Recessed manhole cover - Tips on breaking out old manhole

[diy'er]

Hello,

I'm taking on my first patio - and need to replace the ancient manhole cover with a shiny new recessed one.

The exisiting opening measures 450mm x 600mm, and has a rusty old cast iron collar which the cover sits on. The collar is set straight ontop of the brick chamber.

The height of the exisiting cover is near enough the level I want the finished patio to be at, so I'm thinking I'll need to remove the old iron collar and do a bit of breaking out to fit the new wider plastic frame which the recessed cover sits on.

Can anyone advise on a way round this?
Is there a different type of frame for the recessed cover perhaps?

Thanks

[lutonlagerlout]

your old cover is probably around 35 mm thick
the standard 450 by 600 recessed is 90 mm thick
this means you need to remove 1 course of bricks and rebed your recessed cover
assuming the levels are the same
LLL

[diy'er]

Thanks LLL - makes sense.

[local patios and driveway]

try and fill the manhole cover with say an old duvet or terram or an empty bulk bag, this will save you having to scoop out any debris from the bottom of the chamber when you are finished, a quater brick down the drain can be a complete arse ache