"Anthony Fremont" wrote in message news:gHkRd.13557

The combined heat dissipation is about 47W. Could ventilation be an
issue, especially in an enclosed box on a hot day?

How do you come up with that? 24V across 24.5 Ohms is only ~1A,
therefore 25W. I still say the problem is using DC where AC is
called
for, resulting in cooking the coil. Hunter valves use AC.

Oops, sorry about that, I just realized you mean for two coils. :-) I
haven't had my coffee yet.