SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Old relays might draw too much electricity for modern solid-state controllers. You really need a multimeter to measure the electrical resistance and current draw of the present relay.

The simplest solution is to buy an expensive controller, like a Hunter ICC, which can supply more current to operate the relay.

has the system worked before?i would replace it with what the manufacturer of the pump suggest.also on the transformer which plugs into the wall has a va rating which stands for volt/amps.thats the maximum amout of volt/amps the 24v side of the system can have.to determine the volt/amps of the system requires some skill with a meter.if the system has worked before,then all of a sudden not worked ,i would ohm out the relay coil and solinoid coils.
when the controller calls for a zone to be on does the pump turn on?if not is there 220v sitting at the pump?my suggestion is to call someone quilified to systematically troubleshoot the system,and not just change parts.i cann't see blindly changing parts out when it's not needed.you could end up spending more money.

Just because there have been efficiency improvements in valve solenoids, with the result that entry-level solid-state lawn sprinkler controllers now supply much less power than old motorized controllers did, does not mean that there has been any comparable efficiency improvements in power relays. You are pretty much stuck with having to overspend to supply the power needs of the old relay.