Stephen wrote:
Hello,

My downstairs radiator pipes go into the concrete floor and run
along three of the four walls in the room. This means that they must
be running back and forth the length and width of the house. I am
concerned that these unlagged pipes must be losing a lot of heat into
the concrete floor.

Presuming that the pipework is copper:

I would be more worried about leaks in the pipework due the chemical
reaction between the concrete and copper - than heat loss!

Since we are decorating, I wondered about re-doing the plumbing at the
same time. The only way I could see was to drop pipes from upstairs.
However this would mean that each drop would require its own drain and
I worried that lagged pipes would be too thick to chase into a wall.

You don't lag the 'dropped' pipework (ugly) or 'bury' it in the walls (you
are just storing trouble)!

I read some old posts (2006) that were still on the newsserver in
which someone was recommended to bury his pipes in a concrete floor
after lagging them. Is this the best approach?

If you *MUST* bury copper pipes in concrete, then use the plastic coated
pipe and ensure that any joints are also protected by taping them.

Would lagged pipes loose more heat when surrounded by concrete
compared to air? Is it best to keep them above the floor?

Always best to keep things above a concrete floor - as for heat loss, heat
rises into the room.

What other options are there? Hid the pipes behind the skirting board,
or aren't I allowed to do that in case someone puts a nail through?

Unless you are using microbore, then you will have many problems in hiding
pipes behind the skirting - what about crossing door openings for starters.
You will also have problems hiding microbore as well!

On any exposed pipe-drops, simply box them in - or buy pipework trunking
(plastic)

Unbeliever.