It's this model: http://www.subzero-wolf.com/wolf/ovens/steam-oven/24-inch-e-series-transitional-convection-steam-oven

Never used a wolf steam convection oven....but I sure have cooked many many turkeys.
If I were doing it I would allow 3 hours at 375 in steam mode for a 15 pound turkey.
I would check it with an instant read thermometer in the thickest part of the thigh, and when it reached about 135, I would turn off the steam feature and go with just convection, and check it again in 30 to 45 minutes in the thick part of the breast. When the temperature in the breast reaches 160, remove from the oven, and let it rest for 30 minutes.
I would allow 3 hours....but realize it will likely be done well before that>
THEN....write down what you did....so you will know for next time.

Found this on youtube:

https://www.youtube.com/watch?v=Bo9sc0DoV3U

I don't think you should go with "recommended cooking time". There are too many variables. How wet is your turkey? how cold is your turkey? How fast is the convection fan? How many fans? How much fat is in your turkey's skin? Do you roast up or roast down?

All recommended cooking time tend to overcook for safety reasons.

Just get a thermometer ($10.00 to $100.00) and cook the turkey to exact done-ness. Then use the convection feature without steam to crisp up the skin.

dcarch

BTW, "pressure" steam oven is a sales gimmick.

Thank you all for the feedback!! I will cross post in Appliances - I half wondered if that's what I should have done :)

I've only done parts in my Gaggenau combi-steam. They came out fantastic, but I can't remember doing anything special. I think I just used the same temperature as for chicken (360° F., 20 min. per pound, 60% steam). Whether I'm doing a butterflied whole chicken or a quarter of a turkey, my theory is suntan lotion, seasoning, steam. That is, some kind of sauce, dressing or oil with a little sugar in it for the crisp skin, S&P and/or herbs and spices, and if not the steam oven, then some wine or broth in the pan to steam with. With the combi-steam, just put it in the solid pan and put it in. It's helps if it comes to room temperature first, however, so there isn't as much condensation. While I was offhand about the flavors, above, I do match them together!