consealing central heating pipework within a duct in a concreate floor

[rgreen]

Am installing a new central heating system (building never had heating before) in my 1960/70's bungalow with a concrete floor and wish to minimize the visible pipe runs to the radiators.

The majority of the pipework is in the loft with drops for each of the rooms in 15mm copper, where possible this is being concealed by boxing but would still end up with pipes clipped to the wall above the skirting board to feed some of them and it is these horizontal runs I wish to conceal. The walls in question where the radiators are hung are mainly external cavity walls and don't think the block thickness of the inner skin is deep enough to accept chasing out, sleeving and making good.

Therefore I am considering dropping the pipes to below floor level by tracking the screed adjacent to the walls on which the radiators are mounted for approximately 2-2.5m in each of the rooms and simply coming up through the floor covering to feed each radiator. The vertical drops can either be chased into the walls or more likely encased in some minimal boxing and in either case I propose to stop the plasterboard short of the floor and float the skirting board over the top where it would be easily removable to allow access to the pipes. The length of buried pipe would allow for no hidden joints (connection between vertical and horizontal sections would be behind skirting) and rather than back fill the trench I propose to lay a plywood lid over the pipes before laying underlay and a laminate floor encase future repairs or alterations are required (regs?).

To prevent excessive moment and insulate the pipes I intend on clipping the pipes to the floor and coating them in 13mm foam pipe insulation. My question is then, is this acceptable?

 

[stevetheplumber]

yes usually have timber running lengthways along the edges of the trench rebated so the ply lays flush

 

[Chalked]

You have a lot of work there, but it's a good way of concealing.
I would have done the drops in 10mm plastic coated copper chased into the walls on the vertical, then run like you say behind the skirting. Then a small chase in the floor to come out for the radiator ( couple of inches) then increase the pipe back up to 15 mm for the pe on show up to the radiator.