I'm having a oven built and need some info about vac line set up as the builder has shown concern about heat transfer and gauge damage ect with the set up i planned to use. As the inside of the oven is made from galvanised steel and the bulkhead fitting (and some other bits ect) are steel will mounting them direct through the outside to inside give heat transfer problems ??. The builder thinks the whole vac set up will get to hot. Will the use of a Sython as in the pics be of any use ??.

shouldn't be a problem, i have a similar set up and the heat transfered is no problem, the outside parts stay pretty cool.
what insulation are you using?

I'm told it has 100mm Rockwool compressed a little to give it snug fit. The vac fittings go direct straight through both walls (and rockwool) and the barbs are exposed. I think the fittings ect will be fine its the gauges i think will be the problem as they have 60C Max working temp. The gauges are total RUBBISH!, i bought THREE and ONE works and the same with the little ball valves, Two are really tight to turn (to tight for use on the bag) and One works fine so i've got rid of them all now, I've put one Glycerine gauge on the pump and one on a fitting for bag tests and blanked the gauge side of the fittings off for now so i think it should be fine.

I'm only using 30mm rock wool so 100mm is more than enough, if you're only taking the temperature up to about 80-100c then I wouldn't expect the heat transfered to be much? Best way is to just try it and monitor. If it becomes hot to touch redesign it, but I don't  think you'll have a problem.

Tried them at 65C for an hour and they did not heat up what so ever. 85C for an hour and only the part nearest the wall feels ever so slightly warm if that. 120C for an hour and they get hot to the touch but you can handle them no probs so all should be fine even with gauges.