I posted this a while ago (can’t find old thread) but a “new” issue has arisen.

I would like to have a DW 3m away from the waste, but with the outlet running under the floor for 2m or so. It was thought that the motor could cope with this as the motor is not doing any extra work (given the water is pumped to the high point and just flows down from there).

I’ve just called building control who are not convinced (without a note from manufacturers confirming this) that the motor will cope. He seemed to imply that the outlets normally run in a nice even gradient from the DW to the waste. I’ve previously run them in “U” shape as described above, I doubt I’ll ever get a letter from Hotpoint (or whoever) confirming this will be OK (I’m not a huge customer of theirs) and wonder if I’ll ever convince Mr Building Control about O-level physics.

Any thoughts?

Ours is 2.4m from the waste (basic Bosch). The waste plumbs into the trap under the sink. I had to use some basic plastic pushfit plumbing pieces to extend the pipe, but in the 5 years its been there, there has never been a problem. I didn’t even consider building regs when I plumbed it in 😯 .

I’d only consider trying to keep mr Building Control happy if I lived in a tennament with a risk of flooding the downstairs – even then, I’d be surprised if it wasn’t simply an insurance issue. COuld you not just get the rest certified and then put the DW in at the end?

Another option would be to put an inline shower pump in. Might be a bit noisy though.

Cheers. Seems the crux is whether the waste run can go down to floor level then back up or has to run at a constant gradient.

Initial googles suggest former is fine 😕

Damn Building Control

*bump* for anyone that can contribute *& apologies for being on incorrect forum…

Just called manufacturer – they won’t recommend using a hose linger than 1.5m “because it won’t pump the water out”. Predicably I failed to convince the guy of basic physics & that the demand on the pump is the same given it’s pumping the water up the same height…oh well

Mine ran through 3m of extra hose for two years without issue. It was a rented house so I couldn’t easily change the plumbing and there was only a space for washing machine.

I would have no issues in just doing it if I weren’t creating a new kitchen room and as such Building Control will wnt to approve everything 🙁

Predicably I failed to convince the guy of basic physics & that the demand on the pump is the same given it’s pumping the water up the same height…oh well

I thought about this, while I am no expert, I don’t think your right on this. The hydrostatic pressure will increase with increased volume. The volume in the pipe will increase as you lengthen it to run down and then up. But, ours works fine and has done for 5 years.

This new kitchen thing is very middle class don’tcha know?

I’ve connected our dishwasher to the outside waste via 2 x 3m flexible hoses and it works a treat (I ran he hoses under the kitchen units)

Middle class? I’ve never denied it. Goddam it my Rolex is broken!!!

I thought about this, while I am no expert, I don’t think your right on this. The hydrostatic pressure will increase with increased volume.

I think I’m right…the pressure relates to the height, which remains the same, whether the pipe runs diagonally to the high point or along the ground, then straight up.

cynic-al – Member

Middle class? I’ve never denied it. Goddam it my Rolex is broken!!!

I thought about this, while I am no expert, I don’t think your right on this. The hydrostatic pressure will increase with increased volume.

I think I’m right…the pressure relates to the height, which remains the same, whether the pipe runs diagonally to the high point or along the ground, then straight up.

Well if you insist on buying cheap watches! 😉