On Tue, 10 Mar 2020 18:41:48 +0000, alan_m wrote:

An IR camera works - different thermal characteristics of the
morter v
the blocks.

Not sure a IR camera is going to tell you much about the integrity of
the wall.

Thanks very much for that.Â* Am I right in thinking that it would
be
necessary to remove any obstacles such as shelves, empty bookcases
and
the like away from the wall to get a meaningful result?

Yes otherwise you'll only "see" them.

And experiment with the heating of the room and waiting before
examining. You will also need a camera where the thermal window can be
adjusted (you may only want to look at temperatures, say, between 15 and
30C and have these displayed as full scale so that you can see minor
temperature differences.

Just been able to have a play with a Fluke PTi120 120 x 90 pixel IR
camera. No great surprises apart from one internal wall that is
colder than expected (I suspect it's blockwork spaced from the real
stone wall with gale blowing through the uninsulated cavity).

Great tool for balancing radiators, you can "see" the plume of hot
water entering and rising straight up and judge the rate of flow and
adjust the lock shield valve accordingly. Far easier, quicker than an
IR thermometer and bits of black sticky tape. Especialy on this
system that is very sensitive to adjustments,

The free Fluke software enables you to adjust the scale of saved
snapshots within the stored image range of -20 C to 155 C and
resolution of 0.1 C. So you can have "hot" (white) at say 25 C and
"cold" (black) at 5 C. Snapshots also have a visible (assuming there
is enough visible light!) image stored along with the IR one.

The PTi120 is not exactly cheap though at £700 - £800 inc VAT.

--
Cheers
Dave.