On Sep 12, 11:27*am, The Natural Philosopher wrote:
wrote:
On Sep 9, 10:35 pm, 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.

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.

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?

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

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?

Thanks,
Stephen.

Corrosion is only a problem when the concrete contains flyash.

Total ********. All pip[es corode when there is a mixture of air and
water,

but not to a problematic extent

and any acid makes things worse.

concrete of course is alkaline


Fortunately screed sis fairly
alkaline, so tats on there, but there is still a possibility of dampness
due to absorbed moisture.

yes, which doesnt lead to corrosion in plain mixes without flyash.
We've been thru all this before.


Pipes losing heat: radiators are designed to lose heat from the pipe
to the air, and pipe heat does much the same, so is not normally a
problem.

More ********.

Really? I didnt know there was some fundamental difference between the
rad giving off heat to the room and the tails doing the same

especially if the pipe is buried in uninsulated floor
covered in carpeting, which provides the main thermal barrier to the
cold ground.

in this case the heat output from pipe to room will be very much
smaller, and time delayed a little. To regard it as 'lost' heat is
incorrect.


All pipes buried in concrete should ideally be wrapped in some form of
mechanical and chemical and thermal barrier. Typically split foam is
good - before being buried in concrete.

ideally yes, but IRL lots arent

Otherwise thermal differential
expansion may rip the pipes apart,

true for very long runs, but not for your average house.

and heat loss will be quite bad.

no


The corrosion aspect is probably the lesser problem, but its still not
good to leave pipes in contact with anything whose chemical composition
and humidity content is unknown and variable.

concrete is no mystery. There are millions of houses with copper pipes
in contact with concrete on the exterior, where they get wet every
week. Safety inspectors are entirely unconcerned.


NT