I’m looking at this product to replace my 20+ year old Hunter controller. The enclosure for this controller has a transformer that is connected to my house AC power and is labeled to output 25VAC. I measured it and it’s outputting 28.5VAC. The max power supply voltage of the open sprinkler controller is specified to be 28VAC. Would it be ok to reuse the transformer I have? It would be convenient to do so. I measured the voltage when none of the sprinklers were running so maybe the was part of the reason it was so high.
28.5VAC is ok. Technically the controller can withstand 30VAC at least. Also, AC transformers are not regulated, what you measured is the ‘no-load’ voltage. As soon as you connect it to a circuit or it starts to supply current, the voltage will drop rapidly towards its rated voltage (25VAC in your case).
Thanks!
Yeah, this is what I figured. I’m a retired EE. I did ASIC and system design so my experience with power systems is limited, although I’m not entirely ignorant of them :). I thought that with sprinkler valve load(s) and the long wires to the valves, a higher no-load voltage would be normal and probably necessary.