Air conditioning systems (Boeing)
 

On the 787 each of the four cabin air supply lines has an AH/SC valve. Any one able to tell me what does AH/SC stand for?
On the maintenance page it shows as 0.98 when the compressor is deactivated (I assume this means closed)...in flight it seems to normally show around 0.5.

There is also an AH/SC flow mass.

Thanks in advance

According to the DDG, it could refer to Add Heat/Smoke Clearance.

There are entries for Add Heat valves and Smoke Clearance valves but I can’t find any combination of the two.

Maybe it’s one valve with two different functions?

Think this is in the wrong forum.

Have tried engineers and technicians and no one there knew. Before I started flying I was a Flight Test Engineer on the 125 / Hawker and I knew every component of that aircraft's pressurisation system....was hoping to find a Boeing FTE / Systems Engineer with more knowledge than the guys who maintain them?

Having worked on Lazy B products, I would agree with eckhard with one possible alteration - Additional Heat/Smoke Clearance. On similar systems, the same additional flow is used for both functions i.e. providing heat in, say, Cold Weather operations and driving smoke out of the Avionics Bay and/or Baggage Bays.
To put a Flight Test spin on the query, on CSeries the Flight Test of the Smoke Clearance procedure was considered too hazardous to be carried out even with artificial smoke. A combination of flow verification in flight and simulation on ground with no actual Flight Control or Avionics units installed was used. The risk of contamination to units and possible loss of function was just too great.