Hi, first time Rachio user. Just bought the Rachio 3, 16 zone.
Our old Rainbird has a transformer that is 25 feet away and was spliced in. We plan to do the same with the Rachio because there isn’t an outlet close by.
The rainbird transformer outputs 26.5 VAC 650 mA.
Can I use the existing transformer or do I need to splice in the Rachio transformer?
According to Rachio 3 Compatibility and Tech Specs your transformer is slightly underpowered. Would probably be better to splice in the Rachio transformer - you can definitely try the old one to test the run length and setting up the controller - but depending on your valves and whether you use a master or not, you may find that 650mA may not be enough, or maybe who knows 
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