Hi rmo87,

Was your water removed from your lines during the winter and you are free of freezing temps? I would recommend removing the heads, sparingly flush each zone and replace the heads before using your system. Others may have a more detailed regimen. Aloha.

Yes, the pipes were blown out last fall. Not quite in the clear from freezing temps, but will be come April.

I think my biggest concern is what valves to open (and how far) around the backflow preventer. It's a Febco, if it makes a difference.

Hi rmo87,

I have never lived in freezing winter climate. So this advice is more my common sense with working with newly constructed systems. After you believe any prolonged freezing is past. Intermittent cold at night will be thawed during the day. Remove all the sprinkler heads. Open the auto valve manually one zone at a time and then open the main shut off and then close off the main shut off flushing each zone until you see clean water coming out. It shouldn't take that long. Do this for each zone. Now you can be sure anything that has crawled into you pipes during the winter has been removed. When your done, your pipes are filled with water, you auto valves for each zone are shut and the main shut off is on. Your system now can be operated with your controller. Check that your controller operates all zones and set time and duration less than you do in the summer heat. That should do it. May your yard grow well this season, especially the tomatoes. JMHO Aloha.