T solvented if the only way to deal with a leak was to remove the bath

 

[Madrab]

Water will not run well uphills, especially bath water.

Time to look at using a waterless (HEPVO) inline trap methinks, with as short a flexi as possible running into it. given it's a floor level freestanding bath, it should have come with a flexi andway as you have to hold the bath up, connect the waste to the trap with a flexi then put it back down again. I presume you'll be cutting a section out of the side of the bath anyway to get to connect to the waste run?

 

[oldbutnotdead]

That waste run does look a bit flat/uphill. Is that grey block on the bath a trap or just a coupling?

If the main waste run does actually have a fall to it then looks as if a cutout in the floor to accommodate the trap would work.

There's going to be precious little fall from trap to black waste run....

 

[Madrab]

I do appreciate that it's a DIY job but you do need to be careful, if you don't get it right to start with it will be a real mare to correct afterwards. Even down to taking out the floorboard around the edge to give you that extra 20 odd mill of fall.

I presume that is all to be boxed in?

 

[StephenStephen]

Thanks all, much appreciated.

-The grey fitting on the bottom of the bath is the waste outlet coupling - either horizontal or vertical with a blank for the other.
- I can run the trap and waste under the floor and bring it up again to connect to the T
-I can get to the T behind the bath, and realise that with a flexi waste I can lift the bath to connect/disconnect

-The existing waste run has enough fall (I put the shower on a plinth to make sure!)
- I'm specifically avoiding cutting a hole in the acrylic

- photos to follow