Two 110mm into one 160mm

[MortarThePoint]

When they put in the drive and the rainwater pipe across it, the ground workers asked if I wanted a 110mm pipe or 160mm pipe. It seemed like a small additional cost to go with 160mm pipe. I now need to connect two 110mm pipes to it. They are coming in opposite directions each at 90degrees to the 160mm pipe forming a T shape. Rodding access on each 110mm pipe will be about 3m away via 4D960 chambers. Some options to connect are shown below.

 

It's right at the front of the house, outside a bay window, so I'm keen to have something discrete.

 

Using the equal tee (6D193) feels like a bodge, but a blockage here feels unlikely given the step up on pipe diameter. The two 6D198 feels less like a bodge as could provide rodding access, but doesn't have level inverts. The rodding access could go via a 110/160 reducer to decrease the size of the rodding eye.

 

Floplast 6D900: mixed 160/110 chamber plus 2no 45 bends

 

6UR928: 160mm chamber plus 2no 45 bends or the naughty option on right where the central channel isn't used

 

6D193: 160mm 90 tee plus 2no 110/160 adapters. Feels like a bodge as no access but could add a second to the outlet with the branch facing up to allow access. Level inverts benefit

 

4D960: 110mm chamber plus short pipe, 2no 67.5 bends and 110/160 adapter  Level inverts benefit

SP230: A wildcard option is to use a soil pipe double branch and allow rodding access. Would need a short length of pipe and a 110/160 adapter into the 160mm pipe. I have one of these spare. Feels like a shame to have the combined flow in a 110mm section of pipe even though it would only be about 200mm worth. Level inverts benefit

 

Polypipe 160/110 branch: allows rodding access via a 160mm 45 bend technically compliant down to 600mm depth I think Would prefer a ring seal version

 

 

 

6D198 or 6D218: two of these have the benefit of having 110mm side ports. 6D198 would need 2no 45 bends but have a smoother flow.

 

 

[Mr Punter]

I assume this is all for below ground?  Is this foul, combined or surface water?

[MortarThePoint]

2 hours ago, Mr Punter said:

I assume this is all for below ground?  Is this foul, combined or surface water?

 

It's just surface water from gutters and all below ground

[MortarThePoint]

Looking closer on site, the 160mm pipe is closer to the corner of the house than I thought, so I think I can use the setup below that looks pretty reasonable. May be better to use a 160x160x160 junction to keep all inverts level. I don't think I have to have the optional rodding access as the bends on that branch will be 30 degrees or less meaning I could rod the branch and the 160mm main section through the top Inspection Chamber (I.C.). If space allowed, it would probably be nice to have it after the lower bend and focused on rodding just the 160mm main section.

 

Still interested how people would tackle the original challenge though, but that's relegated to curiosity now rather than necessity.